I've used carb cleaner and brake cleaner.
Curious, what makes you suspect a leak?

 

Dude, you don’t hose the thing down with half a can, it just takes little short spurts aimed at specific points. Unless you are spraying heavy it isn’t going to harm a damned thing.v

 

Dude? That is so funny!! I am 72 years old and have not been called that in over 50 years. I suppose down in the 'hood I would also be called "Dog."

 

If you're worried about it, use something non flammable. LPS No Flash works good, will cause it to spit and sputter if there's a leak

 

The only thing I use propane for is to check for proper AFR mixture at idle.. or if I'm heating up a NOX bottle..

 

Are you talking about spray it around the carb intake manifold seals, and listening to see if RPMs change? Why would brake clean get on the tank? Plus I guess I don't worry about brake clean on pain that much, especially down there,

I believe I've done both. One mechanic said to use a ciggerette smoke the seals, but I am not a smoker.

 

I've used all the above honestly with no issues. Usually I'll just throw water in a bottle with a split lid and squirt the manifold. You'll hear the gurgle and it idle down when you find the spot. Just another option and wont damage a thing.