Alicat P Series Pressure Gauge - Manual (Page 8)

8
USING ALICAT PRESSURE INSTRUMENTS WITH FLUIDS
All of these devices may by used with chemically compati ble liquids providing a
couple of things are taken into account:
1. Water is about 50 ti mes more viscous than air. This is important when
sizing a pressure controller. The PC-Series which can be used to fl ow up
to 20 SLPM of gas, will be limited to roughly 0.5 LPM of water-like fl uid.
The PCR will be limited to roughly 30 LPM of water-like fl uid.
2. The factory PID tune is established using air fl ow. It may be necessary
to adjust the PID tuning parameters if you will be using a controller
with liquids.
SPECIAL CONFIGURATIONS
P, PC, and PCR-Series pressure devices are occasionally ordered with special
confi gurati ons which are covered here:
1. External Sense Port: Occasionally it is necessary or desirable to sense
the pressure at some point other than at the locati on of the pressure
device. All P, PC, or PCR-Series pressure devices can be ordered with
an additi onal NPT port which is connected directly with the pressure
sensor of the device. In these devices the fl ow path through the device
is NOT connected to the pressure sensor. See “PC3-Series Pressure
Controllers” – page 30.
2. Diff erenti al Pressure: Occasionally it is necessary or desirable to
monitor or control a diff erenti al pressure. P, PC, and PCR-Series
pressure devices can be ordered as low diff erenti al pressure devices
(usually 1 to 5 psid). These devices have two ports located on the front
face of the unit for connecti on to the points in the system where the
diff erenti al pressure is to be measured. The upstream port is for the
higher pressure and the downstream port is for the lower pressure. In
these devices the fl ow path through the device is NOT connected to
either leg of the diff erenti al pressure sensor. See “Diff erenti al Pressure
Gauges and Diff erenti al Pressure Controllers” – page 32.
PC-EXTSEN units connect a Pressure Controller (with no internal pressure
sensor) to an end-user supplied external pressure sensor. Designed mainly
for the vacuum coati ng industry, the PC-EXTSEN marries the sensing ability of
an existi ng capacitance manometer or ion gauge with a 16-Series electronics
package and internal PID algorithm. This enables fast and precise control of
extreme vacuum conditi ons in the coati ng chamber. See pages 81-83.
CAUTION! E�ceeding the ma�imum speci�ied �ine pressure ma�
cause permanent damage to the so�id-state di��erentia� pressure
transducer.