Confused about my piston pump?

[canuckamuck]

I finally decided to hook up this piston pump I bought last year, It is a 35000 liter per hour unit, and I mounted a 270 CC 9Hp Honda on top of it. I have never run one of these, but I need to get water higher up the hill, and from last years thread I determined that this is the right pump for that.

When I bought the engine I asked them to mount a pulley wheel to it. It came with a 1.5 inch drive wheel, but that was for a half inch shaft. The Honda has a 1 inch shaft. They mounted a 2 " inch wheel and said it would be fine.

When I got the belts for it, from the guy who sold me the pump initially, he also confirmed that the 2" would be fine.

So I hooked it all up and started it up. And it really didn't want to go so well. When I adjusted the throttle even a little it stalled. But a couple of minutes later, it did allow me to throttle up some, maybe 20%. But the pump noise increased, (more clacking). It seemed happiest at idle. But the motor wanted to a little throttle.

Watching the flow from the outlet, I could see that the volume was about 50% of my last pump. which was about 30,000 liters an hour and upping the throttle seem to have only a small effect on the flow. Even worse, the flow was quite variable. At some points the water would nearly stop running, and then it would start again with pretty good volume. But no change in throttle or pump noise.

So I though I would test it's ability to lift water. I have a tank at 30 meters elevation. The pump did do a pretty good job here, Almost as much flow as the centrifugal pump and no noticeable variation in flow.

However, there are air  bubbles in water, and they continue the whole time. I ran the pump an hour and everything remained the same.

 

I need to know if this is normal for this kind of pump or is there something wrong?

The variation in  flow at zero elevation is bothering me, as well as the air in water. My guess is that it is cavitating. I did try the pump with no foot valve, so there was zero restriction on the inlet. It did not appear to make any difference. I am wondering if it got damaged at the first start up and how could I tell?

By the way I did find a 1.5 inch drive wheel and replaced the 2 inch. No difference in flow, but the motor can be set a little quicker without complaint from the pump

 

Edited March 27, 2017 by canuckamuck

[Crossy]

These little Hondas produce peak power at about 3,000 RPM with a recommended speed range of 2,000 to 3,600 RPM so you want to arrange the gearing (pulleys) so the engine is running in this range.

 

What speed is the pump rated at (should be on the pump somewhere) and what sizes are your pulleys?

 

If you have air in the outflow are you sure there are no leaks in the suction?

[farmerjo]

Hi Canuckamuck,

Did you put a pressure guage and an accumulator in the line to stop the pulsating.

Think in the original thread rpm was talked about and rated pressure of the pump.

How far below the pump is the water level your drawing from.

Think there is a bleed screw on them as well.

Edited March 27, 2017 by farmerjo

[canuckamuck]

4 minutes ago, Crossy said:

These little Hondas produce peak power at about 3,000 RPM with a recommended speed range of 2,000 to 3,600 RPM so you want to arrange the gearing (pulleys) so the engine is running in this range.

 

What speed is the pump rated at (should be on the pump somewhere) and what sizes are your pulleys?

 

If you have air in the outflow are you sure there are no leaks in the suction?

Pretty hard to tell what the RPM's are when there is no tach. But the pump wont let me go faster than about 20 percent throttle at this stage, without noticeable increase in pump noise. The wheel on the pump looks to be about 10 to 12" but I will measure today to know for sure.

There are no indications or suggested RPM's listed on the pump. I would love to know what speed is recommended.

I did my best to eliminate leaks on the intake, But I will try again. It's metal fittings with teflon tape and 36 inch pipe wrench. I am sure I got it snug.

 

[canuckamuck]

9 minutes ago, farmerjo said:

Hi Canuckamuck,

Did you put a pressure guage and an accumulator in the line to stop the pulsating.

Think in the original thread rpm was talked about and rated pressure of the pump.

How far below the pump is the water level your drawing from.

 

I do not have a pressure gauge. Where can I get one?

The pipe configuration has built in pressurization. The main outlet pipe comes straight from the pump and goes 30 meters uphill. All other lines are tee'd into this. There is no pulsing on the lower lines because this smooths out the flow. I ran the sprinklers and they worked fine, and the flow at the pond is smooth but variable (good flow for about 20 seconds and poor flow for about 20 seconds, continually).

I am not noticing a variation in flow under pressure though.

[farmerjo]

All local hardware shops have small pressure guages,not expensive.

Try a bit of grease in between your barrel union on inlet side.

They are generally poor quality here and don't seat well.

