i have a vacuum cleaner pump which i want to use in my final year project to reduce the pressure.bt im not able to find out the suction that the pump is generating.the pump has a closed centrifugal impeller and the speed of the electric motor running the impeller is 20,000 rpm approx.how do i calculate the parameters so that i could find a way to increase the suction?
someone plz help me out with this. my project is stuck bcoz of this problem
2006-09-01 05:31:53 · 7 answers · asked by kudva_amit 1 in Science & Mathematics ➔ Engineering
Need to use the fan speed formula's.
Qa = Qb X (Da/Db)^3 or X (Na/Nb) where Q is volumetric flow rate, D is diameter of fan, N is rotating speed.
You will also need to compensate for expansion. As the vacuum is increased the density decreases and less air is moved per volume unit.
So your free air volumetric flow will be less than the volumetric flow at operating conditions. You also need to have a rating or knowledge of the blowers capacity at some reference speed and pressure.
As you increase the vacuum the capacity of your fan will decrease, assuming no leakage, as some point you will reach a cut off differential pressure where the flow rate will be zero. That is the nature of centrifugal devices.
2006-09-01 06:54:23 · answer #1 · answered by Roadkill 6 · 0⤊ 0⤋
1
2016-05-21 17:41:13 · answer #2 · answered by Blaine 3 · 0⤊ 0⤋
Your question is pretty confusing, however let's take it one by one.
Flow rate:
Insert an orifice plate (a round plate with a hole in centre) at the inlet. Flow occurs from high pressure to low pressure. Take one tapping from either side of the orifice plate - Atmospheric end is high pressure and the other side is low pressure. Connect it to a "U" tube manometer calibrated in mm or inches of water column. You will get the differential pressure. From differential pressure u can derive the flow rate.
"Reduce the pressure" - pressure or suction?
Vacuum is negative pressure (anything less than atmospheric pressure)
Insert a valve in between the suction point and outlet - vary it to get the required pressure or suction. Alternatively, if you want to reduce the suction, insert a leak point (bleeder valve) open to atmosphere. A more efficient way is to vary the RPM of the motor using a suitable drive.
"Find out the suction of the pump" - Use a U tube manometer - one end open to the atmosphere and the other end at the suction point. If you use water as the medium inside the manometer and if the suction is strong enough, it may suck the entire water from the manometer to the pump. Hence if the suction is very high u may use mercury (mm of Hg and do the conversion)
2006-09-01 21:30:00 · answer #3 · answered by kkonline 3 · 0⤊ 0⤋
i have a vacuum cleaner pump which i want to use in my final year project to reduce the pressure.bt im not able to find out the suction that the pump is generating.the pump has a closed centrifugal impeller and the speed of the electric motor running the impeller is 20,000 rpm approx
2006-09-01 05:41:35 · answer #4 · answered by Anubhav A 2 · 0⤊ 0⤋
Not too familiar with vacuum pumps but when u want to start a very large centrifugal pump ,u start against a closed valve. Try measuring the vacuum with different size restrictions.U can calculate the size of the restriction,and graft it out.
Hope this is some help.
2006-09-01 09:56:26 · answer #5 · answered by JOHNNIE B 7 · 0⤊ 0⤋
1. SINCE THE SPEED OF THE VACUUM PUMP IS FIXED, ITS CAPACITY IS AUTOMATICALLY FIXED.
2. INSERT AN ORIFICEMETER AT THE DISCHARGE END SOTHAT YOU CAN MEASURE THE FLOW RATE. USE THE FORMULA FOR COMPRESSIBLE FLOW.
3. IF THE CHAMBER THAT U HAVE CONNECTED DOES NOT HAVE AN INLET THEN THE VACUUM IN IT WILL RISE TO A MAXIMUM VALUE AND REMAIN AT THAT. IF THERE IS AN OPENING THEN THIS VACUUM WILL BE LESS THAN ABOVE.
2006-09-02 06:33:30 · answer #6 · answered by sures 3 · 0⤊ 0⤋
Mass flow rate = (Vol of water delivered)/(time taken for the process) ie m^3/s
2006-09-01 05:44:17 · answer #7 · answered by Kashif 1 · 0⤊ 0⤋