Filter question for Gast 0523 users

[Tom Albrecht]

I have a new Gast 0523. I see that it has felt filters within both the intake and output ports built in behind the screw caps. Do I need to use an additional intake filter of any kind?

 

[Dwight R Rutherford]

The supplied filters that are part of the Gast 0532 have worked well but additionally I have a Fram G-2 filter installed at the bleed relief valve since that will be sucking air directly from my dusty shop while the pump is running.

 

[Bill Boehme]

I have a new Gast 0523. I see that it has felt filters within both the intake and output ports built in behind the screw caps. Do I need to use an additional intake filter of any kind?

Yes, you do. The felt filters should be considered backup if the primary filter fails. When you are sanding, a surprisingly huge amount of dust will be sucked through the wood and it will all wind up inside the vacuum pump unless you have another filter. I suggest the same type filter that is used with air compressors that uses a pleated or porous filter with a rating of 5 microns. Note that many filters are 40 microns, but in order to prolong the time between overhauls of the vacuum pump, a 5 micron filter will more than pay for itself in money saved over the long term. This main filter should be located as close to the rotary coupler as possible so that dust will not get into the vacuum gauge or other components. Additionally, a small filter should be used ahead of the bleed valve to prevent sucking in dusty ambient air. The bleed valve should be a needle valve so that you can have fine tuning control of the vacuum level. have a brass T at the vacuum port of the pump. One side of the T goes to the pump, a second leg has a ball valve that is open to ambient air, and the third leg has a ball valve in line with the hose that goes to the remainder of the system.

 

[Mike Peace]

The bleed valve should be a needle valve so that you can have fine tuning control of the vacuum level. have a brass T at the vacuum port of the pump. One side of the T goes to the pump, a second leg has a ball valve that is open to ambient air, and the third leg has a ball valve in line with the hose that goes to the remainder of the system.

Bill, I understand the need for a the valve to regulate ambient air to regulate the suction pressure at the chuck. Why do you need one at the pump? My system seems to be working fine with just the one valve. I turn on the pump and the control the ambient air valve till I get a reading on the pressure gage that I feel appropriate. I close the valve before shutting off the pump.

What am I missing?

 

[Bill Boehme]

.... What am I missing?

The shut-down procedure described in the instruction manual is what you're missing. If you don't have a manual because you bought the pump used, you can download one at the Gast web site for your model. Instead of the valves that I suggested, you could have a cap to plug the intake and also remove the hose to run open-port. The shut-down procedure involves running the pump for a specified length of time depending on your model with the input open to the atmosphere and then for a length of time with the input port blocked and then finally with the input open to the atmosphere again.

I would guess that many, if not most woodturners ignore the shutdown procedure which is meant to cool the pump and maximize vane life and the time between overhauls.

 

[william noble]

I have sold a lot of these pumps - you may want to look at the article under vacuum pumps on my web site for my recommended setup (www.wbnoble.com) - you absolutely need a second filter - I recommend the cheap (or used) coalescing filters used with air lines - get the kind with at least 3/8, preferably 1/2 inch fittings for flow rate. used ones are fine. Ones that leak a tiny bit under air pressure (for example a few small cracks in the bowl) are fine because vac pressure is much less than shop air.

by the way, I have one of that series pump, I never use the designated shutdown procedure, and it's run well for about a decade - these pumps will run 24-7 for about 5 years before requiring new vanes, and after about 3 vane changes they are pretty worn out - I know this because I sold some used pumps to a location that ran them continually aereating a sewage treatment tank and that is what they said.

 

[Bill Boehme]

I generally followed the shutdown procedure and replaced the vanes just recently. I had owned the pump for eight or nine years. I don't know what sort of care the first owner used, but when I bought it, the vacuum level was still around 24 in-Hg. The vanes weren't worn out when I replaced them, but the max vacuum level was about 21-22 in-Hg and I just happened to have a repair kit. I have been wanting to try resin treating pen blanks and needed a bit more vacuum to do a decent job so that was my main motivation. After rebuilding, the vscuum is essentially meeting the 26 in-Hg of a new pump.

I am speculating that the shut down procedure might be to redude dissimilar metal corrosion that might occur with the hot vanes and housing in contact.