How many HP do I need to run a 22gpm pump to 2500 PSI? I seem to think I read 16 somewhere.
Ian
Ian
HP requirement for 22gpm Pump?
- Thread starter Haywire Haywood
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I had some questions on my own splitter, and someone here said that the rule of thumb is two gpm per HP, so for a 22 gpm pump, you need a minimum of 11 HP, but preferably 13. I'm running a 22 gpm pump with a 10 HP, and it works all right, but probably would work better with a few more horses.
What uncle said. General rule of thumb is 1/2 horse per GPM.
wkpoor
Addicted to ArboristSite
I use 60HP and it does good 
hehehehehe. Can't even tell its on there.
hehehehehe. Can't even tell its on there.HP is GPM times PSI divided by 1714 (at 100% mech efficiency)
Easier to remember, and accounting for mech friction in gears, bearings, etc is GPM x PSI / 1500
If you really mean a 22 gpm pump at 2500 psi, that is almost 40 hp.
If you mean a 22 gpm two stage pump, with smaller stage about 1/4 of total (I don't have the Haldex file with sizes here),
then 5.5 to 6 gpm at 2500 psi is 10 hp.
22 gpm at 650 psi or so is also 10 hp.
Voila, the example of why use a two stage.
-22 gpm single stage pump takes 40 hp to run against full pressure of 2500 psi.
-a 10 hp engine can only turn a 5.5 gpm section to 2500 psi.
-But the 10 hp engine can turn the combined sections of the 22 gpm against a load up to 650 psi, so you get 22 gpm speed for most operation
-When load exceeds the unloader valve setting about 650 psi, the larger 3/4 section unloads its 16 gpm back to inlet at almost no pressure. The engine is now turning only 5.5 gpm against the load and can turn the pump up to 2500 psi load.
-When load decreases below 650, the large section loads back on and the cylinder continues (or retrqcts) at 22 gpm speed again.
I don't want to reopen the past thread arguing how a single speed pump is faster because it never 'shifts down and slows down'. That is true ONLY if you have the 40 hp engine to turn the 22 gpm single stage pump here. That poster mixed apples and oranges big time.
kcj
Easier to remember, and accounting for mech friction in gears, bearings, etc is GPM x PSI / 1500
If you really mean a 22 gpm pump at 2500 psi, that is almost 40 hp.
If you mean a 22 gpm two stage pump, with smaller stage about 1/4 of total (I don't have the Haldex file with sizes here),
then 5.5 to 6 gpm at 2500 psi is 10 hp.
22 gpm at 650 psi or so is also 10 hp.
Voila, the example of why use a two stage.
-22 gpm single stage pump takes 40 hp to run against full pressure of 2500 psi.
-a 10 hp engine can only turn a 5.5 gpm section to 2500 psi.
-But the 10 hp engine can turn the combined sections of the 22 gpm against a load up to 650 psi, so you get 22 gpm speed for most operation
-When load exceeds the unloader valve setting about 650 psi, the larger 3/4 section unloads its 16 gpm back to inlet at almost no pressure. The engine is now turning only 5.5 gpm against the load and can turn the pump up to 2500 psi load.
-When load decreases below 650, the large section loads back on and the cylinder continues (or retrqcts) at 22 gpm speed again.
I don't want to reopen the past thread arguing how a single speed pump is faster because it never 'shifts down and slows down'. That is true ONLY if you have the 40 hp engine to turn the 22 gpm single stage pump here. That poster mixed apples and oranges big time.
kcj
Ok, then what I read was about right... I figure I'm buying used, so up to a point, more is better. A used one might be a little tired. Hopefully I can come up with a 16+ twin. I know where I can get a 21hp twin, but it's $250, a little overkill and I'd have to buy the whole lawn mower. I found a 14hp single Kohler that's supposedly a runner, but the starter has been sold off it, so I can't start it. Still looking. I have some feelers out.
Ian
Ian
wkpoor
Addicted to ArboristSite
I just can't resist. Since I have the real world example. Both me and Earl have the exact same beam and cylinder assembly. We have tested both splitters in the same pile side beside and no matter how you slice it or dice it the single stage pump is way more productive. And I know the math but my Deere can't even tell that 22 GPM pump is on it so I doubt its soaking up 40HP. If it were I would hear the governor kicking in and it doesn't even with the cylinder dead ended. I can out split his stand alone even with the Deere idling. There is still a bunch of apples and oranges here because a Turbo diesel power isn't anything like a small twin gas.
wkpoor
Addicted to ArboristSite
H&H, I wouldn't hesitate to overpower it. I think its nice to be able to throttle back and still have power and speed. If you make it marginal then you have to scream t all the time.
I know what you mean. It calls for 12, so I'm looking for 16. That would give me a 25% cushion. I found a 12 briggs for $75... too small and it's well used to boot.
Ian
Ian
ericjeeper
Addicted to ArboristSite
I was just at a swap meet this morning
I wish I would have known.. I saw a like new vanguard 14 horse for 150. Buddy said he saw a 14 horse at a yard sale yesterday for 60. They are out there. You just have to find em.
