Air system air dryer question.

[ben2go]

I'm upgrading my commercial truck from spring suspension to air ride. I am using a modified York 210 compressor to provide air to the system. This compressor doesn't have an unloader valve on the compressor like a commercial diesel engine style compressor. The air dryer I am installing is a self contained unit with the governor on the air dryer, not on the compressor head. This is the closest dryer I could find that may possibly fit, and work, with my custom installation. The dryer has three air connections, 1/2in tank line, 1/2in compressor feed line, and 1/4in control line to the unloader valve. Since I don't have an unloader valve, do I simply tee in the 1/4in control line back to the 1/2in line from the compressor? If I am understanding the dryer's operations correctly, the control line would purge the dryer once the system comes back up to full pressure after the system bleeds off from use. Am I understanding this correctly? I can't find any info about this online.

I have built air ride systems based on the York 210 compressors before. I used a basic air/water separator similar to a shop air compressor, except I used much bigger industrial unit. I still drained the tanks regularly. I'm hoping by adding an air dryer it will keep me out from under the truck draining the air tanks as often.

 

[RayIN]

Read up on automatic air tank drains. They are 12V powered. You'll still need an air dryer unit though, to avoid frozen air lines in cold weather.

 

[BravoXray]

To use that compressor, I assume you're going have to use an electrically controlled clutch, like an A/C system uses. If so, you'll have to have a pressure switch to turn the clutch off when it comes up to the required pressure, and also an electric solenoid valve that will send reservoir pressure to the purge valve on the air drier. The pressure switch would have 12 volts connected to the C (Common) terminal, the NC (Normally Closed) terminal connected to the compressor clutch, and the NO (Normally Open) terminal connected to the solenoid valve.

 

[ben2go]

All good points. My question was about the control line back to the unloader valve on a engine driven airbrake compressor. I didn't know what to do with it. After a lot of research, I've realized that my set up doesn't need the control line to the unloader valve, because my compressor is controlled through a 12 pressure switch. Once up to pressure, 135psi, the air dryer pops off, like a pop off valve, and any collected moister or debris is ejected out through the bottom of the air dryer. My compressor doesn't dead head into the system like an engine driven airbrake system compressor, so there's no need to unload the compressor for the air dryer to work properly.

 

[BravoXray]

If you're talking about the over pressure safety valve on the drier, normally those are on the top of the drier, and wouldn't expel moisture properly. The dump valve on the bottom of the drier has to be pressurized to do that. What make drier are you using? Is it a regular truck type drier?
If you're not depressurizing the drier with the dump valve on the bottom, it will eventually fill with moisture and pump water through the system.

 

[ben2go]

If you're talking about the over pressure safety valve on the drier, normally those are on the top of the drier, and wouldn't expel moisture properly. The dump valve on the bottom of the drier has to be pressurized to do that. What make drier are you using? Is it a regular truck type drier?
If you're not depressurizing the drier with the dump valve on the bottom, it will eventually fill with moisture and pump water through the system.

It's a WABCO unit from a bus. The control line unloads the compressor using compressed air when the system reaches operating pressure. It's used in place of a pressure switch for a clutch type compressor. Direct engine driven compressors don't have that. Instead they use an unloader valve which uses clean compressed air from the dryer to hold the unloader valve open or closed, depending on the type, and stopping the compressor from building pressure. When the system's pressure drops, the control line pressure drops, and the unloader valve allows the compressor to build system pressure. I won't use the control line. I'll cap it off to prevent pressure loss. I'm using a compressor with a clutch like an automotive AC compressor. My compressor is coming from an old truck with a massive 8 inch compressor clutch.