a few gas line questions

[Toqwik]

1. Can you use radiator hose to go from the filler neck to the tank?
2. Do you need to use gas line hose for the vent, or will any heavy type of hose work?
3. using a poly tank, with the sending unit grounded, does this protect you from static electricity spark, if not what is the best way to make it safe?

Thanks HAMBers....Toqwik

[old beet]

No, Yes and I don't know................OLDBEET

[warbird]

What old beet said.

Use gas filler hose from the neck to the tank. It's not cheap, but will stand up to gas fumes!

You're better off using as much steel tubing for gas lines as you can. I used 1/4" steel tubing for the vent line on my tank, with just a short section of hose to connect it to the nipple on the tank. And 3/8" tube for the gas line, again with a short section of hose as a connection.

I'd think that grounding the poly tank should take care of any static build-up, but haven't had any experience with one.

[BigChief]

Use hose specified for gasoline use. You'll be able to find the larger sizes you'll need for the filler neck at most places that carry marine repair supplies. Your best bet would be to do like the OEM's do....make most of it out of steel and connect the ends with short pieces of correctly sized pieces of gas hose.

Anytime your playing with fuel you need to use steel, aluminum, or gasoline rated rubber or polymer line. It doesn't matter if its the main line, return line or even the vent line. If your going to use lots of rubber line on your car then you can (and should) get the Coast Guard spec marine grade double wall rubber fuel line. It comes in 1/4", 5/16", 3/8" sizes and is also available at most marine supply houses.

The ground strap on the sender your refering to does two things. It grounds the sending unit so that it works correctly and (depending how the sending unit is mounted in the tank) bleeds off static. Some sending units and in-tank fuel pumps require direct grounding. The other thing this strap/wire does is help bleed static off the surface of your poly tank. Polymer tanks built and sold for gasoline storage are made of a conductive plastic that helps the static charge dissipate....avoiding those unplanned barbecues. If the poly tank is touching the frame and held in with steel straps then the static charge should be bleeding off just fine...with or without a ground strap.

Check out any factory poly tank install.....metal filler tube, metal and/or gas rated rubber hose or plastic tubing and plenty of grounding. Follow the same plan and you'll be just fine.

-Mike.

[Toqwik]

The tank I am using is out of a boat, 14 gal, fits perfect. I am sitting it on a piece of rummber mat, because of some imperfections on the fllor of the car. So I should use steel straps, not alum to secure it to the floor? I just want to make sure it is safe as possible....Toqwik

[flt-blk]

[ QUOTE ]
The ground strap on the sender your refering to
does two things. It grounds the sending unit so that it
works correctly and (depending how the sending unit is
mounted in the tank) bleeds off static. Some sending units
and in-tank fuel pumps require direct grounding. The other
thing this strap/wire does is help bleed static off the
surface of your poly tank. Polymer tanks built and sold for
gasoline storage are made of a conductive plastic that
helps the static charge dissipate....avoiding those
unplanned barbecues. If the poly tank is touching the frame
and held in with steel straps then the static charge should
be bleeding off just fine...with or without a ground strap.
-Mike.

[/ QUOTE ]

Sorry BigChief but this is not true.

Plastic HDPE and other olefins are the material used for
most tanks are not conductive. Adding a ground strap to a
piece of plastic will not "Ground" it. Try your Multi
meter on a piece of plastic bucket and see what kind of
resistance you get!!
The amount of static on the surface of a plastic tank or
fuel cell is no more or less than that on the plastic
bumpers and side molding. I bet there is more static from
your cell phone (the reason you should not be talking o nit
at the gas station).

The rest of your advise on grounding and fuel safe hose
materials is spot on, just not the plastic part.

TZ w/ 10 years in the plastics industry.

[JOECOOL]

I just want to throw out another idea on the gas tank vents. I always put a filter on the gas tank vent , remember as your fuel gets used it replaces it with outside air and it can drag a lot of dust in with it .A little one for a lawn mower is probably OK. Just a Thought.

[Model A Vette]

I ran steel tanks for a number of years and then switched to poly tanks. I used as much metal as possible for the filler and clamped wire to the metal pieces jumping over the rubber splices and grounded to the frame. I ran a separate ground for the sending unit and the vent line is grounded to the metal body of the car. I got the large size filler hose, approved for gas, from a local Goodyear industrial supply house. Make sure it says right on the hose that it is good for gas. It didn't say so in the catalog but once the hose got to the counter I saw the stencilling on the hose.

[BigChief]

[ QUOTE ]
[ QUOTE ]
The ground strap on the sender your refering to
does two things. It grounds the sending unit so that it
works correctly and (depending how the sending unit is
mounted in the tank) bleeds off static. Some sending units
and in-tank fuel pumps require direct grounding. The other
thing this strap/wire does is help bleed static off the
surface of your poly tank. Polymer tanks built and sold for
gasoline storage are made of a conductive plastic that
helps the static charge dissipate....avoiding those
unplanned barbecues. If the poly tank is touching the frame
and held in with steel straps then the static charge should
be bleeding off just fine...with or without a ground strap.
-Mike.

[/ QUOTE ]

Sorry BigChief but this is not true.

