What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Tank sealant

togaflyer

Well Known Member
I need to order some stuff from Spruce, so Im considering ordering tank sealant in the same order. I do not see the tank sealant Van's has offered by Spruce, but Spruce has Pro Seal, some 3m products etc. Is Pro Seal or other products from Spruce good to use, or should I just order the sealant offered at Van's.
 
I've always bought the least expensive brand which was advertised as meeting the spec, and have never had a problem.

That said, there are some builders with a brand preference.
 
One thing to note is, last time I checked anyway, Van's sells sealant by the quart at about the same price Spruce carries the cheapest sealant by the pint. Something to consider.
 
Flamemaster

I just ordered Flamemaster from Sky Geek. Price was better than Aircraft spruce. Have been noticing other thinks better prices from them also.
 
I just ordered Flamemaster from Sky Geek. Price was better than Aircraft spruce. Have been noticing other thinks better prices from them also.

Check delivery times from Skygeek. I bought some proseal from them a month ago. Showed XX units available. It took 2 weeks or so to ship. and another couple of days for delivery. I'd have had it in 1/2 the time from Van's, or 1/4 of the time from Spruce.
 
non-tank ProSeal replacement

For places like in the snorkle around the top to make it air tight is there something besides ProSeal that works great? I'd use ProSeal but I need so little and the shelf life is so short it is expensive to use. What about high temp fire wall sealant like 3M-2000? Can I use it in snorkle around the aluminum parts near the top?

Same question for mounting stuff on or thru the firewall. Does firewall sealant act like an adhesive like ProSeal?

thanks
 
For places like in the snorkle around the top to make it air tight is there something besides ProSeal that works great? I'd use ProSeal but I need so little and the shelf life is so short it is expensive to use. What about high temp fire wall sealant like 3M-2000? Can I use it in snorkle around the aluminum parts near the top?

Same question for mounting stuff on or thru the firewall. Does firewall sealant act like an adhesive like ProSeal?

thanks

Fresh, in-date sealant is certainly the best way to go for sealing RV fuel tanks.

However, "pro-seal" remains a very aggressive adhesive for odd jobs for many years if stored in a refrigerator. I have leftover Pro-Seal (may be Flame Master) in the frig at the hangar that is nearly ten years old and I still use it as an adhesive with excellent results. Using the left-over quart kit has been much more convenient for various glue jobs than buying a new batch every time one of these tasks arise. I used it last summer to seal up some oil leaks on an old O-200 and that engine is practically leak free now.
 
Last edited:
Vans Flamemaster

The Vans Flamemaster product has built hundreds if not thousands of leak free tanks. Perfectly good product.
 
Why would the PRC Desoto product be any better than any of the other ones available that meet the Mil Spec?

"...Meets requirements of specifications AMS-S-8802 formerly MIL-S-8802..."

Is it historic or familiarity since the PRC product was the first one generally available for RV tank construction?

Excellent questions. Mooney specifically authorizes other brands, just calling for the mil. spec. Last I looked, PRC brand was roughly 80-100% more money than Chemseal Flamemaster.
 
Fresh, in-date sealant is certainly the best way to go for sealing RV fuel tanks.

However, "pro-seal" remains a very aggressive adhesive for odd jobs for many years if stored in a refrigerator. I have leftover Pro-Seal (may be Flame Master) in the frig at the hangar that is nearly ten years old and I still use it as an adhesive with excellent results. Using the left-over quart kit has been much more convenient for various glue jobs than buying a new batch every time one of these tasks arise. I used it last summer to seal up some oil leaks on an old O-200 and that engine is practically leak free now.
+1 for this. Have done the same thing.
 
Thank you for the input. I bought some Proseal from spruce. Is 6 ounces enough to install both fuel floats (quick build wings). Also, I have a tube of Pro seal thats about 3 years old, but its been kept in the refrigerator. Would it be safe to use it to install the front NACA cabin vents.
 
Fresh, in-date sealant is certainly the best way to go for sealing RV fuel tanks.

