Acoustic resonance in the cross over can be reduced, if not eliminated, by introducing a different vane # impeller that feeds the crossover. i.e. if the pump has all 7 vane impellers, you may have one 5 vane impeller that feeds the crossover. This is the standard for most OEM's on BB3's.
Also...
Agree with all previous comments about checking the lift and coating. If the lift setting on a semi open impeller is too low you could have a rub, too high and you're losing efficiency. Semi open impellers are trimmed on an angle. I'd recommend sending in one complete bowl assembly and asking...
In my experience you won't see a plan 53 installed to performance test a pump. Check that the test setup will even be comparable to site conditions. You're likely testing with water, possibly even off rated speed and I doubt suction pressure will be as high as site conditions.... you won't be...
Portable ultrasonic flow meters are useful, but you have to know how to configure the settings to really trust the readings you'll get.
You should be able to calculate the pump head based on suction and disch pressures. If it's a low head pump don't forget to add back in velocity head and...
You mentioned, The lift station is comprised of 2 pumps which take turns opperating & the pumps pump in parallel. Do you know if the station & pumps were designed to run together in parallel (2 pumps both running)? Where on the curve are you currently operating the pumps, out past BEQ or back...
Impellers may already be at max diameter, find a curve and measure the impeller dia in your pump. 8LN is a very common Worthington pump model, but I don't believe Flowserve supports this anymore... check around for 3rd party pirate shops, replicators, etc. Most pump mfg can reverse engineer and...
It's worth noting Johnston Pump, now Sulzer, has adopted another trim calc for vertical pump impellers Ns > 1000.
Vertical Turbine, Mixed Flow, & Propeller Pumps by John L. Dicmas
"Analysis of a large number of turbine pump impellers in the specific speed range from 1500 to 6000 indicates...
QT,
And to your point #3... I never said a blockage at the suction would not cause a similar curve characteristic.
I said for this small 5" bowl and impeller combination, you won't be able to look into anything. You cannot even run your finger thru the bowl diffusers to check for blockage it's...
And since when is a Francis-vane type impeller not considered a centrifugal pump??? did you mean a vertical tubine pump (enclosed impellers)??
Did you know that 76.4% of all statistics are made up...
You won't damage a small 10 HP mixed flow vertical taking it to shut off during testing... actually it's there that the open impeller to liner fit clearance is "rubbed in" to gain a point or two in efficiency at BEP (little trick).
I can tell you two things for certain working for OEM's for the...
Was the pump operating point stamped on a nameplate?? possibly listing the manufacture... if that pump were to go down today and someone in your plant needed to order parts... where/who would they order them from? Then go to that company's website and start looking for curves.
Did you know that...
Cost and application... between bearing pumps are generally more expensive (2X bearings, seals, etc.) but critical in high Nss (suction specific speed) applications using double suction impellers for lower NPSHr. Suction and discharge nozzles can vary in location (Top/Top, Side/Side, etc.)...
QualityTime,
I don't know where to begin to correct you...
Mixed flow pumps run against a liner, though I'm not convinced this is even a mixed flow pump.
Blockages at the suction, cavitation, or increased clearance would be assoc. with high vibration and noise, which wasn't mentioned...
I agree... cavitation didn't do this damage to the shroud and impeller trailing edge. Much more likely corrosion
Sounds like you were only able to reach 85% of shut off because the check valve was forced open. You were probably further out then 800 GPM as well, but had this been cavitation...
