Wastecorp SludgePro double disc (diaphragm) pumps vs. Penn Valley Double Disc Pump
There are distinct technology differences between a Double Disc Pump and a Diaphragm Pump. Penn Valley Pump Company manufactures a true double disc pump technology while Wastecorp Pumps manufactures a diaphragm pump they are trying to market as a double disc pump.
Penn Valley Pump – True Double Disc Pump Technology
A true double disc pump technology is based on a “non-captive” free disc design whereby two (2) discs are staged in the pump housing. These discs work simultaneously together to perform the duties of both the pumping element and valving element. The hydraulic interaction between the discs creates both vacuum and pressure simultaneously to move fluid from suction to discharge. Since the discs are not captive in the housing they are not subject to the flex fatigue failure pattern associated with captive diaphragm pump designs. The discs are of integral elastomer design with rigid core and do not have any external metal components. The double disc pump has a short stroke length created by eccentric cams pinned to the drive shaft. The pump design provides for positive valving on every stroke since the discs are mechanically driven on the seat. The pump incorporates an inlet side foot valve we termed a clack valve. This device is a priming and re-priming aid and only sees action under a suction lift condition or when the suction line is under a vacuum condition. In flooded suction applications this device does not get back to the seating surface and does not valve. The pump will operate without the clack valve on flooded suction applications. This unique design allows the pump to pass larger solids, rags and debris that will cause designs with internal check valves to clog and fail.
Wastecorp Pump Technology
The Wastecorp pump technology incorporates one (1) “captive” diaphragm that is “sandwiched” between the pump housing and retaining mechanism. Each diaphragm pump is a simplex unit that contains one diaphragm and two ball check valves. A duplex diaphragm pump adds another simplex pump in parallel and then drives it with a common motor. A triplex pump adds a third and so on in order to accomplish higher flow rates. The center of the diaphragm is mechanically attached to a connecting rod that raises and lowers the diaphragm on every revolution. The stroke length is large and leads to a flexing the diaphragm twice (upstroke and down stroke) per revolution. This design also requires the use of internal check valves (ball or flapper) for operation. Without these check valves the pump will not operate.
The “Achilles” heel of the diaphragm pump technology has always been the flex fatigue life of the diaphragm and the clogging of the ball check valves. The check valves rely on gravity to get back to the seating surface and when debris gets trapped between the ball valve and seat the unit stops pumping. The reason these designs have a quick release cap to access the ball valve is that clogging is a frequent occurrence requiring the check valve to be accessed and the debris removed so the pump can be made operational again.
The typical operating life between rebuilds for a double disc pump is thousands of hours since the discs are not captive and therefore not subject to flex fatigue failure. Industry feedback on the diaphragm pump technology is that the lifespan of the diaphragm only lasts in the hundreds of hours given the flexing action of the diaphragm. This is a significant difference in the pump technologies and therefore the reliability and long-term operational costs between a double disc pump and diaphragm pump.
Wastecorp Pumps – Not A Double Disc Pump
Wastecorp has manufactured the Mudsucker® brand diaphragm pump technology for many years and properly called it a diaphragm pump. This technology has never been accepted in the marketplace as an “equal” to the Penn Valley double disc pump and in fact has never been offered as an “or equal” before. It has only been seen as a contractor’s pump and used in relatively light duty applications due the limited run hours between diaphragm failure and low head limitations. It was not until January of 2014 that Wastecorp began marketing the Sludge Pro® branded pump as a double disc pump. They modified the bearing pedestal design so externally the pump looks similar to our design. They renamed the diaphragm a “trunnion” and the external metal plate that attaches the connecting rod to the diaphragm a “disc”. There appears to be no other differences between the Mudsucker Pump and Sludge Pro pump.
Wastecorp literature suggests the Mudsucker pump has an average speed of 60RPM with head limitations of 50 vertical feet and 100 horizontal feed. That would be a maximum limitation of 50ft TDH or 21.6 psi. Wastecorp now says their double disc (diaphragm) pump can be operated up to 110RPM with total heads to 184ft TDH. Higher speeds and heads will greatly impact the life of the diaphgram exponentially.
