Last week the R. L. Deppmann Monday Morning Minute defined NPSHR, and ended with the Hydraulic Institute (HI) definition as the absolute pressure that will cause the total head of the pump to be reduced by 3%, due to flow blockage from cavitation”. Of importance is the fact that it does not say that NPSHR is where cavitation begins.
It’s All About Terms! – Cooling Tower Pumps and Piping – Part 1
Most cooling tower designs and installations are commissioned without any issues. The few percent of times where problems arise will cause multiple meetings, emails, finger pointing, and added costs. The issues are not caused by bad luck or bad Karma; tower water pumping issues are typically caused by air, dirt, or improper application. [Read more…]
Heat Added to Chilled Water Systems Due to Pump Efficiency
We received an interesting question this week from a consultant engineer: “How much temperature increase will I get in the chilled water from the pump? My secondary chilled water pump has a capacity of 1400 GPM at 100 feet” Let’s look at the answer. ANSWER: Centrifugal pumps in hydronic systems do the work of moving gallons per minute of fluid against a differential head in feet. This work is defined as Brake Horsepower (BHP) also expressed in equation 1. [Read more…]