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Section 3: OPERATION
3.1 Starting Procedures
3.1a Starting a Welch Dry Vacuum Pump.
Before attaching the pump to a system it is well to familiarize yourself with the function and action of the
pressure vacuum pump which you have acquired. Review the power requirements as described in Section 2.6.
Welch recommends running the pump for a few minutes to warm it up before use. The warm-up improves the
pumps ability to handle humid air.
3.1
b Cleanliness
Take every precaution to prevent foreign particulates from entering the pump. Particulates will damage the
pump’s performance. If you find that particulates will come off the process during evacuation, a particulate trap
in the foreline will work.
3.2
Leak Detection
The importance of eliminating all leaks in a vacuum system is obvious. The pump must remove this added
volume of leaked gas to maintain the desired vacuum. Leaks for these pump can be located by slightly pressuring
the system and painting the suspected area with a water / liquid dish soap solution. Escaping air will produce
soap bubbles.
3.3
Operating Pressure Range
Models 2090 and 2085 Dry vacuum pumps are designed to be run from atmospheric to their maximum vacuum
level on the intake side. Consult the Specification Table in the back of this manual for the ratings for your
specific model.
3.4
Shutdown Procedures
After use, Welch recommends the pump be run for about 2 minutes disconnected from the vacuum process with
air or dry nitrogen passing through the pump. The air or dry nitrogen pumped through the mechanism will purge
out water vapor or droplets of water condensate that may have formed on the inside of the pump. Purging of the
pump mechanism helps prevent corrosion.
Section 4: MAINTENANCE
Welch dry diaphragm vacuum pumps are 100% oil-free. No maintenance is necessary for the bearings. All
bearings are sealed and permanently lubricated. Lubrication should not be attempted.
WARNING
The pump is not recommended for pumping highly corrosive acid or
base vapors or gases. Serious damage to the pump will result
and will shorten the pump’s service life.
