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Poly/Plastic tanks

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dosmythe(at)cox.net
Guest

Posted: Sat Apr 07, 2007 2:09 pm Post subject: Poly/Plastic tanks

Speaking of Poly fuel tanks, I have all of a sudden found concern.  As  some of you might remember, I had a suspect 582 injection oil tank that appeared  to have cracks near the top filler.  Today, a friend looked at the suspect  cracks and pulled the cap to feel on the inside.  He applied a little  inside pressure and the Poly/Plastic/whatever tank split even more.  So,  the suspected cracks are real and the material appears to be very brittle.   Also, about a year or so ago, my rotary valve tank cracked to the point of  leaking badly.

     My point is, there are a zillion types of Poly/Plastic/  whatever material tanks on the market.  We have no more idea what the  material is than what's in our fiberglass tanks.  The earlier post (to a  web site) about the new tanks to replace our fiberglass tanks did not  mention anything about the material they are made from or the process of  manufacturing.  

     I've now had two plastic tanks fail from cracking  (injection and rotary).  That only leaves the header tank that hasn't  failed yet.  Everyone might want to take a real close look at your  installed Poly/Plastic tanks.  These tanks are flight safety items and I'm  now convinced they will break in a heartbeat.

  

 Don Smythe

 [quote]   ---

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Sat Apr 07, 2007 5:32 pm Post subject: Poly/Plastic tanks

At 03:08 PM 4/7/2007, you wrote:

 	  Quote: 	
		  So, the suspected cracks are real and the material appears to be 

very brittle.  Also, about a year or so ago, my rotary valve tank 

cracked to the point of leaking badly.


	


I'm not sure why it happens. My original polyethylene oil tank 

shattered in my hands before it was even used. I think it was about 

10 years old. All I can think is that polyethylene hardens with age, 

though I haven't verified that. It is true, however, that if I put 

polyethylene tanks anywhere I would make sure they were easy to 

replace, without having to re-cover.

Guy Buchanan

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

barry(at)pgtc.com
Guest

Posted: Sun Apr 08, 2007 1:59 am Post subject: Poly/Plastic tanks

Don, I would guess your tanks are  polyethylene.  This is one of  the best materials for chemical resistance available.  However, it can't  take much increase in temperature.  For gas, and even gas with alcohol in  it, polyethylene should work fine but hot oil might be a problem.

  

 Barry West

 [quote]   ---

Bob

Joined: 24 Oct 2006
Posts: 89
Location: Damascus, Maryland, USA

Posted: Sun Apr 08, 2007 6:12 am Post subject: Re: Poly/Plastic tanks

Happy Easter to all!



I'm still up in the air on what to install, but have learned that the car and boat makers skipped PE and went to HDPE because there  are important differences in chemistry and molecular density. Any material we choose to use will have limitations and I'm sure every mechanic on the group can tell stories about changing Cessna aluminum tanks, Beech bladders, or re-sealing Mooneys.  Anybody have experience with HDPE tanks? 

Bob

do not archive

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barry(at)pgtc.com
Guest

Posted: Sun Apr 08, 2007 6:46 am Post subject: Poly/Plastic tanks

Bob, I have no experience with HDPE as a tank but with other uses.  It is 

stronger than ordinary polyethylene and can take a little higher temperatur. 

Chemical resistance is better also.  Again, it should work great as a fuel 

tank but may be effected by high temperature oil.



Barry West



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davef(at)cfisher.com
Guest

Posted: Sun Apr 08, 2007 6:01 pm Post subject: Poly/Plastic tanks

Don, I checked my oil tank and it says   Naglene  on  it  I think.   It is original and I have put through it   0ver 30 gallons quarts of oil through  it in last 3 years alone  .    Mind you I did change the RV bottle on last engine   after 450 hours TT.  Last year i swapped it out on Rotax exchange  program for a brand new 582 with E box  and it came with  a new RV  bottle  ( i hate to say but i think that they are 60$ alone ) 

  

 Did you get your starter working ok  yet  ?  

  

 Dave 

  

  

 [quote]   ---

davef(at)cfisher.com
Guest

Posted: Sun Apr 08, 2007 6:10 pm Post subject: Poly/Plastic tanks

Those new tanks look  decent .



Question ---  I have a dash tank about 8 or 9 gallons in my IV -- what is it 

made of?



It works well with no leaks .............



If these tanks are similar they will likely be decent.   IF I have ethanol 

issues I will buy  a pair and try them as it sounds like a great solution 

and a fast repair job.  And if I have no issues with ethanol I wonder if I 

can add another tank beside my 6 gal wings  tanks now ? I know a few other 

Kitfox guys near me that would opt for a larger tank in a jiffy.

Dave



---

Bob

Joined: 24 Oct 2006
Posts: 89
Location: Damascus, Maryland, USA

Posted: Mon Apr 09, 2007 4:48 am Post subject: Re: Poly/Plastic tanks

The following is from an engineer/A&P doing some Google searches and applying some experience/common sense, so take it with that grain of salt:

If your tank says Nalgene, then it may be easy to explain.  Nalgene is a company trade name that is mostly used with 3 types of plastic; low density polyethylene (LDPE), polycarbonate, and high density polyethylene (HDPE).  The LDPE wouldn't have the stability of HDPE and polycarbs can be attacked by some oil additives.  All 3 are used in very thin moldings for Nalgene bottles, versus the boat folks using 8-12mm thicknesses for fuel tanks, which is about the thickness of the red gas cans that we all know and love.  Plus, transparent plastics don't typically have UV stabilizer additives, which are typically black. 

Just like the radiator hoses in your car, I'd suggest regularly feeling any transparent plastic for hardening or brittleness.

Bob

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Remember that internet advice may only be worth what you pay.

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Apr 09, 2007 5:33 am Post subject: Poly/Plastic tanks

I think the dash tanks were HDPE



Noel



[quote] --

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Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

cathyboone(at)softcom.net
Guest

Posted: Tue Apr 10, 2007 9:07 pm Post subject: Poly/Plastic tanks

I believe you might want to go to the web sights of Solway advanced polymers 

and Aero Tec Lab. It appears there are all types of polyethylenes out there, 

but the UHMW PE might be what we will need. It appears that Aero Tec might 

be willing to fabricate something specifically for the Kitfox. If not, it 

also appears that the UHMW PE is bendible and weldable. Evidently there are 

some new UHMW welding sticks, but it might take some practice to develope a 

good technique. I am just starting to collect information on this subject.

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