Sercrets of a Pump Wet End

I thought it would be useful to dedicate this article to Wet Ends and to bring to your attention some of the characteristics that are not immediatly apparent and pull together some of the answers to the many questions that we continually receive about Wet Ends.

There are many different types of Wet End. We keep in stock 36 diferent types of Wet End - and these are the most popular!

You can find them all here on the website: http://www.spa-es.es/products/components/wet-end-assembly-and-parts/wet-end-assembly/

 

How can I identify the Wet End that I need?

The majority of Wet Ends do have a serial number that we can use to identify the one that you need.

However it is carefully hidden away on one of the vanes on the back of the Wet End - the side closest to the motor.

If there is no number marked we will have to go though a process of elimination. 

 

 

 

 

 

 

 

 

 

 

 

 

Is it a 48 or a 56 frame Motor and Wet End? 

The physical size of the spa pump motor is referred to as frame. Spa main pumps will have a size of either 48 frame, which are approx. 5.5" diameter, or 56 frame, which are approx. 6.5" diameter. 

   

Check the old motor's ID plate for frame size. If you look carefully at the label or the plaque on the side of the Motor, you should be able to find the frame size, which will be shown as F48 or F56. Sometimes it is hidden in the serial number of the motor.

 

You can also look at the 4 bolt holes on the Motor housing that attach the Wet End to the Motor. 

As a general rule the 56 frame Wet Ends will use the outer holes and the 48 frame Wet Ends will use the inner holes of the motor housing.  

If in doubt, you can easily determine a motor's frame size by measuring the spacing between the bolt holes.

Bolt hole spacing on a 48 frame motor will be less than 4 inches apart.

A 56 frame motor's bolt holes will be spaced more than 4 inches apart.

 

 

Another indicator that you can check is the internal distance between the plates of the Impeller. 

A 48 frame pump will have an internal distance between the plates of around 6-7mm while a 56 frame pump will have an internal distance between the plates of around 13mm.

Be careful with this as there are some anomalies.

We stock a wide range of Impellers which you can find on the website here:

http://www.spa-es.es/products/components/wet-end-assembly-and-parts/wet-end-impellors/

 

 

When identifying a Wet End, please check the diameter of the plumbing pipe for both the inlet and outlet. 

Most small circulation pumps have 1.5" plumbing for both inlet and outlet.

For massage pumps the diameter of the plumbing is usually 2". However there are some Wet Ends that have 2.5 for the inlet and 2" for the outlet and a few with 2.5" diameter plumbing for both the outlet and inlet.

These pictures show you the difference between the 2" and the 2.5" inlets. The boss on the first picture is much wider to fit a 2.5" pipe union.

 

 

When a customer wants to order a new Wet End we will usually ask for the size of the diameter of the plumbing of the innet and outlet in order to check that we send the correct model.

As we have shown before the diameter of the Imperial plumbing pipe is the internal measurement of the pipe which then fits into the union, that is connected to the buttress that then fits onto the Wet End.

1.5" Pipework = Pump thread measures approx. 2-3/8" O.D.

2.0" Pipework = Pump thread measures approx. 3" O.D.

2.5" Pump Pipework = Pump thread measures approx. 3-5/8" O.D.

 

Style and Orientacion 

Wet Ends are either side discharge or centre discharge. However the side discharge Wet Ends are sometimes turned 90 degrees - both clockwise and anti-clockwise. This is quite easy to do. Loosen the pump's four through bolts from the back of the motor and pull them back enough to disengage.  Then rotate the wet end to the desired position, realign and re-tighten the bolts.

 

Wet End Refurbishment

As well as Complete Wet End Assemblies, we also keep in stock some individual parts to refurbish a Wet End - Some Volutes, Face Plates, Impellors and Pump Seals. If you are just replacing the Pump Motor or for any other reason you are seperating the Wet End from the Motor, always, always, change the Pump Seal to avoid problems later on.

We keep a wide range of seals that will fit almost all the Wet Ends available and at a cost of between 5€ - 10€, it is well worth spending the extra to avoid problems in the future.
You can find them here on the website: http://www.spa-es.es/products/components/smaller-components/water-pump-seal-kits/

 

Bill Norris, 31-03-2015