Gas System¶

Basics: The system uses a single pressure sensor (gauge monometer) linked to a controller and two solenoid valves (which are default closed). When the pressure drops below some initial set-point (all this setpoint-1), the input valse will open and allow gas into the system. Once the pressure reaches a second setpoint (setpoint-2) the valve will close. A third setpoint can also be set which will open the release solenoid and allow gas out.

Current settings: The sensor relays a signal at 1V (plus some small amount based on cable impedance) for atmospheric pressure (gauge). Setpoint-1 will engage at 1.048, opening the input valve, at 1.056 (setpoint-2) the valve will close. The readout on the front of the controller will display the current monometer measurement. At Temple, the tank had a very slight leak rate, which led to an oscillation of on-off every 5 to 10 minutes.

Turning the system on/off and making changes: The controller is itself controlled by a laptop nearby. Turn on the controller by the switch in the back. The login pin for the laptop is 3141 (the first 4 digits of pi). After logining in, there is a desktop icon called "platinum". Open this program. (Note: if the last session is running, be sure to close it out and restart the program). You should be directed to a screen with a "Connect" button on the bottom left. Click that to connect to the system. Next you will see the main screen with a box on the right that has buttons that say "wait", "run", "idle", "standby","stop","pause". The important buttons are "run" and "stop". By clicking run, the system should engage and the readout on the screen should match what is on the front of the controller. To stop, click "stop".

[https://redmine.jlab.org/attachments/download/938/M5461-gas-controller.pdf | Gas Controller Manual]

The Controller is is the Omega CS8DPt Universal Benchtop Digital Controller.

To install the Platinum Configurator Software go to the
CS8DPT-Series\Platinum_Firmware_Software_1.4.0.6\Platinum_Configurator_1.5.2.0 folder and click setup. (No additional USB Drivers were needed for Windows 10)

Omega's CS8DPT Platinum Configurator Software Allowed the Setpoint and display resolutions
to be increased from 1 to 3 decimal places.

*Note: The front Panel USB Connector is a full size USB-A Receptacle. You will need a USB Cable with eith Double USB-Male Connectors or an adaptor to change from a USB-B to USB-A male.

• Note: Software does not display more than 1 decimal place. Parameters appear to be accepted to 3 decimal places even thought the software display
  appears to round off to 1 decimal place.

The front panel input pins are labeled from (1-10) Right to Left

The Process (Voltage) is set to +/- 10V as the Omega pressure sensor output is from 1.0 - 5.0 Volts

The excitation voltage is set to 10V (9-30V) allowed range for Omega PX181B-030G5V Pressure Sensor

Note: At baseline (atmospheric presuure) the sensor output voltage measures about 1.043V with short cabling. It goes up to about 1.050 Volts with all 70 feet of cabling attached.

The PX181B Sensor needed to have its Black (-Vin) and Green (case) connected to the controller's Pin 1 Analog Return (Now wired into the controller front panel cable)

The sensor white (Vout) is connected to the controller pin 2 (Analog Positive input)

Both Solenoid Valves assemblies are Gold Ring Part Number 04F20C1108AAF4C05 with Normally Closed Valves; valves are closed when de-energized
and open when energized.

The Valve Solenoid from the Nitrogen Tank is connected to Output 1 (orange plug/socket) which is controlled by Setpoint 1.

The Overpressure Valve solenoid is connected to Output 2 (white plug/socket) which is also controlled by Setpoint 2.

Configuration of Outputs:

NOTE: Outputs can be assigned to either Setpoint 1 or Setpoint 2 (but not both) through the Omega configuration software.

Output 1 (Orange Plug and Socket and which controls the gas inlet) which is governed by setpoint 1 (set to 1.053 Volts) is connected to the SPST Relay (StR1)
whose mode is on/off (oNoF)and whose action is reverse (RVRS) which implies that Output 1 will be activated when Setpoint
1 (1.053V) is reached/exceeded (from lesser to greater voltage/pressure). A deadband (dEAd) of 0.008V was set. This was setup in Ed's shop on 1/28/2020 with the short cabling which read about 1.043V at ambient.

After the sensor voltage exceeds Setpoint 1 (1.053V), once the sensor/process voltage drops, Output 1 will not be deactivated until
the sensor voltage drops to 1.048V. (1.053 minus 0.008V)

Output 2 (White Plug and Socket) which controls the purge/relief valve and is governed by setpoint 2 (set to 1.150V) is connected to the Solid State Relay (dC1) whose mode is also on/off (oNoF) and whose action id direct (dRCt) which implies that output 2 will remain off in most (hopefully all) situations.

Output 2 will activate when the pressure gauge voltage rises to 1.125V. Since no deadband is set, the valve will deactivate once it drops below 1.150V. With a deadband set, that off voltage would be lower (it would take longer to shut the valve off).