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11-17-2019, 08:06 AM
#101
Re: PA-22 fuel sending unit gasket
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11-17-2019, 08:10 AM
#102
Re: PA-22 fuel sending unit gasket
I’m not sure what the ones in the kits are made of, but the ones from McMaster are neoprene. From what I’ve been able to determine neoprene doesn’t stand up well to fuel. Viton would be much better.
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11-17-2019, 08:37 AM
#103
Re: PA-22 fuel sending unit gasket
These bolts are a godsend for this job
Originally Posted by
Steve Pierce
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11-17-2019, 09:22 AM
#104
Re: PA-22 fuel sending unit gasket
Originally Posted by
cozzmo81
I’m not sure what the ones in the kits are made of, but the ones from McMaster are neoprene. From what I’ve been able to determine neoprene doesn’t stand up well to fuel. Viton would be much better.
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I would use buna instead of viton, viton loses its seal in freezing temps, where buna rubber keeps its seal in freezing temps.
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11-17-2019, 09:14 PM
#105
Administrator
Re: PA-22 fuel sending unit gasket
Originally Posted by
SMO22
I would use buna instead of viton, viton loses its seal in freezing temps, where buna rubber keeps its seal in freezing temps.
https://www.manuf-rubber.com/news/bu...he-difference/
According to this at about 5 degrees but sounds like Viton might last longer. The gasket should seal the screws so it is probably kind of a mute point. Made for an interesting read. Only thing I knew about Viton is what Brian at Steve's Aircraft posted about them using Viton in their gascolator and the infinite shelf life. Interesting that the fuel resistant o'rings MS25913 that Spruce sells are Nitrile (Buna, Buna N). I learned something new today.
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11-18-2019, 01:57 AM
#106
Re: PA-22 fuel sending unit gasket
Yes interesting if you like reading about rubber good to know stuff. For those that dont click the link, a few of the differences
Buna vs. Viton: Which Seal for Your Application?
As a sealing option, the crucial difference between Buna and Viton is the temperature range the materials function in. Viton is the choice over Buna for high-temperature applications. Viton seals hold indefinitely at temperatures up to 400°F and can last up to 48 hours at temperatures up to 600°F. Buna is effective to 250°F. However, it can effectively seal mechanical objects at low temperatures to –22°F. Viton seals are rendered ineffective at temperatures below 5°F, with the material becoming hard and inflexible.
Environmental conditions also differentiate the application of Buna vs. Viton for sealing options. Viton offers universal chemical resistance for sealing applications for oils, fuels, and mineral acids. Its weatherability and resistance to mold and fungus, oxidation, ozone, and UV exposure offer additional excellent properties. Buna’s chemical resistance is much less than Viton, and its weatherability and ozone exposure limits its application where such properties are required. That said, in circumstances that do not require such properties, Buna seals do offer superior abrasion and tear resistance, and are more suitable for heavy-duty industrial applications.
Properties of Buna O-rings
Buna is a widely used elastomeric material known for its tensile strength and high fuel and oil resistant properties. It combines resistance with low compression set and high abrasion resistance to make it the seal industry’s most widely used economical elastomer. Buna, also referred to as Nitrile or Buna-N, is an NBR rubber that displays excellent resistance to all petroleum-based oils and fuels, as well as water, various alcohols, silicone greases, and hydraulic fluids. It offers such other advantages as good tear resistance and non-polar solvent resistance. It’s also less expensive than fluoroelastomers.
Properties of Viton O-rings
Viton is a synthetic rubber and fluoropolymer elastomer that is used in O-rings and other molded or extruded products. It offers the best fluid resistance of any commercial rubber. At high temperatures, Viton retains good mechanical properties compared to other elastomers. It remains substantially elastic and is resistant to oils and chemicals at elevated temperatures.
Last edited by SMO22; 11-18-2019 at 02:03 AM.
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11-18-2019, 09:19 AM
#107
Re: PA-22 fuel sending unit gasket
SMO22,
Thanks for the information on the differences between Buna-N and Viton. I wasn’t aware of the cold weather differences.
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11-18-2019, 03:20 PM
#108
Re: PA-22 fuel sending unit gasket
I needed to replace one of those gaskets several years ago on a PA20. Found one at the National Airplane Parts Association with no minimum order required. I believe it coincidentally fit a Ford.
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04-07-2020, 08:09 AM
#109
Re: PA-22 fuel sending unit gasket
I recently contacted Comanche gear re: the sending unit gasket kits and now he is pushing a $50 min. Does anyone have a set of sending units kits they are not using or would someone like to get a set if I order the new min?
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04-07-2020, 10:53 AM
#110
Re: PA-22 fuel sending unit gasket
how much are the single kits
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