Pump affinity laws
Pump affinity laws
(OP)
Dear colleagues,
why do we find two different sets of pump affinity laws in literature and on the web:
One set is correct (according to my knowledge) and says that for constant shaft speed the following is true Q1/Q2=D1^3/D2^3, H1/H2=D1^2/D2^2 and P1/P2=D1^5/D2^5.
The other set of laws that is widespread on the net (almost exclusive) and even in literature says that Q1/Q2=D1/D2, H1/H2=D1^2/D2^2 and P1/P2=D1^3/D2^3.
What is true, and how is it possible that in engineering community agreement is not reached regarding the most fundamental laws of practical hydrodynamics.
Best regards!
why do we find two different sets of pump affinity laws in literature and on the web:
One set is correct (according to my knowledge) and says that for constant shaft speed the following is true Q1/Q2=D1^3/D2^3, H1/H2=D1^2/D2^2 and P1/P2=D1^5/D2^5.
The other set of laws that is widespread on the net (almost exclusive) and even in literature says that Q1/Q2=D1/D2, H1/H2=D1^2/D2^2 and P1/P2=D1^3/D2^3.
What is true, and how is it possible that in engineering community agreement is not reached regarding the most fundamental laws of practical hydrodynamics.
Best regards!





RE: Pump affinity laws
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"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO, BP
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://vir
RE: Pump affinity laws
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If we learn from our mistakes I'm getting a great education!
RE: Pump affinity laws
The second set refers to the same pump. These equalities are not as accurate as the laws relating to rpm denoted by n:
Sulzer, in its Centrifugal Pump Handbook (Elsevier), says that when reducing radial impeller diameters on a single pump:
m = 2 for corrections ≥ 6%
m = 3 for corrections ≤ 1%
RE: Pump affinity laws
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO, BP
**********************
"Being GREEN isn't easy" ..Kermit
http://www.youtube.com/watch?v=hpiIWMWWVco
http://vir
RE: Pump affinity laws
RE: Pump affinity laws
RE: Pump affinity laws
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 that while theoretical capacity and head exponents are 1 and 2, respectively, this applies to radial impellers only, and both exponents increase as a function of specific speed."
Figure 2.20 goes on to show the exponent relationship as a function of Ns based on years of compiled test data.
Did you know that 76.4% of all statistics are made up...
RE: Pump affinity laws