I had been thinking about air tanks and volumes of air and all kinds of things recently. All the talk about airflow and leaks made me wonder just how much air had to leave my tank to make the pressure drop from 200 psi to 165 psi. Well, it really brought up some interesting facts.
My air tank is 20 gallons. When I read that the dual 480c compressors should only be run with 5 gallons each, I was intrigued as to why this number is so low.
Did you know that a 5 gallon tank at 200 psi is actually holding 68 gallons of uncompressed air? At 200 psi, a 20 gallon tank has 272 gallons of air.
To drop from 200 psi to 165 psi, a tank has to expel 2.4 atm. In a 5 gallon tank, 2.4 atm is equal to 12 gallons of uncompressed air that has to be returned to the tank to bring the pressure back up to 200 psi. In a 20 gallon tank, 48 gallons of air have to be returned to the tank to achieve 200 psi.
I am curious about how long it is supposed to take a pair of 480c’s to pump 48 gallons (182 liters) of air.
Viair 480c - 5 gallon tank
165 To 200 PSI - 2 Min. 20 Sec.
That means that dual Viair 480c’s can fill a 10 gallon tank from 165 psi to 200 psi in 2 minutes and 20 seconds. I guess you would double that for a pair of 480c’s filling a 20 gallon tank from 165 psi to 200 psi, so that means that it would take about 4 minutes and 40 seconds for a pair of 480c’s to fill a 20 gallon tank from 165 psi to 200 psi. I will time my setup tomorrow and see if that’s close or not.
Mate, seeing as your in a mathamatical mood. my 8.5g tank recently had a major “relay” fail and the tank pumped up to just over 310psi…how many gallons woz in my tank???
Yeah, my silly self, Im runnin two 480c’s with a 5 gal tank and supposedly its supposed to take 1 Min. 15 Sec. from 165-200 but in a lot of cases, its much faster. This morning i ran it down to about 90 psi and it took 2 minutes to fill back to 200. I dont know if the temperature has a lot to do with it but, it was on the ONE this morning.