Resistance Coefficients - Units?

[tr6]

I know that the Resistaant Coefficients, as listed by Crane/Cameron, are the result of experimental test data for the various fittings, valves, etc. And since the coefficient is also dimensionalless, I am pretty sure that the use of these published Coefficients is independent of the measurement system (SI, US: m/sec, ft/sec) being used.

My question is: is that a correct statement?

 

[abeltio]

tr6,
YES, the published coefficients are dimensionless and therefore independent of the measurement system... one caveat though regarding the use of the formulae supplied by the companies you mention...
e.g. Crane Technical Paper 410, there is as well a 410M version (metric)... why?
although the coefficients are dimensionless the published formulae contain factors that do the conversion to obtain the results in certain units while the factors in the formulae would give the results in OTHER units...
e.g.
Crane Technical Paper 410 - std version
Page 3-4
Equation 3-19
q = 0.0438*d^2*(hL/K)^0.5
Q = 19.65*d^2*(hL/K)^0.5
as you can see the factors are the same but the coefficient is different 0.0438 vs. 19.65
because [q]= cuft/sec while [Q]=gpm

HTH

saludos.
a.

 

[athomas236]

abeltio is correct resistance coefficients are dimensionless, they are just some multiple of the velocity head.

athomas236