API 610 11th , paragraph 6.1.4 Head increase

[Aisyahaulianisa]

Hi All,

Can somebody explain me how to calculate head increase that stated on the API 610 11th paragraph 6.1.4 "Pumps shall be capable of at least a 5% head increase at rated conditions by replacements of the impeller(s) with one(s) of larger diameter or different hydraulic design, variable-speed capability or use of a blank stage"?

For example,
Rated impeller = 299mm
Max.Impeller = 305mm
rated head at rated impeller = 500m
maximum head at rated impeller = 564.6m
maximum head at max impeller = 590m

are the data above have deviation with API 61011th para 6.1.4?

thank you very much

 

[LittleInch]

Not enough data. Your pump increase potential with simply one of those items ( increased impellor diam), is about 4%.

What this is saying is that if, for whatever reason, you need to increase the rated head by at least 5%, there is the potential to do it. The actual maximum head is vendor dependant.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[JJPellin]

The standard states that you should be able to increase the head by 5% at rated conditions, not at maximum head conditions (shut off). You give the rated head with the rated impeller as 500 m. At that same flow rate, with maximum diameter impeller, what is the head? Comparison of those two numbers will determine if the standard is met. Using only the affinity laws, it looks like you are only able to get a 4% head increase given the two impeller diameters.

Johnny Pellin