At Triplex, we spend a lot of time specifying and sizing Waukesha’s External Circumferential Piston or ECP pumps. More commonly known as a Sanitary PD Pump, what distinguishes a Universal 1, 2, 3, and Twin Screw pump from centrifugal pumps is the constant volume that PD pumps displace, regardless of discharge conditions. While centrifugal pumps abide by the affinity laws, PD pumps do not. As head pressure increases, PD pumps continue to pump. This creates a major problem if someone closes a valve downstream. A PD pump will pump until something gives! Most commonly, this is something on the pump such as a seal, shaft, or down stream sanitary flange. The differential pressures created by the PD pump can even cause stainless steel shafts to snap!
To solve this problem, we need to protect a PD pump from dead heading or pumping against a closed system. Most commonly, we accomplish by using a pressure relief valve to create an alternative flow path to reduce the differential pressure the pump sees. Most relief valves are simple- they use a spring-loaded actuator that rises when the pump discharge pressure exceeds the spring cracking pressure. At Triplex, a SPXFlow Platinum dealer, we offer two primary types of relief valves- the 60R and WR60 valves.
Waukesha’s 60R series valve it the simplest way to relieve pressure from a PD pumping system. Featuring a T body with manually adjustable spring, the 60R series is available with Teflon and Stainless seats and 50 lb., 100 lb., and 300 lb. springs. While simple, the 60R series valve is a “manual” valve, with no outputs, and does require some fine tuning with a pressure gauge to set.
While the 60R series is great for pressure relief, sometimes we may want to not only relieve pressure, but also use a relief valve to bypass the PD pump during CIP to maintain downstream line velocity. For these applications, we would specify a WR60 series relief valve. Available in both T and CD body styles, the WR60 series serves as both a relief and bypass valve. With the WR63 configuration, as seen below, we are able to achieve free draining and minimal dead leg relief piping if the line pressure exceeds the set pressure or if the PD pump is bypassed during cleaning.
Additionally, the WR63 valve is available with mountable control top for outfitting with either the WCB, CU4, or 8681 Control Top. And for especially high-pressure applications, the WR63 is available with reduced seat selections to increase maximum holding pressure.
Like the 60R series, the WR60 series does not come preset by the factory. After removing the stainless-steel dust cap, the valve is set by fully tightening and then backing off the set screw to reach the desired cracking pressure.
Using SPXFlow’s full offering of single seat relief valves, we not only protect expensive process equipment, but also minimize system dead legs and enhance cleaning. Triplex Sales Engineers are trained specifically to help you select the right valve for your next sanitary valve application. Contact us today for more information.
