water in my cat

[NobleCarpetCleaners]

sucks but sometimes mechanisms fail earlier then perhaps many other like it. Tiny amonts of water could be sneaking past the piston seals. Just monitor it and see how she goes..

 

[Mikey P]

1200 hours..

 

[Mikey P]

Fresh tank heat must be the culprit

 

[Mikey P]

Or...
The AT is not Last Step injection like I thought and this is the result of the MW 02 rinse I was using..

 

[Desk Jockey]

Looks like a lot of oxidation for just hot water. ???

 

[Mikey P]

Can rinse agents back flush from the chem pump to the Cat?

 

[Desk Jockey]

I don't think so.

 

[Jim Pemberton]

If your chemical pump diaphragm is ruptured it can Mike.

Do you turn your pressure up around 1000 psi and above for hard surface cleaning from time to time?

 

[Mikey P]

Sure but this is a 1500 General Chem Pump.


And the Dweyer gph meter is working fine..

 

[Jim Pemberton]

OK.

I'm not familiar with the pump. Does it have a diaphragm?

 

[Charlie Lyman]

Was oil leaking through the seals?

 

[GeneMiller]

That doesn't look right. Something else is going on. Your water softner is running salt through. Check the water in the tank that goes to the pump. What's really in it.

Gene

 

[Mikey P]

The water in the fresh tank?


No water box on VATs.


Our Kinetico has had its down time...

 

[ronbeatty]

I just had a 5cp pump rebuilt after 700 hrs, Cat said the check valves and seals showed excessive wear. The older style Cat pumps that Butler used would go 3500 hrs plus. My next pump will be a General, half the price and from what I hear a much better pump.

 

[Mikey P]

What made you rebuild it Ron?

 

[Lee Stockwell]

The General is a better pump, with one weak link: It MUST be pressure-fed to avoid cavitation. More so with hot water input.

 

[ronbeatty]

I was experiencing erratic chemical flow and a drop in operating pressure. I got it back after the rebuild it worked for a couple of weeks and then started acting up again. I ordered a new one will be here on Thursday.

 

[dgardner]

I think very slight cavitation is the culprit in a lot of cases when the pump life is less than expected.

 

[Desk Jockey]

Dan is that from too high an inlet temp?

 

[dgardner]

Not exactly. My (probably incomplete) understanding is that cavitation occurs when there is rapid fluctuation in local pressure below the saturated vapor pressure of the water. Temperature is involved because the pressure where cavitation occurs (at a given pressure) goes up as temperature rises. So, increasing the inlet pressure and/or reducing the liquid temperature can cure cavitation.

When the piston draws in liquid through the inlet plumbing and past the inlet valve there is always some pressure drop. Poor plumbing (tubing too small, restrictive fittings) make the situation worse. The water level above the pump inlet makes a difference as well. The higher the level - the more pressure (head, as the pump guys say) is exerted at the inlet, helping the situation. Make the pump draw water uphill (water box below pump) creates low pressure (vacuum) making the situation worse.

You can create cavitation at any temperature (with enough inlet restriction and/or low enough inlet pressure) but high temperature makes matters worse (much worse, as you approch boiling).

 

[Desk Jockey]

I thought pressure would control cavitation from occurring? Or Does it just keep water from boiling?

Off the subject but still about cavitation we use ultrasonic machines to clean fire damage items. It uses transducers to create a frequency that creates cavitation. Its that the same kind of activity that goes on in a pump? Can it damage the pump?

If you leave and item in an ultrasonic machine to too long it will strip the paint or plating off them.

 

[dgardner]

The higher the level the more pressure (head, as the pump guys say) is exerted at the inlet, helping the situation. Make the pump draw water uphill (water box below pump) creates low pressure (vacuum) making the situation worse.

I thought pressure would control cavitation from occurring?

Yes, as I mentioned - pressure does help. Enough pressure (for the temp you're running) will stop the cavitation.

Take a pump that you're feeding 180° water that is cavitating. You could increase the pressure to stop it - or reduce the temperature. It's a little like TACT - What you dont do for one piece you can make up with another piece.

 

[dgardner]

Off the subject but still about cavitation we use ultrasonic machines to clean fire damage items. It uses transducers to create a frequency that creates cavitation. Its that the same kind of activity that goes on in a pump?

The transducers actually vibrate at a certain frequency to produce a pressure wave - which is high and low pressure variations - sound familiar? it's the pressure transitions that create the cavitation (voids) and as the voids violently collapse they generate a shock wave that does the cleaning (in the ultrasonic machine) or the damage (in the pump).

 

[Desk Jockey]

LOL

I feel like I'm back in Applied Physics class. Maybe this time I'll pass.

 

[Desk Jockey]

Take a pump that you're feeding 180° water that is cavitating. You could increase the pressure to stop it - or reduce the temperature. It's a little like TACT - What you dont do for one piece you can make up with another piece.

That's where I always thought it was heat that caused it but from your explanation I now see it can more than heat.

In the ultrasonic its doesn't have to be hot water used but it works better in hot.

 

[dealtimeman]

Which is what is wierd in this situation.

As mikes machine as well as rims machine are newer aerotechs that have the pump Mounted to the floor in the box well below the fluid or water level in the fresh tank.

You will notice the cat pump right in front of blower on floor of truck.

Older trucks like mine have the pump mounted above the blower always above the water line by at least a foot or so and the pump has to pull one foot up and at least two feet across to get the water.

I had cavitation but only because of that General pump fine inlet strainer connected to pump would suck a bit of air, once removed never have had cavitation again. Our tanks after a couple of hours will hover at 150-160 degrees preheated by motor while driving around.

I will pull one of my cat pumps apart to see if I had that type of wear going on.

 

[Desk Jockey]

I will pull one of my cat pumps apart to see if I had that type of wear going on.

That didn't look so much like wear as it did something aggressively attacking it. ???

Dan would the cavitation eat away at the pump the same way an ultrasonic machine will eat at an item left in the tub too long?

 

[dealtimeman]

That is what I mean as the brass plug mike has posted a pic of does not move, it is stationary. The plunger moves in and out of the middle of it creating pressure in the head. So what ever is "wearing or eating" it has to be in the water.

 

[dgardner]

I agree. severe cavitation can/will erode the pump materials but not (in my experience) discolor them like that. Certainly looks like either chemical attack or electrolysis to me.

 

[dgardner]

I had cavitation but only because of that General pump fine inlet strainer connected to pump would suck a bit of air,

It also would have presented some restriction (pressure drop), further reducing the inlet pressure, which would just add to the problem.