Lee, I'm very grateful for your insight, I also think that I will change that soda bottle. have been looking for an odd shape extinguisher bottle..hopefully made of aluminum to save weight, and just for your records i have used AC and refrigerator compressor pumps very successfully in the past! Even do I have a conventional compressor! I always keep one of this sealed pump units at hand and ready to take over... In that way if I'm doing any kind of work and my air supply fails I have not reason to panic..
In an other hand..the PVC pipes for some reason do become brittle I live in FL.. and some times in the heat of the summer the pipe joints give with out any kind of warning...I have opted to use either rubber hose or copper tubing! those ones don't explode just leak and then one make decisions of how to deal with those leaks ..

Thanks again for your help.

Mark.