Pumps Impeller RS?

[carlyai]

How do you know if your pump impeller or impeller housing is rs? Can you tell by looking at it?

Here are some pics of my Mitsubishi WP-305QS pump impeller housing and impeller.

The pump has had a checkered past: been adjusted by many, been a bore pump, house pump, full of sand, and finally pump had very little pressure.

Just got round to installing a new pressure switch: off 2.8 Kg/cm3 on 2.4 Kg/cm3 but no pumping pressure and pump won't switch off.

Before I take it to be completely destroyed at the local Mitsubishi pump shop, is there anything else I can do to get the pump working again?

I bought some pressure guages to install on the pump and at different points around the place, but didn't install them as the pump pressure is a lot less than my Mitsubishi 155 pump.

[carlyai]

What is "rs"?

Sorry, rs is 'rat shit'

[BB1950]

Had a similar problem. My well man pulled the pump and showed me saying it looked good. I looked at it and said no, I wanted him to replace the impeller. It was a replaceable plastic impeller. After he purchased the new impeller he compared the two and agreed the impeller was bad. After the impeller was replaced and the pump installed in the bore hole. The pressure was great once again!

I agree with Arjen there are some deep scratches and wear marks on the impeller cover. The impeller itself looks okay. It should be an easily replaceable item.

As mention above, it should fit very close fit as it makes a water seal between the two when the impeller is spinning.

[carlyai]

I think the best to do is compare it visual with a new stator and impeller. It should fit very close, and (hardly) no visible damage. I can see some deep scratches, what is not a good sign. Is it possible to buy just a new housing and impeller? Then go for that. If the pump does not reach its pressure that are the only parts involved in this. Unless there is huge leakage...

Thanks. There are no leaks as the smaller Mitsbishi 155 W motor is connected in the same position (house water pump), and it runs OK, no problems.

I took the smaller pump out and put the one (with the pictures of the impeller) in its place after I changed the pressure switch just to try it.

The smaller pump is now back in and no leaks.

[carlyai]

Had a similar problem. My well man pulled the pump and showed me saying it looked good. I looked at it and said no, I wanted him to replace the impeller. It was a replaceable plastic impeller. After he purchased the new impeller he compared the two and agreed the impeller was bad. After the impeller was replaced and the pump installed in the bore hole. The pressure was great once again!

I agree with Arjen there are some deep scratches and wear marks on the impeller cover. The impeller itself looks okay. It should be an easily replaceable item.

As mention above, it should fit very close fit as it makes a water seal between the two when the impeller is spinning.

Thanks,

What about the the last two pics and the shiny rectangular bit at the top of the pump housing, looks like the rhs bottom corner is broken, or is that how they are?

Also seem to be some score marks on the inside of this piece of metal, or is that how they are?

Looks like a visit to the Mitsubishi man and a new pump housing, impeller and impeller cover may do the trick.

Probably cost as much as the pump.

[Pib]

Most of the pictures, especially 2 thru 6, seem to show pump damage from cavitation(i.e., forming of and imploding vapor bubbles) at the impeller inlet and outlet areas. Cavitation basically pings/eats away at the metal.

[carlyai]

Most of the pictures, especially 2 thru 6, seem to show pump damage from cavitation(i.e., forming of and imploding vapor bubbles) at the impeller inlet and outlet areas. Cavitation basically pings/eats away at the metal.

I was wondering about that.

I have read about cavatation damage but was not sure what it looked like.

So you are pretty sure those poc marks at the inlet and outlet and in the centre of the pump cover are not the way they finish off the metal, but cavitation damage?

If it is cavitation damage on the pump cover, then it is probably on the pump body under the impeller as well?

So that would mean a new pump body, impeller and pump cover, is that correct?

[Pib]

I couldn't say for sure....it just matches up with images of pump cavitation damage. I would think those areas which look rough, possibly damaged by cavitation, would look a lot smoother, finished than the rough, chipped appearance they have. Just seems a factory finish wouldn't look that rough & chipped in a few places. But even with pump cavitation, unless it's really bad you should still have some pumping action going on...have some pressure/pumping action going on...although you may hear some sounds that shouldn't be there due to possible cavitation.

