Velocity

[2funkids]

I must be looking at something wrong. On these velocity charts that help determine recommended hydraulic line size it looks like my hydraulic system should have 1/2 inch lines....but...its got 3/8" lines. 7.8 (round to 8 gpm pump). With 3/8 lines looks like it calculates to about 25 fps velocity. It looks like 7-15 fps is recommended for pressure lines.

My tractor has 3/8 and 1/4" lines and I am adding remotes. The fittings are -6 JIC. Should I use 1/2" lines for my remotes? If it doesn't have 1/2" lines now is there a reason to use 1/2" for my remotes?

 

[MtnViewRanch]

I must be looking at something wrong. On these velocity charts that help determine recommended hydraulic line size it looks like my hydraulic system should have 1/2 inch lines....but...its got 3/8" lines. 7.8 (round to 8 gpm pump). With 3/8 lines looks like it calculates to about 25 fps velocity. It looks like 7-15 fps is recommended for pressure lines.

My tractor has 3/8 and 1/4" lines and I am adding remotes. The fittings are -6 JIC. Should I use 1/2" lines for my remotes? If it doesn't have 1/2" lines now is there a reason to use 1/2" for my remotes?

Just use the 3/8 lines and fittings, you'll be good to go. :thumbsup:

 

[2funkids]

Thanks, I am probably over thinking this!

 

[MHarryE]

Thanks, I am probably over thinking this!

15 FPS is a nice target for continuous flow but I've got by with a lot higher flow rate, especially on intermittent use circuits.

 

[LD1]

Your tractor is very intermittent, and alot of times not even at max flow. Thats how they get by downsizing the lines.

How often do you run your loader with the RPMs wide open? I rarely do, thus I am getting alot less flow than the max rated

 

[2funkids]

Ok thanks, I'll get back to picking out the hoses. I appreciate all the help.

 

[SPYDERLK]

I must be looking at something wrong. On these velocity charts that help determine recommended hydraulic line size it looks like my hydraulic system should have 1/2 inch lines....but...its got 3/8" lines. 7.8 (round to 8 gpm pump). With 3/8 lines looks like it calculates to about 25 fps velocity. It looks like 7-15 fps is recommended for pressure lines.

My tractor has 3/8 and 1/4" lines and I am adding remotes. The fittings are -6 JIC. Should I use 1/2" lines for my remotes? If it doesn't have 1/2" lines now is there a reason to use 1/2" for my remotes?

15 FPS is a nice target for continuous flow but I've got by with a lot higher flow rate, especially on intermittent use circuits.

Your tractor is very intermittent, and alot of times not even at max flow. Thats how they get by downsizing the lines.

How often do you run your loader with the RPMs wide open? I rarely do, thus I am getting alot less flow than the max rated

These are pertinent to intermittent circuits ... and even more so to their typical use at a somewhat reduced rpm. The pump runs all the time however; pumping fluid to the control valve and back to sump whether it is used for an implement or not. Hoses in these 2 positions carry the flow continuously. If these are 3/8" lines and you are running your tractor at ptorpm to bush hog, etc, the ~ nominal excessive flow is continuous. During this period the fluid heats up due to frictional losses even tho no work is being done. ... It is not critical at your flow levels OP, but if any, these 2 hoses are the ones to change.

,,,I personally see an example of this situation on my 7520 where I have a gauge plumbed to monitor the pressure at the output port of the pump. It is a 17gpm pump running thru 1/2" lines to the valve and return to sump. At full flow I see 700PSI at the pump just to drive the flow thru the lines and incident valve ports. This is several HP down the drain when at full rpm. Fortunately this pressure is much less at my usual working speed of ~ 15-1700rpm.
larry

 

[2funkids]

It's easy enough to use -8 JIC with 1/2" lines for this PB loop so that's what I'll do.