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Toledo – the busy, half-abandoned station
Just about twelve years ago I hopped on a plane bound for Brazil to spend a year as a foreign exchange student. I lived in smaller city named Toledo – in the south-west of the country, not too far from the borders of Argentina and Paraguay, and the famed Iguaçu Falls. It was a nice place – think quaint Appalachian mining town with a little of White Plains mixed in – but hardly a city that would get significant numbers of tourists. While I lived there I had a host brother that was some years older than me, and he recounted his first visit to the United States. As is customary in many South American cultures, the 15th birthday is a big deal, and a lot of upper middle class folks reward their children with a big trip. Most tend to choose interesting places like Disney World, or New York. My host brother had a different idea – he wanted to go to another city called Toledo.
Toledo, Ohio is likewise a city I can't imagine gets immense amounts of tourists (though apparently there are some modern rail hobos), but it certainly is a nice enough place. I'm not too sure what my host brother actually did here when he was fifteen – perhaps took a trip to the zoo – but it really doesn't have the allure of say, Disney. Once upon a time, however, Toledo did get quite a few visitors, and many of them by train. The state of Toledo's rail station today is really a visual reminder of not just the fall of passenger rail travel, but of the steady 40+ year decline of Toledo's population.
In embracing modernity, the above 1800s Toledo station was replaced with the current brick and glass box. People hated this building so much that they cheered when it caught fire and burnt down. I think they're crazy.
The replacement – Central Union Terminal postcard, and tickets from Toledo from 1950.
Central Union Terminal, opened in 1950, is claimed by Wikipedia editors to be the last "great" railroad station built by the New York Central. A modern structure made of brick and glass, it certainly doesn't have the same charm as many of the Central's older stations. When opened, the station had about 55 daily departures – compare that with today's paltry 4 departures. The island platforms that connected to the main station, once filled with people, are relatively dormant today. The passageways leading from these platforms to the station proper have long been shuttered, and are fastened shut with rusted chain for good measure. Some lonely platform canopies protect ripped out platforms, and others just stand over rusted rails. Toledo may be Ohio's busiest railroad station, but from some angles it looks quite abandoned.
The old passageway to the platforms can now hold quite a few chairs… note the doors on either side that led to the island train platforms below. More photos of the event space in the station can be found here.
Martin Luther King, Jr. Plaza, as it is called now, is served by Amtrak's Lake Shore Limited, and Capitol Limited. With trains arriving at the station during hours many are asleep (11:39 PM, 2:50 AM, 5:22 AM and 6:15 AM), the station functions on opposite schedule – the waiting room is open most night hours, and closed during the day. Though the waiting rooms for the trains were once in a more attractive spot on the third floor, during renovations the waiting area was relegated to the bottom floor. The former waiting area on the third floor is now an event space able to hold 650 people… so in reality, this station is pretty cool – if you're looking to host a wedding reception.
If half-abandoned rail platforms aren't your thing, there's at least a bunch of freight traffic through Toledo that you can check out. I even caught my first Norfolk Southern heritage unit… awww. In case you're curious, the folks watching the train in the first photo were the aforementioned "hobos."
Tags: amtrakfreightlake shore limitednew york centralnorfolk southernohioPhotosplatformrailroadtrain stationwaiting room
Next story A summer of derailments, and a revisit to Yonkers station
Previous story A visit to the former Cleveland Union Terminal
Toledo has been known for 2 things,as the home of Triple A baseball team,
the "Mudhens"(remember Klinger from MASH) and the home of Willys Jeep factory,
now part of the Chrysler brand.
CG Todaro says:
Great story and photos!
Appreciate the post. I planned to revisit this station to take photos as well.
Rail hobos? WTF.
Maybe that's what I should call all the freaks that lurk around Waterbury and Meriden? ;)
That "Amtrak: Toledo, Ohio" sign reminds us of how much "character" was lost by the near-ubiquitous adoption of Helvetica.
http://www.youtube.com/watch?v=7JkpYgjbYRg
Steve Dunham says:
I was in Toledo station last year. My wife and I traveled by train to Ohio for a son's graduation from Bowling Green State U. The station is luxurious compared to where we get on and off trains: Fredericksburg, Virginia, which has no waiting room but several "No Trespassing" signs.
Nathanael says:
The problems with 1950s-era architecture:
– it's new enough that it's full of plastic, mass-produced, and lacks all the hand-carved etc. stuff from older architecture;
– but it's old enough that it isn't wheelchair accessible (at all!), is grossly energy-inefficient, and is often made from inferior materials which wore out much quicker than the people of the 1950s thought they would.
In short, all of the downsides of old & new buildings, none of the upsides of either.
John Meola says:
I went to college near Toledo and used to take the train there. To get from the train to the station you walked through one of the doors and went up stairs. From there you walked through a concourse to the main station. Outside was a turnaround where you would meet your ride or grab a taxi. They've significantly downsized it since Amtrak took out the Toledo-Detroit service years ago. Now it's only served by the Lake Shore Limited and the Capitol Limited, and those come at ungodly hours of the night.
STrRedWolf says:
Hmmm…. there seems to be some room (as in track space) to create a hotel there. Sleeper cars can be put in the empty tracks, quite possibly the vintage sleepers (making it a tourist destination).
However, there will need to be some reconstruction needed — rails need to be laid back down, a dedicated hotel-track crossover (depending on how all the trains interact at the station, it could take four tracks, leaving five for the hotel), and maybe an elevated platform for handicapped patrons to get in their cars.
Still, there's opportunity.
guy ludwig says:
from 1975 to 1980, central union terminal was my "home" station. in those days i traveled
regularly (maybe six times a year) between ohio and manhattan and once or twice a year
to chicago. during most of that time, toledo's only train was the lake shore limited – but
also during that time, the old, original waiting room and concourse was used. one
came over the covered bridge, bought a ticket at the original counter and entered either
stairs or a ramp to get down to the tracks. i loved it!! things i remember were large,
functional bathrooms, "modern" elevators (circa 1950) to get down to the tracks if needed,
and a very good heating system — steam — which seemed to work perfectly. i also recall
that, though the building was not air conditioned, the station personel – or the penn central
and later conrail employees who worked there – could rig up the windows so that hot air
passed out toward the roof. it was always comfortable in that building. but what i liked
most about it was that it hadn't really been touched … it was much as it was the day it
opened — which was only 25 years before i first went there. you got a real sense of place — and it was "kept up" pretty good: everything was freshly painted, all the lights
worked and the platforms were in reasonably good repair. of course, there were no
services in the station, other than ticketing and baggage – and pay telephones. the
building originally had a restaurant, a snack bar, a barber and a news stand. all these
were gone by 1975, but their footprints were still easily recognizable. and lo and behold,
a lady eventually did reopen the snack bar! the station also had very good ticket agents;
they were fast and friendly, knew what they were doing and handled the ever increasing
patronage very, very well. fond memories, indeed!
