this switch 97 determines and detects as to whether the relay 18 is to be activated depending upon an increase or perhaps a rapid or accentuated decrease in the signal being detected with the signal then passing through the comparative amplifier 89 63 for conduct of voltage to the contact closure or relay 18 as previously explained the outputs from the amplifier 89 as by way of the circuit lines 98 are for functioning of the relay 18 in addition to the relay indicator 64 and which provide for generation of an alarm or other signal indicating that excessive parameters during fluid flow have been encountered the ouput voltage at 18 may vary between 0 to 5 volts fig6 as previously explained discloses another of the display unit circuit cards generally this circuitry discloses an integrated circuit 99 and which generally functions to take the signal from the detector unit 6 to process it and to provide a readout of digital signals to the display 14 this type of integrated circuit 99 may be of the type that can be obtained from national semiconductor located in connecticut and can be obtained as model no add3701ccn the signal to the integrated circuit 99 is conducted by way of circuit line 100 from the amplifier 85 by way of the identified circuit line 88 and from the lead 101 the various circuitry such as the variable potentiometers 102 and 103 provide a reference and feedback voltage respectively to.