Condec UPC5110 - Manual (Page 10)

Operation 7
Figure 2-3. Pressure or Vacuum Measurement Sequence
NOTE: UPC5100 shown, AC Input (7) and Fill Port (4) are on back side of UPC5110 Rack Mountable Calibrator.
2.5 Vacuum Measurement Sequence
See Figure 2-3 above and proceed as follows:
1. Turn the MODE SELECT valve (10) to the VACUUM position.
2. Close the COARSE ADJUSTMENT valve (2) clockwise and open the VENT valve (8), counter-clockwise.
3. Zero the unit by pressing the ZERO button (12).
4. If only pressure measurements greater than atmospheric pressure are required continue to step 4.1. If
simultaneous pressure measurements above and below atmospheric pressure, or if a vacuum level higher
than 27” Hg are required, go to step 5.
4.1 Close the VENT valve (8) (approximately two turns to its stop) and open the COARSE
ADJUSTMENT valve (2) slowly by rotating knob counter-clockwise until the numerical display
begins to move. It will immediately activate the vacuum converter. A vacuum as low as 27” Hg can
be maintained in the system without the use of an external vacuum pump. In general, the pressure
may be changed rapidly until reaching approximately 90% of its desired final value. Closing the
COARSE ADJUSTMENT valve (2), clockwise will deactivate the vacuum converter and trap the
vacuum in the system.
NOTE: The vacuum may be vented by opening VENT valve counter-clockwise or switching the MODE SELECT to the
PRESSURE position and opening the COARSE ADJUSTMENT valve counter-clockwise.
4.2 Use the COARSE ADJUSTMENT (2) and VENT valve (8) to obtain a specific pressure reading.
Both provide precise control. As the pressure approaches the desired value, the valve being used
for control should be rotated slowly clockwise to its closed position.
4.3 To obtain exact pressure readings, slowly rotate the VERNIER control (13) knob in the direction
required (counter-clockwise to increase vacuum) as indicated by the electronic numerical display.
5. If simultaneous pressure measurements above and below atmospheric pressure are required, or if a
vacuum level higher than 27” Hg are required, connect a vacuum pump to the VACUUM/VENT port (15)
as shown in Figure 2-3 on page 7.
6. Open the VENT valve (8). Close the COARSE ADJUSTMENT valve (2) and apply power to the vacuum
pump and allow it to evacuate the system for several minutes or until the digital display reading reaches
equilibrium near zero PSIA. Press the
ZERO button to establish a zero reference on the display.