Is there a hazard with the 2nd tank having too much air in it? How does the 2nd tank not overfill itself?
by Marc Carraway
This is a question just for an explanation on how or why something works.
I'm sure theres not much danger adding a 2nd tank to an air compressor. But what my mind cant understand is how the 2nd tank doesnt fill up past what its rated for or is supposed to hold. In other words, if I have a 21 gallon air compressor, I add a 2nd 15 gallon tank or something like that, what makes sure the 15 gal tank doesnt end up with 20 or 30 gallons of pressure inside of it, possibly making it crack, break or explode or something?
See what I'm saying, or not understanding?
My mind isnt acting right for some reason. (and its not what some of you may be thinking) I simply really just cant understand it mentally. Thanks a lot for any explanations helping me 'get it'.
Thanks for a good question, Marc.
Ask yourself where the compressed air that is going to the second tank is coming from? It's either plumbed from the first tank or a tee from a line from the discharge coupler on the air compressor, right?
What stops the air compressor from overfilling the first tank? Two things, the pressure switch which shuts the compressor off when the first tank pressure reaches the cut out setting. The second is the PRV, protecting the air circuit by allowing air to blow off once the pressure inside the tank gets past the normal cut out (the pressure switch didn't work) and reaches the PRV cracking pressure point.
OK, now, if we are supplying the second tank with air from the first, there is no way that the compressed air pressure in the second tank can reach a danger level, as it's protected by the two devices in the first tank / air compressor.
How to drain the air compressor tank?
How to drain air compressor tank?
Thanks for writing in.
I've uploaded a picture for you to see what I'm talking about.
Under the tank, usually at the lowest spot on the tank, you'll find a valve, one of which you can see in the photo.
Turn this valve one way and the air and water can flow out of the tank. Turn it the other, and the valve closes keeping your compressed air in the tank.
When I'm finished using my air compressor I open this valve to drain off the collected water, and I leave it open until the next time I want to use the compressor.
Don't forget to close it before you turn on your air compressor. Most of them are so loud you won't be able to hear the air escaping out the drain valve is the compressor tries to fill the tank.
That the drain valve is open is one of the many reasons why your air compressor runs but doesn't build pressure in the tank.
One other thing. Expect the drain to have water in it, so when you open the valve you'll get water with crud and oil in it all over your hand. I wear a glove when I drain my compressor tank. :-)
Convert an LP tank to an air tank
by John Lees
I have a 250 gallon LP tank that I want to convert to an air tank. The rating on the tank is 250 psig at 125 degrees F. My compressor produces a maximum air pressure of 125 psi. Do I have to use a conversion factor to compare psig to psi? And, the tank has a pressure relief valve installed. Will it work for air as well as lp gas?
John, see the pages on gauges that provide information on what PSIG versus PSI are.
While I suspect the PRV will work for compressed air too, since I have nothing to do with LP gas or storage, I cannot say unequivocally yes. Perhaps another visitor might comment?