Diaphragm Type Metering Pumps

In addition to selecting wetted end materials to handle the liquid to be pumped, Madden offers several types of check valves to be considered when specifying a metering pump.  Check valves are an integral part of the wetted end of the pump.  We have prepared the following discussion to help you prepare a specification that will satisfy the needs of your application.

In an earlier blog article on specifying a metering pump we stressed the importance of matching the liquid to be pumped with wetted end materials of construction that can safely and economically handle the liquid.  We want to prevent leaks and spills, and specifying appropriate materials will accomplish those goals.  As a reminder, the wetted end is any part of the pump that comes into contact with the liquid being pumped.

Madden makes three series of diaphragm metering pumps to cover a wide range of flow capacities.
Here are some options to take into consideration as you are specifying the check valves for a metering pump:

The JN Series diaphragm metering pumps have the smallest flows, with six models in the series ranging from the smallest model with 1 gallon per hour maximum capacity, up to 11 gallons per hour for the largest model in the series.  The check valves in the JN Series pumps have double ball checks for both the inlet and the outlet valves.  The valve body is always the same material as the solution head.  For example, a pump with a PVC wetted end will have a solution head of PVC, and the valve bodies which include the piping connection will also be PVC. The valve seats for the JN Series pumps are made of glass filled Teflon to resist the chemical action of most liquids that a metering pump will be required to handle.  The valve gaskets are also Teflon.  The choice that is available is in the ball checks which can be 316 stainless steel, ceramic, Hastelloy C or Teflon.  The lowest cost check ball option with a satisfactory chemical resistance for the chemical to be pumped should be selected.

The middle capacity range is the MF Series diaphragm metering pumps, with capacity starting at 5 gph for the smallest model, up to 75 gallons per hour for the largest model.  Here again the valve body and piping connector are the same material as the wetted end selected.  Several types of valves are offered for the MF Series pumps.

  • The ball type check valve with a rubber seat that is the same material as the diaphragm is the most common valve and it will work well with most liquids.  The valve body is the same material as the pump solution head.  Buna and Teflon gaskets are offered.  Check balls are available in 316 stainless steel, ceramic, Hastelloy C and Teflon.
  • For viscous liquids over 400 cps viscosity we offer the Type M-200 spring loaded valves.  The spring assists the check ball in seating which improves the pump output and repeatability.  The valve spring we offer is stainless steel.  Valve bodies, balls, seats and gaskets are offered in the same materials as for the standard ball type check valves.
  • Cone type valves feature a conical stainless steel valve body and integral seat with a stainless steel poppet in place of a check ball.  The sealing ring on the poppet is normally the same material as the pump diaphragm.  The cone type valves are used for pumping abrasive slurries such as diatomaceous earth.
  • Type M-115 guided ball valves are also offered for abrasive liquids.  The body and seat are stainless steel and any of the available check balls can be used with this type of valve.

The MH Series diaphragm metering pumps offer four models ranging from a capacity of 96 gallons per hour, up to 180 gph for the largest model.  The valve bodies will always be the same material as the solution head, and the valve gaskets are always Teflon in this series.  Standard valve seats are glass filled Teflon which is great for most liquids.  Stainless steel and ceramic valve seats are offered for abrasive slurry pumping.  Valve ball options for the MH Series include 316 stainless steel, Carpenter 20, Hastelloy C, and Teflon.

Specifying the most economical and durable check valves for a metering pump will guarantee trouble free pumping with the maximum service life between repairs.   For help in specifying metering pump valve options consult the Madden Pump Selection Guide on our website, call us, or send us an email inquiry.  We are always quick to respond.