And where you said you installed a new pressure switch and don't have any pressure? Did you have pressure before changing that switch? If you did, must be a switch/switch installation problem.

And maybe the pump just needs to be primed through its primping hole on top of the manifold assembly....you should have two plug holes which have screw-on caps...one cap covers the water inlet backflow valve and the other is the primping hole. When screwing the cap back on don't over tighten as you can easily strip the plastic threads. The pump is suppose to be self priming....I know I have never had to prime my Mitsubishi WP-255 pump after its pressure tank has been completely drained and my pump is the same design as yours but with a little less power/wattage. But since the pump does include a priming hole I guess the pump may need to be primed in some cases, has a worn pumping/impeller assembly, etc. Prime the pump and see what happens. Good luck.

[carlyai]

I couldn't say for sure....it just matches up with images of pump cavitation damage. I would think those areas which look rough, possibly damaged by cavitation, would look a lot smoother, finished than the rough, chipped appearance they have. Just seems a factory finish wouldn't look that rough & chipped in a few places. But even with pump cavitation, unless it's really bad you should still have some pumping action going on...have some pressure/pumping action going on...although you may hear some sounds that shouldn't be there due to possible cavitation.

And where you said you installed a new pressure switch and don't have any pressure? Did you have pressure before changing that switch? If you did, must be a switch/switch installation problem.

And maybe the pump just needs to be primed through its primping hole on top of the manifold assembly....you should have two plug holes which have screw-on caps...one cap covers the water inlet backflow valve and the other is the primping hole. When screwing the cap back on don't over tighten as you can easily strip the plastic threads. The pump is suppose to be self priming....I know I have never had to prime my Mitsubishi WP-255 pump after its pressure tank has been completely drained and my pump is the same design as yours but with a little less power/wattage. But since the pump does include a priming hole I guess the pump may need to be primed in some cases, has a worn pumping/impeller assembly, etc. Prime the pump and see what happens. Good luck.

Yeah I do have some pumping action going on, but very weak and nothing compared to my other WP115 pump now doing the job.

I didn't have much pressure before changing the pressure switch. A while ago (months, the pump has been waiting for me to fix it for months), I didn't have much pressure so took it to the local tractor/pump place for them to test it. All they did was change the spring in the pressure switch. Don't think they tested it. The screw adjustment had been screwed off, there was no screwdriver slot anymore, so I decided to change the whole pressure switch. Had lots of trouble getting a new one, until I got onto the unhelpful Mitsbishi mob in Bangkok and hastled them until they gave me an agent in Mukdahan, then last week got the new pressure switch and installed it.

I did prime the pump, several times and checked the water level, because I also drained the pump tank. Lots of sand came out.

The only other thing I can think of is that the first time when I had not much pressure, before changing the pressure switch, I took the impeller cover off to have a look, and maybe I put the cover back on the wrong way, don't know if you can, and it probably wouldn't work at all, but If I didn't put the impeller cover on the correct way and the inlet holes in the cover were at the bottom would the pump still work?

[Pib]

The only other thing I can think of is that the first time when I had not much pressure, before changing the pressure switch, I took the impeller cover off to have a look, and maybe I put the cover back on the wrong way, don't know if you can, and it probably wouldn't work at all, but If I didn't put the impeller cover on the correct way and the inlet holes in the cover were at the bottom would the pump still work?

I doubt it would work or at least be severely impaired. Probably worth pulling the impeller cover off to check and see if you installed it right especially since it only takes removal of 4 screws/bolts which are easily accessed.

[RichCor]

Haven't come across any original or replacement part images to verify what it's supposed to look like.

But the photos seem to match this this graphic illustration from Vacuum Pump - Regenerative Blower Wiki

Or this graphic illustration from Regenerative Turbine Pumps: Unsung Heroes For Volatile Fluids

Edited October 2, 2015 by RichCor

[carlyai]

The only other thing I can think of is that the first time when I had not much pressure, before changing the pressure switch, I took the impeller cover off to have a look, and maybe I put the cover back on the wrong way, don't know if you can, and it probably wouldn't work at all, but If I didn't put the impeller cover on the correct way and the inlet holes in the cover were at the bottom would the pump still work?

