2006-09-08 22:06:55 · 3 answers · asked by Prashant 1 in Science & Mathematics ➔ Other - Science
The best way to calculate this is to measure the amount of fluid
(water or air) you expel or impel in say 5 seconds. The you take the mass of this fluid and divide it by 5. So now you know how much fluid you are expelling in 1 second(the mass flow rate). Then you take this number and you divide it by the cross sectional area of the discharging pipe and the density of the fluid. The number you get is the velocity( or pumping speed) of the fluid being discharged. This method only works for steady state incompressible flow.
2006-09-08 22:52:37 · answer #1 · answered by zamir 2 · 0⤊ 0⤋
The pumping speed of a vac pump is normally mentioned by manufacturer, but actually in the system it is much below this due to conductance.
So do one thing, connect a N2 gas chamber with ur test vessel by a nozzol with gate valve arrangement and pump connected. start vacuum, let the N2 flow into vessel at a constant rate. after some time ur pressure reading will be stable at say (1E-4torr). then shut off the N2 gas by closing gate valve. record time and pressure. take Pressure reading after t sec. use below formula
effective pumping speed S = V/t x ln(Po/P)
S=pumping speed in liter/sec
V = chamber volume in liters
t = time to go from Po to P in sec
Po = starting pressure in torr
P = pressure in torr after 't' sec
if need further, i can be contacted by kmishra@ipr.res.in
2006-09-11 07:45:34 · answer #2 · answered by kishor_sac 2 · 0⤊ 0⤋
By measuring, flow of water, expelled. Hydro-dynamics.
2006-09-09 05:14:55 · answer #3 · answered by Anonymous · 0⤊ 0⤋