I have a couple questions about air receiver safety. I have a 20
gallon ASME carry tank (Grainger 4TK10). It has two 1/2" air outlets,
but I want to use it to honk an old fire horn which is not working
when I plumb from just one of the 1/2" outlets. I need more flow to
maintain proper blowing pressure at the horn. So my questions are
these:

1. Is there a known maximum safe discharge rate for a 20 gallon ASME
tank? The tank has a plate rating of MAWP 175 PSI @ 475 F. I need to
meter out half-second blasts at a rate of approximately 80 CFM. Is
this safe to do from a 20 gallon tank? What about from a pair of 20
gallon tanks?

2. Can I plumb the two 1/2" outlets into a common 3/4" or 1" tee? Is
there any safety reason not to?

3. Lastly, the tank has a 1-1/2" NPT inspection port that has a 1/4"
hole tapped in it for a guage. Can I replace this plug with a
1.5"-to-1" hex bushing and plumb right from there, or is this a no-no.

I want to get full flow to the horn, but I don't want to do anything
that is likely to cause the tank to lose integrity or fail
explosively/implosively. I've found lots of useful information about
maximum tank pressures, but I can't find anything on the web about
maximum discharge rates or air tank implosion.

Thanks,

Adam
adam at airraidsirens dot com