TECH TIP: How to Avoid Oil Contamination in Vacuum Gauges

The most common problem affecting the operation of electronic vacuum gauges is oil contamination. Oil and other contaminants in the sensor may affect the ability to detect changes in a vacuum level. All electronic vacuum gauges are subject to oil contamination. The most common source of contamination is from the vacuum pump.

It is best to locate the sensor away from the vacuum pump. If the sensor must be located close to the pump, isolate the pump from the vacuum gauge with the valve before turning the pump off.

Oil is also present in all AC/R systems and can move through the piping or hoses during evacuation or pressurization of a system.

To minimize the chances of oil getting into the sensor:

• Inspect signs of oil before connecting the vacuum gauge
• Keep the sensor vertical when possible
• We recommend connecting the vacuum gauge to the side port of a YJ 18975
o Allows the removal excess fitting valve core for faster evacuation
o Properly isolate the system from the pump and hoses during the vacuum hold test

If system oil is going to move into the piping or hoses, it will happen during the first part of the evacuation when flow rates are the highest.

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