Spool valve help me understand

[jdhacker]

Ok I have a log splitter that I fixed up and is in good shape. What I want to understand is, I put a gauge on the splitter. And it will build to 2200 psi. My question is if you have a 3000 psi pump ( I put a new speeco pump, it said 4000 but I dont believe that) a 3000 psi cylinder but a 2200 psi valve what good is that. And I look at valves and they say 3000 psi 2200 psi relief. What am I not understanding. Also I have a 3.5 in cylinder, what is it putting out at 2200 psi 2500 psi and 3000 psi.
Thanks for the help I am new with hydraulics and want to learn.

 

[J_J]

Ok I have a log splitter that I fixed up and is in good shape. What I want to understand is, I put a gauge on the splitter. And it will build to 2200 psi. My question is if you have a 3000 psi pump ( I put a new speeco pump, it said 4000 but I dont believe that) a 3000 psi cylinder but a 2200 psi valve what good is that. And I look at valves and they say 3000 psi 2200 psi relief. What am I not understanding. Also I have a 3.5 in cylinder, what is it putting out at 2200 psi 2500 psi and 3000 psi.
Thanks for the help I am new with hydraulics and want to learn.

The valves come set at factory setting.

You need to set the relief to pump setting.

You can set the kick out pressure.

 

[bulldogshotgun]

having the relief set under the rated pressure is usually a good idea, in theory you could have the set a little closer but remember that the number you read on the gauge after the relief opens is not the pressure that was on the system right before it opened i have seen pressure spikes as high as 300Psi over what a relief was set at, before the valve opened. ram pressure is simple to calculate its Pi x the cylinder Bore radius squared. so a 3.5" bore 2200Psi=10.5 tons 2500Psi=12 tons 3000Psi=14.4 tons.

 

[IceStationZebra]

Just want to add to what Bull Dog and JJ said. You need to keep the relief pressure set below the lowest rated part in your system, which includes the hoses and fittings (on the pressure side). If you have any galvanized pipe it is only good to a couple hundred psi, change it out.

The other thing to watch is available power. You didn't state the pump size or your power source, but assuming it is a small gas engine, you could cause it to stop if you raise the relief too high. (same gpm, higher pressure = higher power required)

ISZ

 

[jdhacker]

It's a 11GPM 5hp engine 3.5 in bore. And thanks for all the help guys.

 

[bandaidmd]

not sure what the pressure rating is on galv pipe but that 200 seems awfully low especially in the smaller diameters. I know over the years i have used plenty up to 1"and never had a issue.

 

[jdhacker]

It don't have any galvanized pipe on it.

 

[IceStationZebra]

not sure what the pressure rating is on galv pipe but that 200 seems awfully low especially in the smaller diameters. I know over the years i have used plenty up to 1"and never had a issue.

This is what I could find for galvanized fitting pressure ratings.
schedule 40: 150psi (at 73°, 1/2 - 2" sizes)
schedule 80: 200psi (at 73°, 1/2 - 2" sizes)
class 125 or 150: 300psi (at 73°, 1/2 - 2" sizes)
class 300: 1/2-1" 2000psi
1-1/4 - 2" 1500psi
plugs and bushings: 125-300psi, depending on material

For one thing, do you know which spec the fitting conforms to? Another potential issue is that pieces of the coating can flake off and float down stream in the system causing havoc. Uncommon, but some oils may react with the zinc. And personally I shy away from pipe thread whenever practical because it is one of the least reliable joints from a leak standpoint.

Realize that rated pressure and burst pressure are two very different things. The materials and processes are selected with the rated pressure in mind. (steel grade, rolled vs. cut threads, heat treat, etc.) Burst pressure is typically at least 3-4x rated pressure but it could be much higher especially in the smaller sizes. If you routinely go above the rated pressure you are really eating into the safety factor. It may well work 99.9% of the time, but get a bad one from Timbuktu.....!

ISZ

 

[J_J]

Just reset the pressure with the cyl maxed out.

About 100 psi below the pumps max. pressure

 

[bandaidmd]

This is what I could find for galvanized fitting pressure ratings.
schedule 40: 150psi (at 73°, 1/2 - 2" sizes)
schedule 80: 200psi (at 73°, 1/2 - 2" sizes)
class 125 or 150: 300psi (at 73°, 1/2 - 2" sizes)
class 300: 1/2-1" 2000psi
1-1/4 - 2" 1500psi
plugs and bushings: 125-300psi, depending on material

For one thing, do you know which spec the fitting conforms to? Another potential issue is that pieces of the coating can flake off and float down stream in the system causing havoc. Uncommon, but some oils may react with the zinc. And personally I shy away from pipe thread whenever practical because it is one of the least reliable joints from a leak standpoint.

Realize that rated pressure and burst pressure are two very different things. The materials and processes are selected with the rated pressure in mind. (steel grade, rolled vs. cut threads, heat treat, etc.) Burst pressure is typically at least 3-4x rated pressure but it could be much higher especially in the smaller sizes. If you routinely go above the rated pressure you are really eating into the safety factor. It may well work 99.9% of the time, but get a bad one from Timbuktu.....!

ISZ

wow, according to that chart a lot of shops compressed air systems or over the rated limit of sch 40. Glad I used cpvc on mine.