jhollin1138
Mechanical
- Nov 16, 2001
- 5
I would be grateful for any and all help. I am trying to find a formula for estimating damper valve leakage rates.
I replaced a gentleman at a small damper valve company that passed away. He didn’t leave me any notes on how to do these calculations. All he left me were answerers.
I found the following formula for discharging a tank through a nozzle in my Fluid Mechanics book. I thought it would work.
W = A*SQRT((2*g*k*P1^2)*((P2/P1)^(2/k)-(P2/P1)^((k+1)/k))/(R*T1*(k-1))
W = Weight Rate (lbs/sec)
A = Area of hole (ft^2)
g = Gravity (ft/sec^2)
k = Adiabatic Exponent (Air = 1.4)
P1 = Absolute Pressure in the Tank (lbs/ft^2)
P2 = Atmospheric Pressure (lbs/ft^2)
R = Gas Constant (Air = 53.5 (ft*lb)/(lb*Deg R))
T1 = Absolute Temperature in the Tank (Deg R)
I can assume a uniform clearance between the damper disc and the valve body seat of .015”, so I can estimate an area. All other items are known, except for W of course. The problem is when I compare my numbers with his numbers; they are not the same. I am off about a factor of 5.
Does anybody have a better formula to use or is this one right?
Again, Thank You!
Jim
I replaced a gentleman at a small damper valve company that passed away. He didn’t leave me any notes on how to do these calculations. All he left me were answerers.
I found the following formula for discharging a tank through a nozzle in my Fluid Mechanics book. I thought it would work.
W = A*SQRT((2*g*k*P1^2)*((P2/P1)^(2/k)-(P2/P1)^((k+1)/k))/(R*T1*(k-1))
W = Weight Rate (lbs/sec)
A = Area of hole (ft^2)
g = Gravity (ft/sec^2)
k = Adiabatic Exponent (Air = 1.4)
P1 = Absolute Pressure in the Tank (lbs/ft^2)
P2 = Atmospheric Pressure (lbs/ft^2)
R = Gas Constant (Air = 53.5 (ft*lb)/(lb*Deg R))
T1 = Absolute Temperature in the Tank (Deg R)
I can assume a uniform clearance between the damper disc and the valve body seat of .015”, so I can estimate an area. All other items are known, except for W of course. The problem is when I compare my numbers with his numbers; they are not the same. I am off about a factor of 5.
Does anybody have a better formula to use or is this one right?
Again, Thank You!
Jim
