As a practitioner who works with pumps, you know there are two broad categories of pumps: 1) centrifugal pumps and 2) positive displacement pumps (“PD pumps”). Centrifugal pumps can be deemed to be “flow generators” where their flow is variable based on the pressure they have to pump against. Basically, a centrifugal pump’s flow is inversely related to the pressure it is pumping against; the higher the pressure that the pump is pumping against, then the lower the flow from the pump.
Day-in and day-out, pumps perform their intended task, but then a system upset can occur when, as an example, a valve on the line is inadvertently closed. With a centrifugal pump, the pump can operate briefly without damage against a closed discharge valve and only generates a pressure equal to its shutoff head.
PD pumps, in contrast, can be viewed as “pressure generators” where the PD pump will generate more pressure to offset changes in the pressure that it is pumping against. Basically, a PD pump will work “harder and harder” by creating more pressure to keep flow constant. Same example as above, if a valve on the discharge side of the pump is inadvertently closed, then the PD pump will build up pressure to try to overcome the system pressure.
Pressure Generated by PD Pumps Needs a Place to Go
PD pumps create flow and if that flow is blocked, pressure in the system downstream of the pump builds rapidly. Pressures several times the designed operating limit can be attained in seconds. The pump will keep pumping harder and harder – until there is a catastrophe. What could happen…a pipe separates at a joint and leaks chemical and sprays an operator with a hazardous chemical. To protect the piping, the system, the operator, etc., a pressure relief valve has to be in place! With a pressure relief valve in place, the pressure has a place to go. The pressure relief valve is installed on the discharge side of the pump, then when an unexpected valve closing occurs, pressure builds up, the PRV does it job and relieves the pressure and “no harm, no foul.”
All Types of PD Pumps Need Pressure Relief Valves
There are many types of positive displacement pumps: gear pump, progressing cavity, vane pump, diaphragm pump, piston pump, etc. Regardless of the style of positive displacement pump, a pressure relief valve is needed to 1) protect the equipment, 2) protect from spills and 3) protect the operator.
Griffco Valve offers the Right Solutions for Your Applications
Griffco Valve provides a wide variety of solutions solution for this need. They provide a customizable valve that can fit your desired application. Available in a wide range of materials in plastics and metal (polypro, PVDF, 316 Hastalloy-C & many more) and a variety of configurations (2 port, 3 port, flanged, threaded, and a wide pressure range) makes finding the right valve easy. Griffco pressure relief valves are made right here in the U.S.A! With Griffco’ s high quality standards for over the past 20+ years, this has led to the successful installation of over 300,000 valves and other chem feed accessories (and counting)!
Have questions? Contact Progressive Pumps, your local Griffco Valve & PD pumps distributor.