How much margin to allow for internal wear?
How much margin to allow for internal wear?
(OP)
Good morning guys. Another question. Man I am taking over this forum. 
How much margin on head do you recommend, or have you seen, to allow for the wear of internal clearances in a centrifugal pump?
The references I've seen (Karassik et al.) recommend 8%. My application is a split-case multistage BFW pump of about 3800' TDH, so 8% would be a lot of additional head to burn up across a control valve until the pump wears... The RFQ package is already out, so if I need to add a margin, now is the time to do it. I just don't want to oversize these things.
Thanks guys!
Pete
How much margin on head do you recommend, or have you seen, to allow for the wear of internal clearances in a centrifugal pump?
The references I've seen (Karassik et al.) recommend 8%. My application is a split-case multistage BFW pump of about 3800' TDH, so 8% would be a lot of additional head to burn up across a control valve until the pump wears... The RFQ package is already out, so if I need to add a margin, now is the time to do it. I just don't want to oversize these things.
Thanks guys!
Pete





RE: How much margin to allow for internal wear?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: How much margin to allow for internal wear?
"Wait a minute, you're the guy with the 50% spare."
...and the fancy control system, which is getting fancier by the minute.
To answer your question, 3800' TDH is the load to the pump with the generators at full load - the 'rated' condition, as some like to say. This is what they have to deliver. With this TDH, I am burning up 10 to 15 psid across the inlet rate controllers to the generators.
I have 20% factor of safety in my friction loss calcs. The lines are not too long - several hundred feet.
Thanks!
Pete
RE: How much margin to allow for internal wear?
Phitsanulok
Thailand
RE: How much margin to allow for internal wear?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: How much margin to allow for internal wear?
Of course, it's all the fault of the pump manufacturer - cause he doesn't know what he is doing.
Phitsanulok
Thailand
RE: How much margin to allow for internal wear?
BigInch
-born in the trenches.
http://virtualpipeline.spaces.msn.com
RE: How much margin to allow for internal wear?
Phitsanulok
Thailand