Let's Talk: Pumps

[MaytagA710]

Here is a topic most of us don't really put much effort in to! PUMPS!

They are the life blood of many machines we adore, especially washers and dishwashers. Some could argue the blowers on dryers are pumps, but for the purpose of this thread, we will discuss pumps that move water and whatever else that is in them.

There are two basic pumps I have discovered are featured in appliances, centrifugal and turbine. Both types are different in many ways, and each has its own set of advantages and disadvantages.

The pumps discharge is known as pump "head". Some pumps are known as 'positive displacement' pumps, and others are not.

First, lets start off with a Centrifugal pump.

Centrifugal pumps intake into the centre of the impeller (or the eye), and discharge through the side of the pump. They use the side of the casing to turn the velocity generated in the pump, in to pressure. Centrifugal pumps are not positive displacement pumps. This means that if you were to close off the discharge, the pump can keep going without any issue. Although, eventually, the water around the impeller would heat up as it is friction on the impeller, and it would then heat the bearings up and eventually destroy the pump.

An advantage of this style of pump is that debris don't really have to be broken into little bits like in a turbine pump. In other words, dirty dish water from dishwashers can be handled in these pumps.

A huge disadvantage is cavitation. Cavitation occurs when the pressure of the liquid drops below the pressure point at which the liquid will turn into a vapour. In other words, if the liquid will turn into a vapour at 20psi, the liquid has dropped to 15psi, and has now become a vapour/gas. This causes bubbles, which will collapse when they enter an area of higher pressure in the pump. This causes excessive vibration and wear on the impeller. It can only happen on the intake side of the pump.

Contrary to popular belief, GE DWs feature a classic example of a centrifugal pump. As you can see in this picture, the intake from the sump goes directly into the centre of the pump. The impeller then flings the water outwards, where the velocity is converted into pressure along the volute casing. You can see this as the side of the pump casing seems to get wider as it goes up towards the top, and makes it look like the motor sits offset of the centre of the assembly.

 

[MaytagA710]

Another type of centrifugal pump is the Centrifugal pump with diffusers. Some Maytag dishwashers feature this style of pump, such as the first generation direct drive tower DWs of the early 90s.

Diffusers around the impeller, or directly after them (in the case of the MT DWs) to add more pressure to the water.

Here is a picture of an impeller from one of those MT wobble tower DWs. You can see the water is drawn into the centre of the pump, and discharged through the side. The water would leave the side of the impeller, and then travel up along a dome. Inside the dome were vanes, these would be the diffuser vanes that would add more pressure before it would discharge the pump head to the spray arm.

 

[MaytagA710]

Here we can see a very dirty, ravaged pump from a WP BD. This pump is also a centrifugal as the intake sends the water into the centre of the impeller area. You can also see where the velocity is turned into pressure, on the volute casing. The volute design can be noticed on the bottom of the picture. Its the area that progressively gets further and further away from the impeller.

These styles of pumps are great because as I said before, lint and large dish water debris won't get caught as easily.

 

[MaytagA710]

Next type of pump is the Turbine Pump. These pumps can also be known as Regenerative pumps. A classic example can be found in GE washers, or in Maytags, like in this A712.

These pumps are unique as the water usually enters the side of the pump, and is slung around almost 360 degrees to the discharge. The distance between the impeller and the pump casing is the same all the way around, unlike in the centrifugal pump. There are tiny vanes on the impeller that create impulses in the pumped water.

These pumps can generate head pressures and velocities several times greater than a centrifugal pump. These pumps are also, not positive displacement.

These style pumps are great for trying to move a large quantity of liquid in a short period of time, say a drain sequence. They can also lift high pump head, meaning the discharge can be lifted much higher than the discharge of a centrifugal pump.

 

[MaytagA710]

These are the two most common pumps you will find in appliances.

I mentioned positive displacement pumps. These style of pumps are mostly rotary pumps like screw or lobe pumps (like a supercharger on a car), or a reciprocating pump (like a piston on an air compressor). The difference is that regardless of the discharge.head volume, the pump will ALWAYS output the designed amount. So even if you shut the discharge valve of a positive displacement pump off, it will build pressure up and up and up until the pressure will blow seals and cause leaks.

Centrifugal pumps will only develop friction heat on the impeller if the discharge is blocked, it should not and will not over-pressure to blow off seals and hoses, so that it can potentially dump everything all over the floor.

