Added capacity

I use a lot of air tools, one of the most irritating things is waiting for, air pressure to build or rebuild,
A plasma cutter will putter through a lot! of air in a hurry, and a 3/4" drive air wrench will dump 20 gallons at 90 psi in a heartbeat.

Soo....
I picked up an old 250 gallon propane tank and ran 3/4" pex around the shop for a supply line,
After drilling and tapping the propane tank for a 3/8 pipe I added a ball valve at the bottom of one end and propped the other end 2" higher to effect a useful drain.

In a section of the 3/4" supply line next to the electrical panel I added 5 female quick connects  backed by a ball valve (I use "industrial M" for connectivity across all tools).

I brought out a 50 amp, single phase line to a definite purpose contact controlled by a water pressure pump control switch.
(Why a pump control switch? It has a manual overide that must be held closed until the pressure reaches 20lbs (if a line breaks the compressors won't run until they catch fire!))

(Edit On reflection the definite purpose contactor could be left out and use the pressure switch directly if you could find a 50 amp rated pressure switch....)

Off of the 50 amp contactor I set an old 6 pole breaker box with 5, 20 amp 120v breakers wired to five simplex 20 amp outlets.

Now I have my old one lung 1/2 hp oil lubricated compressor feeding into the supply line (and charging the 250 gallon tank),
with its local control set to cycle between 100 - 120 psi,

(via a double male ended 6' hose! (hence the ball valve behind the quick connect))

it can keep the system charged, and the water pressure switch will turn it off in the case of a line break when I'm not in the shop.

When I have a  big job to do I simply add my two 1/2 hp oil less, portable contractor type, compressors into the next two ports and plug into a simplex outlet,
They are set to cycle between 90 and 110 psi.

If I still need greater capacity two more can be plugged in (I'll keep an eye open at the dump (people throw them away all the time!))

Still to come, a lean to, to get the air compressor racket out of the shop!!

old propane tank as air compressor tank..
having been in accidents that changed my life I believe in safety first.
all the residue need to be flushed from that tank or you might be putting yourself in danger.
there have been accidents including one that really sticks in my mind with such a set up.
a farmer did just as you are, used an old propane tank to use as an air tank.
in hot summer he was filling a tractor tire and combustable residue in the tank caused a violent explosion in tractor tire and killed him dead.
the tank needs to be cleaned of all liquid propane residue to be sure you're safe.

Yup!!

Your local Propane company can evacuate the tank if you don't barbecue....

Then take out the top valve, and put an air line into it, unsealed..... flush it out with air (or better yet argon or nitrogen) thoroughly prior to drilling on it!!

Leave all the valves and openings open while you are working on the tank proper......better to have a pressure relief point, pointed away from you, than the only one available the one your working on.

bruce Fine wrote:old propane tank as air compressor tank..
having been in accidents that changed my life I believe in safety first.
all the residue need to be flushed from that tank or you might be putting yourself in danger.
there have been accidents including one that really sticks in my mind with such a set up.
a farmer did just as you are, used an old propane tank to use as an air tank.
in hot summer he was filling a tractor tire and combustable residue in the tank caused a violent explosion in tractor tire and killed him dead.
the tank needs to be cleaned of all liquid propane residue to be sure you're safe.

I've done this on a smaller scale with old 30lb RV tanks. I'd love to scrounge some larger tanks...

My take on residue was to get the valve off, rinse with water, and then leave the tank open for a couple years. When I got back to it, the tank no longer had the distinctive scent of the propane additive.

I took this as a good sign, and perhaps this practice.is an excess of caution... but I really prefer not exploding..

Hey guys... this is a good topic of the sort that people deeper into homesteading would be interested in. Please cross-post to https://permies.com/t/102420/Homemade-Rigs-Equipment-Apparatus

Also, if possible, maybe illustrate with some pics.