Would this be good for an onboard air application? How many gallons do you think it is?

 

Think of it in terms of a 5 gallon bucket. About that size or smaller/larger? Yes the multi port design is what is required. Most of the welding gas places have a service which will pressurize the tank for you up to what your limit is for a fee. They have a cage that they use to do this in.
Built to 150# wp means working pressure. So if it is still up to those specs then it would be a good air tank up to say 120# max. JMHO

 

I want to run my A/C comp. as my air source and use this tank as storage.

 

Looks like a air tank off a tractor trailer, which I think are 3 or 3.5 gallon.

 

try plugging some of the hole with fitting from a hardware store...fill it with water...then dump the water in a bucket that can be measured in gallons

 

Same thing I thought.... But truck air tanks are available in different sizes...
But a 3.5 gallon one is a pretty standard size...

 

I passed on it. It went for more then I wanted to pay. But thanks for the help!

 

I just recently bought a 2 gallon from Summit Racing for $35.

http://store.summitracing.com/partde...5&autoview=sku

They do have larger tanks for around $55.