Measurement Specialties 9116 user manual Leak Mode Inputs, Supply Air

Pressure Systems, Inc. Model 9116 User’s Manual

2.3.6.4LEAK Mode Inputs

The purge/leak charge valve design includes a leak check feature capable of testing the integrity of user pneumatic connections as well as those within the Model 9116 module. For the leak mode to be used, all RUN mode pressure inputs must be dead ended (closed) by the user. When the Model 9116 is commanded into the LEAK-CHARGEposition, the CAL input port will be pneumatically connected to module run side inputs. Common reference modules will connect only the numbered run side inputs to CAL (RUN REF is not charged). True differential (reference per port) modules will connect both the measurement input and reference port to CAL. While in the LEAK-CHARGEposition, a test pressure may be applied through the CAL port which will charge the dead ended run side tubulation.

Note

Test pressures applied to the CAL port during the leak check operation must not exceed the full scale pressure of any internal transducers.

Once the lines are charged, the Model 9116 may be commanded back to the RUN position. This will reattach the charged run side lines to their corresponding internal transducer. Consecutive pressure readings from the Model 9116 will now allow user calculation of the line leak rates. Once returned to the RUN position, lack of a pressure indicates a gross leak. A slowly declining pressure indicates a slight leak. A leak is more difficult to detect as tubing volume increases. In the case of true differential units where both sides of the sensor are pressurized with the leak test pressure, an initial differential pressure of 0.0 psi should be measured when the unit is placed in the RUN position. If the measurement or RUN side of the channel leaks at a rate greater than the reference side, a resulting negative differential pressure will be measured. Likewise, if the reference port tubing leaks at a rate greater than the measurement side, a resulting positive differential pressure will be measured.

2.3.6.5Supply Air

The Model 9116 modules require an 80 psig minimum dry air (or inert gas) supply which is used to shift the internal calibration valve between its different positions. Each module contains a fitting marked “SUPPLY” for this input. Internal solenoid valves direct this supply pressure to the proper control port on the calibration valve as required by instrument commands. The absence of sufficient supply air to the module will prevent the calibration valve from shifting into requested positions (i.e., RUN, CAL, PURGE, LEAK-CHARGE).

WARNING! Supply air should not exceed 125 psi (875 kPa). Excessive pressure may damage the internal solenoids.

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