PCM-2 Manual.pdf - Voss Associates

Gas use is expressed as the percentage of time the inlet valve has been opened in
order to maintain pressure. The long-term value represents total consumption
since the counter was last reset (or since the unit was powered on). Short term
use covers the latest five minutes. If a gas leak occurs, the short term number
will increase more rapidly than the long term value.
If the control knob is pressed, the display will prompt for entry of a password.
This value is permanently set at "1287". Rotate the knob until the first number
"1" shows, then press the knob. Repeat this procedure for the other three digits.
If the knob is pressed and held for 3-4 seconds during normal operation, both gas
use counters will be reset to zero. This should be done after purging the system
to obtain steady-state gas consumption values. No password is required to reset
the counters.
Once a correct password has been entered, the first screen displayed is pressure
setpoint. Rotate the knob to increase or decrease this setting. To accept the
displayed value, press the knob.
The second control screen offers to initiate an automatic purge. If the knob is
rotated one click, the word "NO" will be replaced by "Yes." Press the knob to
accept the displayed choice. If "Yes" is accepted, another window will be
displayed in which the desired purge time may be set. Rotate the knob until the
correct value is displayed, then press to begin the purge cycle.
Finally, another "Yes/No" screen will offer to reset the long-term gas use counter.
Again, rotate the knob to make a selection, then press it to accept.
Calibration
When initially setting up an instrument, initiate a detector purge and adjust the
flow valve to approximately 800 cc/minute. Allow a minimum of 4 hours at this
purge flow rate to completely purge all of the PCM-2's detectors. Reset the flow
rate thereafter to approximately 150 cc/minute for normal operation.
Zero Pressure
Reference Reset NOTE: This step should only be performed ifthe gas manager's pressure
transducer is replaced or if IlOIl-zero pressures are displayed when
the instrument is actually at zero pressure. Resetting the zero
reference when there is actually pressure in the detectors will result
in higher than desired operating pressures and may damage both the
detectors and the pressure transducer.
Before resetting the zero reference, disconnect the system exhaust hose from the
gas manager. This will insure that the pressure transducer is actually at zero (i.e.
atmospheric pressure).
1776 rCM2.M/\N/ Il:;v /\I/\p/i) 19%