David Patch says:
Just discovered this entry, Emily, while looking for an estimate of how many trains used C.U.T. when it opened. They're planning an event next week to mark its 65th anniversary, and Greyhound today confirmed that it plans to move its Toledo bus station here by next spring. So while the train count remains just four per day, at least the facility will at last have intercity buses, too, and will once again become the city's busiest intercity terminal of any kind (train + bus > Toledo flights).
When in use, BTW, the third-floor concourse had both stairs and ramps down to track level, but those ramps were too steep for rational wheelchair use, so yes, the building was definitely lacking in that regard. Surely one of the reasons that, when it was renovated, the Amtrak facility was relocated to the first floor, even though that effectively ended the ability for more than one train to be in the station at the same time. During the 19 years that have followed, that has rarely been a problem.
David Patch
Your pictures remind me of decaying platforms at Pennsylvania Station in Pittsburgh, where the Amtrak hovel was burrowed under the remaining tracks when the beautiful terminal was apparently carved up into corporate condominiums. Breaks my heart.


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Flow Measurement Research Does It Have A Future?
A numerical simulation of the flow field inside a 0.203 m ID pipe operating at a Reynolds number of 7,300,000 with natural gas has been performed. The pipeline geometry consists of two diameters of straight pipe upstream of two 90o elbows separated by one pipe diameter of straight pipe. The two elbows are mounted such that the planes of the elbows are at 90o to each other. Downstream of the elbows, fifty pipe diameters of straight pipe are present. The inlet condition to the pipeline segment is fully developed flow. The initial solution obtained was for smooth pipe walls. The two elbows out of plane generated a large vortex centered on the pipe centerline which causes the flow to swirl around the pipe centerline. Subsequent simulations incrementally increased the wall roughness. As the pipe wall roughness was increased, the flow became axisymmetric quicker, the axial velocity centerline velocity increased along with the axial velocity near the wall decreasing and the swirl decreased in magnitude.
The paper reports about velocity profiie measurement downstream of several pipe configurations according to OIML-recommendation OIML-R-32 and systematic investigation of the efficiency of well-established flow conditioners to figure out their most useful application. The report covers the experimental verflcation of OIML-R-32 by means of flow profde measurement downstream of the pipe configuration and flow conditioners, the evaluation of the efficiency of flow conditioners and the investigation of the development of the flow profdes. Up to now more than twelve flow conditioners have been evaluated.
We demonstrate a method for correcting the reading of flow meters exposed to notfully developed pipe flow. The method is demonstrated with the measurement of the two components of the wall shear stress along the circumference of the pipe wall slightly upstream of the meter. Making use of a physical model for characterizing the disturbances in the flow as caused by installations and a neural network approach allows to correct the reading of a meter (here: Venturi) without having knowledge of the specific type of installation.
A new type of non-invasive multiphase meter is presented which is based on a radiofrequency dielectric measurement principle using a slow-wave resonator. A major advantage of the metering system is that it requires neither flow modifiers nor field calibration. The data analysis is based upon a theoretical treatment of the metering system where the fluid constituents determine the dispersion and hence the measured resonance spectrum. The measurement concept is explained and the theory is verified by experimental results.
The effects of small amounts of entrained water on orifice metering of low pressure air flows (58 kPaa) has been examined for a 101 mm, 0.61 beta ratio (b) orifice plate at an orifice flow Reynolds number of 1.3x105 . Using orifice flow correlations developed for dry gas flow 1, a measurable meter shift (MS) in predicted flow rate from dry gas conditions was observed for water to air mass ratios (z) ranging from 0.22% to 5.9 %. All observed shifts were positive, with some reaching a maximum and then decreasing as z was increased to greater values. The shifts were not as expected based on previous studies reported in the literature. It was found that the MS could depend on the location of the orifice temperature measurement in some circumstances (i.e. upstream or downstream of the meter). The unexpected MS trends were due to evaporation of the water when the air entering the test section was unsaturated. This was evident form the different trends observed in measured flow temperatures upstream and downstream of the orifice plate. Such trends should be used as an indication that phase change is occurring. These results illustrate the importance of accounting for phase change between the liquid and gaseous states of gas/liquid mixtures to properly characterize metering errors that may occur with orifice meters.
The ability of a flow meter to respond predictably to the presence of liquid and gas is important to the natural gas industry and to users of steam. In both cases, the gas can become saturated and some liquids can condense in the line. The response of orifice flow meters to the presence of liquids is erratic and produces considerable uncertainty. Turbine flow meters can sustain severe damage when subjected to two phase flow. The slotted orifice flow meter (Morrison, et al.1) has been developed to address the problem of upstream flow conditioning. This device has been shown to be insensitive to the upstream velocity profile. To further evaluate the flow meter for use by the natural gas industry, the effects of adding liquid to a gas flow upon the meter performance has been investigated by subjecting a slotted orifice flowmeter with an equivalent ratio of 0.50 to a two phase flow consisting of air and water.
There is an increasing interest in using ultrasonic gas metering technology in gas production and transmission. However, there still remains some hesitation in applying the technology for fiscal and sales gas metering until wider experience has been obtained, and industry standards have been established. This interest is highlighted by the research groups of nine of the leading European gas companies joining together to undertake studies on a number of practical problems associated with multi-path ultrasonic meters. In this paper, the participants share some of the concerns they have experienced in the use of ultrasonic meters, and the results from this research work which addresses those concerns.
An ultrasonic multi-channel flowrate measuring system has a bright prospect, if the gas transportation pressure loss does not occur and the calibration inspection is simple and cheap, under the conditions that the inner diameter of a gas transportation pipe becomes larger and the range of measuring the flowrate gets wider. But, under these conditions, there are problems in realizing a flowrate meter based on the traditional ultrasonic pulse transit time difference method or the phase dtierence flow velocity measuring method. The fundamentalproblem is to result from the drifi (deflection) of the ultrasonic transit due to the damping of the ultrasonic wave in gas and the larger changing width of the gas flow velocity. As the problems questioned in the paper and their resolving method, a radial ultrasonic multichannel flowrate measuring method based on a new phase difference method and a transit time difference method using a fi-equency modulated ultrasonic wave is suggested. The flow velocity measuring method is also successfidly adaptable to a liquid flowrate measurement.
This paper proposes a new technique of directly measuring the flow velocity averaged along the finite length of the pipe as well as over its cross-sectional area. Unlike the conventional flowmeters, the proposed technique exploits the onedimensional plane waves that propagate uniformly across the pipe cross-sectional area. When a fluid flows along the pipe, the plane waves are superimposed with the flow field such that the positive-going and negative-going plane wave components undergo the change of their wave numbers. Such wave number variation due to the mean flow velocity has provided a major motivation for developing a new way of measuring the mean flow velocity in the pipe. To shed light on theoretical understanding about the acoustical phenomena and to examine the feasibility of the new measurement technique of the mean flow velocity in the pipe, dedicated experimental setups have been also developed in this work. It consists of three major parts: the microphone arrays used to measure the change of wave number along the pipe, the horn-driver generating a standing wave inside the pipe, and a flow rate controller tuning the flow conditions along the pipe. Experimental data observed so far, including the comparison of measured results obtained by the KRISS standard flow measurement system, are shown in with discussions.