Nice set up.

According to the pulley calculator if the pump pulley is indeed 12 inch you should be able to run your engine at 3100 rpm which is at 3/4 throttle.

I think the pumps are rated for 4 bar,that's why you need the guage otherwise you may damage the leather seats.

Edited March 27, 2017 by farmerjo

[Gary A]

Those piston pumps are usually very reliable and will run for many years with no problems. You didn't mention the source of your water. If it is a borehole, it sounds like you are pumping the casing dry and the borehole is simply not recovering quickly enough. The pump can be damaged by running it dry. It should run fairly quietly with no clattering. You should have no air in the output. Some pulsing is normal.

 

We have a fifty meter deep bore hole. The water level is about three meters from the top of the casing. It drops during the dry season when you need the most water. My wife's relatives have a large piston pump  that they wanted to sell. I told them that it wouldn't work but they were convinced it would. I told them that they could try it and if it worked, I would buy the pump. It was powered with our Kubota tak tak. After three days of working on it, it wouldn't work. I bought a one HP submersible that works well.

 

ADDED - I should add that you do need a foot valve and an air reservoir at the output to eliminate the pulsing.

Edited March 27, 2017 by Gary A

[canuckamuck]

19 minutes ago, Gary A said:

Those piston pumps are usually very reliable and will run for many years with no problems. You didn't mention the source of your water. If it is a borehole, it sounds like you are pumping the casing dry and the borehole is simply not recovering quickly enough. The pump can be damaged by running it dry. It should run fairly quietly with no clattering. You should have no air in the output. Some pulsing is normal.

 

We have a fifty meter deep bore hole. The water level is about three meters from the top of the casing. It drops during the dry season when you need the most water. My wife's relatives have a large piston pump  that they wanted to sell. I told them that it wouldn't work but they were convinced it would. I told them that they could try it and if it worked, I would buy the pump. It was powered with our Kubota tak tak. After three days of working on it, it wouldn't work. I bought a one HP submersible that works well.

 

ADDED - I should add that you do need a foot valve and an air reservoir at the output to eliminate the pulsing.

No, the source is a pond. the suction height is not much more than a meter.

 

To update, I have taken apart the intake connections and I will be hooking it up a little different. I need to eliminate any question of air intake before I can trouble shoot further.

 

There are three removable brass fitting two on the top and one in the front of the pump.

The two on the top are for priming. not sure why two. But what is the one on the front for? If I open it while the pump is running, it squirts and sucks alternatively.

[farmerjo]

http://www.pumpvr.com/joomla/index.php?option=com_content&view=article&id=72&Itemid=134&lang=en

The second video the guy leaves it open,also notice his raised pipe on the outlet.

[Gary A]

1 hour ago, canuckamuck said:

No, the source is a pond. the suction height is not much more than a meter.

 

To update, I have taken apart the intake connections and I will be hooking it up a little different. I need to eliminate any question of air intake before I can trouble shoot further.

 

There are three removable brass fitting two on the top and one in the front of the pump.

The two on the top are for priming. not sure why two. But what is the one on the front for? If I open it while the pump is running, it squirts and sucks alternatively.

 

If by the front you mean the discharge end, it is likely for an air tank that eliminates the pulsing. Around here they use PVC pipes reduced and capped on the top end. Cheaper than buying a tank. I think you'll eventually get it working properly and be quite happy with it. Since you have taken it apart, the most critical part to look at is the check valve. It is a simple valve that opens for suction and closes for discharge. Dirt can cause a problem but it normally self cleans in the suction phase. Hopefully you have a fine mesh filter on the suction pipe. You have plenty of horsepower. I doubt that the engine will need to run faster than a high idle.

 

ADDED - If the plugs are on the discharge end of the pump, it should not have any suction, only water spraying out.

Edited March 27, 2017 by Gary A

[thoongfoned]

got one of those pumps in the garage. i have always found that they pump up well but pumping along they are not that good. have  driven it by the thai tactac tractor heads and also  by an electric dynamo., same results, good from the ground up but not  much pressure  going along.

[canuckamuck]

I think I have it sorted now. I tried a few types of connectors, but had air leaks on all. Finally got tired of it and made it a straight PVC connection, all glued.I hate to go that way, I got to cut it off if I need to change something. But I figure there is only going to be water for three weeks at the most over here and I can do it smarter next year.

I do still get fluctuations in flow at zero elevation. But I don't need it for that, so I don't care. Going uphill it is consistent.

Thanks everyone, I really appreciated the help.