Fuel & Cooling Hose Questions

[Philcurtis]

Hello,

I have been researching some fuel & cooling hoses but I have some questions before I purchase anything. If you have the time to look these over &/or answer I will be appreciative.

OBJECTIVE:
Find Clear & Colored Hose suitable for low-pressure fuel lines & cooling system lines.

1. When considering low pressure fuel lines, are the only hose options Thermoplastic or Fluoropolymer(Fluoroplastic) compounds, or are there other choices? Which one is superior & recommended?
2. When considering hi-temp (250 deg.F) cooling system lines, is the only hose option PVC, (Nylobrade or Vardex) or are there other choices?
3. Is PTFE hose available in colors or striclty translucent white?
4. What is a Fluoropolymer? A Fluoroplastic, same thing?
5. What is the relationship between Fluoropolymer & Teflon?
6. Where do Plastic Nylon Fuel lines sit relative to Thermoplastic & Fluoropolymer fuel lines?

Thank you for your time,
Phil Curtis
philcurtis@att.ne

 

[patprimmer]

Phil

From your question, you obviously know very little about chemistry or polymers.

You are making life hard on yourself by specifying clear or by specifying a specific colour. Why do you need this.

Is this for a one off project that will depend on hose being available, or will it be an OEM project that might enable hose to be custom made.

If it is for a marine application, special care needs to be taken for several reasons, as follows:-

You do not say what fuel.
If it is diesel, the following is not nearly so critical. If it is petrol, it is critical as the fuel vapour is heavier than air, and if a very small leak is allowed to leak inside the hull for some time, vapour will build up to the point where a spark can cause an explosion.
If a raw water hose fails, and is not noticed, a very large amount of water can be taken aboard before it is noticed. If the line is then submerged and in an area of difficult access, the boat might sink.
If the parts fail when out to sea, who knows what could result, but you sure can't walk to a phone and call a tow truck, unless you have a radio aboard. In the meantime you are exposed to wind, and tide and may drift into danger.

Back to your questions.

re fuel:-

1) Other choices are various rubber compounds.
Straight nylon is good, straight rubber is good. Some reinforcement fibre in the hose structure with the above materials is even better. Braided stainless steel fibre reinforced hose is even better still, if you have the budget. PTFE is not so good, as it is very soft, and will not stay reliably clamped, unless it is reinforced quite well. Also, it is slightly porous, and allows fuel vapour to leak through.

2) PVC is not really suitable at temperatures above about 180 deg F, and even than, not under pressure. PVC will not resist much pressure at more than about 130 to 140 deg F.
I don't know Nylobrade or Vardex, but I guess they are nylon fibre reinforced PVC. Reinforced rubber or maybe hot water hose for washing machine or dishwasher is suitable. These are reinforced thermoplastic composites designed for "HOT WATER and MAINS PRESSURE" together.

3) PTFE can be coloured, but it does not colour as well as many other plastics. Wither coloured PTFE hose is available I do not know, but it could be made if the volume warranted it and you are prepared to pay the premium.

4) fluoropolymers are a range of polymers where some of the hydrogens are substituted by fluorine. PTFE is Poly Tetra Fluoro Ethylene, where all 4 of the hydrogens in ethylene are substituted by fluorine. I have not heard the term fluoroplastics, but PTFE could be considered a fluoroplastic.
Not all fluoropolymers are plastic, but all fluoroplastics will be fluoropolymers. PTFE is a very difficult to process plastic. There are other fluoropolymers that are easier to process and therefore do not result in porous mouldings, as does PTFE.

5) Teflon is DuPonts brand name for their PTFE and some other fluoropolymers.

6) Nylon is a thermoplastic, as is PTFE. it is a bit like the analogy of "not all dogs are Cocker Spaniels, but all Cocker Spaniels are dogs.
Thermoplastics is a very broad group, but Nylon and PTFE and PVC for that matter are specific types within the broad group.

On my boat, I use R6 grade reinforced rubber or heavy duty reinforced Nitrile rubber for fuel lines and heavily reinforced rubber for water lines.

I use good quality clamps that do not degrade in salt water.

I use the heavy reinforcement so as to resist heat, pressure and abrasion, and to resist kinking.

I use nitrile rubber for fuel, as it has exceptional fuel resistance.

People like Goodyear or Pirelli should able to advise.







Regards
pat

eng-tips, by professional engineers for professional engineers

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[Philcurtis]

Hi,

Thanks for the info Pat. Sorry for the confusion. This is not for a marine applicatiion but for a motorcycle I am working on which is calling for clear hoses. You cleared up alot for me, and no, I do not know much about polymer science. No harm in wanting to learn though.

Phil

 

[franzh]

To add what my illustrious colleague Pat says, there are other reasons to use specific hoses when carrying hydrocarbon or pressurized fuel. Certain regulatory authorities specify which hose material may or may not be used for a certain product. I know of one specific OEM project which had to retrofit over 500 vehicles from the OEM because they did not meet with regulatory standards.

Some of us are young to remember the open engine compartment hot-rods of the late 50’s and 60’s which had clear or red tinted fabric reinforced plastic fuel hoses, and which promptly turned to jelly when alcohol based or nitro based fuels were introduced, spraying the engine compartment with pressurized fuel!

