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Mark:
Your posted query indicates to me that you are somewhat confused. I assume that when you say "between engine and pump", that you are talking about a reciprocating pump which is driven by an engine. It is the reciprocating pump which is the source of the pulsations ... not the engine drive. You would not install a pulsation dampener between the engine and the pump ... in fact, it would not be possible to do so. You would install a pulsation dampener on the discharge of the reciprocating pump to absorb the pressure shocks created by the reciprocating pump.
I suggest that you do a Google search on "pump pulsation dampeners" and you'll find many vendors who specialize in designing and selling such dampeners. I would not advise you to try it yourself.
Milton Beychok
(Contact me at www.air-dispersion.com)
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