Impeller Design

[Trojan]

I was wondering if anyone could help me with improving the TDH of a standard End suction pump with a closed impeller?
A brief history:
The pump has a full size impeller
The speed conforms to the speed of the sales curve.
The Pump delivers 5m head lower then the performance curve ..at Shutoff head.
Any info would help greatly!!

 

[MortenA]

Could the impellars be worn?

Best Reagrds

Morten

 

[butelja]

Have you checked the wear on the impeller wear rings? Verify the correct clearange bewteen the impeller inlet shroud OD and the pump casing inlet wear ring ID. If it were a semi-enclosed impeller, then check the impeller end clearance.

 

[PUMPDESIGNER]

You did not provide anywear near enough info so we can only wildly guess. Wear ring clearances as butelja suggested often cause performance loss and the smaller the pump and the lower the Ns of the pump the more effect wear ring clearances have.

What hp and what rpm, NPSHA vs. NPSHR, Pump Nss and Ns, impeller diameter? Whatever you have would help.

PUMPDESIGNER

 

[HomeMadeSin]

Also, make sure your calc's are correct (adjusted to centerline of the pump). Some pump manufacturers calculate the performance of the pumps they publish, so it isn't uncommon to find one "out-of-spec". Also, they only guarantee one performance point, not the whole curve.

Also, what type of drive. I assume direct and not magnetic.

 

[TD2K]

I doubt Trojan is still watching this thread, the last time they are showing as logging in to the site is October 24, 2001