4.5 - GREEN MACHINE
™
- North America - Installation, Operation, Maintenance, & Troubleshooting Manual
Chapter 7: Maintenance Procedures
Page 103
7.4
Pressure Sensor Verification Test
This procedure was written to verify the Pressure Sensor is operating properly and within
specifications: The Pressure Sensor reading on the VST Control Panel PLC Main Screen is
checked against atmospheric pressure at the Pressure Sensor.
7.4.1
Safety:
Use lockout-tagout procedures prior to starting work.
7.4.2
Procedure:
1.
Turn OFF power to the VST Control Panel at the Power Switch located on the front of the VST
Control Panel.
•
This will allow 24 VDC power to the PLC and the Pressure Sensor but will disconnect 115 VAC
power to the GREEN MACHINE. Power to the PLC and Pressure Sensor will remain ON.
2.
Follow lockout & tagout procedures prior to starting work.
3.
Unlock the hasps and remove the cover from the GREEN MACHINE.
4.
Turn the handle on the 3-way ball valve located below the Pressure Sensor to horizontal (Closed)
so the Pressure Sensor will read atmospheric pressure.
See Figure 7-8
•
With the 3-way valve handle turned horizontal (Closed), the valve will not be open to
gasoline vapor.
5.
Remove the ¼”
NPT Hex Plug from the side of the 3-way ball valve.
See Figure 7-9.
6.
Wait at least 2-minutes for the pressure to equalize before reading the pressure on the PLC Main
Screen.
7.
At the VST Control Panel PLC Main Screen, make sure the Pressure reading is 0.0 +/- 0.10 IWC.
See Figure 7-10.
The Pressure Sensor Specification at atmospheric Pressure is 0.0 +/- 0.10 IWC.
•
If the pressure reading is within specifications, the Pressure Sensor is reading correctly.
•
If the pressure reading is outside the specification, replace the Pressure Sensor.
In the IOMT Manual, See Chapter 9, Section 9.4 for replacement procedures.
8.
After testing
is complete: Reinstall the ¼” NPT Hex Plug
on the 3-way valve. Use gasoline
resistant PTFE tape on the ¼” NPT Hex Plug pipe threads prior to installation.
9.
Turn the handle on the 3-way ball valve located below the Pressure Sensor to vertical (Open) so
the Pressure Sensor will read UST pressure.
See Figure 7-8.
(CAUTION: IF THE 3-WAY VALVE HANDLE IS NOT VERTICAL AS SHOWN IN FIGURE 1, THE GREEN
MACHINE WILL NOT OPERATE PROPERLY AND MAY CAUSE DAMAGE TO THE VACUUM PUMP.)
10.
Put the cover on the GREEN MACHINE and lock the hasps.
11.
Turn ON power to the VST Control Panel at the Power Switch located on the front of the VST
Control Panel. The GREEN MACHINE
is now operational and will operate if the UST pressure is
greater than or equal to 0.20 IWC.
12.
Check the VST Control Panel to make sure the Main Screen is showing and there are no alarms.
