Vacuum System Piping

[John King]

Now that I have a vacuum pump I need to start thinking about how to pipe it up. I have seen galvanized pipe and copper pipe used for vacuum system piping. Both seem to work well. Both have installation advantages and disadvantages.

Has anyone used heavy wall (sch 40 or sch 80) PVC pipe for vacuum system piping?

Seems like it should work. Reinforced vinyl tubing (1/4" and 3/8" ID) does not collapse in vacuum service. Cannot imagine that heavy wall PVC would collapse. Besides, if it does collapse, it's not a safety risk.

Appreciate any thoughts/comments you may have on use of PVC in vacuum system service. - John

 

[Rob Wallace]

Why do you need a hard-piped vacuum system?

John:

In order to answer your question, I have to ask what you're using the vacuum system for.....

In contrast to pressurized air systems, I have not seen hard-piped vacuum systems, particularly when used for vacuum chucking (or for vacuum clamping or veneering using vacuum bags). Virtually every system I've seen or read about for vacuum chucking simply uses vacuum tolerant hose between the pump and the vacuum adapter at the lathe, through some form of particle filter (to protect the pump from sucked-in debris) and a vacuum "adjuster" (essentially an air-leaking system and vacuum gauge). What would be the point of hard-piping the vacuum system? Are you intending the pump to do multiple service to several pieces of vacuum-requiring equipment?

Can you provide more information to explain why you intend to have a hard-piped system?

Rob Wallace

 

[Steve Worcester]

I would have to agree with Rob, because you want to have the pump as close a possible to the lathe so that if you have a sudden leak, it is less area to evacuate and get you back to your chosen maximum vacuum.

 

[Owen Lowe]

John, I used copper from the pump to the pressure relief valve. I don't see why heavy walled PVC wouldn't work.

Here's a pic of my setup:

 

[John King]

Rob/Steve - The vacuum pump will be located away from the lathe for two reasons - 1) lower exposure to dust/debris generated during sanding and turning and 2) remove noise of the vacuum pump from the lathe working area. Hard pipe seems to be a better option than vacuum tubing for the long run (15 ft or so) of pipe from the vacuum pump area of the shop to the lathe area of the shop. Vacuum pump will be attached to hard pipe via flexible vacuum hose. Lathe vacuum spindle adapter will be attached to hard pipe via flexible vacuum hose. And of course there will be the usual assortment of valves, gages, etc. on the lathe end of the system.

Hope this clarifies what I plan to do. - John

P.S. Owen - Thanks for the picture of your installation.

 

[laymarcrafts]

John I can see no reason why this would not work, the only area that you may wish to consider is the Size and the Distance as you will have to evacuate the total volume.

Dust will not enter the system only via the Piping which is only open at two points, the Work Piece and the Balance Port which will be close to the Lathe and should have a filter.

Noise is not normally an issue with the Pumps I have sen used over the years.

In my opinion the Closer the better, my system [see my web site] is within 2ft of the Lathe.

Richard
http://www.laymar-crafts.co.uk

 

[Bill Boehme]

Almost all types of vacuum pumps are rather quiet running so it is not necessary to remotely locate them (my lathe makes more noise than my vacuum pump) -- in fact if is usually inconvenient to not have the vacuum pump close to the lathe. In any case, there is no good reason to use rigid pipe as part of the system. Use heavy walled rubber or plastic hose such as air hose for the entire length and the cost will be less because of fewer fittings and it is more convenient to be able to move things around. My set up uses heavy wall reinforced clear food grade plastic hose -- just because it was available, but regular rubber air hose is the tubing of choice for most woodturners. Also, if you are using a rotary vane pump, part of the operating procedure described in the Gast manual is to go through a shutdown cycle running open port and blocked port on the pump for several minutes each. If you have the pump remotely located, it will just make that part of the shutdown procedure less convenient.

Just a note about the shutdown procedure: many woodturners ignore it or don't know about it because they didn't read the manual, but the vanes in the pump will last much longer if you do follow the manufacturers recommendation.

 

[Steve Worcester]

I have been using rubber air compressor hose forever. My current GAST is 7 CFM and I have had no issues with collapse, etc.
The only way I could see a noise issue is ir you were using an air compressor fed venturi vacuum system. The rest are fairly quiet.

 

[Wipedout]

A

Just a note about the shutdown procedure: many woodturners ignore it or don't know about it because they didn't read the manual, but the vanes in the pump will last much longer if you do follow the manufacturers recommendation.

Shutdown procedure?? Do tell

 

[Bill Boehme]

Shutdown procedure?? Do tell

OK, I will tell.



excerpt taken from manual for oilless rotary vane pumps.

Bill

 

[John King]

End of Thread

Okay. I now believe that I was making it more complicated than necessary. I will locate the vacuum pump in close proximity to the lathe and use short runs of flexible tubing - no hard piping for all connections. Thanks to all for the good guidance and the keep it simple recommendations. - John

P.S. Glad we had this exchange today. Electrician is coming tomorrow morning to run electrical circuit for vacuum pump. Now the electrical outlet will be in the correct place near the lathe - not on the other side of the shop where I had planned. Again, thanks for the inputs. - J

 

[Ed Koenig]

I have been using rubber air compressor hose forever. My current GAST is 7 CFM and I have had no issues with collapse, etc.
The only way I could see a noise issue is ir you were using an air compressor fed venturi vacuum system. The rest are fairly quiet.

