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Intake and Exhaust Port Modifications


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.

11/27/2005 ęCopyright HyVac Products, Inc. All Right Reserved
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