Three acoustic methods for flow measurements in pipes or ducts are presented here. These methods are based on plane wave acoustics and on the fact that the phase of a traveling plane wave will vary monotonically with frequency and distance traveled and will carry information about the flow velocity, The proposed methods have the advantage of being non-intrusive, and insensitive to pulsation. In fact, the pulsation and the noise present in the fluid serve as the acoustic source in the measurements. The first method called Three Station Method explores the changes in the phase of standing waves between two points in a pipe. The computation of the flow was made simple by effecting the calculation at certain frequencies where significant simplification was possible. This method provided reasonable results as an estimator method for the flow. The second method, the Two Station Method makes use of a single two-channel measurement of dynamic pressures at two stations located some distance apart in the pipe. The simplicity of the calculations required by this method makes it very attractive for field use. A variation of this method is also included here. The third method, called the Four Station Method makes use of four measurement transducers in the pipe. This method is sophisticated in its demands for data manipulation and computation but can be easily incorporated into an on-line flow measurement system. This method can be very precise in determining the mean flow rate under various conditions.
Mass flow measurement systems employing both thermal and acoustic methods have reached a high level of sophistication in recent years. 1, 2, 3 The use of Doppler shift methods for measuring average gas speed in a duct is one of the more actively studied areas in flow measurement research and development 4. While this technique has many attractive features, it is an expensive and computationally intensive methodology. The latter issue relates to the algorithms needed to extract the flow information from the multiple sensors heads and not to the steadily decreasing cost of the computation itself.
Measurement Accuracy Of 1/4 (6.35 mm) Thick Orifice Plate Installed In An 8 (200 mm) Orifice Fitting Designed For 1/8 (3.175 mm) Thick Plate.
In the current Standards 1, 2, the recommended orifice plate thickness for an 8 (200 mm) orifice flow meter is 1/8 inch (3.175 mm). A 1/8 thick orifice plate installed in an 8 fitting has a maximum allowable differential pressure limit of 150 inches of water column (37.3 kPa), which limits the maximum flow rate through the meter. The plate clearance, in a commercially available 8 orifice fitting designed for 1/8 thick plates, is adequate for installation of 1/4 (6.35 mm) thick plates with a special seal. Mechanical tolerances specified in the standard do allow installation of 1/4 thick orifice plates in an 8 orifice fitting designed for 1/8 thick plates, provided the beta ratio is less than 0.64. This experimental study was to evaluate the measurement accuracy of a 1/4 thick orifice plate installed in an 8 fitting designed for 1/8 thick orifice plates. Based on the data presented here, a 1/4 thick plate with beta ratios between 0.2 and 0.6 can be installed in an 8 fitting designed for a 1/8 thick plate and precise flow rate measurement is achieved without any modification to calculation method and/or secondary instrumentation. For the same beta ratio, a 1/4 thick orifice plate can be subjected to a higher differential pressure than a 1/8 thick plate. Hence increased flow rates through the meter can be achieved by using a 1/4 orifice plate in existing 8 orifice fittings designed for 1/8 thick plates.
This paper presents the preliminary results of a research effort aimed at developing a compact multi-tube orifice flow meter/header installation configuration. By exploiting the benefits of flow conditioners as part of the meter installation, it may be possible to reduce the overall size, footprint, and weight of a typical multi-tube meter/header installation by approximately 50% without adversely affecting flow rate measurement uncertainty. Capital savings due to such a reduction in size of typical offshore flow meter installations are estimated to be on the order of 250,000 to 500,000 (1999 U.S. dollars) per offshore structure. It may also be possible to extend the allowable range of orifice beta ratios (i.e., the ratio of the orifice diameter to the meter tube diameter) in such installations. The current beta ratio limit for short orifice meter tubes is 0.45.
The NOVA-50E flow conditioner has been extensively and successfully tested for its performance as an isolating type of flow conditioner in orifice meter applications. However, it has only been tested in 4inch meter tubes. Although the flow conditioner is designed to be scalable, the claim was verified in the present tests in an 8 inch line size. The disturbance was generated by using two elbows out of plane, with zero spacer between the elbows. The 8-inch flow conditioner has been placed at several distances from the installation and from an 8 inch orifice meter. The tests were carried out at the Didsbury Gas Dynamic Test Facility in natural gas, at static pressures in the range 5000 to 6000 kPa. The orifice meter performance in the presence of the flow conditioner was compared to its baseline performance when placed downstream of a 19 tube bundle + 80D long meter run. The reference flow, in both cases, was a bank of sonic nozzles traceable to the primary gravimetric system. Results indicate that the flow conditioner is scalable and performs as expected in larger meter runs. In addition to the flow conditioner performance tests, some results of the 8-inch orifice meter without the flow conditioner are also presented. These results agree very well with the data available in literature.
Qualification Of A Flow Condtioning Device According To The New AGA Procedure.
The new AGA 3/API 14.3 standard on concentric square edged orifice meters suggests that if installation effects can be shown to be less than about 0.23%, then there is no need to apply any additional uncertainty to that of the basic discharge coefficient. This has revived interest in flow conditioners that can assure this performance, without the need for long straight upstream lengths of pipe. A feature of the new standard is that it specifies performance acceptance tests for evaluating other flow conditioners, which were not included in the previous versions of the document. In this paper we will review this procedure, and show results from a device that is currently being qualified in this manner.
The critical flow nozzle is a very accurate and reliable flowmeter and as such is frequently used in laboratories to calibrate other flowmeters. The critical flow nozzle must initially be calibrated itself, usually against a gravimetric facility or some other primary standard, in order to obtain the coefficient of discharge. The uncertainty in Cd is also analysed. However, this uncertainty analysis does not take into account fully the thermodynamic uncertainty in the theoretical mass flowrate, most likely because it is not known. This paper rectifies this situation by developing a method to estimate the thermodynamic uncertainty in the theoretical mass flowrate of a gas through a critical flow nozzle. The method estimates this uncertainty by considering the uncertainties in density, speed of sound, enthalpy and entropy from the equation of state used to calculate the theoretical mass flowrate. Over the range 250-400 K and up to 15MPa the uncertainty in the theoretical mass flowrate for nitrogen, methane, argon, and carbon dioxide lies in the range 0.06/0 to 0.4/0.
The Effect Of Using Atmospheric Air In Critical Flow Nozzles.
The critical flow nozzle is commonly used with atmospheric air. This poses a problem as the equations of state used to calculate the theoretical mass flowrate for air are based on dry CO2-free air. The air must be dried, and the CO2 removed before use or the effect of atmospheric air accounted for. This paper analyses the effect of water vapour and CO2 on the critical flow of air. The analysis utilises the AGA8 equation of state, which can be used for dry and moist air. Using recent data for the water vapour pressure enhancement factor, the analysis covers the temperature range 0 - 50C at pressures up to 15 MPa. The results show that the effect of the carbon dioxide present in atmospheric air is small, but that the effect of water vapour can be significant. As the maximum mole fraction of water vapour in air goes down with increasing pressure and up with increasing temperature, the effects can be most significant at low pressures and high temperatures. A previous correction factor for water vapour in air, developed for low pressure, is shown to apply well over the range. A new correction factor is presented which removes the need to calculate the mole fraction of water in air.
