Dryer Shuts itself down

I have an older American Tex-Air EGE 60. The gas shuts itself down constantly and I cannot figure out why. I have had an HVAC crew in many times to look at it but they cannot give me an answer. Has anyone else out there dealt with this?

This happens every day in the world of screenprinting! It is either a safety issue or
Equipment/ component failure which leads to shut down. Who has been responsible
For maintanance? Good HVAC tech should have picked up the issue in a reasonable amount
Of time. Need to know more info to point you in the right direction. Give me a call if you like!
All the best
Winston
904.3430848