I have two 80 gallon, 5 hp, two stage air compressors I'd like to hook together to run air sanders. Someone told me to pipe the tanks together, then pipe one compressor to the main pipe that runs into the shop. Another guy said just T them both onto the main pipe that runs to the shop. What's the best way to go?
From contributor K:
Either way should work for the piping. The issue will be the kick in pressure of each. Unless you take the time to adjust them the same, one of them will do most of the work.
#1, run your piping in a closed loop layout. If you only have a straight run, you will starve the tools at the end of the line.
#2, draw your air off the top of your pipe to eliminate moisture.
#3, make sure you have large enough supply piping. We run a 25hp rotary screw compressor with 45cfm capacity and found that we had to send 1 1/2" supply lines to both ends of our shop to feed into our 3/4" loop system.
We also added an 80 gallon tank 3hp compressor (with our loop dumping into a side port on the tank to use it as a backup reservoir) on opposite end of shop that kicks in when pressure drops to 90lbs (this rarely happens). If you tie both your tanks together and set the threshold on one of your compressors 10lbs lower than the other, you will use both to fill your system upon startup, but rely primarily on one compressor to top off 160 gallons of capacity and you should be okay. If this does not do the trick, you really need to consider more capacity.
I have been running two 5 hp 80 gallon compressors just as contributor A said since 1997. For me, it is the only way to go. When I replaced the unloader on one - I still had shop air while locating a new unloader.
Don't forget to check motor rotation after you rewire them up if they are three phase!
While you're at it, you might want to think about tossing the worthless petcocks on the bottom of your tanks, and replacing them with 10 or 20 feet of good air hoses with ball valves on the ends, so you can drain the water from the tanks without having to crawl around underneath them. You can then drain them right into a mud bucket or something. Your tanks will get drained much more often when it is that easy.
The compressors come on simultaneously and go off simultaneously, which is exactly what I wanted - the most air in the least amount of time having to listen to them chugging.