Plastic HDPE and other olefins are the material used for
most tanks are not conductive. Adding a ground strap to a
piece of plastic will not "Ground" it. Try your Multi
meter on a piece of plastic bucket and see what kind of
resistance you get!!
The amount of static on the surface of a plastic tank or
fuel cell is no more or less than that on the plastic
bumpers and side molding. I bet there is more static from
your cell phone (the reason you should not be talking o nit
at the gas station).

The rest of your advise on grounding and fuel safe hose
materials is spot on, just not the plastic part.

TZ w/ 10 years in the plastics industry.

[/ QUOTE ]

I stand (sort of) corrected. We use conductive polymer tanks here (at work) to allow (static) charge to dissipate from solvent tanks as they are filled. I assumed the polyethylene tanks used for fuel storage were also formulated to be conductive. The polymers (HDPE, Nylon, etc) commonly used for fuel tanks are good insulators which is also exactly why it still is a good idea to use a bonding strap (or at least good contact with the frame) to dissipate the charge that builds up on the tank surfaces. With static we're talking about surface voltages here, not the conductivity the material itself exhibits. Non-conductive materials build static charges on their surfaces. These surface charges (static) dissipate slowly or not at all on their own as they would with a metal tank. If you build enough voltage on the surface your going to jump the nearest gap to ground with a spark and run the risk of igniting fuel vapor. This is very uncommon, but a real risk nonetheless.

Most major fuel companies have precautions regarding static hazards and proper refueling procedures. They’ve recently determined that the charge built up in the gasoline itself (also a non-conductive material) while it passes through the hose during refueling can be passed on to the storage tank in the car. Charge build up has also been observed just from fuel sloshing in the tank. …..thus the reason we use conductive storage tanks for some of our flammable solvents. We pump solvent *miles* here. The charge build-up while its pumped can be tremendous. When it hits the tanks you want to be dissipating it for sure. Theoretically we could build up a charge large enough to ignite the fuel vapor in the tank. It only takes about 1000 volts to ignite gasoline vapor at STP. Putting a metal strap around the tank and making sure everything metal connected to the tank is grounded properly is a good safe guard against static build up in and around the tank.

Many polymers, especially polyolefins like polyethylene, are low (or negative) in the Triboelectric series meaning that they love to collect negative charges. The metal components in and surrounding the tank and even the fuel inside the tank are higher on the list (more positive and love giving up electrons/negative charge) which means that without at least some grounding (through a bonding strap or other contact to ground) these negative charges can build up on the tank surfaces and positive charges will build up in the other materials. One big danger is an electrically insulated conductive component sitting in the tank....such as the metal sending unit in a polymer tank connected to the fuel system using rubber lines. This is one reason they send a ground wire for the sending unit that is mounted in a polymer tank. The insulated conductive part (metal fuel sender in this case) can act like the output sphere on a Van De Graaf generator collecting and storing the charge from the tank and/or fuel till it discharges.

As far as conductive polymer formulations go...... Many black/opaque polymers have a carbon load in the slurry when the pellets/flakes are formulated. The carbon black acts as both coloring agent and conductor when used in these polymers. Some companies such as Pelestat offer additive packages for polymer manufacturers to be used specifically for the purpose of dissipating static charges in their own products. Ticona offers Celcon acetal copolymer that is tough and can be formulated to dissipate static. Dupont now makes Zytel, a polyamide-based polymer that was designed specifically for the dissipation of static charge in non-metallic fuel/solvent delivery and storage components. Other companies have surface treatments for polymer products that help with static dissipation while new as well. Although not as common as the HDPE cans commonly used, these materials have been finding their way into tanks and delivery system components.

-Bigchief.

[BigChief]

[ QUOTE ]
The tank I am using is out of a boat, 14 gal, fits perfect. I am sitting it on a piece of rummber mat, because of some imperfections on the fllor of the car. So I should use steel straps, not alum to secure it to the floor? I just want to make sure it is safe as possible....Toqwik

[/ QUOTE ]


Any metal strap is fine. Make sure your sender is grounded too.

-Mike.

[Toqwik]

lots of good tips...Thanks for the info...Toqwik

[SlowLearner]

Great Post!!
Brother-in-law gave me a poly gas tank out of a SAAB 90(?). It's a black polymer (dunno what composition) tank. Was mounted with steel straps with rubber wear strips between tank and strap.
I never thought of grounding or even static charge!
Thanks for this one! http://www.jalopyjournal.com/ubbthreads/images/graemlins/smile.gif -Keith

[dadseh]

The difference between radiator hose and approved gas hose for filler necks is not apparent to the naked eye unless you know where to look. THEY ARE IN FACT THE SAME CONSTRUCTION WITH ONE SMALL DIFFERENCE.There are 2 types of 'gas hose. One has an impervious polymer layer 0.3MM thick moulded within the wall of the hose.the second and older method is to treat the inside of the hose with a layer of liquid plastic which dries and becomes impervious to fuel hydrocarbons.GM specifications for fuel hose permit an evaporative fuel loss of 30grams per square meter of hose per DAY. sounds a lot but remember the surface area of your normal filler neck hose is probably less that 1/20 of a square metre. 30 grams of fuel is about1/10 of a beer can ( aussie style). do the math, 30gm X .05sqmtr = 1.5 GRAMS PER DAY. Most fuel hose has a loss of 0.00001gm these days.

ever wonder why you smell petrol first thing in the morning in your garage? dont store fuel in plastic containers for good reasons.

DADSEH