Critical Venturi nozzles of ten pieces essentially complying with 1S09300 whose machining errors were less than lpm were calibrated by a constant volume tank system using air at absolute pressure of 0.1-O.5MPa with the Reynolds number of 5X104-1.2X10G. All the measured discharge coefficients were distributed along a fitted curve, which had been obtained from calibrations of other 23 critical nozzles with negligible machining error performed at atmospheric pressure and lower with Reynolds number up to 2.4x105, with scattering of 0.l?ZO. The curve agrees with 1S09300 with the uncertainty of the 1S0, but it has a steeper gradient and significant deviation from the 1S0. One of the nozzles indicated a boundary layer transition at the Reynolds number around 106 as abrupt decrease of the discharge coefficient by 0.0570. In view of the fact that the 1S0 is rather suitable for larger Reynolds number up to 107 with turbulent boundary layer, the fitted curve is considered to be better to be employed at low Reynolds number below 106 where the laminar boundary layer is expected.
This paper describes the results of two intercomparisons using a sonic nozzle as the transfer standard. They were initially conducted in line with the activities of EUROMET, a grouping of European flow metering laboratories which were subsequently joined by NOVA, CEESI and SwRI. Two types of comparisons were made, between European and North American gas flow metering installations and between the methods used by those laboratories to calculate the critical flow function C*. The transfer standard used was a critical flow Venturi nozzle. The calculation methods considered were the ISO 9300 standardized equations for dry air and natural gas, the different versions of the AGA8 method, as well as several other methods developed by the laboratories, some of them based on the free energy equation. A comparison of these calculation methods shows that deviations exist in the results found in natural gas and that the deviations are smaller in dry air.
This paper describes the investigation of the Cd deviation between the actual and the theoretical compact nozzle Cd due to different kinds of piping configurations. The compact nozzle array consists of thirteen single nozzles. Each nozzle has actual volumetric flow rate of 40 m3/h and was calibrated individually by the primary nozzle based on the ISO 9300 pipe configuration (designated as reference case A). Other piping configurations for the nozzle array constitute a straight pipe with flow conditioners (case B), two and four elbows (cases C & D), respectively. To avoid the interference effect between nozzles, the distance between neighboring nozzles was placed following the requirements of Park 1 and Stevens 2. In case A, except for one nozzle, all other Cd values lay within a band of f0.2/0 1S0 9300 curve. In case B, deviation of C. varies from 0% to -0.3%, when actual volumetric flow rate was raised from 40 m3/h to 520 m31h. Deviations of Cd for cases C & D were less serious. However, the data had a similar trend as that in case B, with the ed deviation changing from 0.05/0 to -O.12/0. The expanded uncetiainties of these Cd deviation were O.155/0 at 95/0 confidence level. The reason for the strong shifl of Cd as observed in case B is not clear but may attribute to difference in temperature measurement of the in-coming flow. Thus, firther study will focus on the interaction of asymmetric flow field with the temperature probe to resolve the phenomenon observed in the present research. It is believed that for accurate flow measurements, the discharge coefficient Cd of a compact nozzle array would best not be taken directly from single nozzle data.
This paper describes 15 Venturi tubes manufactured in a range of diameters from 50 mm to 200 mm and of diameter ratios from 0.4 to 0.75. They have been calibrated in water and high-pressure air. An equation for the discharge coefficient in water has been obtained with an uncertainty of 0.75 per cent. In air the situation is considerably more complicated. Equations fitting all the air data with an uncertainty of approximately 1.25 per cent have been derived. Of these equations the one with a physical basis gives an uncertainty of the difference between the air and the water data of 0.75 per cent. However, when modifications are made to the tappings to seek to determine the limitations of the equations, the data fit the equation which is less well founded physically further work is being undertaken to understand the phenomena observed.
When a subsonic venturi is used to measure the flow of a compressible fluid there will be a density difference between the two pressure taps. This effect needs to be accounted for by a term called the gas expansion factor. A theoretical gas expansion factor is traditionally applied to measurements made with a venturi element. The degree to which the theoretical value is applicable to a particular venturi depends on the design as well as the flow conditions. In some cases a meter specific gas expansion factor must be determined. This paper describes the process for determining gas expansion factor based on calibration data. A test plan has been developed and applied to two different devices. The effects of Mach number, Reynolds number and gas species are described. Calibration data from both devices are presented and discussed.
The paper describes a novel positive displacement meter that features an extremely large range of more than 1 : 400 and pulsation free operation. This meter, when used as a reference meter will allow a significant improvement in the uncertainty that can be achieved in meter calibration. Its performance is virtually insensitive to installation effects such as swirl or uneven velocity distribution. Being of a true positive displacement construction, its pressure dependence, if at all present, will be very small. The pulsations of this meter have been minimised by using two metering cartridges in parallel and connecting the rotors to generate pulsations in opposite phase. The elimination of any residual pulsations by incorporating a flexible membrane retains the superior characteristics of the meter at high pressures. Experimental data on range, repeatability, sensitivity to installations and on pressure dependence are given in the paper.
The United States Air Force Metrology and Calibration Program has recently procured a sonic nozzle/venturi Gas Flow Transfer Standard (GFTS) for use as a correlation standard. The purpose of the correlation standard is to verify the specifications of gas flow primary standards at Air Force Precision Measurement & Equipment Laboratories (PMELs). The GFTS will be sent to individual PMELs for dynamic testing of bell provers, piston provers, and other gas flow measurement standards. The paper discusses the specific features of the GFTS hardware and software. The initial calibration data from the National Institute of Standards & Technology (NIST) is presented. Plans for deployment and operation in a remote calibration mode are discussed. The paper will provide a basic overview of the USAF correlation-testing concept for gas flow measurement standards. The intended audience consists of individuals who are considering the addition of a correlation method to their current support of gas flow measurement standards. The correlation method can reveal errors that are not detectable with a fundamental unit calibration.
Ultrasonic meters are becoming increasingly accepted for the custody transfer measurement of natural gas. This is reflected in the most recent standards, regulations, and codes of recommended practice, such as the AGA Report Number 9, the Regulations and Guidelines of the Norwegian Petroleum Directorate, and the UK Department of Trade and Industrys Petroleum Measurement Guidelines. Although these documents encourage the use of ultrasonic meters, they do not provide rigorous installation instructions and it is possible for design engineers to place meters in locations not suitable for ultrasonic measurement. One common concern for operators is the possibility that ultrasonic noise present in the pipeline might interfere with the meter and thereby compromise its performance. Such noise is typically generated at points with significant pressure reduction, such as flow control valves.