Suffice to say, if this project is to be used in any actual running application, you should verify compliance with any road authorities having jurisdiction. In the US, it’s the DOT, with the Federal Motor Vehicle Safety Standard (FMVSS), and the NFPA. Ever wonder why you don’t see clear or semi opaque fuel hoses in more vehicles?

Franz

 

[patprimmer]

Phil

No harm at all in wanting to learn. That is exactly what this forum is for.



Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Philcurtis]

So why do you not see more clear/opaque fuel lines? Have none been invented which meet gov't regulations or is there just no demand?

Phil

 

[patprimmer]

Phil

Some more definitions

Clear is like glass of water. Light passes through without change in colour nor scatter.
Tinted is see through but coloured like an emerald, ruby or saphire. Light passes through with a change of colour, but no scatter.
Transparent can be clear or tinted. Light passes through with no scatter
Translucent is like semi opaque or frosted glass. Light passes through but is scattered.
Opaque is like a pice of steel, wood or coal. No light passes through.

For fuel lines:-

Lightly reinforced plasticised PVC is reasonably clear and will work with petrol for a while at low pressure and moderate temperature, but it will go hard and brittle within a few years. It is gradually degraded by sunlight and heat. The plasticisers are leached out by solvents such as petrol. It is most probably NOT approved by regulatory authorities. Other fuels will destroy it rapidly.

Nylon is mostly translucent, but some grades are almost transparent and some very expensive ones are transparent. It is not very flexable, and prone to kinking if bent. Nylon has excellent resistance to most solvents and fuels. Carby parts are often made from it

PETG is clear, but I have never seen a flexable tube. It is probably to rigid. It has excellent resistance to almost all solvents and fuels

PTFE is translucent to opaque, like the froth on your beer. It is also VERY soft and susceptible to accidental damage. It has perfect resistance to virtually all chemicals. It is OK if used as a liner in steel braided line where it is protected from physical damage. It leaks very slowly due to it's porosity.

Polypropylene is normally translucent, but reasonanbly transparent grades are now avaliable. It is the plastic most likely used for ice cream tubs. It will also be reasonably rigid and prone to kinking when bent.

TPX is transparent and chemical resistant. It has similar properties to Polypropylene.

Polyurethane has a noticable straw coloured tint, but is tough, flexable, stretchy and chemical resistant to fuels.

For water hoses.

Very few plastics will withstand boiling water under pressure for any reasonable length of time and therefore, I think this one is not within the reach of current technology.

The only slight chance might be reinforced TPX hose or rigid TPX tube sections with rubber hose at each end for attachment. TPX rigid mouldings have been used with some succes as the housing for an inline radiator water filter.

Acrylic and polycarbonate do not have the chemical resistance necessary for any fuel or hot water lines.

All thermoplastics will melt if exposed to high heat. The reason they are called thermoplastics is because they can be melted and moulded to shape.



Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[MacGyverS2000]

I wish there was an easy to find FAQ with all of the definitions listed above. I'm trying to remember as much as possible, but I know full well I won't remember a single bit when I could use it years down the road

 

[funnelguy]

PTFE is not a melt processable polymer. Typically, PTFE powder and lubricant are pressed through tooling by a ram extruder. The lubricant is volitalized off in a heated chamber. The remaining fragile and directionally oriented extrudate is then sintered to obtain the final product. The raw materials are expensive and there are fewer processors. PTFE is also given to cold flow. Not a good choice for hoses, IMO.

Nobody has mentioned braid reinforced silicone rubber. Excellent cooling hose. Expensive, but readily available and adequate for some pretty severe temperatures. I've never seen translucent industrial hose, only some medical applications.

 

[76GMC1500]

My motorcycle has transparent fuel lines, I think they are some kind of neoprene. I don't have any here with me so I can't tell you for sure. They start off blue, but after a few years they turn brown on the inside and lose some of their transparency.

 

[patprimmer]

76GMC1500

Your fuel line will be PVC. It starts as a light blue tint to cover the natural straw tint. It goes brown from degradation due to exposure to heat and or UV light. Once it is a mid to dark brown, it will have become hard and brittle and should be replaced for safety.

Neoprene is opaque.

Regards
pat pprimmer@acay.com.au
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[ckenny]

Philcurtis,
You can find the line you are wanting at

http://www.whitebrothers.com

. Look in intake. They have it in black,clear,red,green,blue and yellow. I have used this line on motorcycles when I need to match the body colors and it has held up well.

ken

 

[Philcurtis]

All excellent posts. Thank you everyone. After all my research, I have ended up buying some Polyurethane hose from a company called Helix which markets this stuff as fuel line. We'll see how it works. Not the best price but I am now in a pinch. Just found out I will be shipping out in three days. Was supposed to be a month from now. Hey, this is why we do what we do huh.

Phil

 

[mburgess]

Just as a side not a mate qualified for a wild card entry into 125cc GP class a few years back and was running on AV gas all year as it was legal in the local series. When he got to the GP he had to use FIM spec unleaded. This proceeded to dissolve his existing fuel lines in a matter of minuits... Had to beg for some fuel line off one of the existing teams. The fuel was far from pump available unleaded. Might be worth checking with a fuel/oil distributor on what the best grade of hose for your application.
Cheers,
MB

 

[Philcurtis]

I'll check it out. Thanks

Phil