# How long will it take for compressed air to reach 29 psi?

## Main Question or Discussion Point

A large tank filled with air is compressed to 49 PSI. A valve is open and air escapes through the hole (d = 0.04 ft) to the atmosphere. How long will it take for the compressed air to reach 29 PSI.
Assume constant temperature.

Not exactly sure how to approach this problem since the flow rate will change as the pressure changes.
I've been trying to use Bernoulli's Equation to get velocity and therefore flowrate, but that is instantaneous velocity so it doesn't help much. If anyone could point me in the right direction that would be much appreciated.

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anorlunda
Mentor
Is this homework?

No it isnt homework, just something Im working on

JBA
Gold Member
The volume of the tank is required to calculate the time. What is the volume of the tank?

The volume of the tank is required to calculate the time. What is the volume of the tank?
Volume of tank is 1050 gal or 140.365 cubic ft

JBA