Recent developments in microfabrication technology have spurred novel designs of ultrasonic transducers. This paper presents the characterization and modeling of capacitive microfabricated ultrasonic transducers. Such transducers, which are made using the techniques of the semiconductor in- dustry, can transmit and receive ultrasound in both liquids and gases. Trans- mission has been demonstrated in air at atmospheric pressures at frequencies from 1 MHz to frequencies in excess of 10 MHz. The devices have a dynamic range of at least 110 dB at a bandwidth of approximately 5%. Devices with bandwidths of approximately 50% have been realized, but have a dynamic range of approximately 90 dB. Preliminary data indicates that the devices are extremely broad band in high pressure environments, though at the time of press conclusive data was not available. Data is presented which demon- strates that no substrate cross-coupling between array elements is observed in air, thus conrming the feasibility of beam steering applications. Broad- band transmission has also been demonstrated in liquids. Transmission from 1 MHz to 20 MHz has been observed width bandwidths in excess of 50% in the low MHz range. Capacitive microfabricated ultrasonic transducers are anticipated to enable new generations of ow measurement devices.
Until recently, the universe of Transit-Time Ultrasonic Flowmetering has been divided into the worlds of Clamp-On and Insert Spool Section instruments. The obvious convenience, higher reliability, lower installation and maintenance cost advantages of Clamp-On instruments was tempered by the security in having transducers pre-installed on a flow profile conditioned and factory calibrated Insert Spool. Advances in Clamp-On Transit-Time Flowmeter and Wide Beam transducer design have now permitted development of Custody Transfer capable field installed Clamp-On (Refractive Beam) ultrasonic flowmeters, and pre-calibrated Wide Beam Clamp-On Spool Section instruments with superior performance to that achievable by the Wetted Transducer (Orthogonal Beam) Spool Section. This has been made possible by advances in Clamp-On Transducer technology which permit matching the transducer to the Sonic Waveguide parameters of the Spools pipe, so that the pipe now becomes an integral part of the ultrasonic flowmeter, rather than an uncertain interposition into the sonic beam. Liquid Signal to pipe Noise ratios exceeding 1000 to 1 has been achieved permitting calibration stability of better than 0.1%. Advances in Sonic Signal Analysis, such as the development of MultiPulse transmission, have resulted in extremely high flow detection sensitivity and calibration stability. Injection of Phase Markers in the MultiPulse sonic transmission signal permits precise measurement of the actual sonic Transit-Time, essential to accurate flowrate computation. Accordingly, Dual Beam Clamp-On Spool Sections now achieve accuracy better than 0.25% of actual flow over flow ranges as high as 100:1. Custody transfer accuracy is also maintained despite substantial variation in the sonic properties of the liquid, as is frequently encountered in actual applications. The paper describes these Wide Beam based Transit-Time instruments, and provides experimental and field data in support of their accuracy and stability. Also presented is data testifying to the accuracy of Wide Beam Clamp-On Transit-Time ultrasonic flowmeters installed in multiple Site Station pipeline management systems.
The measurement of a natural river flowrate based on a traditional ultrasonic multi-channel flowrate measuring method for an open sluice way has not been firmly fixed on the basis of the theory and experiment to evaluate the accuracy (error) of the flowrate measurement with a higher reliability. That is why seeing the distribution of the water stream cross section along the river length as much as 3 to 5 times longer than the river width the cross section shape and area are not equal even at any place, and also the flow velocity of the revolving component is compositely developed. For it, river flowrate measuring hydrology circles does not have a higher reliability on the ultrasonic flowrate measuring method. The paper is supposed to question problems in the flowrate measuring hydrology circles and suggest several methods for resolving these problems.
This paper presents results obtained from the testing of a 3inch Micro-Motion Coriolis mass flow meter. The meter was tested at the Didsbury Gas Dynamic Test Facility (GDTF), near Calgary, in natural gas, at static pressures of around 5700 kPa. The meter performance was compared to a bank of sonic nozzles traceable to the primary gravimetric system. Results indicate that the meter showed a bias of 0.49% when compared to the reference nozzle bank. Such a bias could be eliminated by flow calibrating the meter in natural gas. A flow calibrated meter has a repeatability (2s) of 0.3%. This is within the stated accuracy of the device which is 0.5%. Within its repeatability and accuracy, the meter can be used downstream of installations such as two elbows in plane and elbows out of plane without the use of a flow conditioner.
Although widely used, turbine meters are very sensitive to installation effects. They require minimum straight pipe lengths, even when existing flow conditioners are installed. Therefore, Gaz de France has developed a new flow conditioner, the SMM conditioner, specially designed for use in pressure reducing stations upstream of turbine meters. The use of this conditioner results in much smaller stations, meaning less building work, lower installation costs and reduced environmental impact, while at the same time providing an excellent measurement accuracy. This device totally eliminates the effects of strong flow disturbances. It allows the turbine meter to be mounted directly downstream of any pressure regulator, without affecting the metering accuracy. The conditioner was rigorously tested by Gaz de France, Gaz du Sud-Ouest and CERT/ONERA, using LDA experimental measurements, and compared to the most efficient existing flow conditioners. Validation tests have been successfully carried out under real operating conditions, on a delivery station of the Gaz de France network. This paper presents this new flow conditioner, the experimental tests and their results, and gives some conclusions on its efficiency.
Tachometric gas flow sensor with levitating rotor is a kind of novel electrifiable flow sensor, which has a very simple structure. This paper introduces the sensors operating principle and its structure. In this paper the levitation and the rotation mechanism of the rotor are described. The design considerations cmthe levitating rotor and the sensors internal flow channel are outlined. The experimental test results are reported, The leading features for this new type flow sensor are summarized. It is expectant that this new type flow sensor VW become next generation for tachometric flow sensor.
A new class of gas turbine meter is presented that evaluates the accuracy of the meters mechanical output by using the well-known transfer proving method. The accuracy is determined under actual operating pressures and temperatures without interrupting the normal service of the meter. No pressure or temperature measurements are required for determining accuracy. The built-in master meter is a second turbine meter built into the outlet of the meter body. Other types of transfer proving systems could be integrated into the meter, however, such as, a differential pressure meter or an ultrasonic meter. The primary function of the built-in master meter is to determine error in the main cartridge resulting from changes in mechanical friction. A second function is determining meter error due to upstream swirl caused by the effect of the installation. Tests have shown that the meter accuracy agrees within 0.20% of the accuracy obtained from a primary standard for extreme changes in mechanical friction or severe upstream swirl. The meter can also detect and warn of other causes of meter error, such as, jetting, pulsating flow, on-off flow, partial blockage, and bent or broken rotor blades although the measured accuracy may differ from the true accuracy.
To assure the consistency in their individual claimed error and measurement uncertainty, four participating laboratories in Asia Pacific area, including Center for Measurement Standards/ITRI (CMS) in Taiwan, Korea Research Institute of Standards and Science (KRISS), Shanghai Institute of Process Automation Instrumentation (SIPAI), and Daqin Design Institute & Measurement Research Institute (DDIMRI) in China agree to adopt the generally accepted practice of the international flow measurement community to conduct an inter-laboratory comparison round-robin test of water flow measurement facilities. Test program exhibits DN 100 twin-orifice plates with associated tubings used as a transfer standard, DN 100 water flow measurement facility chosen in each laboratory with test flowrate selected about from 19.7 to 117 m3/h, and precision differential pressure measurement ranging from 4.4 to 156.8 kPa approximately. The resulting Time Youden plots finally were drawp from intercomparison data to statistically illustrate degree of conformance at 95% confidence level for all four facilities. The measuring capability and performance of precision differential pressure measuring device Rosemount Model 3051 C applied for intercomparison program during these two years is also being reviewed and reassessed. This intercomparison test campaign is part of a continual realization and promotion to prospectively facilitate formation of a regular group for exercising the key comparison in flow measurement field around the Asia Pacific area.