I hope you enjoyed the lesson, I will do a few more on different things like blowers and seals.

 

[arbilab]

Fascinating, thanks. I had no idea a 'Tag pump was any different from any other.

 

[cfz2882]

pumps

i used to use washer pumps for a variety of different purposes-interesting to see
so many different designs...This is what i remember the different brands used in
thier automatics
Turbine:
-maytag
-unimatic
-1-18
-very early BDs
-DDs
-perf tub FFs
-perf tub SQs-drain section
-philco ford
-mid-'60s up norge
-some westy TLs(black pump,two section)
-late '60s franklin
-horizon 2000 franklin
-WP combo
-GE combo
centrifugal:
-rollermatic
-ST hotpoint
-ST filter flo
-ST SQs
-ST norge
-F/L westy
-most T/L westy(white pump)
-70s/80s franklin
-'60s kelvinator
-mid-'50s up BDs
-blackstone
-perf tub SQs-filter section

Two pumps i disliked were late'60s/early '80s era norge as was common to find fins
stripped off the impeller and i also didn't care for ST hotpoint as the bronze
impeller hub/seal seat was held to the motor shaft with a setscrew that was
always seized...also the motor shaft would rust and cause runout of the impeller

 

[gelaundry4ever]

turbine pumps

Lets not forget about the 1995 and later GE washers. Also, what type of pumps did whirlpool dishwashers use? Did they use centrifugal or turbine pumps?

 

[gelaundry4ever]

pumps

I've wanted to talk about pumps for sometime.

 

[cfz2882]

earlier plastic tub GEs used a variation of the centrifugal pump known as a "vortex"pump:basicly a centrifugal pump,but with a hemispherical volute and open-vaned impeller deeply recessed opposite the intake port-this design can pump through lint clumps and other debris well(vortex pumps are common as sewage pumps)The WP "world washer"design made down in Mexico used almost the same vortex pump as the GE(same pump supplier for both.)A fan-cooled shaded pole motor drives these pumps.Later plastic GEs,~2001 up,use PM synchronous "magnetic" bi-directional centrifugal pumps.WP dishwasher pumps are centrifugal for both main and drain sections.some vintage dishwashers used axial flow "propeller"pumps:GE up through about 1966 or 67-also found propeller type on a 1978 thermador,and ~1976 Japanese monkey wards portable dishwasher.

 

[gelaundry4ever]

point voyager whirlpool pumps

I noticed later tall tub dishwashers by whirlpool starting in 2000 had a dual pump system. What style of pump setup is this?

 

[Chetlaham]

Vortex Pump

I'm not familiar with this pump. Can anyone tell me more about it?

 

[cfz2882]

vortex pump

there are some animations on Youtube showing vortex pumps-if I can find one of my early plastic GE vortex pumps i'll add some pics

 

[gelaundry4ever]

vortex

I believe the hydrowaves had vortex pumps. Please correct me if I'm wrong.

 

[gelaundry4ever]

whirlpool dishwasher pumps

Some of whirlpool's dishwasher pumps are vertically mounted, while others are horizontally mounted. Do the whirlpool tall tubs have centrifugal or turbine pumps? This includes the point voyager and wash right designs.

 

[cfz2882]

hydrowave pump

on my Hydrowave,2008,the pump is the same PM centrifugal as the later transmission plastic GEs-mounting and fittings are the same for the early and late pumps,i could install the earlier vortex punp on my Hydrowave if I wanted to

 

[abcomatic]

Portable Hoover spindrier machine.

The pump in my Hoover portable spindrier machine. I don't know but the pump in this washer is awful. The washer section and spin tub do their thing, but the pump won't pump for some reason so I can't use the machine. What do I do to remedy this? Thanks

 

[mickeyd]

HI Gary ~

I took one apart many years ago, and pump's housing and impeller reminded me immediately of a blender blade. They seize up from mineral and detergent residue. Just a few few years back, when a newer machine's pump failed, I simply rerouted the drain hose from the back of the machine to the bottom, under the wheels, and now drain by gravity.

The nice thing about the 'Oovah is that the water stays in the wash tub even with the hose on the floor, as long as your valve switch is still working. The spinner drain remains open but that's okay. Mine is in the basement so the hose drains right into the gutter then the sump.

In my world, that's A FIX, (smile), not to mention a smashing success :'D