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Glassfiber tanks and ethanol (Kreem)

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Fox5flyer
Guest

Posted: Wed Apr 04, 2007 4:32 am Post subject: Glassfiber tanks and ethanol (Kreem)

Good morning everyone!  This is a very good topic and has far reaching

effects for most of us Kitfoxers.  For all you folks who have been around

Kitfoxes for a long time, most of you already know all about the Kreem and

the problems we've had with it in our wing tanks.  For those of you who are

relatively new Kitfoxers, whether builders or buyers, it may pay you to

search the archives with key word "Kreem" and read all you can about it

because there is a ton of information on it.  Sportflight.com has an

extensive searchable archive of Kitfox topics, not to mention Matronics.

Historically, the early Kitfoxes used to have aluminum tanks, but the

flexing of the wings tended to cause them to crack and leak.  Not all of

them cracked, but often enough that Skystar decided to change to fiberglass

tanks.  Even these tanks were troublesome because the glass fibers would

wick fuel through the tank wall and the tank tended to seep fuel.  Again,

not all of them, but enough to take action and the action taken was Kreem.

Kreem is a fuel tank sealer that is used throughout the fuel tank industry,

often in fuel tanks that have rusted inside and have slight leaks.  It does

a good job if it's applied properly.

In the case of the Skystar tanks, they were not properly prepped, meaning

the mold release agent wasn't thoroughly cleaned out and the result was that

over time the Kreem tended to flake off in sheets, often before the tank was

even installed in the wing.  These builders were the lucky ones because it

was easy to fix the problem with the tank out of the wing.  Some poor souls

had to recoat the tanks with the tanks installed.  Not an easy task.

Not all people recoated their tanks and to my knowledge had no problems.  I

personally did recoat, but my tanks were not yet installed and it wasn't

that big of a deal to do it.  So far, after six years, no problems.

Supposedly the Kreem is resistant to alcohol and it's derivatives, but at

that time, there wasn't much of it being used in fuels so it's a wait 'n see

thing on that.  Personally, I'm not going to make any moves and hope the

Kreem does it's job when the Ethanol becomes common place.

Currently I don't know what material is being used in the fuel tanks being

manufactured for the Kitfoxes, but I hope whatever it is is resistant to

Ethanol.  Actually, our problems are insignificant to others.  The in-ground

fuel tanks being used for mass storage in gas stations must be resistant or

we're going to have some serious pollution problems in the future.  Whatever

they're using I would suspect would be the answer.

Sorry for the length of this.  I just wanted to bring everyone up to speed

on this to answer questions I'm sure many have in their mind about their

fuel tanks.  As far as each individual goes, it's probably best to assess

what tanks you have, whether they're coated or not, then make a decision as

to whether you need to take action to avert problems down the road or not do

anything unless there's a problem.  My recommendation would be the latter.

Rotationally molded plastic seems to me to be the long term answer, but it's

expensive to produce unless in large quantities.  I think Rans has been

using them for many years.

If any of the above is inaccurate, feel free to straighten me up.  OK, I'll

get down off of my milk crate now.

Deke

NE Michigan

40f, windy, overcast with snow on the way

---

davef(at)cfisher.com
Guest

Posted: Wed Apr 04, 2007 4:46 am Post subject: Glassfiber tanks and ethanol (Kreem)

Deke,



I will wait and see my self and then look for replacement tanks if they fail

dosmythe(at)cox.net
Guest

Posted: Wed Apr 04, 2007 4:53 am Post subject: Glassfiber tanks and ethanol (Kreem)

Deke,

    I think your history lesson is close enough to bringing everything up to 

present.  My long post was meant to open everyone's mind to look in another 

direction when it comes to protecting the base fiberglass material with a 

barrier product.  This was an opinion with no testing to prove it.



Don Smythe

Do Not Archive



---

Bob

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

Posted: Wed Apr 04, 2007 7:13 am Post subject: Re: Glassfiber tanks and ethanol (Kreem)

Great job on capturing the subject by Don and Deke.  Since I'm just finishing my tail and about to start on the wings, plus we do have 5-10% ethanol in our car gas in Maryland, so this is extremely timely for me.  Thanks to both of you. 

