ok, we have a 2750 cu. in. tank pressurized at 4000 psi. i want to know how long will it take the tank to empty if output pressure is regulated at 500 psi. outlet orifice diameter approx. 1/2". output to atmosphere.
2007-07-24 09:40:48 · 4 answers · asked by gsotrout1 2 in Science & Mathematics ➔ Engineering
Edited
First figure the mass of air in the tank. Is the tank size 2750 cu.in or is the air a standard volume of 2750 cu.in which has then been compressed to 4000psi?
Is this a cascade system with a with a fixed, sharp-edged orifice following a pressure regulator in series ? The flow will be in two stages through the orifice - mostly at sonic velocity and then varying below sonic. The limiting element will be the orifice which will have a regulated upstream pressure of 500 psi until the pressure in the tank drops to and below 500 psi. Then the regulator will open wide to attempt to hold a downstream pressure of 500 which will be impossible and the tank will empty.
The initial critical flow thru the orifice will be at a constant rate at sonic velocity until its upstream pressure (p1) drops to about 250 psi. That constant pressure drop thru the orifice will be the critical pressure drop of about half the upstream absolute pressure. I suppose you are using absolute pressures; if gage add 15.
For the initial flow rate use 500 for p1. Assume a constant (459+70) deg F for T. A is 0.196 sq.in.
lb/sec = .3246A p1/ T ^-2 for the initial sonic part.
The formula for the rest of it is just too complicated to get into here. By that time most of the weight of air will be out anyway.
Time for bed, I think.
2007-07-24 11:57:44 · answer #1 · answered by Bomba 7 · 0⤊ 0⤋
Something doesn't match in your approach, The flow meter is releasing air to the atmosphere at Vo, then you have a Vi in the same circuit that is different from Vo. How can you have two different flows in the same circuit? The quantity of air released through the meter must be the same that is allowed to flow due to the resistance of the ball. then Vo = Vi so your formula doesn't apply to the situation, as the example because as a law whatever enters from one side must come out for the other, in other words, if the reading at atmospheric pressure is 1 l/sec then the flow in any part of the circuit must be the same that is 1 l/sec. What changes is the velocity of the air flowing.
2016-04-01 00:12:48 · answer #2 · answered by Anonymous · 0⤊ 0⤋
If at all possible can you get the cfm rating on that regulator, then it is an easy calculation.
The specs for that regulator are not common in the line of work I am in or else I could of made a good estimate on the time.
2007-07-24 10:47:27 · answer #3 · answered by Mike J 4 · 0⤊ 0⤋
umm........im still in 4thgrade so i dont think i know an answer for this question.
2007-07-28 06:32:03 · answer #4 · answered by crazyDog 2 · 0⤊ 0⤋