An instrument was developed for the direct mass flow calibration of gas flowmeters that does not require measurement of temperature, pressure, or specific volume. This instrument measures the weight of gas collected in a container and makes measuring those thermodynamic variables unnecessary. The need to measure the weight of the gas container is eliminated by submerging it in a liquid (presently water) and balancing its weight with the force of buoyancy. The accuracy of this Gravimetric Calibrator is unaffected by the pressure and temperature of the gas. The Calibrator can also measure reactive, corrosive, and non-ideal gases. The container remains connected to the process by a torsion capillary, and a load cell measures the changing gas weight continuously throughout the measuring process. A prototype was designed for gas flows ranging from 1 sccm of hydrogen to 10,000 sccm of tungsten hexafluoride, constructed, tested, and used to calibrate flow devices. Experience with the prototype and results are presented, and plans for further developments are discussed.
This paper describes the test methodology and results of the flow test conducted on various pipe vent configurations. Free vents like long radius bend, mitre cut bend, canopy vent normally used in petroleum storage vessels, were tested for establishing its breathing capacity. Wire meshes of various porosity, were kept at the vent inlet to study its effect on the breathing capacity of the free vent. The tests were carried out in the suction mode so as to simulate the conditions as that during the outflow of petroleum products from the storage vessel. Suction pressure of 20, 25.3 and 30mm of water column was maintained inside the vessel during these flow tests, to establish the flow curve for each free vent. For some of the vents out-breathing flow capacity was established by operating the system in the pressure mode, so as to simulate the conditions of flow into the storage vessel.
Ford Motor Company is involved in accurately measuring the air mass flow rate into their internal combustion engines for improved fuel economy and for meeting the required level of pollutant output. In this endeavor, Ford has constructed many different flow stands which measure air mass flow rates during various fabrication and manufacturing processes. To be assured that each flow stand is measuring the mass flow correctly, a Measurement Assurance Program (MAP) has been implemented. This paper describes the physical hardware (artifact) which consists of piping sections and three Critical Flow Venturis (CFV). It presents the methodology of obtaining calibration data on two CFVs (installed in series), and how to combine the results for the three CFVs to determine the accuracy of the measured air mass flow rate. The MAP artifact has been used for inter-laboratory comparison. Data from several internationally known flow laboratories is presented. Two laboratories (NIST and CEESI) have performed multiple calibrations on the artifact over a period of several years, while four other laboratories have performed a single calibration. The presented data shows the comparison between laboratories and estimates whether the differences are due to systematic or random effects by a Youden analysis.
The critical flow venturi (CFV) has long been recognized as a high quality gas flow calibration artifact. A program is underway to compile data to be used in determining the intrinsic repeatability and reproducibility of a CFV. This paper describes the initial results of the program, it is divided into three parts. First, primary calibration data from a single CFV are tracked over a 30 year period. Second, results of a test program are presented with the objective of classifying short and long term random effects. Third, results from two test programs are presented with the objective of identifying the source of random effects.
Advances in natural gas primary device metering research, technological evolution of instrumentation and the wide-spread implementation of electronic flow measurement has enabled the timely creation of accurate measurement data for a meter run. This paper presents the implementation of an information management system which: collects measurement data from 2000+ electronic flow measurement devices at 1000+ measurement points validates the operation and maintenance of the measurement facility automatically finalizes the data as custody transfer measurement for use in the gas allocation and billing systems or initiates corrective maintenance and finalization of the data manages the changes to measurement data resulting from the corrective maintenance and finalization process summarizes the individual meter run data to meter station data and meter station data into summary meter station data for management of groups of stations creates estimates of future measurement and manages the refinement of these estimates until valid measurement data has been received from the meter station and publishes the resulting hourly meter station custody transfer transaction records (with validity and business acceptability values), operation and maintenance, and audit information.
An experimental test program was conducted to investigate various combinations of parallel critical flow venturis (CFVs) mounted inside a common inlet chamber. The test program was designed to determine if an increase (or decrease) in accuracy or repeatability is obtained by utilizing multiple CFVs to measure an air mass flow rate instead of a single CFV. Data is presented for various CFV combinations ranging from a single CFV to eight CFVs operating in parallel at three distinct flow rates. In addition to the classical data presentation of throat Reynolds number versus discharge coefficient, Youden analysis is presented. The test program was repeated at three different time intervals to investigate long term repeatability as well as short term repeatability from a single test.
A newly developed referencing calorimeter is described which performs with accuracy, provides rapid measurement, is robust and economic both in its initial investment and for continuing costs of ownership. A flow of gas is mixed with air and directed to a ceramic/platinum element (PIM) which is operated at a constant temperature above 800C. The temperature of the mixture rises rapidly when passing through the temperature gradient between the structure entrance and the PIM body. In passing through this gradient, all gas components are heated and auto-ignition temperatures are exceeded. Oxidation of the gas releases chemical energy which is immediately quenched transferring the heats of combustion to the PIM. Molar gas flowrate is measured using pressure methods. No catalysts are involved or required. The PIM temperature is maintained constant by changing the supplied electrical power. Combustion energy contacting the PIM is interchangable with electrical energy and is a direct measure of heat evolution. The PIM is confined within a structure designed to contain explosive conditions. Quenching is very effective, prevents flames and provides rapid cooling of combusted products. Measurement are made at the stoichiometric ratio or with excess air where the gas/air mixture is always maintained lean.
A method and device have been developed which accurately measure the BTU content of hydrocarbons at pipeline conditions. The cost of this device will allow some users who currently collect samples to have the advantages of on-line BTU measurement. The device measures, reports, and logs the BTU value per unit volume several times per minute. As the cell is nearly isobaric with the pipeline, the energy flow through the pipeline can be computed directly as the product of the BTU value per unit volume times volumetric flow rate. BTU and composition are measured via optical absorption spectroscopy in the vicinity of 900 nm using a spectrograph and a silicon array detector. In contrast to longer infrared wavelengths, the natural gas absorption spectrum in this spectral region is a linear combination of the spectra of the component species. The observed spectrum can therefore be accurately fit to yield the concentration, in molecules per unit volume, of all C1 to C6 hydrocarbon components and water. The energy content of the components is then summed to yield the BTU per unit volume. Additional information such as the compressibility, density, and specific gravity can also be obtained from the measured gas compositions.
