Do not start the pump if the oil temperature is below 13 °C (55 °F).
The Microvac pump is water cooled and must be connected to a water supply.
The 1/2 inch NPT water inlet connection is located in the pump housing on the drive side near the bottom (Refer to
Figure 2 item 4, Figure 3 item 6, and Figure 4 item 16).
Insert a valve in the water inlet line to regulate water flow so that the temperature of the oil in the reservoir is 60-
71°C (140-160°F). Oil temperature kits are available that automatically control the water flow to maintain the proper
oil temperature (Contact Edwards for additional information). If the pump is located outside a building and subjected
to freezing temperatures, the pump water jacket should be drained or filled with anti-freeze.
The 1/2 inch NPT water outlet is located in the pump housing (Refer to Figure 2 item 12, Figure 3 item 5, and Figure 4
item 11).
The water outlet should be connected to an open drain to permit the operator to check the flow and temperature of
the outlet water periodically. There should not be a valve or back pressure in the drain line. In some cases, cooling
water must be discharged to a pressure drain. In such cases, discharge pressure must not exceed 2.41 bar (35 psig)
and no block valve should be placed in discharge line unless a 2.41 bar (35 psig) relief valve is provided to protect
pump from high inlet pressure.
Note: If condensables are present in the process gas and gas ballast is operating, the cooling water supply should
be adjusted to raise the operating temperature to the level for gas ballast (Refer to Section 4).
3.9 Pump lubrication
The performance of this pump depends largely on the type of oil used. An initial charge of oil is included with each
pump. This standard oil is V-Lube F which is recommended for general operating conditions in a relatively clean
environment. V-Lube F is a multi-grade petroleum oil fortified for oxidation protection, containing detergent
dispersants with excellent flow characteristics at low temperature.
If the pump is to be operated at vacuum levels that cause the oil temperature to exceed 71 °C (160 °F) for extended
periods of time, a heavier grade oil should be used. Stokes V-Lube G is available for oil temperatures up to 94 °C
(200 °F).
Special operating conditions may require the use of special oils. Consult Edwards for specific recommendations when
other than regular petroleum oils are being used.
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