Losses on vaccum pipes

[piNion]

Hi,
I have a little circuit and a pump installed on it, it pumps water for laboratory practice.
Is it possible to calculate friction losses on vacuum lines just by looking at vacuum gauge? I've already done this on discharge line simply by doing the following:
(pressure after pump - pressure at circuit end), this gives me the energy loss in pressure form caused by friction of fluid flow on pipe. Please any help would be appreciated.

 

[quark]

What is your problem? How are you pumping water with a vacuum pump? [PS: If you are circulating the sealing fluid, then you have other better option in the form of a centrifugal pump].

To be precise (and keeping fun aside) you can use vacuum gauges to check the pressure drop in the vacuum piping system. You have to install two gauges, one at the end of the loop and one at the vacuum pump suction (not discharge). The difference of these two readings is your system pressure drop.

What do you want finally? Water or vacuum?

Regards,


Eng-Tips.com : Solving your problems before you get them.

 

[piNion]

Thanks quark,
However I believe I have to be more precise. Sorry for my english.
First of all I think I didn't express myself well, it is not a "vacuum" pump, it's an ordinary centrifugal pump that takes water from a tank and discharges somewhere else. I need friction losses on all circuit: suction + discharge. What I really need is the system curve. Like I've said I've got already the discharge losses, only suction missing, but I do not have 2 gauges on suction line, just one. Can I just calculate losses on suction line with the difference between pressure on bottom of tank and suction gauge lecture at pump suction port?
PS:I need to have real system curve not theoretical system curve.
Thanks &
Best Regards

 

[quark]

That is quite easy if you maintain constant level in the tank. Just note the discharge head and add the height of water column in the tank above the level where you installed your pressure gauge.

For example, if your pump discharge head is 30 meters (roughly corresponding to 3kg/cm²), you maintain a constant water level of 2 meters in the tank and your pressure gauge is installed 1 meter above ground level (I am pressuming both tank bottom and pump are at same level), then your total system resistance will be 30+(2-1) = 31 meters.

If your tank level is varying, you will have different system curves for a constant maximum flow rate.

Regards,


Eng-Tips.com : Solving your problems before you get them.