The Petroleum Measurement Tables document the volume correction factors (VCF) which correct the effect of thermal expansion and compressibility on hydrocarbon liquids. This paper gives insight into the format of the 1980 revision to the tables which transformed the tables from hard copy format to an algorithm and implementation procedure format. The Petroleum Measurement Tables are designated as API MPMS Chapter 11, ASTM D1250, and IP 200. Details are provided on the various updates and revisions to the tables which include the integration of compressibility and thermal expansion correction into one process, the use floating point math over integer math techniques, the expansion of the tables limits to higher density and lower temperature ranges, and the introduction of a new temperature base (20o C), are discussed. Finally, the paper discusses future considerations in the publication of the tables. Possible formats and mediums are presented.
The NRLM large water flow calibration facility, which sets the primary standard of water flow rate in Japan, is one of the largest calibration facilities for water flow meters in the world. This facility covers a flow rate range of 0.014 to 0.83 m3/s (50 to 3000 m3/h). The test lines range from 100 to 1100 mm in diameter (D) with a minimum upstream straight pipe length of 100D. The flow rate is measured using the weighing and timing method. The uncertainty of this facility has been estimated in accordance with the ISO Guide to the expression of uncertainty in measurement. The expanded uncertainty of the flow rate (k 2) was estimated to be 0.034%. The major error sources and their contribution to the standard uncertainty of the flow rate were the measurements of (a) the mass of the water in the weighing tank (0.0130%), (b) the duration for which water flow was diverted to the weighing tank (0.0085%), (c) the buoyancy for the correction of the mass of water in the tank (0.0070%) and (d) the density of the water (0.0025%). The results of an international comparison with the primary standard in Sweden are also described.
Comparison measurements become more and more important to perform traceability and to confirm the accuracy of flowmeter calibration facilities. But intercomparisons between different laboratories are very complicated, expensive and time consuming. Therefor a method is proposed to prove different components of the the total measurement uncertainty by internal comparison measurements between different flow measurement devices within the laboratory. The paper describes this method and its realization in the new primary standard for water flow measurement at PTB (being under construction now). This test rig represents a combined double type standard containing a gravimetric and a volumetric part, connected by a set of turbine meters in parallel, and offers the possibility for carrying out comparison measurements between two metrologically independent measurement devices, a gravimetric and a volumetric one. The set of turbine meters is needed to overcome differences in volume and flowrate ranges. The influence of the turbine meters on the uncertainty of comparison measurements (it is expected to be smaller than 0.01 %) was investigated using a special test installation. The results of various measurement series using this test installation are reported.
pigsar is an officially recognised high-pressure test facility designed for testing and calibrating gas meters used in fiscal metering at flow rates between 8 m/hr and 6,500 m/hr and pressures ranging from 14 - 50 bar. This paper presents the test facilitys calibration chain and describes an analysis of its uncertainty based on closed uncertainty propagation of all influential variables. This approach meets the requirements of the ISO Guide to the Expression of Uncertainty in Measurement. Owing to the relatively short calibration chain, the exclusion of installation-related uncertainties by consistently avoiding changing meter installation configurations during the calibration process and the use of uncertainty-reducing regression methods, the calibration uncertainty achieved for gas meters calibrated at the high-pressure pigsar test facility is not much above 0.1 %. Correlations between standards connected in parallel are taken into account. The results of the uncertainty analysis have been confirmed by the scatter found when recalibrating the pigsar working standards. Employing uncertainty budgets to make the sources of uncertainty and their effects on calibration uncertainty transparent not only makes it possible to specify individual uncertainties in detail but also to optimise the calibration and test methods of the test facility itself. Where deviations are found between calibration levels of different test facilities, the uncertainties determined for the test facilities involved can be used to decide whether the deviations observed are significant or whether - in view of the prevailing uncertainties - the results can be considered the same.
The latest revision of the ANSI/API-2530 orifice meter standard introduces significant changes in order to improve the performance of the orifice meter when subjected to non-ideal flow conditions. In the case of bare tube installations, existing recommendations have been changed and additional recommendations have been provided for new types of pipe fittings. The major finding was that users of orifice meters have to be particularly careful in selecting meter run lengths for installations which generate flow swirl, for example, headers or elbows out of plane. For applications using flow conditioners several revisions have been made. The use of the 19 tube bundle flow straightener has been subjected to several new restrictions. To obtain optimal performance from an orifice meter for a given application, the flow straightener has to be used in accordance with recommendations for its locations, meter tube length and orifice b-ratio. Moreover, the new tube bundle flow straightener has to meet defined mechanical specifications and tolerances to deliver the expected performance. The standard also provides a performance test procedure, which would allow the use of other flow conditioners, for example, isolating type flow conditioners. Specifications for orifice meter run lengths have been revised by using high quality data, evaluated by well defined rules within the framework of practical considerations. These changes will result in a metering device, which is more accurate, repeatable and reliable and can be considered on par with other metering technologies. The present paper describes the process, which was used to accept data and develop new recommendations for the orifice standard. It provides the necessary background information, which can help users understand the reasons behind the proposed changes and demonstrates that the recommendations indeed result in a much improved orifice meter performance.
The results presented in this paper are a portion of a suite of flow tests proposed to verify that a meters performance is within the bounds specified in American Gas Association (A.G.A.) Report Number 9. Baseline performance of 12-inch Daniel and Instromet multipath ultrasonic meters with four types of commercially available flow conditioners is presented along with bare meter tube performance. The baseline results are used as a reference for tests involving a single 90 elbow upstream of the meter. The work was sponsored by the Gas Research Institute (GRI) and was performed at the GRI Metering Research Facility (MRF) at Southwest Research Institute. The results indicated that flow conditioners may change the bias associated with a meter, but this change was generally less than 0.2%. When either brand of meter was installed with 10D between the meter and the elbow, the results without flow conditioners showed changes in meter bias error, relative to the baseline, of less than 0.2%. This result was independent of the meter orientation relative to the elbow and as good or better than the results obtained with flow conditioners.
In the present article the authors present results from model cavities using numerical simulations, visualisations and Laser Doppler Velocimetry (LDV). The agreement between the three different methods is good, both inside the cavities and in the main flow past the cavities. The present results show that the combination of using experimental investigation together with numerical simulations is a powerful tool when investigating complex flow structures.
In March of 1999 CEESI completed construction of a natural gas calibration facility located in Clear Lake, Iowa. This facility is specifically designed for the calibration of high flowrate custody transfer meters. The calibration of these flowmeter must be made using a method that is traceable to NIST with an uncertainty analysis of that traceability. This paper describes certain aspects of the traceability methodology and uncertainty analysis.
Many flowmetering devices exist which incorporate a vast range of technological and installation complexity. Much research has been accomplished establishing the applicability, accuracy, and reliability of these flowmeters. The fact remains, the accuracy of any flowmeter is a function of installation configuration, upstream flow characteristics, and calibration. It is optimal, to yield maximum flowmeter accuracy, to perform In Situ flowmeter calibrations using a calibration device which itself is insensitive to installation and upstream flow characteristics. This paper presents design, calibration, and verification results of an Advanced Calibration Device developed for use in calibration of Nuclear Fuel Supply Industry fuel assembly test facility flowmeters. Results from calibration and verification testing are presented illustrating the ability of the Advanced Calibration Device to yield a proper and constant conditioned flow regardless of entrance flow characteristics. While illustrating the accuracy and applicability of the Advanced Calibration Device for In Situ calibration of test facility flowmetering devices, this paper presents actual industry applications of a flow conditioning device, flowmeter, and upstream flow characteristic test results. Calibration testing was performed for the Siemens Power Corporation test facility using the Advanced Calibration Device, confirming previously applied flowmeter mass flow correlations.
