Hydraulic QA Coupler Sizing Questions

[Porchfan]

Thanks Everyone.
On the teflon tape, I hear you. I think they put that crap all around the new 3rd function valve. I guess that's what you get when you spend $950?
At the 3rd valve, the two QA couplers on the lines are female. On the valve block are two male fittings. I take it these are closed when disconnected otherwise 3000PSI of fluid would be spewing everywhere? They're identical to the 4 fittings for the loader bucket up down/curl hydraulics. The one time I used my tractor without the loader, I just capped these with rubber boots with no issues. They are tucked away so no worries.

Here's a picture of one of the QA male fittings on the valve.



It looks like ISO_7241 series B
ISO 7241-B Quick Disconnect Nipple

Even with rubber boots on the ends when I don't have the implement on the loader, I would think these are more easily damaged than female?
Either way, I need to be a little careful not to damage these. Maybe add a female adapter that is hard capped on the other end. Seems to me that would be more rugged and less prone to abuse

 

[SweBota]

Npt requires sealant.

I understand that, but why use it then if its unsuitable?

Jic and o-ring fittings do not.

Nor does BSP, metric, ORFS or any other type I have encountered. I would consider it a requirement for high-pressure connections not to rely on sealant...

/Marcus

 

[Porchfan]

On leaks and sealants. I just found this. Seems pretty informative. http://www.sbp.noaa.gov/resources/engineering/docs/Hydraulic_Systems_Leak_Free.pdf

 

[varmint]

Npt requires sealant. Jic and o-ring fittings do not.

Good point LD1- obvious if you know it, maybe not obvious otherwise..

 

[LD1]

I understand that, but why use it then if its unsuitable? Nor does BSP, metric, ORFS or any other type I have encountered. I would consider it a requirement for high-pressure connections not to rely on sealant...

/Marcus

I am not saying not to use sealant. Sealant IS required for NPT. Just not the tape kind. Patricals/shreds of tape that find its way into a hydraulic system will mess up valves. Liquids and pastes won't.

 

[varmint]

As a side note, my brother owns a company that manufacturers geo thermal valves and equipment. When he started it, pretty much all the items used NPT for fittings. Years ago, they started switching to an O ring seal, sort of like the Shark bite fittings... The warranty claims for the NPT leaks vs. the O rings are like 100-1. If the market didn't insist on them, they wouldn't even offer the NPT.
Of course, on a tractor, the mechanical connection is also important, due to the stresses placed on hoses and such.

 

[LD1]

99% of all NPT leaks I have encountered are improper installation.

While I agree that JIC fittings are better for hydraulics, I dont like o-rings as much. O-rings fail. But NPT fittings can hold back thousands of PSI on hydraulic systems. 100psi water and air systems should be a cakewalk.

 

[SweBota]

I am not saying not to use sealant. Sealant IS required for NPT.

We are talking past each other here, I'm asking why use NPT fittings if they aren't suitable for hydraulics. If they need additional sealing they clearly are not...

I haven't seen a single NPT fitting on any of my Kubotas, so they seem to be used for add-ons only, or ?

I'm not familiar with your type of O-ring fittings either. Standard here is BSP or JIC fittings. Both are flange-sealed. Against a block thread I would add a metal bonded o-ring to a standard fitting.

If there is a better solution, why not use it?

/Marcus

 

[LD1]

We are talking past each other here, I'm asking why use NPT fittings if they aren't suitable for hydraulics. If they need additional sealing they clearly are not...

I haven't seen a single NPT fitting on any of my Kubotas, so they seem to be used for add-ons only, or ?

I'm not familiar with your type of O-ring fittings either. Standard here is BSP or JIC fittings. Both are flange-sealed. Against a block thread I would add a metal bonded o-ring to a standard fitting.

If there is a better solution, why not use it?

/Marcus

I am sure there are NPT fittings on your kubota somewhere. NPT fittings ARE suitable for hydraulics.

Lets break it down.

1. NPT CAN be used for hydraulics
2. NPT requires sealant.
3. There are 3 common types. Liquid (like loctite 545), Paste (like the white PTFE paste), and Teflon tape.
4. Dont use tape on hydraulics cause shards of it can mess up valves.

O-ring fittings come in 2-types here. ORB, and ORFS. ORB is the most common. And the threads are the same as a JIC male fitting. But instead of the cone to seal, they are just a flat end like a NPT fitting. BUT, at the base of the threads there is an o-ring, and a mating machined flat surface on the female part.

I dont think I have EVER seen a hydraulic cylinder with JIC ports. So that pretty much leaves NPT, or ORB fittings to adapt to whatever hoses you choose. IIRC, MY kubota has NPT fittings on the cylinders, and on the quick couplers. And the loader valve is ORB fittings. The hoses are JIC.

So.....you have a cylinder with an NPT to JIC adapter. And a valve with an ORB to JIC adapter. And the hose has JIC fittings to go between the two adapters. So in 1 simple circuit, there are 3 fitting types. And they are all pretty common here.

 

[downsizingnow48]

My Kubota quick couplers are NPT female.