Double Disc Pump vs. Mechanical Diaphragm Pump
|Features||Penn Valley Pump – Double Disc Pump||Wastecorp Pumps – SludgePro Double Disc “Diaphragm” Pump|
|Technology||A true double disc pump technology based on “non-captive” free-floating disc design whereby two independent discs perform duties of both pump and valve. Short stroke length not subject to flex fatigue failure and operates into the thousands of hours between rebuilds.||A traditional single “captive” diaphragm technology that requires internal ball check valves for operation. Long stroke length and captive diaphragm leads to flex fatigue failures in the hundreds of hours.|
|Discs||Integral (no external metal components) reinforced elastomeric component that is both the pumping and valving element.||Wastecorp’s disc is external metal plates that sandwiches diaphragm from above and below.|
|Trunnion||Sealing device in a true double disc technology that is molded to flex only in the downward stroke extending flex life. Provides no pumping action. Only 9” diameter on largest model and reinforced to eliminate catastrophic failure.||Diaphragm has been renamed a trunnion based on PVP terminology. This is a captive device that is 14” diameter and flexes on both upward and downward stroke leading to twice the flexure rate and therefore shorter life.|
|Drive Arrangement||Inexpensive to replace, simple V-belt and Pulley Drive System.||Expensive to replace mechanical gear-motor arrangement close coupled to drive shaft.|
|Pump Drive Assembly||Short stroke length cam arrangement. Utilizes non-corrosive lightweight aluminum modular pedestals and connecting rods. Eccentric cams are cast bronze-alloy and pinned to shaft with Spirol® drive pins that absorb reciprocating load of pump.||Long-stroke cam arrangement. Utilizes ductile iron pedestals, connecting rods and eccentric cams which rust and corrode. Cams are keyed to shaft with traditional keyway and setscrew arrangement which is inferior for reciprocating loads.|
|Internal Check Valves||A double disc pump does not have internal check valves. The inlet clack valve is a priming device that only operates under suction lift and high vacuum installation. Pump works without this device on flooded suction applications.||Pump will not operate without the 5-1/4” ball check valves or flapper check valves on suction and discharge side. These items rely on gravity to get back to seat and if there is debris on seat the pumping stops.|
|Pumping Action||Short stroke length produces small pulses and relatively smooth flows.||Long stroke length produces large pulses and large pressure spikes in flow.|
|Maintenance||Maintain-in-Place design with integral hinged housings. Allows pump to be serviced without removing pump from mounting frame or disturbing piping. Staged assembly allows for disassembly one section at a time.||Pedestal assembly requires complete removal when diaphragm fails. On multiplex units all pedestals have to be removed even when only one diaphragm fails. Ball check valves clog requiring frequent clean out.|
|Base Frame and Covers||Standard in SS304||Carbon Steel, painted. Pumps must be mounted on elevated concrete foundation that is the owners or contractors responsibility.|
|Pump Configurations||Units are simplex design with single motor. Provides easier maintenance.||Duplex, Triplex and Quadraplex units are large footprint with multiple pumps mani-folded together and driven by single motor.|
|Installations||Over 10,000 units installed and operating in North America.||Introduced pump to market in January 20014. Few if any installations for this branded technology and none long-term.|
|Spare Parts||All parts kept in stock for same day shipment.||???|
|Warranty||Two (2) Years||One (1) Year|
|Company Established||1980||2005 (Based on LLC origination)|
|Manufacturing Location||Made in the USA||Product Made in Canada, Holding company in the US.|
It is clear that Wastecorp decided to reconfigure their pump and call it a double disc pump with the hope to capitalize on the successes of this technology over the last 37 years. The use of the double disc name, along with renaming the diaphragm a “trunnion” and the external metal plate a “disc” is a direct attempt to confuse the marketplace into thinking this new line of pumps is the same as our technology. The Wastecorp SludgePro pump is a diaphragm pump and changing the name and copying our terminology does not change this fact.
Check the Facts
We encourage you to conduct the proper due diligence in investigating the differences in the technologies and long-term operating installations.