Vacuum Setup Help with Pics

[Ed Scolforo]

These, hopefully will help diagnose my problem . If I plumb directly to the pump, eliminating a filter, I get a reading of 20 with the breather filter on the output side and 27 with the breather off. With JUST the bigger filter on, I get a drop to 13 with the breather filter on, and 18 with it off. The gauge needle fluctuates heavily. I epoxied where the 1/2" barb goes into the bottom of the filter and also where the short nipple comes out the other side of the filter to try to eliminate leaks. Blue compressor hose and clamps. Observation: sometimes I hear a few knocking noises from the pump, which is brand new. Is this normal? I'll finish this up in the next post.
Ed

[Ed Scolforo]

Here's the other setup I tried, using a lawnmower fuel filter. An interesting thing here is that it doesn't matter if I have the breather filter on or not, I get a reading of 18 either way. And the needle flutter is much less if I have the breather filter on. What do you guys usually do with the outflow side? I'm hoping that someone smarter than I can help me figure this out. Thanks!
Ed

[Kurt Rosenzweig]

Hey Ed! It sounds like the big filter was leaking and you solved it with the lawn mower filter. As far as the output side I just let it dump in the attic where I have my pump. Also I remember reading somewhere not to use Teflon tape at the pipe connections but I can't remember why. I didn't have that problem cause I used copper pipe and soldered all my connections. Your gonna also need another filter on the Tee that you have your ball valve on cause when you adjust the valve to reduce pressure to center a piece it's gonna be sucking from there. Here's a picture of my setup. The filter on my Tee was picked up from my local auto parts store. Looks like a little K and N filter. The switch goes to the pump in the attic. 18 sounds a little low but I may be wrong. As far as the sounds your hearing from the pump I know my pump is pretty smooth and quite

http://i99.photobucket.com/albums/l3...g?t=1166636295

[Ed Scolforo]

Hey Ed! It sounds like the big filter was leaking and you solved it with the lawn mower filter. As far as the output side I just let it dump in the attic where I have my pump. Also I remember reading somewhere not to use Teflon tape at the pipe connections but I can't remember why. I didn't have that problem cause I used copper pipe and soldered all my connections. Your gonna also need another filter on the Tee that you have your ball valve on cause when you adjust the valve to reduce pressure to center a piece it's gonna be sucking from there. Here's a picture of my setup. The filter on my Tee was picked up from my local auto parts store. Looks like a little K and N filter. The switch goes to the pump in the attic. 18 sounds a little low but I may be wrong. As far as the sounds your hearing from the pump I know my pump is pretty smooth and quite

http://i99.photobucket.com/albums/l3...g?t=1166636295

Kurt, based on what others report their vacuum pulls to be, it sounds like I still have some major leaking. Thanks for the tips.
Ed

[Jim Becker]

Ed, I merged the thread so all the pictures would be in the same place. You can add more than five pictures to a thread merely by replying to your own message...that gets you five more each and every time!!

Jim
SMC Moderator

[Jim Ketron]

Ed Did you try what I sugested in the other post?
http://www.sawmillcreek.org/showthread.php?t=47941

[Ed Scolforo]

Ed Did you try what I sugested in the other post?
http://www.sawmillcreek.org/showthread.php?t=47941

Jim, I tried (by hand) to unscrew that thing, and that puppy won't budge. I'm going to have to get an oil filter wrench.

[Bill Boehme]

Ed,

One problem I see is it appears from the picture that you are putting the blue hose onto threaded nipples with hose clamps. You need to use a barbed fitting or some other type designed for the purpose. The hose clamp cannot compress the hose enough to provide a seal on a threaded fitting -- there will be a spiral leakage path along the screw threads and it can very significantly affect the amount of vacuum that you can pull.

Another problem is that you are using Teflon tape. That works for sealing water lines, but not vacuum lines. You must have perfect metal-to-metal connections and use the type of sealant that is used on gas lines. When connecting to a flexible hose, use a metal to hose adapter that will give a positive seal and don't put any kind of sealant on it because the sealant will inhibit the proper functioning of the metal to hose connection.

Does the automotive in-line filter have barbed fittings? Barbed fittings would be ideal, but if they are screw fittings, you should get an adapter to go to barbed fittings. I am not sure that the automotive gasoline filter is suitable for this purpose, because it may not filter out really fine dust.

The muffler that I see on the outlet of the pump is different from what I was expecting. It looks like a muffler with the top broken off. The variety that I am familiar with look like a truncated cone that stands about an inch tall above the nut. By the way, it is not a filter, it is a noise muffler. It needs to be on the outlet side of the pump to keep the noise level acceptable.

It would be very helpful if you could give the model number of the pump? That would help a lot to determine what the vacuum ought to be. If it is a 0523, 0823, or 1023 series pump, then 26 in-Hg is the spec value for maximum vacuum. Some other models have a spec value of 20 in-Hg, and there are even some with a spec value of 10 in-Hg.

This question has nothing to do with air leaks, but does the air filter have another port on the side or is the port on the top the only other one? Just wondering because I have not seen this configuration before.

Bill

[Bill Boehme]

I re-read your post an I think that I understand a bit more clearly what you are saying. I was getting confused over all of the configurations and finally realized that when you mentioned the breather filter, you meant the muffler and not the in-line filter on the vacuum side.

What all of this says to me is that the vanes in the rotary pump are not providing a good seal and that there is a lot of back-flow. The difference that you give between having the muffler on or off is the main reason for my diagnosis. In a situation with the inlet side basically blocked, there should be very little difference between measured vacuum with the muffler on or off.

A rebuild kit contains new vanes, shaft seals, and gaskets. It would also be good to get a new muffler. All of this might set you back about $50 -- I haven't checked the price in a long time so I may be way off. There is also a flushing fluid that you should get while ordering parts. It needs to be used periodically to clean the crud out of the pump.

Bill

[Bill Boehme]

Jim, I tried (by hand) to unscrew that thing, and that puppy won't budge. I'm going to have to get an oil filter wrench.

I think that you have to push and turn sort of like the prescription bottles with the safety caps.

Bill