I wish I would have known.. I saw a like new vanguard 14 horse for 150. Buddy said he saw a 14 horse at a yard sale yesterday for 60. They are out there. You just have to find em.
Boogieman142
ArboristSite Guru
spin mine with a 11 hp briggs ic. works fine for what i need. now if i were to use it for a business then itd be a little bigger. they say half the gpm is the hp. the TW-5 timberwolf splitter has a 22 gpm pump with a 11 hp motor, good enough for them good enough for me.
wkpoor
Addicted to ArboristSite
I'm on a 4" cylinder so I don't know for sure how much more oil that cylinder will eat up without doing some math. I'll bet its close. If we are in nasty wood the smaller units spend a fair amount of time shuttling. Your bigger cylinder would limit that. What is your cycle time? Mine is 6sec.
That's the one I was thinking about... recommended HP=16 according to that surpluscenter site. Maybe that 21hp engine my buddy has isn't as bad overkill as I thought. Still... $100 more for the pump and close to double for the engine.
Ian
I'd for sure go the twin cylidner route. I have an 18 hp flat twin and it is smoooooth running about 2500 rpm.
Even at 22 gpm or 28, you only need say 12 hp in low speed at high pressure. BUT the big advantage is you can drive the large flow to higher pressure before unloading the large section. With 10 or 12 hp in example above, it was 650 psi, so the pump unloader needs to be set about there. Anytime load is higher, it unloads the big stage and slows down.
With say 16 hp, still only need 12 hp at 2500 psi unloaded, BUT it can drive the large flow up to maybe 900 psi before stalling the engine. So if you set the unloader properly, you can split 900 psi logs while still at high speed instead of slowing down. Of course if you leave the unloader setting at 650 psi then more hp has done absolutely nothing. And slowing the throttle cuts speed, doesn't change force/pressure at all (unless the system is seriously leaking and worn out).
Since the price jump is a lot from 16 to 22 gpm, (different series of barnes pump with larger body) but not so much from 22 to 28 (same series, just slightly larger gears) if you have the twin cylinder hp available I would for sure go that route, then go 28 gpm pump, especially on a 5 inch cylinder. The price increase ripples, as lines, filter, and spool valve all need to be larger. Larger spool valve is harder to find and not as many built, thus just like the pump the prices are a lot higher then the 11 16 gpm stuff.
kcj
Even at 22 gpm or 28, you only need say 12 hp in low speed at high pressure. BUT the big advantage is you can drive the large flow to higher pressure before unloading the large section. With 10 or 12 hp in example above, it was 650 psi, so the pump unloader needs to be set about there. Anytime load is higher, it unloads the big stage and slows down.
With say 16 hp, still only need 12 hp at 2500 psi unloaded, BUT it can drive the large flow up to maybe 900 psi before stalling the engine. So if you set the unloader properly, you can split 900 psi logs while still at high speed instead of slowing down. Of course if you leave the unloader setting at 650 psi then more hp has done absolutely nothing. And slowing the throttle cuts speed, doesn't change force/pressure at all (unless the system is seriously leaking and worn out).
Since the price jump is a lot from 16 to 22 gpm, (different series of barnes pump with larger body) but not so much from 22 to 28 (same series, just slightly larger gears) if you have the twin cylinder hp available I would for sure go that route, then go 28 gpm pump, especially on a 5 inch cylinder. The price increase ripples, as lines, filter, and spool valve all need to be larger. Larger spool valve is harder to find and not as many built, thus just like the pump the prices are a lot higher then the 11 16 gpm stuff.
kcj
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Chuck Diesel
ArboristSite Operative
Question- How do you reset the unloader valve for low psi on high volume?
If it works as is, maybe you are satisfied with the current setting. I want as much speed as possible with every log, so I want to get as much use as possible out of the engine hp. Sounds like you do to.
Not that hard to do once you understand what is going on. Review the two stage concept written elsewhere by many good descriptions. Also, I keep reiterating that the pressure is determined by the log/load. Relief valves and unloaders only set a MAXIMUM pressure until some control function happens. Anytime the load is below that point, adjusting the RV or unloader will not seem to have any visible effect.
On most pumps there will be two cartridges. A cap/plug on one side that is a check valve, no adjustment possible or needed. It simply isolates the small stage from going backward through the section being unloaded. Nearby, maybe on the other side, is a either a cap/screw slot behind it, or maybe a jam nut and hex adjustment. Turning it CW inward loads the spring and increases the setting. Just like setting the relief valve, except it works differently inside.
Bump it up a bit and split, and see if it overloads the engine.
It is hard to use only a gauge because there is no easy steady stage condition to measure this setting.
1. The best way is to put a flow meter and relief valve in the pressure line and measure pump output vs. pressure while doing the adjustments. That also measures the health of the pump. (BTW, simply holding 2500 psi on a gauge does NOT mean the pump is good. Another topic.) I will assume you don't have those.
