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Gasboy Gilbarco Global Pumping Unit Operation Manual User Manual

Page 39

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MDE-4447A Global Pumping Unit Operation and Service Manual · May 2008

Page 35

Vapor Lock Causes

Reasons for Vapor Lock

It takes 1 inch of vacuum by the pump to overcome the restriction of 60 feet of horizontal
piping from the tank to the pump. See

Figure 6-8

.

Figure 6-8: Compensating for Horizontal Piping

2

To obtain the inches of vacuum required to deliver the product, simply add A, B and C.

With 9.4 inches of suction to work with and only 8 inches of vacuum required, conditions are
normal and the pump delivers the product without vapor locking.
Note: This condition exists when the product is at 60° F.

A. 9 feet of lift = 6 inches of suction

B. Angle check or foot valve= 1 inch of suction

C. 60 feet horizontal run= 1 inch of suction

TOTAL 8 inches of suction

60 Feet of Horizontal Piping = 1 inch of Vacuum

60ºF