To Minimize Foreline Pump Damage From Ammonia - HP 5973 MSD Hardware Manual

 Maintenance
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To minimize foreline pump damage from ammonia

Gas ballasting for an hour every day removes most, of the ammonia from the pump
oil. This will greatly increase the life of the pump.
C A U T I O N Only perform this procedure if the pump is at normal operating temperature. The water in
the air can cause condensation of the ammonia at the ballast valve if the pump is cold.
Ballast control
1 Open the ballast valve on the foreline pump all the way (several turns
counterclockwise)
2 The sound of the pump will get much louder.
3 Leave the ballast valve open for one hour.
You can continue to run samples while the pump is ballasting.
4 Close the ballast valve.
Leaving the ballast valve open all the time will result in loss of pump oil and damage
to the pump.
C A U T I O N Always purge the flow module with methane after flowing ammonia.
The use of ammonia reagent gas also requires that the foreline pump oil be changed every
2–3 months instead of the usual six months.
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