calculating compressor tank size

" snipped-for-privacy@hotmail.com" wrote in news: snipped-for-privacy@f1g2000cwa.googlegroups.com:
Not enough info.
You can't calculate unless you have some numbers to go from. How many CFM at what pressure do you need? You gave the time. Without the other two variables, no calculation is possible.

I agree that you do not have enough information, but the site below might be helpful.
Note that at 90 psi, with an outlet of 100 feet of 1 inch pipe, the pressure drop will only be 28 pounds at 350 SCFM! (The chart stops at 350 SCFM). (In other words, if the end of the 100 foot pipe is wide open, the actual SCFM will be more than 350 SCFM). 350 SCFM is a lot of air. 5 seconds at 350 SCFM is 29 SCF, which is only 5 cubic feet at 90 PSI. My guess is that you don't need a 100 gallon air tank, that 20 gallons might be enough. Finding a 20 gallon air tank with a one inch pipe thread outlet might be a problem. My 60 gallon compressor is piped through a 1/2 inch valve, but it appears that the tank has a 2 inch outlet. A length of 6 inch pipe might have plenty of gallons for your purpose.
But of course, I don't know if 350 SCFM is enough in your application.
Richard
snipped-for-privacy@hotmail.com wrote:

Thanks for trying to assist. If I understand correctly the scfm refers to the pump filling the receiver and depending upon pump size/tank size is how long the pump operates before cutting in again. I am more interested in how long the tank will last and if I assume a typical tank has a max pressure of 150psi then I am trying to figure out how big a tank might be needed for a five second run - through a one inch pipe - say 150psi dropping to 100psi.
Thanks again

You probably will need to follow up some of the technical refs listed by other posters, but as a practical data point, 6-gallon tire bead seating tanks with 1.5" valves empty in less than a second or two. (Example pictures at and where the last one is an 8-gallon tank, possibly with a bigger valve, and a small picture of it in use.)
-jiw

It ultimately depends on how much SCFM you need, which refers to both pump size (flow in) and usage (flow out). SCFM is very relevant to solving the problem of how large a tank you need, as well as how much air might flow through a given pipe at a given pressure drop.
I think that it is very unlikely that the amount of air you need is as much as would come out of a one inch pipe that was wide open. What are you trying to do?
You might be best advised to borrow or rent a compressor to play with, and figure out what you need experimentally. I am guessing that you do not have an engineering or other background that would enable you do answer this question with a pencil and a calculator.
Another problem with your application is that since the tank pressure will drop during the 5 second use period, so will the airflow. A pressure regulator large enough for the kind of flow you are talking about might be large and expensive, although it should produce a relatively constant flow as the tank pressure drops. You could use the pressure regulator, combined with a throttling valve downstream of the regulator, to control the airflow.
Richard