Hydraulics Flow questions. 22gpm pump and 1/2" ports??

[LD1]

Hopefully I can keep this short:laughing:

Still in the planning stages of building a splitter. Wanting to get a pump, cylinder, and valve ordered. I have the rest of the stuff as well as a 16HP electric start motor.

Now usually I am one to always advise that it is cheaper to buy a unit instead of build. But all I need is the hydraulics. And the bought units arent fast enough. So my goal here is speed.

I want to run a 22GPM pump (28 is pushing the limits of the 16HP briggs). But I dont want to use the big honkin 5" cylinders that they are usually paired with. Again, speed is the goal. I like the looks of a 6.5 second cycle time using a 22gpm and 4" cylinder.

But here is the issue, 4" cylinders are only 1/2" working ports. While the 5" cylinders are 3/4". Any issues trying to cram 22gpm through 1/2" ports?? According to a handy thingy I found online...Interactive Nomogram for Sizing Hydraulic Hoses
1/2" ports are only good for ~14gpm while keeping velocities within recommendation.

I called baileynet.com to inquire on a custom cylinder. (larger ports and larger rod), but he advised that I wouldnt have any issues with a 22gpm and an "off the shelf" 4" cylinder with the 1/2" ports. So basically I am looking for someone to back that up.

I can find 4"x24"x2" rod cylinders for ~$200. Baileys starts at like $500 for custom stuff. I am considering taking a $200 cylinder and welding in my own larger ports. (after disassembly of course). And if I took the time to do that, I would likely upsize the base end port to 1" just for good measures.

So just wondering how hard and fast the rule is on fluid velocities. Especially with a logsplitter that only runs for 1-+2hrs max at a time, and a good portion of that time is sitting idle or in low speed. So my 2 main concerns are heat generation, and loss of speed. And if it matters, the reservoir I will use is a round canister ~23gallons of fluid.

 

[kennyd]

It's close, but since the fluid is not flowing constantly through those 1/2" ports I'd tend to agree with the Baily tech. Now way would I use it on the pump or valve, but I think you'd be fine on a cylinder.

 

[atgreene]

Yes, 1/2" is fine. Run oversize hoses as that is where the bulk of your friction loss will be.

 

[J_J]

You should have no problems as it has been done many times before.

This is not rocket science where you need .005 tolerance. A few psi lost because of fittings is not going to matter much.

Using a 4 in cyl, and say a loss of 50 psi, you will only lose about 628 lbs of force which is minuscule in terms of ton's.

The cyl will not see pumps full capability as the relief will cut in and send excess fluid to tank and regulate the pressure to relief set pressure.

You may even see a small loss because of heat.

 

[atgreene]

A smaller port isnt going to restrict pressure, only flow. Pressure is the same throughout the system, it's friction loss that will matter. You could run it through a 1/4" hose, power would be the same, speed wouldn't be good.

 

[J_J]

Maybe if you consider this , it might change your mind.

How does the venturi principle work.

Type of coupling & adapters.

Any change in bore or change is direction [ such as with a 45 degree or 90 degree elbows can increase the amount of pressure drop.

Flow Rate - Pressure drop increases with flow rate for same size hose.

Length of hose will change pressure.

 

[LD1]

My concern isnt any pressure or power lost. But flow and speed.

Since the idea is to use a 22gpm and 4" cylinder, it is obvious I want speed. So I am wondering if the flow loss of running it through 1/2" ports is worth it. Or if I would only be seeing speed of a 16gpm pump when in high flow mode??

I also like the fact that the 22gpm pumps are usually 6-7gpm even in low. Which should still be pretty fast with the 4" cylinder.

 

[MHarryE]

It's late, I'm tired, so my quick calculation might be off but I calculate about 37 feet per second line velocity on 1/2" I.D. Hose at 22 gpm which is stretching the limit. Gates, for example, suggests 16 fps maximum fluid velocity. I have pushed an application with SAE100R2A hose to flows like that and had liner erosion at the couplings resulting in leaking past the crimp. My applications have been high hour compared to what I visualize a log splitter though. I've gone as high as 25 fps without problems except generating heat due to pressure drop when operated at continuous high flow rate. Still I see a lot of equipment plumbed with small diameter hose with apparently good results. I probably will never get past my mindset of 10,000 hour minimum life with one hose replacement mid-life.

 

[LD1]

Velocity in the hose itself isnt a big deal cause I can and likely will upsize to 5/8 or 3/4 hose. My only concern is the 1/2" working ports on the cylinder. Most 22GPM pumps have an outlet of 3/4", same with the splitter valves I am looking at. (which I am considering an auto-cycle).

So with everything else being 3/4", then a drop to 1/2 at the cylinder, I was concerned with loss of speed mainly. Since a custom cylinder is out of the question, And my only way to get larger fittings on a 4" is to do it myself, I may just try it with the 1/2" ports. And when I make hoses, I will go 3/4" all the way around and use and adapter at the cylinder. That way if I decide to cut the fittings off and make 3/4" ports on the cylinder, I wont have to remake the hoses.

Anyone use one of them auto-cycle valve setups? Looks like a 2-spool valve with 2 handles. The description says to pull both levers (they are detent). And when the cylinder extends fully the one spool will kick out and the cylinder will go into retract mode. When fully retracted that spool will kick out. To restart the cycle, pull both valves again.

 

[J_J]

You could call Baileynet who make cyl and ask them about the option of changing port sizes and the effect it will have . They probably have engineers that know that kind of data.

You could put a flow meter and pressure gage in the circuit and determine the outcome of modifying the ports.