Pump Rating

[goof008]

I have an older splitter and I wanted to try to find out the pump output, but am not sure how to do it. It is a single speed pump that was hooked up to a 5hp Briggs engine. The cylinder is approx. 3.5-4 inches diameter (tube, not shaft).

Any ideas how to estimate what the gpm of the pump is?

I am looking to upgrade the pump to a 2 speed, but want to make sure it's worth it.

I replaced the old 5hp briggs with a new 5.5hp briggs (wish I would have gone with a 6 or 8!!) so I can run a 2-stage 11/2.9 gpm unit on it.

Any help would be great

 

[goof008]

thanks....I won't be out the the woods, where my splitter is, until tomorrow, but I'll measure it up and time it at WOT.

 

[triptester]

If the pump is a single stage a 5 hp. engine will only be able to push about 2.5gpm max. at full pressure. The 5.5 hp. engine normally will handle a 2-stage 11 gpm pump to 3000 psi.

 

[goof008]

I figured it was low, but just didn't know the exact numbers. I'll get the cycle time and dimensions tonight.

One other question. What is the rule of thumb about gpm and amount of fluid your splitter will hold. Mine only holds about 5 gallons. If i get a new 2-speed pump, do I need to add fluid capacity?

 

[husky455rancher]

well i would say if you dont increase the size of the pump then no. i run a 2 stage 11 gpm pump and i have maybe a 4 1/2 gallon tank. also if you jumped up in pump size you would need a bigger motor. its a viscious cycle.

 

[goof008]

OK, the cylinder is 4" in diameter, 28 inches long and the piston shaft seems to be 1 3/4".

Husky Rancher, thanks for the info, I'm running a single stage pump right now and want to make sure if I move up to a 2 stage like you have, that I will have enough fluid on board. Looks like I will.

 

[Straightgrain]

Dang!

You guys really know your stuff.
I am learning a lot here.

Thanks!

 

[drmiller100]

OK, the cylinder is 4" in diameter, 28 inches long and the piston shaft seems to be 1 3/4".

Husky Rancher, thanks for the info, I'm running a single stage pump right now and want to make sure if I move up to a 2 stage like you have, that I will have enough fluid on board. Looks like I will.

how long does it take to push the shaft OUT say full extension.

 

[AKKAMAAN]

A great way to measure time on a cycle, is to use a video camera, shot the whole cycle, dump the movie clip into your pc, and start the video editor, like Windows Movie Maker.

When you look att the video clip there in the clip board you can see the time line and exact how long time the cycle takes....

Of course this requires some PC skills, but it works great, especially on very short sequences......



In this case after figuering out the cycle time for an extract stroke, you will need the actual rpm's aswell....

In the hydraulic industry, pumpsize is discribed as the displacement per rev. like cui per rev or cm3 per rev...
In this forum, pumpsize is usually mentioned as GPM, which require the rpm's as a reference...

Your extract stroke volume is 1.524 USG if bore is 4" and stroke 28"
Example: If that stroke takes, lets say 12 sec, pump flow is 60/12*1.524 which makes roughly 7.6 GPM

 

[goof008]

I appreciate all the help, but it'll take a couple of days. The engine started not wanting to stay running, and I can't get to it right away...it's always something!!

I don't have a tach to throw on it either, but the engine is a year old B&S 5.5 hp off the shelf from TSC, if that helps any. Just guessing, the pump being a single stage pump that had an old B&S 5hp on it, the pump can't be very high gpm...maybe 3gpm?

 

[goof008]

ok, I cleaned the carb and got the thing running.

The time to extend the ram is 7.9 seconds.

 

[triptester]

If the extend time is 7.9 with a 4" bore and a 28" stroke the pump would have to put out 10 to 11 gpm. A single stage pump at this gpm would stall a 5.5 hp. engine before it got up to 1000psi.

 

[goof008]

I'll time it again tonight.

The cylinder is 28" long, so the stroke will have to be shorter, but I couldn't extend it and measure it before yesterday....I'll measure the length of the stroke and get back to you.