Hydraulic hoses but made of Viton

[implmex]

Good morning All:
Last Thursday I had a catastrophe in the shop.
A hose split in the dielectric system for my sinker EDM and I pumped gallons of dielectric oil onto the floor in seconds.
It seeped down into the downstairs tenant's space and did some damage there.

I want to rebuild the system so it is safer...it uses polyethylene tubing and compression fittings and I've had them spring leaks unexpectedly before, but never like this.

I'd like to use the same style of hoses that hydraulic systems use...I only have 100 PSI to deal with but the idea of an NPT fitting on one end and a swivel NPT fitting on the other end with a reinforced hose and swaged on fittings gives me comfort.

Sadly, the dielectric oil will eat the Buna N rubber that most hydraulic hoses seem to be made of, but Viton is impervious.
The hoses need to be flexible to actually connect all the bits together...I have to go from the pump, through the filters, through the chiller and into the flushing system, and the path is tortuous.
Also I fear rigid pipes might crack from the pump vibration.

So far I haven't found a source for Viton Hydraulic hoses, do any of you know where I could go for something like that?
I'm motivated to pay whatever it takes, so if custom hoses are in my future I can live with that.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[Rollerman]

Can you put a drip pan under the machine?
Maybe look into silicone rubber hoses.
The hose should have a braided reinforcement

 

[Mark Rand]

Not sure about Viton, but it should be possible to get at least PTFE of PE lined hydraulic hoses from a local supplier. Any of them that know of a compatibility chart should know enough to supply suitable hoses.

Having said that, I'dathunk that EDM oils were a normal alkane oil. Are they ester based or something?

 

[Joe Gwinn]

I'd assume that if the hose breaks the pressure will drop from 100 psi to essentially nothing. If so, I'd be tempted to add a safety - if pressure drops below say 50 psi, shut pump off.

 

[Scottl]

Check this out. Maybe you could find a shop that would crimp the fittings for a fee.

https://www.redhorseperformance.com/content/Tech/Tech_cross-022317.pdf

You definitely want to use braided hose with Viton inner and crimped fittings.

I've made up hydraulic hoses before and while a simple bottle jack press could supply the pressure the dies are quite expensive. Basically 4 segments that fit into a tapered recess in a heavy block. You screw a cap or plug onto the fitting and then push it up through the bottom of the block and hold the hose until the dies close enough to grab it.

Cheaper and easier to just pay a hydraulic shop to do it.

 

[Robert R]

You may have already seen this polymer compatibility list for EDM fluid:

https://houghtonintl.com/sites/default/files/resources/technical_bulletin_-_edm_seal_and_hose_compatibility_service_information.pdf

Parker manufactures a non conductive high pressure (2700 psi) nylon lined hose :

https://ph.parker.com/us/en/non-conductive-thermoplastic-hoses-518c-518d/518d-10

Gates manufactures nonconductive hose rated between 800 to 1500 psi with a teflon lining:

PTFE Hydraulic Hose and Couplings

When it comes to extreme temperature, chemical, and abrasion resistance, Gates hydraulic hoses are designed to deliver. The Polytetrafluoroethylene (PTFE) material is inert to most commercial chemicals, has a low operating friction coefficient, and is impenetrable by both hot and cold moisture...

www.gates.com

These hoses are used in construction equipment that may come in contact with power lines.

 

[ratbldr427]

I used to use a lot of stainless braided Teflon hoses ,for hi temp purposes.I bought the reusable fittings and made op my own. Parker and a few others made them.

 

[implmex]

Guys these are great tips on where to look.
I really appreciate it!

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[implmex]

Hi Guys:
Just a follow up...I had a good conversation with a local technical hose guy from Green-Line today.
We settled on PTFE lined braided stainless steel hoses.
He can't get Viton lined hoses in small enough diameters.

Interestingly, I looked at the polymer compatibility chart you referenced in post #6, Robert R and it lists Buna N as one of the compatible materials with EDM oils.
I KNOW Buna N will rot in a year in my oil ...I have to replace the tank door seal yearly.
I wonder if there is something about my oil (Rustlick 250, 15 years old, run with copper trodes) that's off...oxidized or contaminated or something else bad.
Now that it's all on the floor and in the absorbent spill socks, maybe this is my chance to go synthetic.


Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[4GSR]

There are many different flavors of Nitrile (Buna-N) Rubber out there. Some are peroxide cured, your typical sulfur cured, and the latest version hydrogenated cured, sometimes referred to as HSN or HNBR. It's mainly available in molded products where the customer owns the mold/tooling but starting to show up in O-Rings. I am certain that HSN will handle the fluids you use. With Viton, just like Nitrile, there are over 25 variations of it for the many applications out there. Ken

 

[DDoug]

Did it spray very far from the machine (negating the addition of a pan)
if so, add fire sleeving.

 

[implmex]

Hi DDoug:
Yeah it was the pump discharge line that let go.
It ripped the end right off the hose.
80 PSI directly onto the floor and far wall.
It shot about 8 feet from 18 inches up in the air.
The time between when it blew and when the tank float switch turned the pump off was seconds.
I recovered about 3 gallons of oil with a string mop and maybe another quart or so in the spill socks.
Maybe half a gallon went downstairs through the junction between the second floor slab and the second floor west wall.

It was a big fucking mess that no catch pan was ever going to do anything about.
So bulletproof braided stainless hoses with teflon lining is the way forward.
I want it like a brick shithouse and I don't care how much it costs to get there.

That oil costs a fortune...I'm looking at well north of a thousand bucks to re-fill the tank, probably more like 1500 bucks.

I'm still so pissed!

What's "fire sleeving"?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[implmex]

Hi Ken:
I was not aware there are so many formulations of Buna N and Viton...naively, I just assumed there was only one flavour of each.
But sadly the point is moot...I know teflon lined braided hoses will be indestructible in this application, and I can get them made up easily.
Finding Viton lined hoses in the correct diameter was hopeless, and nobody seems to know if the dielectric oil will attack standard hydraulic lines.

Sadly often it's what you can actually get in Canada that drives the decision...I've always been envious of the access to resources that my American friends have.
But this will work and give me peace of mind when I fire up the old girl again.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

 

[DDoug]

Hi DDoug:
Yeah it was the pump discharge line that let go.
It ripped the end right off the hose.
80 PSI directly onto the floor and far wall.
It shot about 8 feet from 18 inches up in the air.
The time between when it blew and when the tank float switch turned the pump off was seconds.
I recovered about 3 gallons of oil with a string mop and maybe another quart or so in the spill socks.
Maybe half a gallon went downstairs through the junction between the second floor slab and the second floor west wall.

It was a big fucking mess that no catch pan was ever going to do anything about.
So bulletproof braided stainless hoses with teflon lining is the way forward.
I want it like a brick shithouse and I don't care how much it costs to get there.

That oil costs a fortune...I'm looking at well north of a thousand bucks to re-fill the tank, probably more like 1500 bucks.

I'm still so pissed!

What's "fire sleeving"?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Add the fire sleeving.
Your Hose shop slips it on (before crimp IIRC) and it's a loose sleeve of knitted material. When your hose "blew" it was a small hole, and made a jet of oil, that travelled far.
The sleeving keeps the jet from forming, you just see the oil dripping (or pouring) down the sleeve/hose.
And then have a pan constructed to put under the machine.