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Wow..... Do we see some stuff..... People tie the most crazy valve
arrangements off these pumps. Leaky valves, sweated fittings, check
valves, and compression fittings, we have seen it all. We do not
have a problem with the user creating a custom manifold or valve
arrangement of the intake and exhaust ports of the pumps, encourage it,
but there are some things you need to recognize.
Use our PST sealant to seal all threads. There are so many times
that these new additions leak all over the place because of improper
sealing. Teflon thread is nice, but we do not use it. In fact
no serious player in our industry uses it, hopefully
enough said.
The intake and exhaust ports sometimes are FNPT female national pipe
threads. These are tapered pipe threads. If you take a male
national pipe thread and gorilla it into a female national pipe thread in
one of our pumps you can crack the center plate casting, a very expensive and time
consuming part to replace. The pump has to basically be rebuilt from
scratch at this point. Tighter is not necessarily better in this
application. Take it easy. Medium light wrench tight with the proper
sealant, that is all that is required for a good vacuum seal.
Some of our competitors use British Fine Threads with an o-ring back
seal. Why they ever started down this path is a mystery outside of
trying to make their parts unique so you had to buy it from them. I
dunno. We have adapters for this type of thread. Generally we
take you to a NW style flange so we can get back to some semblance of
industry standard and stay away from all this fine thread work that is
tough to seal.
We make just about everything you can imagine to hang off these pumps, so
why reinvent the wheel? Yeah, our stuff might be a little more
expensive, but you get proven tested solutions and our aggravation
contribution to your current problem is a lot less.
On the exhaust side, less care needs to be taken, because it is simply an
exhaust channel to atmospheric pressure. It is not required to be
vacuum "tight". You don't need vacuum rated
seals and fittings on the exhaust port. It's at atmospheric pressure
NOT vacuum. If you have some harmful gases coming through the pump
then the exhaust should be leak tight to a hood or exterior vent. It
is not a good idea to "neck down" in any shape or size the diameter of
this port. Reducing the diameter can cause "back pressure" in the
pump during the high pressure pull down cycle and may put undue stress on
things like shaft seals or o-rings that are internal on the pump.
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