Specific Speed Limit Issue 2

[virata]

Hello gents,

Our project specification has a specified maximum limit for suction specific speed which is 12000 (for less than 30kW) and 11000 (for greather than 30kW). Our vendor had offered Nss over the specified Nss for 4 pumps and told us that these are their best selection. Is this acceptable? 3 pumps (with 1 VSD) have fluid of tempered water, while 1 pump has caustic liquid. What are the parameters I should consider to meet our specification?

Need your thoughts on this.

Thanks,
V

 

[1gibson]

Relatively high MCSF could be based on vibration limits as well, possibly but not necessarily a factor of inlet conditions.