 

My tanks are from the very first lot of Series 5 parts, probably built in 1993, and never installed, so I've been researching possible approaches before I install them.  The simplest was from one of the more experienced people in the group and he suggested rinsing the old fiberglass tanks out with acetone, then re-Kreem.  He did point out that Kreem does have a "life" and after a half-dozen years the tanks may again need to be rinsed and re-Kreemed.



The extreme "other end" approach is to make new tanks out of plastic. I started researching this by Googling what the car makers have done.  They've kept treated steel as the tank material in a number of vehicles for cost. Otherwise, the automakers started wide-spread use of HDPE (like red plastic jerry cans) in the early 1990s and their tanks are expected to last a minimum of 10 years.  Their current problem is that basic HDPE is permiable and some fuel components will outgas, so they are going to multi-layer plastic tanks, but this is way past what we are concerned about. The bottom-line is that HDPE as a material should work for us.



Next part of the puzzle is how to make the tank.  The car makers form theirs through rotational or blow-molding, which is out of our cost league.  However, the boat industry seems to be getting along fine with welded tanks.  Google found that they are going to 8-12mm HDPE with baffles every 300mm and doing proof tests at 0.2 bar (2.9 psi) pressurization.  Aviation pressure requirements are 3.5psi, so a Kitfox tank would need to decrease the baffle spacing.  



There is a plastic welding firm in Baltimore that has done good work for me before and making various types of plastic industrial tanks is most of their business, so I'm seriously looking at whether this is something I want to do. I'll probably still have to stay away from auto gas here because of the downstream issues, such as replacing the fuel lines (easy), carburetor concerns (hmm), etc.  Any input would be appreciated.



Bob

home email = dswaim1119 at comcast dot net



ps - Thanks to Jeff and a couple of others for reminding me that Rustoleum dissolves with MEK - I couldn't remember if it did or not.  I used the Rustoleum as a temporary measure to keep the steel from rusting until I can get epoxy paint.

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

lcfitt(at)sbcglobal.net
Guest

Posted: Wed Apr 04, 2007 10:10 am Post subject: Glassfiber tanks and ethanol (Kreem)

A couple of things here.



On the way to the Desert Fox fly-in we overnighted in Overton, NV and our 

host took us on a tour of the local builders hangars.  One had a Rans 

rotationally molded tank.  I am not entirely clear on this, but when the 

tank comes it is rather hourglass shaped - at normal contour at the ends, 

fore and aft, but collapsed in the middle of the flat surfaces. Their 

instructions call for filling with water to reform the tanks to more or less 

the countour of the airfoil.  These have no internal baffles to help hold 

the shape or to keep the fuel from sloshing.  Using them as part of the 

airfoil as the Kitfox fiberglass tanks would be unwise as they will most 

certainly change shape as the amount of fuel in them changes - just like the 

jugs we use will bulge out when full and return to their manufactured shape 

when empty.



The Tans tanks hold about 10 gallons or so each and are mounted on top of 

the drag - antidrag tubes.  They definitely introduce an entirely new set of 

issues.



Regarding the Kreem.  I checked again this morning for the purpose of this 

note, the floats I have been soaking in denatured alcholol and mogas.  As 

reported previously, the vinyl ester resin float has the typical (typical as 

far as this test is concerned) dull mat surface going to a frosted white 

appearance in some areas.  The Kreem coated float also has it's typical 

appearance - a shiny surface not different in any way from the day it was 

inserted into the alcohol bath.



I have read that when resins cure, they cure in chains of molecules forming 

a matt like matrix with areas of lesser cured resin interspersed - much like 

glass mat with resin.  It is my thought that the alcohol attacks the 

interspersed resin which gives the dull non reflective surface and also 

explains the multitude of tiny bubbles given off when the float is once 

again returned to it's bath and taken up to the test altitude of 14,000 ft 

in the bell jar.