I doubt it would work or at least be severely impaired. Probably worth pulling the impeller cover off to check and see if you installed it right especially since it only takes removal of 4 screws/bolts which are easily accessed.

Yeah I did check and it is installed correctly, but just wondering if I installed it correctly before, but you're right it probably wouldn't work at all.

[carlyai]

Haven't come across any original or replacement part images to verify what it's supposed to look like.

But the photos seem to match this this graphic illustration from Vacuum Pump - Regenerative Blower Wiki

Or this graphic illustration from Regenerative Turbine Pumps: Unsung Heroes For Volatile Fluids

Thanks Rich

I've googled some cavitation pics but they all look a lot more severe than mine, so not sure if it is the metal finish or not. Will try and take another pump to pieces and compare them.

[Artisi]

Appears to be likely erosion on the impeller and case with a fair bit of damage (metal removal) in and around the discharge port. Being a regenerative pump it relieves on fairly close running clearances to ensure the maximum pressure is generated. I would suggest it has exceeded its useful live as a pressure pump.

Pumping sand is a killer on this pump style as the sand is recirculated round and round many times within and between the impeller blades.

[carlyai]

Hi and update.

I replaced the impeller but it looked fine or it looked the same as the new impeller but the results were completely different and the pump was working up to pressure again.

I tried very hard to get a new impeller seat and housing but the pump guy kept saying I don't need one as it would cost a bit more. I finally gave up.

One month later and I have replaced the pump again as it is becoming noisy, and this time I will replace the impeller housing as well, and probably need a new impeller as well.

[RichCor]

If it's breaking down that fast I would think you need to investigate why so much hard particles like sand are being drawn into the system.

I'd look into where the pipe 'foot' is in relation to the sides and bottom of your well, and what size screen it's using. There are also separators you can add prior to the pump.

I'm sure there are better articles to link to, but this one came up first on my google foo research:

What To Do When Your Water Well Begins To Pump Sand Or Grit

CleanWaterStore.com | Post by GERRY BULFIN | DECEMBER 5, 2012

[Artisi]

Is there any signs of sand in the water supply?

Please describe the pump installation, where is it connected, how is it connected, connected to a tank, direct connected to town supply, lifting from a well?

Have reviewed your original photos and can see signs of cavitation but don't think this is your main problem, they showed signs of erosion and what could be some mechanical degradation from entrained solids.

Edited December 23, 2015 by Artisi

[RichCor]

One month later and I have replaced the pump again as it is becoming noisy, and this time I will replace the impeller housing as well, and probably need a new impeller as well.

Was the pump still providing water at pressure, even with the new noise? Just wondering if the noise issue is related to the impeller or the motor.

Enggcyclopedia > Pump Cavitation Causes

Pump Cavitation Definition

Pump cavitation is the formation and subsequent collapse or implosion of vapor bubbles in a pump.

It occurs when gas bubbles are formed in the pump due to drop in absolute pressure of the liquid below vapor pressure. These gas bubbles occupy space inside the pump and affect the pump's operating pressure and flow. With vapor bubbles in the low-pressure zones of the pump, the motor's energy is wasted expanding the bubbles instead of bringing more liquid into the pump. As the bubbles pass into the pump's high-pressure zones, the motor's energy is wasted compressing the bubbles instead of expelling the liquid from the pump. The bubbles can collapse as they pass from low- to high-pressure zones in the pump.

When vapor bubbles collapse inside the pump the liquid strikes the metal parts at the speed of sound. The noise generated from these collisions of gas bubbles into the metal parts of pump sounds like pumping marbles and stones.

Causes of Pump Cavitation

...are also listed in the link, including poor inflow or poor pipe layout design (sharp elbows, valves, other fittings and obstructions causing more frictional pressure loss in the pump suction).

When you get time, maybe answering Artisi's questions might help indicate a cause.

[Artisi]

The noise could be cavitation, that is why there is a need to establish how /where the pump is installed, but as said previously the cavitation appears to be minor and not the cause of the wear patterns shown in the original photos.

