Gasboy Gilbarco Global Pumping Unit Operation Manual - Manual (Page 26)

Troubleshooting Vacuum Gauge Readings (Inches of Mercury)
Page 22 MDE-4447A Global Pumping Unit Operation and Service Manual · May 2008
Vacuum Gauge Readings (Inches of Mercury)
The following table shows normal vacuum gauge readings for a variety of lift vs. run
situations.
Notes:1) The following table shows normal vacuum gauge readings for general lift vs. run
situations. This is intended as a guideline only. Readings will vary depending on
other factors, such as pipeline size, number of bends, elevation, fuel composition and
so on.
2) Readings are listed in inches of mercury (in-hg). Some gauges may read in
centimeters of mercury (cm-hg), Pounds per Square Inch (PSI) or bar. See
Conversion Factors .
Conversion Factors
• 1 in-hg = 2.54 cm-hg
• 1 in-hg = -0.491 PSI
• 1 in-hg = -0.034 bar
• 1 ft = 0.3048 meter
Use Gauge Readings to Troubleshoot Self-Contained
Dispensers
There are a variety of conditions that can contribute to no delivery or slow delivery. A
pressure/vacuum gauge is an important tool in determining whether the problem is on the
vacuum side or pressure side of the pump.
The vacuum gauge reading can help you determine if there are restrictions of flow in the
suction piping system. It will also help you determine the ability of the pumping unit to pump.
Note: Vacuum gauge readings in the following sections are shown in inches of mercury.
Testing Pump Vacuum
To test the vacuum of the pump, proceed as follows:
1 Remove the pipe plug in the center of the strainer or filter cover. The cover is marked for easy
identification.
2 Install the vacuum gauge.
3 Start the pump and open the nozzle to full flow for a true reading.
Vertical Lift (Feet) 3 4 5 6 7 8 9 10
Horizontal Run - 0 feet 3.0 3.6 4.3 4.9 5.5 6.1 6.8 7.4
Horizontal Run - 60 feet 3.9 4.5 5.2 5.8 6.4 7.0 7.7 8.3