I agree with Steve. I too use rubber air hose between my lathe and the pump which is mounted inside a ventilated mdf box on casters some 20' from the lathe. It was not about sound, although it is more quiet, but about gaining space.

Be well.
Ed

 

[Vernon Oberle]

noise???

I don't know what kind of pump you guys are using but my Gast 220v unit sounds like a 747 on takeoff. I put in on the wall behind the lathe and have a bulkhead connector in the wall to hook each side up to. I then us a 220V remote to turn it off and on. the relief valve is on the back of the lathe with the vacuum guage. Total run about 8 ft. I have thought about adding a reserve tank on the lathe side that would also give a little cushion if the power goes off.

Vernon

 

[Richard Baker]

If hard piping were required, schedule 40 pvc should be adequate. Be sure whatever hose/pipe between the filter and pump is clean (inside, of course) before starting up your system.

 

[hughie]

vac systems

I am in the process of build ing a new workshop and will be hard piping my vac system with PVC pipe. As I have three lathes I will run the piping up to each one then flexible from there. The vac unit will be out side under a lean to or annex.The piping will run around close to the ceiling and have droppers for each lathe.On the long run I am fitting a compressed air connections at both end for those blocks that will occur from time to time.
The unit will be 1.5hp three phase and so I will fitting an inverter to it. Its an old cast iron industrial blower/vac used to vacate comfined spaces prior to entry,orginally a portabale unit...if you were king kong :😀


As with PVC and wood dust theres static consideration so I will run an earth strap along all my PVC piping to an earth stake outside as well.

I have a semi portable unit for the bandsaw which will be located in side on wheels and double up as a vac cleaner for the floors etc

 

[Bill Boehme]

I don't know what kind of pump you guys are using but my Gast 220v unit sounds like a 747 on takeoff. I put in on the wall behind the lathe and have a bulkhead connector in the wall to hook each side up to. I then us a 220V remote to turn it off and on. the relief valve is on the back of the lathe with the vacuum guage. Total run about 8 ft. I have thought about adding a reserve tank on the lathe side that would also give a little cushion if the power goes off.

Vernon

It sounds to me like your unit must be missing the exhaust muffler. If not that, then there is something wrong with it. The noise that my vacuum pump makes is about the same as the noise level from a scroll saw.

Using an accumulator to help retain vacuum for a few extra seconds would be of dubious benefit if the vacuum pump is located remotely so that you can't tell when it shuts off -- in that situation, the first indication of a problem would be when the bowl goes flying off the lathe after the vacuum level in the accumulator disappears. BTW, unless your planned accumulator has a check valve between it and the vacuum pump, when the pump stops, the vacuum will almost instantaneously dump its vacuum through the pump.

 

[laymarcrafts]

I am in the process of build ing a new workshop and will be hard piping my vac system with PVC pipe. As I have three lathes I will run the piping up to each one then flexible from there. The vac unit will be out side under a lean to or annex.The piping will run around close to the ceiling and have droppers for each lathe.On the long run I am fitting a compressed air connections at both end for those blocks that will occur from time to time.
The unit will be 1.5hp three phase and so I will fitting an inverter to it. Its an old cast iron industrial blower/vac used to vacate comfined spaces prior to entry,orginally a portabale unit...if you were king kong :😀


As with PVC and wood dust theres static consideration so I will run an earth strap along all my PVC piping to an earth stake outside as well.

I have a semi portable unit for the bandsaw which will be located in side on wheels and double up as a vac cleaner for the floors etc

Hughie I think we have our Vacuum [as in Vaccuum Chucking] lines crossed here?

Richard

 

[Vernon Oberle]

Loudness

I have a muffler on it. This particular unit is just loud even in the other room, but works great. I was thinking of the reserve to give a second to shut the lathe down if the vacuum pump quits. Trust me I can tell when this pump quits.

Vernon

 

[Bob Chapman]

Bill,

Do you mean that this procedure should be followed every time you finish a session of using the vacuum chuck? It seems more likely (to me) that it's a procedure to be carried out when the pump is being shut down or decommissioned for an extended period of time. Certainly I've been using my Gast oiless rotary vane pump for a couple of years now without following that procedure and without experiencing any problems.

Incidentally I use that reinforced plastic piping that is also used for compressors. No problems, it's never collapsed in use.

Bob

 

[Bill Boehme]

It's not what I mean, it's what Gast means.

The purpose is to have a proper cool down for the Kevlar vanes and to purge wear particles from the vane slots. If the procedure is not followed, the accumulation of powder-like wear particles in the vane slots will result in sticking vanes, worn slots, and greater leakage with an accompanying decrease in vacuum capability. It can also eventually lead to broken vanes. At the rate that most woodturners use their vacuum pumps, any problem would not be immediately apparent since it is a slow insidious type of failure mode. These pumps are most often used in industrial applications where wear-out becomes a more significant factor because of a greater level of usage. I can't speak for Gast about light duty use by woodturners, but the pumps do get very hot even after short periods of use -- so you can pay your money and make your choice about which way to go on preventative maintenance.