[carlyai]

Is there any signs of sand in the water supply?

Please describe the pump installation, where is it connected, how is it connected, connected to a tank, direct connected to town supply, lifting from a well?

Have reviewed your original photos and can see signs of cavitation but don't think this is your main problem, they showed signs of erosion and what could be some mechanical degradation from entrained solids.

[carlyai]

Is there any signs of sand in the water supply?

Please describe the pump installation, where is it connected, how is it connected, connected to a tank, direct connected to town supply, lifting from a well?

Have reviewed your original photos and can see signs of cavitation but don't think this is your main problem, they showed signs of erosion and what could be some mechanical degradation from entrained solids.

Sorry to have misled you.

My point was that i replaced the impeller, but wanted to replace the impeller housing as well, but the pump guy wouldnt have it. I should have replaced the lot.

The replacing the pump impeller fixed the pressure problem, but i still felt that if the impeller was worn then so would the housing be worn.

The noise the pump was making became louder but the pressure was still ok. Because we were going away for a few months, i didnt want to leave a potentially faulty pump delivering the sptinkler water.

The pump is the house pump and not the bore pump.

The pump is fed from a 3000 l tank through 3 large filters and i am confident there is no sand now getting into the pump.

So my conclusion was that when the impeller was replaced for B 1000 i should have replaced the housing etc for less than B3000 and then i would have known all that area was ok.

When i first suggested the impeller they daid no way then started changing everything including the capacitor.

[Artisi]

Is there any signs of sand in the water supply?

Please describe the pump installation, where is it connected, how is it connected, connected to a tank, direct connected to town supply, lifting from a well?

Have reviewed your original photos and can see signs of cavitation but don't think this is your main problem, they showed signs of erosion and what could be some mechanical degradation from entrained solids.

Sorry to have misled you.

My point was that i replaced the impeller, but wanted to replace the impeller housing as well, but the pump guy wouldnt have it. I should have replaced the lot.

The replacing the pump impeller fixed the pressure problem, but i still felt that if the impeller was worn then so would the housing be worn.

The noise the pump was making became louder but the pressure was still ok. Because we were going away for a few months, i didnt want to leave a potentially faulty pump delivering the sptinkler water.

The pump is the house pump and not the bore pump.

The pump is fed from a 3000 l tank through 3 large filters and i am confident there is no sand now getting into the pump.

So my conclusion was that when the impeller was replaced for B 1000 i should have replaced the housing etc for less than B3000 and then i would have known all that area was ok.

When i first suggested the impeller they daid no way then started changing everything including the capacitor.

Are the filters on the inlet or the discharge side of the pump?

[RichCor]

Is there any signs of sand in the water supply?

Please describe the pump installation, where is it connected, how is it connected, connected to a tank, direct connected to town supply, lifting from a well?

Have reviewed your original photos and can see signs of cavitation but don't think this is your main problem, they showed signs of erosion and what could be some mechanical degradation from entrained solids.

Sorry to have misled you.

My point was that i replaced the impeller, but wanted to replace the impeller housing as well, but the pump guy wouldnt have it. I should have replaced the lot.

The replacing the pump impeller fixed the pressure problem, but i still felt that if the impeller was worn then so would the housing be worn.

The noise the pump was making became louder but the pressure was still ok. Because we were going away for a few months, i didnt want to leave a potentially faulty pump delivering the sptinkler water.

The pump is the house pump and not the bore pump.

The pump is fed from a 3000 l tank through 3 large filters and i am confident there is no sand now getting into the pump.

So my conclusion was that when the impeller was replaced for B 1000 i should have replaced the housing etc for less than B3000 and then i would have known all that area was ok.

When i first suggested the impeller they daid no way then started changing everything including the capacitor.

Are the filters on the inlet or the discharge side of the pump?

I believe he only just recently added the filters just last month, so is a new addition, as chronicled in the listed thread.

From the image I can't determine if the filters are:

"post Bore Pump / pre Holding tank",

"post Holding Tank / pre Pressure Pump", or

"post Pressure Pump"

Water Testing and Filters Advice

Started by carlyai, 2015-11-13 09:23