The TNO Institute of Applied Physics experimentally investigated the impact of vibrations on the output of five different make 3 inch industrial vortex flowmeters in an air flow circuit under atmospheric operating conditions. To our knowledge the impact of pipe-wall vibrations on the accuracy of vortex flowmeters under flowing conditions has not been investigated in detail so far. Various installation effects, such as swirl, a-symmetry of the flow profile and pulsations are investigated and reported amongst others by Mottram 1. We have investigated the impact of flow pulsations on the accuracy of the five different vortex flowmeters in an earlier study as reported at the Flomeko 1998 2. In the investigation we performed pipe-wall vibrations were imposed in three directions over a wide range of frequencies and vibration amplitudes. It was shown that under these conditions vibrations can cause large systematic errors in flowmeter reading depending on make flowmeter, vibration frequency and amplitude. These errors are caused by the sensor, picking up not only the dynamic forces from the vortex shedding, but also the wall vibration. Subsequently, the sensor cannot distinguish between the vortex signal and the pipe-wall vibration. The reading of the vortex meter at zero or low flow rates is primarily determined by the vibration frequency. This effect was observed already at low vibration acceleration amplitudes in the order of 0.25 g peak. This is, for the frequency range above 20 Hz, below the acceptable level of 20 mm/s peak, regarded as acceptable for pipe systems in a design stage from dynamic stress point of view. This vibration criterion differs from those used in vibration tests intended to check the structural integrity of the meter according to IEC 68-2-6. Concluding, it can be stated that one should be careful with the use of vortex flowmeters when pipe-wall vibrations are present near the metering section with frequencies within or nearby the operating range of the flowmeter, even when the amplitudes of pipe vibrations are small. It should be noticed that the tests are performed for air at atmospheric conditions, the sensitivity for pipewall vibrations will decrease if the medium density increases. The different measures, chosen by manufacturers to decrease the sensitivity of vortex flowmeters for vibrations are so far not fully succesfull and further improvements on construction, electronic filtering, sensor type and sensor location should be investigated.
A flow measurement system was developed to measure, in real-time, the exhaust gas flow from vehicles. This new system was based on the vortex shedding principle using ultrasonic detectors for sensing the shed vortices. The flow meter was designed to measure flow over a range of 1 to 366 lps with an inaccuracy of +1% of reading. Additionally, the meter was engineered to cause minimal pressure drop (less than 125mm of water), to function in a high temperature environment (up to 6500C) with thermal transients of 150C/s, and to have a response time of 0.1 seconds for a 10% to 90% step change. The flow meter was also configured to measure bi-directional flow. Several flow meter prototypes were fabricated, tested, and calibrated in air, simulated exhaust gas, and actual exhaust gas. Testing included gas temperatures to 6000C, step response experiments, and flow rates from 0 to 360 lps in air and exhaust gas. Two prototypes have been tested extensively at NIST and two additional meters have been installed in exhaust gas flow lines for over one year. This new flow meter design has shown to be accurate, durable, fast responding, and to have a wide rangeability.
The design of a vortex shedding flowmeter has been optimized for its standardization. The optimization was achieved by evaluating the linearity of the flowmeters with various bluff bodies. It was found that the Strouhal number of the optimized flowmeter has a constant value of 0.2503 in the Reynolds number range of about 105 to 2 x 106. The effect of the installation conditions of the flowmeter on the measurement error was examined. The sensitivity of each flowmeter dimension to the K-factor of the flowmeter was also evaluated. The results indicated that the uncertainty of dry calibration of the flowmeter is satisfactorily small and actual calibration results of many flowmeters demonstrated the practical usefulness of dry calibration. Most of the experiments were carried out using the test facility for water meters at NRLM, and additional experiments to evaluate the performance of the flowmeter in a higher Reynolds number range were performed using high pressure gas meter test facilities in many countries.
The need for accurate and reliable measurement of three-phase flow streams is well documented. To this end Daniel have developed a high-accuracy multiphase flowmeter based on the sound measurement principle of gamma-ray absorption. The ultimate aim of such technology is to replace the measurement function of the traditional test separator with a cheaper, lower-maintenance and calibration-free alternative. At present, due to its high-accuracy water-cut (WC) and real-time performance, MEGRA has also been utilised for well management programs downstream of such traditional test separators. This paper outlines the basic principles behind the multiphase flow measurement and highlights some of the advantages of the present technology. The use of relatively low-energy gamma-ray emissions and high-resolution solid-state detectors lends an enhanced sensitivity to the measurement. Consequently, water-cuts and gas volume fractions can be determined to high accuracy ( 2%) in relatively short measurement times (seconds). A method of measuring changes in the process water salinity, which seriously affects most multiphase flow measurements, and an extension of this method to achieve full calibration-free operation in the field, is discussed.
The effects of low liquid (ethylene glycol) loads on orifice metering of high pressure (4600 to 5000 kPa) natural gas has been examined for three different orifice beta ratios (b), 0.31, 0.60 and 0.69. Using orifice flow correlations developed for dry gas flow, a measurable meter shift (MS) in predicted gas flow rate from dry gas conditions has been observed for liquid to gas mass ratios (z) ranging from 0.25 to 6.0 %. The magnitude and direction of the observed shifts varies with z, meter gas flow Reynolds number, Reorf (2.8x106Reorf11x106) and b. The greatest positive shifts (up to 1.4%) occurred for the larger values of z (2%) and the lower values of b. For z 2% and b of 0.60 and 0.69, MS was initially negative (as low -0.7%). The results observed in this work agree with trends from earlier work reported in the literature, done with different liquid/gas combinations and pressure ranges. The reason for the observed shifts has been speculated but at this time more research is needed to confirm if these speculations are correct. Flow visualization would be an important next step to enhancing the evaluation of these phenomena.
An extended throat flow nozzle has been examined as a device for the measurement of very high void fraction (a 0.95) multi-phase flows. Due to its greater density and partial contact with the wall, the equilibrium velocity of the liquid phase appreciably lags that of the lighter gas phase. The two phases are strongly coupled resulting in pressure drops across the contraction and in the extended throat that are significantly different than those experienced in single-phase flow. Information about the mass flow rates of the two phases can be extracted from the measured pressure drops. The performance of an extended throat flow nozzle has been evaluated under multi-phase conditions using natural gas and hydrocarbon liquids at 400 and 500 psi. Two hydrocarbon solvents were used as the test liquids, Isopar M O (sp 0.79) and Aromatic 100a (sp 0.87). These data are compared to prior air-water data at nominally 15 psi. The high and low pressure data were found to be consistent, confirming that the temperature, pressure, and size scaling of the extended throat venturi are correctly represented. This consistency allows different sized devices to be applied under different fluid conditions (temperature, pressure, gas and liquid phase composition, etc) with confidence.