Fourced
ArboristSite Member
When a spool valve is rated for 25 g/m, is that all the bigger pump you can run?
Hydraulic question
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My spool is rated 25 gm with a 28gpm pump, but I don't run the motor at full speed.
It's lasted 25 years.
It's lasted 25 years.
The problem is in the size of the ports down in the valve. pushing more oil thru smaller ports results in more back pressure and more heat. Probably aught to take that into consideration.
Fourced
ArboristSite Member
By smaller ports do you mean the work ports or the open center?
Most every splitter I have ever seen running a 28 gpm pump is using the 25 gpm valve. Stepping up to a larger valve that will have over 25GPM rating is a BIG money difference.
The spool, a very fine piece of pipe stuck into a very precisely bored mono block will have ports a certain size. Meaning that the real bottle neck is in the valve itself. The 1/2" work ports are actually capable (barely) of 25 gpm. The 3/4 in, and out ports are not a problem. Once you have a valve that can handle the flow, your hoses are the next thing to create resistance. I will state that personal experience that 1/2 inch hoses are marginal at 16 gpm, and not workable at 22 gpm. I tried...
The ports on the cylinder are the next thing to think about, and naturally the larger the better.
The ports on the cylinder are the next thing to think about, and naturally the larger the better.
Fourced
ArboristSite Member
I think I have it figured out, I am going to run a dual pump, the section that runs the main ram will be 26 g/m the second section will be 22 g/m to run everything else.
I actually have 25gmp valves with a 28 gpm pump on my splitter, as I want the heat in my system. I'm running an oil cooler so I can control the temp. Otherwise the rest of the system is almost too efficient and doesn't get warm very fast when it's cool out.
I'm trying to figure out the best way to explain this since I dont have the actual link to post. To get the proper flow with the least resistance is the best way to manage heat. Somewhere I read this, but, sqin area for a 3000psi port should be somewhere around a velocity of 25 to 30 ftsec. Port dia would need to be .0642 sqin for every 5 gpm of flow. I am using the the conservative high end range for recommended line dia. Figureing a 28gpm flow and rounding to 30gpm for simple math, you would need a port/line size of 30/5 x.0642 sqin or .3852. A 3/4 port would have a area of .4418, so should flow the 28gpm of oil. But on retraction of cyl, oil flow can be twice as much as the actual flow, where as the 30gm flow is filling a cyl rod end area that can be less than half the area of the base area of the cylinder. All depending on the dia of the rod. Twice the flow would need twice the area, if pressure remained at 3000psi. Return oil should be low pressure, not exceeding 100psi. Velocity would be increased but pressures should be less. I think selecting a valve, one would want to know if the 25gpm rated flow of that valve is oil in or oil out, as the actual flow out could be twice the flow rate in on cy retraction. I suspect rating might be for total flow and be misleading for someone selecting a valve for a high flow application. Someone can feel free to correct me since I am basicly just guessing about the how the valve may be rated.
Edited to add: I found this chart to explain things better than I can. http://www.womackmachine.com/engine...n-of-plumbing-size-for-hydraulic-systems.aspx
Edited to add: I found this chart to explain things better than I can. http://www.womackmachine.com/engine...n-of-plumbing-size-for-hydraulic-systems.aspx
This is the guy I dealt with when building mine and he shows a couple valves with 3/4" ports that claim 30 GPM capacity. I thought he had told me he could get even bigger ones but the cost was way up. Thought it was autocycle but don't quote me on that. I'm running the standard 25 gpm autocycle with a 28 gpm pump with no issues.
http://www.splitez.com/log-splitter-valves.html
Look at the very bottom of the page 15 1nd 16.
James was always super nice to answer questions. He builds all kinds of custom splitters so he can tell you what works and what doesn't.
http://www.splitez.com/log-splitter-valves.html
Look at the very bottom of the page 15 1nd 16.
James was always super nice to answer questions. He builds all kinds of custom splitters so he can tell you what works and what doesn't.
In theory a 25 gpm valve is too small for a 28 gpm pump but in reality the vast majority of people seldom run their splitters at max rpm's. A 28 gpm pump at 3/4 throttle is only putting out 21 gpm.
olympyk_999
Addicted to ArboristSite
i dint get it from him, but I have the prince RD5000 30 gpm single spool with 3/4" in/out, and work ports...was quite a bit more money than the 25 gpm valves...
A valve with 3/4 ports should flow 30gpm at 3000psi with a little room to spare. Port size would have to match galley size internal of the valve for this to be so. Taking a valve with 1/2in ports and opening it up to 3/4 isnt the same as a valve made for 3/4 ports. One must remember that the valve also contains a spool which takes up room inside the oil galley. If the galley is sized to the oil flow with consideration given to the room the spool takes up, which if its advertised for a given flow rate, I think it should be. This a pic of a v70 valve rated for 70gpm just for size reference. You will notice the ports are pretty large. 1 1/4 IIRC without going and actually measureing them. Work ports are #16 boss O-ring =1inch
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