Compressed air storage volume

[Ike Carlson]

I am in the process of getting my larger air compressor put together. My existing tank is 60 gallons and the new one is 120 gallons. I am thinking of plumbing them together for more storage. Who can argue with 180 gallons of air?

My problem is I feel bad using such a sturdy tank (325 psi @650°F) at such low pressure (175 psi). My old pump didn’t make a ton of air, but it would pump to at least 285 psi. (That was the pressure switch cutoff)

I think the 120 gallon is rated for at least 250 psi. I’ll have to check again. Would it make much sense to run both pumps and let the old one top off the tank to ~240 psi? That’s a lot more usable air before it kicks back on again.

The new compressor should make around 17 cfm. The old one is maybe 2-4 cfm. The old tank is still in very good condition.

 

[OccupantRJ]

 

[PCustoms]

Yep....

@Ike Carlson post the tags on the tank.

 

[mike93lx]

Yep....

@Ike Carlson post the tags on the tank.

And the pump info...

 

[Ike Carlson]

This is the existing tank/pump. The tank is extremely heavy. I can’t find anything for the 2g compressor online. I’m thinking that means 2 cfm at whatever speed it is rated for? I was running it at about 850 rpm. It made enough air for light shop work and filling tires.

The new tank is a 120 gallon propane tank. The pump is a saylor beall 705 clone that will run at about 660 rpm for about 17 cfm. I will upload those pictures in a little bit.

 

[finn]

Those small high pressure low flow pumps were probably used to run some sort of air actuators in an industrial application.

In my case I decided that adding storage capacity won’t buy me much in return for the lost floor space and added clutter and complexity. It‘s really pump delivery that limits me when running the blast cabinet or die grinder / cutoff wheel. My tank is 80 gallons, and it doesn‘t take real long to use the head between my regulator setting, say 100 psi, and the high pressure cutoff setting, 165 psi.

Your tanks are obviously larger, though.

Once I reach the pressure switch ( or more properly regulator setting ) lower limit, air delivery is 100% limited by pump delivery, and having a larger storage capacity doesn’t help much. In fact having a larger storage capacity then means the pump has to run longer to get the system back to pressure.

For me, a higher horsepower motor, ie 5hp and associated pulley to spin my Champion R15 pump a little faster is about all that would help.

 

[Ike Carlson]

This is the new tank. It is 240 psi working pressure.

 

[American Locomotive]

My recommendation is not push 70 year old pressure vessels to their limits.

 

[PCustoms]

My recommendation is not push 70 year old pressure vessels to their limits.

At minimum they need to be hydrostatic tested. Plenty of threads here how to safely do that.

 

[Ike Carlson]

I can/will test it myself. That's for sure. I’m not worried about it failing because it has been closed and there was still just a little bit of propane left in it. I will do an internal/external exam/cleaning and pressure test with water.

I will obviously have to add a water drain. I might run a dip tube from the top for that to avoid drilling/welding on the bottom of the tank. The westinghouse tank has a dip tube that comes out the side.

 

[logical]

What are your compressed air needs?

 

[Ike Carlson]

What are your compressed air needs?

Air tools: die grinder, impact, ratchet, blow gun, drill, small blast cabinet, tire chuck, air chisel/hammer, spray gun, nail guns, palm nailers.

 

[finn]

Air tools: die grinder, impact, ratchet, blow gun, drill, small blast cabinet, tire chuck, air chisel/hammer, spray gun, nail guns, palm nailers.

These all operate at about 100 psi, give or take. Your electric bill is going to take a severe hit if you want to store above the typical 160-175 psi, too.

Sorry, but I don’t see where any of those tools really benefit by a larger than ”normal”, ie more than 60-120 gallon, tank.

This sounds like one of those “I have access to a giant tank, what can I do with it?“ deals rather than a rational plan to resolve a real issue.
Or maybe I’m missing something….

A SB pump, five or 7.5 hp motor, and standard 60 or 80 gallon tank at 175 should handle everything you throw at it.

Turn the propane tank into a smoker and throw a bbq party for the neighborhood this summer. Put it on a trailer and start a second career as a Pit Boss. You’ll be money ahead.