Can build pressure in tank but not out the hose

by kyle
(wyoming,MI,usa)

checked regulator and know i dont know

craftsman 4hp, 25gallon,

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Bill says...

Kyle, if your air tank has pressure in it, and you open that tank to atmosphere, air will flow out. Open the tank drain for a second if you want to see what I mean.

Therefore, if the air isn't coming out of the hose, and you have more than 15 PSI air pressure in the tank, you have a blockage in the discharge line.

Make sure the regulator is open (what pressure is on the gauge) as some of them can have the pressure turned down to zero, and then air won't flow through them.

Other than that, since I don't know what you've got connected up to the discharge port on your compressors, I can't comment on what might be stopping the air flow.

Cheers,

Bill

Plumbing air lines; materials & sizes

by Chuck Miller
(Battle Creek, MI USA)

I'm installing an IR fixed compressor in my shop. It's a 5HP 2 stage unit rated at 15.8 CFM at 902 PSI and 175 PSI max. pressure. I'm planning about 200 ft. of air lines around the shop. I like the idea of PEX pipe and have been looking at using PEX-AL-PEX tubing with max. pressure rating of 200 PSI. Is this overkill? Is there a cheaper PEX solution that would function as well?

On the air line size, I'm planning on 3/4" lines around the shop. But I'm stumped as the compressor has a 1/2" NPT outlet. Does that mean 3/4" pipe would be overkill? I think not, but want to confirm. The outlet size on the compressor could only be changed by drilling and tapping a larger hole, it appears.

Thanks,

Chuck

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Bill says...

Hello there, and thanks for your questions.

15 CFM at 90 PSI, surely?

Before using any plastic for compressed air, contact the manufacturer for approval. I know of very few plastics that don't lose pressure rating as temperature goes up, and even in Battle Creek MI you get summer... sometimes! :-) If the temps exceed the pressure rating of your line, and that is quite possible, then boom!

You can plumb any size line around your garage you like. The larger the line the more air you have pre-compressed in that line. The air mains act as a small reservoir, and there is no down side to that. Make it larger rather than smaller.

Make sure you read the plumbing pages about how to get water out of the mains so it doesn't run down your drop lines.

I would have no problem using 1/2" polyethylene tube (this is rated for compressed air) as the main and drop lines of 3/8" or 1/4" poly too, but the size really depends on what the drops are feeding. If they are feeding air tools, maybe use 1/2" hose as the drops, as you won't restrict flow as much this way. More info on hose, tube and fittings here on the site for you.

Cheers,

Bill