2. Second best is to put a simple relief valve in the pump outlet line and slowly apply a load until it unloads the pump and read the gauge. I will assume you don't have those either.
3. Simplest and close enough is to read the pressure when it continues to split at slow speed (unloaded). You don't know when it unloaded because it happens quickly, but you will know the unloader is set somewhere below that. Then bump it up and try again.
Example: Starts split, pressure rises to say 750, but it already unloaded to slow speed. You don't know where it unloaded because it occurs quickly, but it is somewhere below 750, and was not stalling the engine before unloading. So turn it in a half turn and repeat. Eventually you will find a log that just happens to require the psi that almost stalls the engine before unloading the first section. Back off a bit if the engine seems workiing too hard when it unloads.
I don't have a picture, although someone did have one here recently. Can someone else chime in or repost the pic? Try a search.
For the 'inquiring minds' an unloader and relief valve are both spool valves moved via a pressure signal. The difference is that a relief valve references the pressure line just above the spool, and opens just enough to hold the line pressure at the high setting. Oil going across relief (say 2500 psi) is converted to HEAT and wastes engine power and fuel. An unloader valve references the line on the other side of the check valve and any time the main line pressure is high, the second pump section is unloaded back to suction at very low pressure drop, maybe 100 psi. Less heat, less engine load, thus all the engine hp goes to turn the small pump section to high pressure.
You can do it.
kcj
Not that hard to do once you understand what is going on. Review the two stage concept written elsewhere by many good descriptions. Also, I keep reiterating that the pressure is determined by the log/load. Relief valves and unloaders only set a MAXIMUM pressure until some control function happens. Anytime the load is below that point, adjusting the RV or unloader will not seem to have any visible effect.
On most pumps there will be two cartridges. A cap/plug on one side that is a check valve, no adjustment possible or needed. It simply isolates the small stage from going backward through the section being unloaded. Nearby, maybe on the other side, is a either a cap/screw slot behind it, or maybe a jam nut and hex adjustment. Turning it CW inward loads the spring and increases the setting. Just like setting the relief valve, except it works differently inside.
Bump it up a bit and split, and see if it overloads the engine.
It is hard to use only a gauge because there is no easy steady stage condition to measure this setting.
1. The best way is to put a flow meter and relief valve in the pressure line and measure pump output vs. pressure while doing the adjustments. That also measures the health of the pump. (BTW, simply holding 2500 psi on a gauge does NOT mean the pump is good. Another topic.) I will assume you don't have those.
2. Second best is to put a simple relief valve in the pump outlet line and slowly apply a load until it unloads the pump and read the gauge. I will assume you don't have those either.
3. Simplest and close enough is to read the pressure when it continues to split at slow speed (unloaded). You don't know when it unloaded because it happens quickly, but you will know the unloader is set somewhere below that. Then bump it up and try again.
Example: Starts split, pressure rises to say 750, but it already unloaded to slow speed. You don't know where it unloaded because it occurs quickly, but it is somewhere below 750, and was not stalling the engine before unloading. So turn it in a half turn and repeat. Eventually you will find a log that just happens to require the psi that almost stalls the engine before unloading the first section. Back off a bit if the engine seems workiing too hard when it unloads.
I don't have a picture, although someone did have one here recently. Can someone else chime in or repost the pic? Try a search.
For the 'inquiring minds' an unloader and relief valve are both spool valves moved via a pressure signal. The difference is that a relief valve references the pressure line just above the spool, and opens just enough to hold the line pressure at the high setting. Oil going across relief (say 2500 psi) is converted to HEAT and wastes engine power and fuel. An unloader valve references the line on the other side of the check valve and any time the main line pressure is high, the second pump section is unloaded back to suction at very low pressure drop, maybe 100 psi. Less heat, less engine load, thus all the engine hp goes to turn the small pump section to high pressure.
You can do it.
kcj
Picture should be in post #5
http://www.arboristsite.com/showthread.php?t=95190
http://www.arboristsite.com/showthread.php?t=95190
This opens up new ideas in my feeble mind.
What would be the difference between running a 22gal pump with a 16HP engine at regular settings vs running a 16gpm pump with the same engine and resetting the unload valve since I'd have a lot more engine than the pump requires? Seems like you would get similar performance with a less expensive pump. Is that more wear and tear on the pump?
Ian
Edit: Now that I've thought about it, the 22gal pump would be faster unloaded naturally, and I'm betting the low gear in the 22 gal pump moves more fluid than the low gear in the 16.
What would be the difference between running a 22gal pump with a 16HP engine at regular settings vs running a 16gpm pump with the same engine and resetting the unload valve since I'd have a lot more engine than the pump requires? Seems like you would get similar performance with a less expensive pump. Is that more wear and tear on the pump?
Ian
Edit: Now that I've thought about it, the 22gal pump would be faster unloaded naturally, and I'm betting the low gear in the 22 gal pump moves more fluid than the low gear in the 16.
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