Pump Suction Uptake Vortexing
Pump Suction Uptake Vortexing
(OP)
I have some pumps that are under-performing, and my local Viking guy has suggested that this is the result of vortexing inside the tank I am pumping out. We are seeing about one-half the expected flow. (I don't know how the pumps sound; they pumps are at a remote location, and I am getting somewhat poor support from my guys out there.)
To facilitate more complete emptying of the tanks, my suction nozzles turn down toward the floor of the tank. The gap between the opening of the uptake and the tank floor is such that the cylindrical surface traced by projecting the pipe inside circumference onto the floor equals the inside cross-section of the pipe. My Viking guy says that the gap should be a full diameter to avoid vortexing. Wouldn't vortex formation be governed by flow, viscosity, and specific gravity, such that the critical gap would be different form fluid to fluid, and from pump to pump?
Any other ideas on what might be causing this problem?
(The pumps are Viking internal gear pumps, and the media is motor oil and motor oil components.)
To facilitate more complete emptying of the tanks, my suction nozzles turn down toward the floor of the tank. The gap between the opening of the uptake and the tank floor is such that the cylindrical surface traced by projecting the pipe inside circumference onto the floor equals the inside cross-section of the pipe. My Viking guy says that the gap should be a full diameter to avoid vortexing. Wouldn't vortex formation be governed by flow, viscosity, and specific gravity, such that the critical gap would be different form fluid to fluid, and from pump to pump?
Any other ideas on what might be causing this problem?
(The pumps are Viking internal gear pumps, and the media is motor oil and motor oil components.)





RE: Pump Suction Uptake Vortexing
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Here is a picture of a simple one. I've even had success with one that was inserted through the flange and held in place like an orifice paddle with the "X" welded to the paddle and inserted in the nozzle of the tank.
RE: Pump Suction Uptake Vortexing
http://virtualpipeline.spaces.msn.com
RE: Pump Suction Uptake Vortexing
RE: Pump Suction Uptake Vortexing
Does flow improve if level is raised?
Do pumps run in parallel or one at a time? Any chance for reverse flow back to tank?
There are too many causes for low flow to diagnose without more information.
RE: Pump Suction Uptake Vortexing
We have not observed that tank level has a dramatic impact on flow.
Each tank has one dedicated pump.
There is a path for fluid to return to the tank, through a PRV. I doubt that this is happening, because that would require a full stoppage, and I am certain that this does not exist.
RE: Pump Suction Uptake Vortexing
RE: Pump Suction Uptake Vortexing
-motor speed and gear ratio against flow curve (measure actual shaft speed if possible)
-leakage thru piping psv back to tank
-setting of integral pump psv (sometimes factory set to minimum)
-calibrate/check method of flow measurement
-suction/discharge pressures against predicted
RE: Pump Suction Uptake Vortexing