Pressure Systems 9022 - Manual (Page 27)

Pressure Systems, Inc. NetScanner™ System (9016, 9021, & 9022) User’s Manual
www.PressureSystems.com 2 - 10
Test pressures applied to the CAL port during the leak check
operation must not exceed the full scale pressure of any internal
transducers.
WARNING! Supply air should not exceed 125 psi (875 kPa).
Excessive pressure may damage the internal solenoids.
2.3.6.4 LEAK 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 9016 module. For the leak mode to be used,
all RUN mode pressure inputs must be dead ended (closed) by the user. When the 9016 is
commanded into the LEAK-CHARGE position, 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-
CHARGE position, a test pressure may be applied through the CAL port which will charge the dead
ended run side tubulation.
Once the lines are charged, the 9016 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 9016 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.
2.3.6.5 Supply Air
The 9016 models require a 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).