Dave’s Corner: EX-Air Valves

When we refer to EX-Air Valves we are talking about electrically controlled shuttle valves as opposed to a pump that uses a c-spool piloted by an air signal from the pilot valve. The EX-Air Valve is available on all pumps except the NDP-5 and NDP-15 series pumps.

This type of valve can be directly mounted on the pump or remotely mounted. It is available in single or dual solenoid versions and is available in 12VDC, 24VDC, and 115VAC.

A pump equipped with this type of valve is used for metering and batch control. It is used with our YSC-3 controller or can also be used with a PLC.

The standard valve that is used with our YSC-3 controller is 12VDC, single solenoid. Below is a matrix for selecting the appropriate valve for your EXAir application.

EX-air valves

Dave’s Corner: Determining Correct Center Disk and Center Rod

There seems to be some confusion regarding what center rod is used with the various diaphragms. Hopefully this article, and the chart below will add some clarity to this issue.center-post
On pumps 1/2” in size and smaller (NDP-5/DP-10/DP-15/NDP-15), regardless of the diaphragm material, the shaft length and center
disk diameter will be the same.

On the 3/4” and 1” pumps (NDP-20/NDP-25) the shaft length will remain the same whether you are using a rubber diaphragm or a PTFE diaphragm; although the metal pumps will use a longer center rod than the plastic pumps.

The center disks will be a smaller diameter when using PTFE diaphragms, as opposed to a larger diameter for rubber diaphragms.

The stroke is short when using the PTFE diaphragms, this destroke
is accomplished by changing the thickness of the air side center disk instead of shortening the center rod.

On the larger pumps the (NDP-40/50/80) PTFE center disk will
be a smaller diameter than the rubber center disks. In addition,
the center rod used with the PTFE diaphragm will be shorter than the center rod used with the rubber diaphragms.
You can use the following chart to help identify which center rods and center disks you have.


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