AIR RECEIVER PRESSURE EQUALIZATION BETWEEN TWO DIFFERENT SIZE AIR RECEIVERS

Thanks for the equation. I appreciate it.

Any ideas for questions #2 or #3

When the higher pressure air expands from the smaller tank it will become lower in temperature than ambient. As it enters the larger tank and begins to compress it will rise in temperature. The temperatures must be taken into consideration.

p1*v1/t2 = p2*v2/t1

As a WAG a 2" pipe and valve should allow arriving at an equilibrium pressure in approximaely 10 minutes or less. Air flows freely compared to water which would take a long time.

Hi,

For item 1- The basic is the PV=MRT equation, you must have the intial volume of 30,000 gal. You can calculate it by this method

P₁V₁ = M₁R₁T₁

P₁/V₁ = P₂/V₂

Wher V₁ = 30000

P₁=150 lbs/in2

R₁ = R₂

T₁ = T₂

Item2 - Size of your pipe will be determined by how much velocity you are looking at.

Item 3 is the derivative of your volume devide by your time.

where: ∫dv/dt

v₁ = 30000

t₁= 0

t₂ = ?

V₂ will be determined from item 1.

p1v1/t1 = p2v2/t2

p1 = 150 psi

v1 = 30,000 gallons

p2 = x

v2 = 60,000 + 30,000 = 90,000 gallons

t1 = t2 =1 after new equilibrium established

90,000x = 30,000 (150)

x = ((30,000) (150))/90,000 = 50 psi

Just to add another point to take into consideration: that's about a ton of air you've got to move.

The major question, as I see it would be what is the size and at what rate is the pipe delivering the air to the 30,000 gallon tank? If the connector pipe between the two tanks is the same or larger than the pipe delivering the air to the tanks, there would be no lag in time between the equalization of the two tanks since, as one gallon of air is delivered to the first tank, a gallon of air will be moved into the second tank with no loss of velocity since the pipes are of equal delivery capbility. If the first tank is empty or at zero pressure at the beginning of the filling process, the air would expand as it enters the tank. However, it would expand at such a fast rate as to be at ambient pressure when it displaces a like volume to the second tank.

I think you are missing the objective of the excersize. The problem has nothing to do with the compressor delivering air to the first 30,000 tank. Ignore the compreesor at this point because the compressor is not delivering any air at this time. The problem only consists to two seperate air receivers, one 30,000 gallon tank presurized at 150 psig, and a second empty isolated 60,000 tank. Question 1) what would be the eqaulization air pressure of the two tanks when the valve is opened? Question 2) what size pipe is required to to equalize the pressure between the two tanks within 5 to 10 minutes? Question 3) How long would it take to get the air pressure to within 10 PSIG between the two receivers, with the samller receiver having the higher pressure?

Thanks for your input. It is greatly appreciated.

Ah, you caught me napping, or nearly so. It's been a long day! You are absolutely correct, I did, indeed, miss the point of the exercise. I humbly leave you to the answers set before mine. They adequately answer all that I am capable of and more. Thank you.

Hi N6377B

If you are or were a military man, thank you.

Ans:

1. 50 psig

2. We assume that the distance between the two reservoirs (pipe length) is less than 100 feet without excess fittings and bends? If so 3" ID pipe will equalize the tanks between 5 and 10 minutes, approximately 7 minutes.

3. If the assumptions of #2 are correct and you select 3" ID pipe the pressure in the 30,000 gallon tank will fall to 55 psig with 45 psig in the 60,000 gallon tank in roughly 3 minutes.

Will let us know how it works out? This answer is like horse shoes, hand grenades and influenced minds; close counts.

Tom,

Thank you for your Information, I greatly appreciate your input. The information looks pretty good. If it is not too much trouble, could you provide how you arrived at you answers? It would be a great help.

Once Again thank you for your help.

PS: I used to be in the military, I an honored by your recognition.

Tom,

Thank you again, the reason I am interested in how you arrived at your answers is because I am a firm believer in the following philosophy:

"If you feed someone a fish, they eat for a day, but if you teach them to fish, then they eat for a lifetime".

Thanks again, if you could briefly show me how you solved the problems, it would be of enormous benefit to me.

N6377B "Can someone advise me with a equation or solution to the following application?" HOMEWORK???

Suddenly you ask for too many details. ThIS appears to be a homework problem which you should have ferreted out for yourself instead of posting on CR4.

We DON'T do HOMEWORK !!!

Dont ask again. Most if all will ignore you or make fun of your inquiry!

Stan,

With all due respect, you don't know what you are talking about. This is an application for something I am working on. I am 48 years old and have already finished my degree. This is a special application which most people are not familiar with. I am only requesting how people came to their conclusions. In the event, I cross this road again, I will be in the position to resolve it. This is the whole point for this forum. This not does constitute asking too many questions. In conclusion, I leave you with one thought. "It is better to remain silent and appear stupid, than to open your mouth and remove all doubt".