R. L. Deppmann Company Monday Morning Minutes addressed corrections to system GPM (gallons per minute) and system friction head during the last three weeks. Today we look at the pump selection. Centrifugal pump curves and the brake horsepower required changes depending on the fluid. In HVAC design we normally assume water is the pumped fluid. There are many times when the assumption is water, since there is no fluid mentioned on the schedule, yet we find a glycol makeup unit attached to the system.
Centrifugal Pump Curve Corrections for Glycol in for HVAC Systems
Pump curves are based on water, but I am pumping a glycol solution. How will this affect the selection? This week we define the first of three glycol corrections. There are three glycol corrections when designing a hydronic or process cooling system; heat transfer correction, pressure drop correction, & pump curve correction. The first correction we’ll look at is heat transfer correction. When choosing chillers, boilers, heat exchangers, and terminal units, it is important to select them using the correct system fluid. [Read more…]
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