An engineer in Michigan called about a large project with several pumps being selected in parallel for a plant chilled water system. He commented that the Bell and Gossett pump curves are flat vs. processing pumps which often times are steep. His question was, “Why are B&G curves so flat?” I’ve not heard this comment for many years. What did he mean? The term steep curve comes from the process industry. This old term refers to a large change in pump head with a small change in flow rate.
Large Centrifugal Inline Pump Installation
In our last Monday Morning Minute, we suggested using the Base Mounted Bell and Gossett series 1510 series end suction or VSX series double suction pumps when the design capacity requires over 10 HP. We do occasionally see our series 80 and series 80-SC inline pumps specified in applications up to 100 HP. Often the reason used for this application is limited floor space. Today let’s examine floor space required by these pumps.
Centrifugal Pump Selection for Hydronic Systems (Part 2)
You’ve selected the GPM (gallons per minute) flow rate and the pump head. You corrected the head for the fluid as described in the last few articles. It’s time to select a pump. Why do you select one pump over another and how do you, as the specifying engineer, make sure the submitted pump is remotely close to the one you selected. The R. L. Deppmann Monday Morning Minutes continues Pump Selection today.
Centrifugal Pump Selection for Hydronic Systems (Part 1)
You’ve selected the GPM (gallons per minute) flow rate and the pump head. You corrected the head for the fluid as described in the last few articles. It’s time to select a pump. Why do you select one pump over another and how do you, as the specifying engineer, make sure the submitted pump is remotely close to the one you selected. The R. L. Deppmann Monday Morning Minutes looks at this starting today.
Glycol in for HVAC Systems (Part 3) – Pump Corrections
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…]
Centrifugal Pumps and Pump Curves for HVAC and Plumbing Systems
Centrifugal pumps are the “heart” of hydronic heating, cooling, and plumbing systems. Over the next few weeks, the R. L. Deppmann Monday Morning Minutes features some basic and advanced pumping topics. Let’s start with a quick review of the information contained on the pump curve. For our example, we will use an ITT Bell and Gossett model 1510 end suction base mounted centrifugal pump model 5E with a nominal speed of 1750 RPM. The horizontal axis is flow rate in GPM or gallons per minute of water. [Read more…]