There are numerous applications wherein it is desirable to obtain discrete or continuous samples from fluid transportation systems or fluid processing enclosures. Enclosures and fluid transportation systems, as used herein, refer to any closed containment structure without respect to its size. Thus it includes such small enclosures such as cans that may be used in shipping starter bacteria from a culture lab. On the other end of the spectrum, it includes large tanks and associated pipelines, which may have capacities of several thousand gallons, such as are used in the dairy processing industry.
Efficient and effective techniques and apparatus for obtaining aseptic samples from such systems and enclosures, are particularly desirable. Examples of industries that require such aseptic sampling include, but are not limited to, the pharmaceutical, bioengineering/biotechnology, brewing/distilling, food processing and dairy processing industries. Applications for such samplings range broadly from process monitoring to laboratory and research applications. For example, sampling is commonly used on dairy farms for herd management or in regulated manufacturing facilities. The sampling is used to detect and control microbial contamination, spoilage microorganisms, food-borne illness, and environmental mastitis both within systems being sampled and externally of such systems. While preferred embodiments of this invention will be described with respect to its sampling use and application in the dairy industry, it will be understood that the invention is not to be construed as limited to use in that industry or to the application described, or to any limitations associated with the specifics of the components or methods disclosed with respect to such preferred embodiments.
Various methods and devices have been employed to perform sampling tasks. Typical sampling techniques commonly involve discrete or isolated sampling from a laminar portion of a fluid transport line. Typical such sampling systems and techniques that have been used in the dairy processing industry are described in U.S. Pat. Nos. 4,941,517; 5,086,813; and 5,269,350. To the extent that such patents may be used to assist the reader in understanding principles and examples of sampling apparatus and methods, they are herein incorporated by reference.
While the apparatus and techniques described in these patents are particularly applicable to systems designed to accommodate them, there also exists a need to perform sampling in existing enclosures and fluid transportation systems that have not been designed for sampling functions. Such systems typically require redesign or retrofitting to accommodate sampling functions. Such retrofitting can be expensive and/or difficult to achieve, can require significant system downtime in implementation of the sampling function and/or replacement of parts to maintain the system, or can lead to system degradation or contamination of the system being sampled. For example, one known method of discrete sampling of fluid involves inserting a needle through a sealing gasket located between connecting ends of pipelines of the fluid transportation system. Problems arises from this method as this method is not aseptic because the gasket becomes so perforated after repeated sampling that the gasket may lose its sealing integrity or introduce contaminants into the system through the perforations. This method requires that the gasket be replaced, which can become expensive both in labor costs and shut down costs.
There are many applications wherein it is desirable to obtain a continuous sample from fluid transportation systems or fluid processing enclosures. The discrete sampling methods typically extract a discrete sample size limited to the volume of a hypodermic needle and syringe. Typically the needle is inserted, fluid is drawn, and the needle is removed. It would be beneficial in some applications to have a system that could draw a continuous, controlled and constant sample volume over an extended period of time. A sampling device that facilitates this feature would also need to accommodate larger volume samples and a means to cool the sample during longer sampling time periods. While continuous sampling techniques have been tried, they have generally not been particularly effective, efficient or reliable in maintaining the aseptic condition of the system during the sampling interval.
Known discrete sampling techniques have not proven to be readily adaptable to continuous sampling techniques. For example, if the sample is taken from a region of laminar fluid flow, the sampling needle can create a venturi effect in the fluid flow being sampled, which can cause reverse flow siphoning from the collected sample and back into the sampled fluid. If such suction effect is disrupted by providing the sampling system with an air gap, the aseptic nature of the sampling system is compromised.
Improvement in methods and devices for sampling is needed, generally to better accommodate: ease of repeated continuous sampling of large volumes; structural integrity of fluid transport equipment; management of contamination; and convenience of continuous and controlled volume sampling. The present invention addresses these and other needs for continuous sampling of fluid transportation systems or fluid processing enclosures.