Hydraulic lines (3/8 vs 1/2) when to choose one over the other??

[J_J]

I understand what you are saying,but I think some of you are missing the point. Of course if you use different hose characteristics, you can make all the hoses the same pressure rating. but look at this chart, using the the same characteristics except the size.

Can you not see that if you go larger, that the rating of the hose will decrease in pressure. .

Go to the bottom of the page and look at Technical Specifications:

Look at max working pressure for 1/4 hose, and then look at 1 in hose.

SAE 100R2AT 2-Wire Hydraulic Hose

 

[J_J]

pharmvet,

Your switch is a good thing as long you stay within the range of the pumps pressure. You don't want to put a 2500 psi hose in a 3500 psi hyd pump system. More volume, and less resistance with larger hose.

 

[Discount Hydraulic Hose]

JJ has already explained this, and thanks for linking to our site, by the way.

I should add that if you really NEED to use a larger hose, you can always look at other options (hose types) that are rated for the pressure you need.

For example, 1/2" SAE 100R2AT hose will handle 3,500 PSI working pressure.

If you use the same hose, but increase the size to 3/4", the rated working pressure is only 2,250 PSI.

However, if you change over to another hose, like SAE 100R12 (4-wire), you can increase the hose size to 3/4" or even 1" and still handle up to 4,000 PSI working pressure.

Obviously, 4-wire costs more then 2-wire hose, but for some people, that is what they need, and that is what they will use.

Another thing to remember is that the increased flow rate of a larger hose will usually make things move faster as well. If it took 10 seconds to raise a boom with a 1/4" hose, you may be able to move it in half the time with a 3/8" hose.

That may be a good thing or a bad thing, depending on your application.

 

[pharmvet]

Thanks guys for all the good information. Mike

 

[jinman]

Mike, didn't you say this hose is for your disc? Isn't it just a hydraulic cylinder, probably a 3" cylinder with maybe 12" to 14" rod length? You just don't need a 1/2" hose for that kind of application. Most likely you just want to raise your disc for transport. You don't need to make it jump into the air like a frog. Going to the bigger hoses is okay, but they are far more bulky and not a requirement for your application. I'd bet 1/4" hoses would work just fine and be extremely easy to handle.

Your remotes may be 1/2", but that's because some people will use the remotes to run hydraulic motors on augers and other similar applications where maximum flow is critical. Your loader uses 3/8" hoses because they have a smaller bend radius and are much easier to route and plumb. I'd bet your loader moves plenty fast and you don't need that disc to move even as fast as the loader.

Again, except for your convenience and routing, the 1/2" hoses are fine, but a bit like using a baseball bat to kill a gnat.

 

[AKKAMAAN]

I do not belive this to be true. I mean the part about smaller lines being capable of greater pressure.

A smaller inside diameter hose/tube can withstand higher pressure than a larger diameter, IF the hose/tube wall have the same thickness and material/wiring. Thats because the inside wall area is smaller, and that make the total net force. If you look in a hose catalog, you can see that pressure rating drop with increased inside diameter...and if you want to stay at a certain pressure rating while increasing diameter, at a certain size, you will have to choose a hose with more wiring, from two wire to four wire....
Used this picture on a similar question about bore size on cylinders...
Take a racingbike tire that is 3/4" inside diameter, and compare it with a tractor tire with 12" inside diameter...the bike tire can take a 150psi+ inflation and the tractor tire, with a lot of steel wire inforcement can barely take more than 35psi...

Jinman is right...an application that do not cycle frequently, will not need a hose that eliminate restriction (pressuredrop>>heat). As long as your PRV do not open for high pressure, the smaller sized hose wil NOT slow down your cylinder.

 

[MHarryE]

Hydraulic design rule of thumb is fluid flow should be less than 15 feet per minute, but quite often designs go to 20 feet per minute. Besides heating due to restriction, high hydraulic flow can actually eat away the inner liner. I have cut open hoses leaking at the coupling and found the inner liner eroded away to where the oil could leak through the wire braid reinforcement and out the crimp.

On the other hand larger diameter hose also requires larger bend radii when you route the hose. But since you are routing the hose to a disc, I can't imagine bend radius being a part of the problem.

As mentioned before, pressure rating drops with hose size for a given hose rating. For example, hydraulic hose in 2 wire braid SAE 100R2 will be 5000 psi working pressure for -06 hose (3/8") and 4250 psi for -08 hose (1/2"). Go with 1 wire braid SAE 100R1 hose and working pressure is 2,600 psi for -06 hose and 2350 psi for -08 hose.

One thing to remember as an advantage to buying the higher pressure capability hose is that in addition to getting higher pressure capability, you have an extra layer of wire to wear through if your hose rubs against something.

 

[RickB]

Operating characteristics of a simple standard agricultural hydraulic cylinder will not be noticibly different if the only variable is the 3/8" or 1/2" nominal I.D. of two 7 or 8 foot hoses connecting it to the tractor. One would need a good eye, steady fingers and a good stopwatch to even quantify the difference.

Some of you guys need to close the books and get out in the real world once in a while. A lift cylinder on a disc is an intermittent demand, not a continuous flow situation.

 

[Discount Hydraulic Hose]

For example, hydraulic hose in 2 wire braid SAE 100R2 will be 5000 psi working pressure for -06 hose (3/8") and 4250 psi for -08 hose (1/2"). Go with 1 wire braid SAE 100R1 hose and working pressure is 2,600 psi for -06 hose and 2350 psi for -08 hose.

I'm sorry, but the pressure ratings above are incorrect. Since manufacturers often design hose to meet multiple industry specifications (SAE, DIN, etc.), it is not unusual to find a hose marked with a particular specification that is rated for even more pressure than that specification requires.

SAE specifications for maximum working pressure are as follows:

100R1AT -- HOSE -- 100R2AT
One-Wire -- SIZE -- Two-Wire
2,750 PSI -- 1/4" -- 5,000 PSI
2,250 PSI -- 3/8" -- 4,000 PSI
2,000 PSI -- 1/2" -- 3,500 PSI
1,500 PSI -- 5/8" -- 2,750 PSI
1,250 PSI -- 3/4" -- 2,250 PSI
1,000 PSI --- 1" --- 2,000 PSI