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Keene P-180 Plastic Pump Intake, Impeller Efficiencies And Tolerances


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Edit: this topic was split from this thread on modifying a pump intake.

Steve,

I believe that "plastic cuff" you are referring too on the P-180 dictates the pressure of the pump?

I had one P-180 setup that I had a pressure gauge on the outlet side of the pump. (4" dredge)

New, I think it was about 38 lbs. of pressure.  I filed off the "stop ring" on the plastic inlet fitting and tapped it in towards the impellor until I felt it start to drag.  I now had 54 lbs. of pressure at the outlet.

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36 minutes ago, LipCa said:

Steve,

I believe that "plastic cuff" you are referring too on the P-180 dictates the pressure of the pump?

I had one P-180 setup that I had a pressure gauge on the outlet side of the pump. (4" dredge)

New, I think it was about 38 lbs. of pressure.  I filed off the "stop ring" on the plastic inlet fitting and tapped it in towards the impellor until I felt it start to drag.  I now had 54 lbs. of pressure at the outlet.

I can see that having some effect. Took the pump housing off to install some drain plugs and I was surprised to see how rough the casting on the inside is. I wonder if porting and polishing would make a huge difference? Also I found large globs od silicone inside at the 3/4 side port. I cut that out as it was just sloppy install work.

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Yes, driving the plastic right up against the impeller seals the system and prevents blowback around the impeller. That is the way they are supposed to be installed. In other words, the water goes right into the center of the impeller to be slung out.

The old Keene pumps were super loose tolerance and the plastic cuff was really critical. The newer pumps have really tight machining and it would be much less an issue, but still real. In fact, are not the lastest pumps using a full metal intake? Good call Harry, was not really thinking of that but it would be something to be aware of and work with or around.

The old Pro-Mack pumps have no such spacer but were already machined up to the tolerances that Keene pumps have only reached in the latest versions.

Edit: yup, just looked, and the old P-180 is now one of the last Keene pumps using plastic cuff intakes. Here is the new HP-160

IMG_0255.JPG

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I was told that the looser tolerance  was to allow some sand to be inhaled. If you tightened the tolerance, sucking dirty water was a no no.

New design would not allow any adjustment.(and maybe you can't inhale any sand?)

I know increasing the pressure really increased the sucking at the business end.  You had to watch the fingers!

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I don't think Proline, Dalke, Precision, or anyone else making high efficiency pumps would agree with that. I don't recall anyone else ever having anything except metal intakes. The water is supposed to go into the middle of the impeller and get slung around the outer part of the housing and out of the pump. Any gap between the impeller and inside of the intake area is non-productive. The pump intake should always be kept out of sand to reduce wear - mine stayed bungeed to the bottom of the floats. Old Keene pumps were simply inefficient and they have improved over time.

The pump is supposed to pump water, and sand and gravel goes up the main suction line. If people need to suck sand and gravel through a pump, that is what trash pumps are for. A good high pressure fire fighting dredge type pump should be built to best do what it is designed for, and that is to give you the most suction power possible in the lightest weight most fuel efficient design possible. And that means good, close tolerances.

However, if you have to suck lots of sand through a pump for some reason the Keene adjustable plastic intake does allow for wear and adjustment.

I serviced a lot of pumps for people over the years and never really saw much sign that impeller abrasion from sand was an issue. More often somebody loosing a screen and plugging the impeller with rocks, and even then no damage done. But if you always left your intakes in sand bars I guess it could be an issue.

Really though, the old P-180 pump is just a leftover of days gone by. No other pump in the Keene lineup has that sort of setup now, and nobody else has for many years, if ever.

keene-engineering-direct-mount-pumps-2017.jpg

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LipCal, with the increased PSI were you able to run your motor at a lower rpm and have the same performance? I'm thinking this may be a good tweak to help save fuel. Anything I can do to keep from hauling in fuel is worth looking into.

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If your pumps are new the plastic cuff is already supposed to be mated up directly to the impeller on newer P-180 pumps. There should be nothing to tweak unless something is out of spec. From Keene pump instructions:

HOW TO INSTALL THE HOSE ADAPTOR PUMP INTAKE COUPLER: (For all models except the P-50 and P-300 Series).

The tolerance of the Hose Adapter is critical for proper pump performance. The hose Adapter should be installed as close as possible to the intake portion of the impeller. Center the adapter into the housing opening and press in by hand to locate it into place and place a wooden block against the outside of the adapter and gently tap until the adapter is firmly seated against the face of the impeller. Pull the starter rope until the engine turns. When the coupler is properly seated, the engine should be somewhat difficult to turn over, making sure that the adapter is against the face of the impeller.

There are many styles of P150, P160 and P180 pump and impeller, and if getting replacement parts it is easy to get a mismatch, resulting in larger than intended gap in tolerances. If I recall correctly P150 and P160 was 2" in and 1.5" output, P180 went to 2.5" intake and 2" output. All mounted to various 5 - 6.5HP motors with the only real difference being the impeller and housings. They all share the same backplate, etc.

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Ok, looking at my P180. It looks to be a newer model. 

The pvc fitting can only go into the alluminium housing so far as it is machined with a stop on the case.

IMG_1514.thumb.JPG.673919d55c4fa265e504b9f050c51ade.JPG

Looking down the ejecter port you can see the aluminum casing matting close to the impeller.

The new impeller has a nose cone instead of the aluminum intake on it. Looks like Keene took that off the impeller and added it to the case instead of using the pvc fitting.

 

IMG_1523.thumb.JPG.087879b6526bc781b5bf78b442840db5.JPG

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