Technical Cunifer tubing with 37 degree flare

I am using 3/8 cunifer tubing for fuel lines with a 37 degree flare to An fittings. Should I be using a single flare or a double flare on the tubing considering the cunifer is softer material then like stainless which usually has single flare I believe ? What do you guys recommend single or double flare ?

 

It's really not what some guy(s) recommend, but what's correct. AN 37 degree requires a single flair, and 45 degree inverted fittings require a double flair.

 

Single.

 

Thanks guys. I was thinking a single flare but wanted to get an opinion. We had used a single flare for aluminum 1/2 inch tubing for a race car fuel line low pressure before and it seamed to work ok. My first time working with the cunifer tubing for a high pressure fuel line.

 

I'm going to use the 3/8" Cunifer tubing for my fuel line also, but I am going the other way on several of the fittings using a compression fitting.
We used then for years in industry and I like how they work.

 

Aluminum tube is used with 37 degree single flares on aircraft and racing. I would think cunifer would be just fine.