It is interesting to note that the liquids in the tubes have darkened in 

color as illustrated in the photo. From left Vinyl Ester (VE) in California 

auto fuel (6% EOH), VE in 97% EOH, Kreem in 97% EOH, VE in 97% EOH (This 

needs explanation,  The 2OZ refers to the mixing container I used.  In this 

case it was one of the small 2 oz. condiment containers commonly used in 

restaurants (?) for on the side salad dressings, tarter sauce, etc.  I 

wondered if the brief contact with the plastic cup would contaminate the 

resin - conclusion, yes.  The resin for all the other floats was mixed in a 

glass container).  The far right tube contains auto gas with the JC Whitney 

tank sealer, which behaves identically with the Kreem, but as you can see it 

is snow white and did not change the color of the fluid bath.



The other photo is of the floats in the 97% EOH.  Notice the sheen on the 

Kreem and the frosty patches on the VE resin.  A fingernail on the VE resin 

indicates some softening.   These have been soaking in denatured alcohol for 

six months and 4 days.



 A note on VE resins.  There are numerous formulations for various 

applications.  It is difficult to impossible to find in small quantaties as 

we would need for tanks.  The material I used is from ACS and comes in an 

essentially non labeled can.  From their catalog it is listed as a 3M 

product and that is as far as it goes.



Lowell

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Fox5flyer
Guest

Posted: Wed Apr 04, 2007 10:47 am Post subject: Glassfiber tanks and ethanol (Kreem)

Great report Lowell.  Thanks.  Am I correct that your personal opinion is

that properly applied Kreem is an effective deterrent against damage from

Ethanol?

Deke

do not archive



---

dosmythe(at)cox.net
Guest

Posted: Wed Apr 04, 2007 1:13 pm Post subject: Glassfiber tanks and ethanol (Kreem)

lowell,

    As usual, you get down to some serious testing even to the point of 

making those professional little labels.  I will sometimes back down and can 

even change my mind when solid facts are presented.  As Deke implied, are 

you getting prepared to say (from your test) that Kreem might be an 

acceptable product to protect the fiberglass tank from ethanol.  I still 

have to ask, what if a small section of the tank gets untreated or a crack 

develops later down stream?

    I once made some little fairing covers that went on the bottom of my 

wings over the bottom tank vents.  I used Styrofoam eggs (cut in half) from 

the hobby store.  Once they were shaped and drilled, I practically soaked 

them in West Epoxy and then painted to match the plane.  A couple months 

later, I noticed one of the looking a little wrinkled.  Sure enough, I had a 

small gasoline weep and it had eaten all the Styrofoam of the egg and on the 

epoxy and paint remained.



Nice testing job,

Don Smythe

Do Not Archive



---

lcfitt(at)sbcglobal.net
Guest

Posted: Wed Apr 04, 2007 4:11 pm Post subject: Glassfiber tanks and ethanol (Kreem)

Deke and Don,



This is a tough question to answer actually.  At one time, and Deke is privy 

to this, I used the Kreem over an epoxy base on the floats.  I guess the 

idea was to create a firm base for the Kreem like in our tanks.  We had one 

instance where the epoxy bubbled under the Kreem causing a mechanical 

interference with the float's movement.  I had had the low fuel system in my 

Model IV for about four years and this was a real heads-up. Since then I 

have been looking at a single coating system for the floats.  What I want is 

the failure mode to be false positives as might happen if the float lost 

buoyancy rather than simple non operation like the Ray Volk report when he 

told me that the optical cone in his optical low fuel indicatior system 

simply melted in the fuel and dropped, as he said, to form a Hershey's Kiss 

like mound on the bottom of his header tank.



My feelings are that Kreem is pretty much impervious to auto gas and 

alcohol - at least for the 6 months duration of my test and expect the Kreem 

to go on for a long time in the future.  I am curious how long the Vinyl 

Ester will keep the floats floating.  My advantage with the floats is that 

they are of balsa wood and the Kreem will soak into the outer fibers and 

there is no way the Kreem will come off.  There is one difficulty that has 

arisen when the end grain of the balsa has large pores.  The Kreem will not 

bridge these even with the three brush coats I give them.  I will then mix a 

bit of micro balloons with some Kreem and apply it to the pores with a very 

small spatula.  I give the floats the three coats with a full drying period 

in between.  I guess the past experience would suggest that the weak spot in 

the system is the preparation of the glass surface for Kreem adhesion 

coupled with Kreems inability to bridge large voids (Maybe #60 drill size). 

