1/5/2024 0 Comments Viscosity units mu![]() ![]() However the following link supports the conclusion. I'm not saying my logic is 100% correct (is it really completely laminar. (2B)+(2B)' ? RE: Which viscosity (kinematic or absolute) for piston and diaphragm pump ? electricpete (Electrical) 2 Jan 13 14:31 If chart gives correction to positive displacement pump flow rate in terms of viscosity, then I’d think it should either be absolute viscosity, or else the assumed density should be identified along with the kinematic viscosity.Īt least that’s my thinking, not knowing a whole lot about pd pumps – open to comments or corrections. Kinematic viscosity (mu) should be the one that is of interest for predicting pump performance parameters of DP and volume flow rate without considering density. ![]() This is velocity that would flow through a tight clearance at a given DP under laminar assumption.Īlternatively we may say that viscosity effects dominate over inertial effects (that is already known the moment we assume laminar flow).Īs long as we are viewing pump parameters in terms of velocity, volume flow rate and DP (not head and mass flow rate), then density and kinematic seem like superflous parameters. Set the expressions for f equal to each other:Ģ*d*DP / = 64 * mu / Here’s my logic (I’m coming from wandering through a few first principles, not from detailed knowledge of pumps.)Īssume the important viscous effects are related to flow of high viscosity fluids in small clearances.į = 64 / Re = 64 * mu / where mu is absolute viscosity I tend to think kinematic viscosity is used in many different contexts where absolute viscosity is of more interest, only as a result of historical reasons stemming from the fact that kinematic viscosity is more convenient based on measurement method using gravity. kinematic viscosity is only of interest if we know s.g. My viewpoint is that absolute (dynamic) viscosity has the more fundamental importance to the problem. ![]()
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