However, "pro-seal" remains a very aggressive adhesive for odd jobs for many years if stored in a refrigerator. I have leftover Pro-Seal (may be Flame Master) in the frig at the hangar that is nearly ten years old and I still use it as an adhesive with excellent results. Using the left-over quart kit has been much more convenient for various glue jobs than buying a new batch every time one of these tasks arise. I used it last summer to seal up some oil leaks on an old O-200 and that engine is practically leak free now.

+1 I just used some 15 yr old to seal a cover plate on the firewall. It's been kept in the fridge all that time. That said I just ordered fresh to finish the tanks on my current build. The leftovers will replace the 15 yr old stuff in the fridge.
 
Excellent questions. Mooney specifically authorizes other brands, just calling for the mil. spec. Last I looked, PRC brand was roughly 80-100% more money than Chemseal Flamemaster.

Interestingly the Grumman factory repair kits (for the Tiger/Cheetah) referenced the Mil-spec but supplied the FlameMaster product by part number.
 
Minor detail....

Proseal is often used as an adhesive. For sure, a lot of the adhesive applications don't actually require much strength. That said, it wouldn't be good to overestimate the holding power of polysulfide sealant, which is actually quite low.

Per standards, minimum tensile strength is only 200 psi. Test samples are typically 250~275. It is allowed to drop as low as 50 psi after 14 days in hot fuel.

For comparison, oil-resistant Permatex Ultra Black (aka Loctite 598) silicone sealant is rated at 260 psi per the TDS. 3M FireBarrier 2000 silicone is rated at 350 psi. West System 105 epoxy is 7,900 psi.

Probably the best reason to use proseal as a low strength adhesive? It's paintable.
 
Why would the PRC Desoto product be any better than any of the other ones available that meet the Mil Spec?

"...Meets requirements of specifications AMS-S-8802 formerly MIL-S-8802..."

Is it historic or familiarity since the PRC product was the first one generally available for RV tank construction?

I think its obvious, but Just because a product "meets the spec" does not necessarily mean they are all created equal. In my past life working on and around the big birds the only thing I ever recall seeing/using was PRC.

And if I'm not mistaking, most of the "soft gooey sealant" issues that have cropped up over the years on builders tanks that were blamed on the blue dye, were determined to be sealed with flamemaster.

And yes, I choose products based on past performance, familiarity and history, ones that I know work. I do not choose products based on the lowest cost, I have found that you generally get what you pay for.
 
Last edited:
properties

Dan, great to know. As a comparison, here is what West System shows for some of their products:

http://www.westsystem.com/ss/typical-physical-properties/

wzH2WAJ.png
 
And if I'm not mistaking, most of the "soft gooey sealant" issues that have cropped up over the years on builders tanks that were blamed on the blue dye, were determined to be sealed with flamemaster.

I have not seen indication of that.
I am personally aware of it occurring with both products at least a couple of times.
 
I think its obvious, but Just because a product "meets the spec" does not necessarily mean they are all created equal. In my past life working on and around the big birds the only thing I ever recall seeing/using was PRC.

And if I'm not mistaking, most of the "soft gooey sealant" issues that have cropped up over the years on builders tanks that were blamed on the blue dye, were determined to be sealed with flamemaster.

And yes, I choose products based on past performance, familiarity and history, ones that I know work. I do not choose products based on the lowest cost, I have found that you generally get what you pay for.

The challenge is knowing how many tanks were sealed with Flamemaster products versus others. I'd guess a huge percentage of the tanks on Van's designs were sealed with Flamemaster, because it is less expensive and easy to buy through Van's. If there have been a handful of failures with Flamemaster and any at all with other products, that doesn't point to a problem specific to Flamemaster.
 
Soft gooey vs. firm

Some blue dye and a flammable smell revealed 3 small leaks on a 23 y/o RV-3 I bought in 2015. Locations are fuel sender terminal, bolt on fuel sender plate and fuel line fitting to tank. I pulled everything off and noticed a difference in the way some areas "cut" with the utility knife. Some areas cut some and clean and some "mushed" out of the way. The leaky areas were the later.

So, now I need to rebuild the whole enchilada as we say in SOCAL. Is it possible these are two different sealants? And how the Heck do I pull the plate with the fuel pickup line? That baby won't budge.
 
Back
Top