That said, I suspect  voids in the lay-ups that large to be quite rare to 

non existant.



I like Kreem's resistnce to alcohol and Mogas and have had it in my tanks 

for nine years - I did re-slosh one tank about three years ago, though. 

When building, I had one tank not fit the wing spars - not jigged properly 

when closed at the tank shop and as a result I have tanks from two separate 

batches.  The (good) left tank was the replacement tank, ca. July 1993, 

whereas the resloshed tank was in the kit, ca. March 1993.



After re-reading this, I know it doesn't answer all the questions.



Lowell

---

dosmythe(at)cox.net
Guest

Posted: Wed Apr 04, 2007 4:34 pm Post subject: Glassfiber tanks and ethanol (Kreem)

lowell,

    I still have the original low fuel warning you sent me "years" ago.  We 

went through a couple exchanges on floats but the last one is "still" 

working just fine.  Actually, it will flash a couple times under different 

circumstances such as a bump in the air.  The flash is re-assuring that the 

unit is still works.  When the fuel is actually low, it comes on bright.



Don Smythe

Do Not Archive

---

smokey_bear_40220(at)yaho
Guest

Posted: Wed Apr 04, 2007 10:16 pm Post subject: Glassfiber tanks and ethanol (Kreem)

Another keeper for my files Deke,



Thanks.  I'll probably be facing this issue sometime

in the future too.  This is the kind of stuff that

makes this list so important.



Kurt S.



Do not archive



--- fox5flyer <fox5flyer(at)idealwifi.net> wrote:



 	  Quote: 	
		   Good morning everyone!  This is a very good topic

 and has far reaching

 effects for most of us Kitfoxers.  For all you folks

 who have been around

 Kitfoxes for a long time, most of you already know

 all about the Kreem and

 the problems we've had with it in our wing tanks. 

 For those of you who are

 relatively new Kitfoxers, whether builders or

 buyers, it may pay you to

 search the archives with key word "Kreem" and read

 all you can about it

 because there is a ton of information on it. 

 Sportflight.com 


	




 

No need to miss a message. Get email on-the-go 

with Yahoo! Mail for Mobile. Get started.

http://mobile.yahoo.com/mail

kitfoxfugit(at)yahoo.com
Guest

Posted: Sun Apr 08, 2007 10:23 pm Post subject: Glassfiber tanks and ethanol (Kreem)

"Bob" <dswaim1119(at)comcast.net> wrote:



"Since I'm .. about to start on the wings, plus we do

have 5-10% ethanol in our car gas in Maryland, so this

is extremely timely for me.  ... My tanks are from the

very first lot of Series 5 parts, probably built in

1993, and never installed, so I've been researching

possible approaches before I install them. ...The

extreme "other end" approach is to make new tanks out

of plastic."



Bob, the wing structure of the Rans containing plastic

tanks is different from the Kitfox.  My understanding

was that plastic tanks could be a problem in the

Kitfox wings.  The plastic 6 gallon cans I use to fuel

mine have no structural properties and do expand and

contract when filled and emptied.



Since your tanks are out, maybe you could test them

directly.  Mine were made about the same time as

yours.  I tried short-term tests on mine with ethanol,

acetone, and MEK, and found no effect.  Since Rotaxes

don't like lead, and I didn't want to pay a dollar per

gallon more for 100LL, plus TCP, I then decided to

just use CA car gas without sloshing.  I have noticed

no problems in the year since.



Too bad someone on this list can't get some wrecked

Kitfox tanks from various periods and test them

long-term directly.



John Allen, Kitfox IV Speedster Rotax 912UL

 

Bored stiff? Loosen up... 

Download and play hundreds of games for free on Yahoo! Games.

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