View Full Version : Compressed air- filtering and pressure regulating

08-16-2010, 04:25 PM
As some of you know, I've recently completed plumbing for compressed air distribution in my garage workshop.

I have a 2-stage 5hp 60-gal. Quincy (175 psi, 15.4cfm@100psi) and 3/4" copper pipe with a series of Z-shaped cooling runs close to the compressor. The cooler is supposed to be quite efficient in removing water. Each outlet drop of the distribution system has its own drainable drip leg.

For now I'm going to have a sandblasting cabinet (780-TL by TP, requires 10-15 cfm@80 psi, 125 psi max), some simple air tools (wrenches, die grinders, etc.) and air blow guns.

I'd like to have your opinions on the following issues:

1. What pressure would you suggest to maintain in the tank/distribution system?

2. What filters and air regulators do you think will be necessary, and were would you install them? Any particular brands/sources you could recommend?

Thank you.

08-16-2010, 04:32 PM
Shop air pressure is your choice, assuming your lines can handle it. I run 115 psi max because that's all my single stage will put out.

Like you, my primary use is air guns and a blast cabinet. No special filtering required for that.

Air tools require oil, for occasional use it suffices to squirt a few drops of oil in the tool before use. If I were using air tools all day long, I might look at an inline oiler.

I don't see the need for filters unless you get into paint guns.

08-17-2010, 12:21 PM
So, in your case, you have no regulators or filters at all, correct?

I could, definitely, decrease pressure in the tank so that no additional regulators will be required, but wouldn't it be a waste of the compressor capabilities?

Higher pressure in the tank or system means higher air capacity (possibly important for high volume applications such as sandblasting). Besides, higher compression would allow better water condensation, so the air may become drier.

It appears to me that the most efficient way would be to keep the tank and piping at the full pressure, and then regulate and filter it at each outlet.
But this would require multiple filters and regulators and, in addition to this, the regulators will need to have the full pressure capacity. This will increase the cost dramatically. Naturally, I can make the filter/regulator assembly portable and just move it from one outlet to another, but it would largely negate the convenience of the piped distribution system. Besides, having non-regulated high pressure at the quick connectors can be asking for a trouble should I connect a tool or gun directly.

I was thinking about a compromise: keeping the tank and the cooling run at the full pressure and placing the filter and regulator after the cooling run. However, I have certain areas that are designed to drain back into the tank, and I'm not sure the condensate will be able to travel back through the regulator. Again, if I place a filter after the regulator, will the returning condensate be able to simply drip into the filter? If I choose this scenario, what type of filter should be used? Does the following sequence sounds optimal: tank- cooling run- regulator - filter- distribution lines?

08-17-2010, 12:50 PM
Higher pressure means more heat created and less volume delivered. In a recent post about compressors this was coved a lot. Forrest explained clearly that reducing pressure and increasing pump speed would deliver more volume.

The air needs to be cooled before filtering, so place the filters as far from the compressor as possible.

Bill Pace
08-17-2010, 01:15 PM
I would think you will need regulators, more than one probably. As for cost I use regulators from HF, four of the small thumb controlled regs costing about $10, and then a bit more sophisticated one - about $30 - for spray painting. The small regs are used on the mill and lathe to keep from blasting my full tank pressure of 125psi toning the blow guns down to around 30psi, another is on my shop made butterfly wrench spindle bolt remover, being necessary to get it at about 90psi. Then I have one just stuck at an outlet at random to just have if I need it. 2 of the small regs and the larger one are at least 10 yrs old and never given problems sitting there holding that 125psi - and I generally leave my compressor on 24/7.

Moisture removal for me and my 2 buddies just isnt a problem here in my area, apparently it is elsewhere - therefore I dont have any devices except for the occasional tank drain.

I also dont have any filters, and I do a fair amount of spray painting - but, here again, I dont have a problem with moisture...

08-17-2010, 04:36 PM
I bought two of the HF 95439 regulator/oilers. I took one unit apart and tossed the oiler section. I put a male connector on the IN and a female quick connect on the out on both. I also put 90 degree fittings on the regulators so I can easily see the pressure gauge. I'm just one, so I just made portable regulators, one with a tool oiler. I move them around the shop where needed. The shop lines are black iron and run about 120 PSI.

Alternately, You could just get one, take off the oiler and use a whip+oiler for any air tools.

PS - all my drops have a shutoff prior to the output port and they all stay off unless I'm using that port.

08-18-2010, 02:12 PM
Good points and hints, everyone! Thank you.

If anyone has more suggrestions or thoughts on the issue, please shoot! I'm all ears.