Max water pressure of clear acrylic pipe?
Acrylic can handle 180F, and isn't rated for pressure. Clear schedule 80 PVC is rated for pressure, but can only handle 140F. Check out McMastet-Carr online if you want more material specs. 

Maybe look at this problem from another direction? Air getting sucked into a water line typically only happens on/near the inlet side of a pump, so check around the pump inlet first. Often times it's from cracked PVC fittings or a leaky o-ring when I've seen it in pools. 

Instead of looking for the air in the water line, intentionally pressurize the water line with air and look for where water leaks/mists from the pipe. Even without water in the line you'll be able to hear it it if you can't see it.

Depending on how large your system is, and how large of an air compressor you have, you may need to add shutoff valves to isolate parts of the line. Use a regulator if you don't want to pressurize everything to 100+ psi which is probably higher than the pressure rating of your pipe and equipment. 

On the same note, you can do a pressure drop test to confirm its not leaking if you're trying to rule sections of pipe out.