BACK PRESSURE SETTING FOR A BAUER CAPITANO 6 CUFT 3 stage

[rjack321]

When does a compressor run balanced and unbalanced?

balanced is when the forces on the 3 (or 4) cylinders and the cam shaft are equal which only really happens at one specific pressure.

unbalanced is when you are above or below that pressure

 

[rddvet]

Agree with what's already been posted. I was always told for any compressor set the PMV at 2000-2500 psi

 

[NAM001]

When does a compressor run balanced and unbalanced?

Idealy untill it exceeds the ballanced psi. if the psi for ballance is 2300 than you set the BPR to 2300 and it runs ballances like a ballanced tire on your car. once the pressure goes above that it progressivly runs more and more out of ballance. Im not sure whether your question was a serious one or not but if it was it is a matter of making all stages equal force on them. equal in piston surface area * psi. first stage = second stage= ... to last stage. the last stage psi is dependant on the back pressure form the tank if no bpr is used. So if the required force per sq inch is 2300 and the final piston has 1 sq inch area then the PSI has to be 2300. if the final piston is less then the psi has to be higher to achieve 2300 force. the higher you pump the tank the more out of ballance it gets. idealy you have it run ballanced until the final compression range from say 2300 to 3000 psi being the only time it is out of ballance as opposed to low out of ballance from start reducing untill it gets ballanced at 2300 and then increasing high out of ballance untill tank is full.

 

[Miyaru]

I get that, but the PMV or back pressure valve is not meant for the balance. It's purpose is to keep the pressure in the oil separator and filter stack to a minimum of 150bar, ensuring specific dew points so the molecular sieve can do an effective job.
My compressor keeps the banks topped up, I start it when the lowest bank reaches 180bar and stop it when all banks are full (highest pressure 300bar). With these pressures, the compressor is always running unbalanced. The construction makes sure it can handle these forces, PMV doesn't have much to do with that.

 

[rjack321]

I get that, but the PMV or back pressure valve is not meant for the balance. It's purpose is to keep the pressure in the oil separator and filter stack to a minimum of 150bar, ensuring specific dew points so the molecular sieve can do an effective job.
My compressor keeps the banks topped up, I start it when the lowest bank reaches 180bar and stop it when all banks are full (highest pressure 300bar). With these pressures, the compressor is always running unbalanced. The construction makes sure it can handle these forces, PMV doesn't have much to do with that.

But when you are starting with 40bar in an "empty" tank the compressor will run balanced up until it surpasses the PMV value - if its set at the same pressure as the 3 stages. But differential ring wear over time is going to mess up that balance anyway.

I'm like you and not worried about when or if the compressor is running balanced. The PMV is to help remove water that's it.