Gasboy Gilbarco Global Pumping Unit Operation Manual User Manual
Page 41
MDE-4447A Global Pumping Unit Operation and Service Manual · May 2008
Page 37
Vapor Lock Causes
Vapor Lock Conditions
Multiplying the 2.7 Working Pressure by 2 equals 5.4 inches of vacuum that the pump can
create before the product turns to vapor. See
.
Figure 6-11: PSI and Vacuum Equivalents - Vapor Lock Conditions
It still takes 8 inches of vacuum to deliver the product, but with higher temperatures, there is
only 5.4 inches of vacuum to lift the product. The result is Vapor Lock.
Figure 6-12: Vapor Lock Conditions
The pump plays a very small part in vapor lock situations. The main reasons for vapor lock are
as follows:
• Installation
• Amount of product in the storage tank
• Vapor Pressure of the product
Note: Vapor lock does not occur in diesel pumps because the Vapor Pressure of diesel is
approximately 8 PSI.
The only solution for vapor lock in hot climates is to keep the installation and pump cool.
PSI
Vacuum
2.7 PSI = 5.4 inches of Vacuum