Pressure gauges can read in "PSIG" and "PSIA" just for this reason. We read in PSIG because it's a little easier to understand.
log splitter hydraulic psi question
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Pressure gauges can read in "PSIG" and "PSIA" just for this reason. We read in PSIG because it's a little easier to understand.
Marc
Addicted to ArboristSite
Plus gauge pressure devices are much cheaper to make and easier to calibrate than absolute pressure gauges.
Deereman76
ArboristSite Operative
And really, Who cares of a 5000 psi gauge is ready PSIA or PSIG? I Sure can't tell the difference!
Marc
Addicted to ArboristSite
Lab and manufacturing auditors do, I can vouch for that. My lab gets audited several times a year by outside organizations. They throw big hissy fits if we have ANY equipment anywhere near the lab not calibrated to ISO 17025. They actually seem to find lots of reasons to throw hissy fits, truth be told.
I suspect that it's mostly to justify their existence. :biggrinbounce2:
AKKAMAAN
ArboristSite Guru
Nothing of this have any major impact on a hydraulic system, unless we study the "suction" part of the pump, which includes the tank too....
I always try to use the term "suction" carefully, since it all is about pressure... definite zero pressure is vacuum, which will be zero on a PSIA gauge, atmospheric pressure varies around 14.7psi which will become zero on a PSIG gauge....
Chop
ArboristSite Lurker
Dang ...
I got here too late to make my highly germane point that viscosity would necessitate a pressure gradient at the pump in order to move fluid whether in atmosphere or (theretical-mebbe liquid Helium?)vaccuum, gravity or zero-G .... but then someone had to whip out invicids ... sheesh, careful where you point that! LoLz ... you guys are total NERDS! :-D I feel right at home! B-)
My contribution to the discussion would be, "I've seen far more splitters push the "wedge" off the frame than I've seen fall short on PSI." That's worth at least what you paid for it. Anchor the wedge more-than-securely and make it plenty wide, so your rig endeavors to split long before it tries to cut fibers.
I got here too late to make my highly germane point that viscosity would necessitate a pressure gradient at the pump in order to move fluid whether in atmosphere or (theretical-mebbe liquid Helium?)vaccuum, gravity or zero-G .... but then someone had to whip out invicids ... sheesh, careful where you point that! LoLz ... you guys are total NERDS! :-D I feel right at home! B-)
My contribution to the discussion would be, "I've seen far more splitters push the "wedge" off the frame than I've seen fall short on PSI." That's worth at least what you paid for it. Anchor the wedge more-than-securely and make it plenty wide, so your rig endeavors to split long before it tries to cut fibers.
Hmmmm, that Prince RD5200 splittervalve, is a two spool valve, why not second spool for the log lift???
OK... AKKAMAAN... since you are usually The Man when it comes to hydraulics, I felt it necessary (ok... maybe just FUN) to point out that you missed the point of his selected Prince 5200 series valve. It is an "auto-cycle" valve. It requires both spools for the single automatic cycle function on the splitting cylinder. The additional valve he mentions is perfectly correct in this case.
AKKAMAAN
ArboristSite Guru
Thank you 2fatguys!
That was way over my capacity to catch that one..LOL.
some times my fingers are typing faster than my brain thinks....
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Good deep technical discussion but really not needed for the question.
To simplify:
A positive displacement pump is capable of a _lot_ (shade tree term) of pressure but only sees it if the cylinder stalls.
The valve does two things. Determines where the fluid is going and limits the amount of pressure the system will develop _at stall_.
Thus to answer the ops question. The valve bypass setting determines the system 'stall' pressure. Of course that needs a motor big enough todrive the pump that will provide that pressure. To small a motor and the system will stall (motor die) before max pressure is achieved.
Harry K
To simplify:
A positive displacement pump is capable of a _lot_ (shade tree term) of pressure but only sees it if the cylinder stalls.
The valve does two things. Determines where the fluid is going and limits the amount of pressure the system will develop _at stall_.
Thus to answer the ops question. The valve bypass setting determines the system 'stall' pressure. Of course that needs a motor big enough todrive the pump that will provide that pressure. To small a motor and the system will stall (motor die) before max pressure is achieved.
Harry K
I am new to arborist site, my first post. I recently bought a tractor powered(via hydraulics) Black Diamond log splitter rated at 22 tons max. It says in the manual to never exceed 3200 PSI to avoid damaging the system. The splitter came with ports for 1/2'' hydraulic hoses, so I promptly had two 8 foot hoses to reach my tractor. How can I be careful not to run too much pressure? I tried it once with my Case2290 tractor, which has variable hydraulic flow control; there is also a control valve on the splitter. Should I plum in a pressure gauge to know my operating pressure? Or can I tell a reasonable pressure by the cycle time with no load? My manual lists certain cycle times based on certain pressures. I felt like I was in a safe zone, but I didn't try splitting any very large logs.
Ol' Brian
ArboristSite Guru
+2. My Dad is pretty well versed in Hydraulics, and he always hammers on this: Pumps do NOT create pressure, they create FLOW. Resistance to flow creates PRESSURE. From here, you can go way out in the weeds. Pedantic, I know. But, if you want to have an accurate UNDERSTANDING of it, you have to look at it this way.
"And that's all I've got to say about that," LOL!!
Ol' Brian
ArboristSite Guru
Most tractors are fairly "low pressure" on the hydraulics, I think in the order of 1800 to 2500psi, depending on the tractor.
In any case, the valve on your splitter should have a pressure relief valve in it that will allow the hydraulic flow from the tractor to bypass back into the return line should the pressure reach this 3200psi number. That is probably what the pressure relief valve is set to.
Myself, I wouldn't worry about it. Take it out and split wood.
Your tractor has a pressure relief setting at 2250 psi.
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Ol' Brian
ArboristSite Guru
Wow, closed center hydraulics. Impressive!
.........
I had to look up that tractor... much bigger and older than I imagined. I was thinking it was a newer CUT or Utility tractor
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I had to look up that tractor... much bigger and older than I imagined. I was thinking it was a newer CUT or Utility tractor
Check the manual to make sure the pump can run a light load and high flow like a motor circuit. If it is actually load sensing you should be fine. If it is a closed center pressure compensated pump, it may not like running an open center splitter valve. Piston pumps need a light load to hold the pistons and slippers down on the swash plate. Some don’[t last long running almost no load and high flow.
