From the 1400 parts drawing, it does looks like the ballast valve goes into the lower port, which is connected via a passage in the plate, to the high pressure, second stage, roter chamber. Isn't that where we want the bleed air to go?
The top port looks like it may be in some sort of oil passage way connecting the two stages of the pump, but outside the rotor chambers.
If the LOWER port is the one to vent, then it will probably need an elbow and a short vert1cal nipple to mount the actual bleed valve air inlet above the pump chamber oil level. If not, oil will run out the valve, if the pump is shut off with the valve open. That may be why the Welch OEM ballast valve has such a long needle valve body.
Created on Tuesday, April 10, 2001 7:45 PM EDT by Thomas D Dressel