Refrigerated Compressed Air Dryers

[Air Dryer Tech]

Does any one out there work on or specialize in industrial compressed air refrigerated dryers? I have worked for a compressor service company for 26 years. The last five I have specialized in air dryers along with another co worker with 30 years experience. It is full time 365 days a year for us. I have seen no other mention on this forum regarding this large industry. Sullair, Ingersol Rand, Hankison,Great Lakes, Pal, Donaldson, etc...

[bamatech]

I do some compressed air work also but we have all dessicant dryers.IR and zeks dryers. IR and Gardner Denver screw compressors.

[Air Dryer Tech]

I worked for a Gardner Denver distributor back in 1985. I still work on them occasionally. I work on desiccant dryers often. Desiccant dryers provide a much lower dew point than refrigerated dryers. Desiccant -40F to -100F. Refrigerated around +37F. Our desiccant applications are usually for customers that have compressed air piping and uses in cold spaces or outdoor uses in the winter when ambient temps are below +37F

[ryan1088]

The contractor I work for does work on industrial air compressors and driers. It's an interesting field for sure. Sometimes a welcomed break from the grind of the ac world.

[Dr.phil]

I've got a few that I work on. The problem is the big noisy air compressors in the same room. Even with ear plugs I feel the vibrations the rest of the day.

[crab master]

I've got a few that I work on. The problem is the big noisy air compressors in the same room. Even with ear plugs I feel the vibrations the rest of the day.

No that's your hand in your pocket... :grin2: Couldn't resist.

I've just worked on the smaller ones for pneumatic control systems. Most of them like 2' cubed.

[pbulldog]

We do in Canada, company called Canadian Air Dryer Services...it is a specialized industry and there are few companies that specialize in it...its also a hard industry to develop as most people ignore them until they break down and then they call local compressor house

[Dr.phil]

Ok, air dryer guys. Question of adjusting a new txv. I replaced a compressor in a Pneumatech ad-1000 today. Reportedly it has been changed twice before. Mechanical problem, it was running but not pumping. After changeout, check to see why it failed, and find it flooding the comp. I can tell the power element on both the txv, and the hot gas valve have been changed in the past. A red tag on the txv warns against adjusting it. It wants you to order an oem. The book says factory set at 8-10 deg. superheat. Taking into account the hot gas pressure control, how do I adjust the txv? Both condenser fans are pressure controled. Do I try to control the load, or run it wide open? I should mention the hot gas enters right after the txv. I think.

[lafittejdubb]

Ok, air dryer guys. Question of adjusting a new txv. I replaced a compressor in a Pneumatech ad-1000 today. Reportedly it has been changed twice before. Mechanical problem, it was running but not pumping. After changeout, check to see why it failed, and find it flooding the comp. I can tell the power element on both the txv, and the hot gas valve have been changed in the past. A red tag on the txv warns against adjusting it. It wants you to order an oem. The book says factory set at 8-10 deg. superheat. Taking into account the hot gas pressure control, how do I adjust the txv? Both condenser fans are pressure controled. Do I try to control the load, or run it wide open? I should mention the hot gas enters right after the txv. I think.

The first thing I'd do is verify the sensing bulb is clean, placed correctly on the suction line, and that it's responding correctly <--(when dryer is operating). I'd do this by removing it, sanding the line and bulb and then reattaching it at the 4 or 8 o'clock position.

Given your TXV is adjustable, you can remove the nut from the bottom of the valve. There you'll see a superheat (SH) adjustment stem. Measuring SH, adjust the stem approximately 1/3 to 1/2 turn at a time.
Wait at least 3-5 minutes (minimum) to see the SH lows/highs and to prevent flood-back.

The hot gas desuperheating valve is fairly common in refrigeration apps requiring dehumidifcation even during low-load conditions (dryers). Is it pressure or temp responsive?

Regarding your condenser fans, maintain the condenser between 98 - 122 degrees, roughly. (Not sure what refrigerant your using). Ex. R-22 Fan Cycle Controller cut-in would be 267 psi and cut-out would be 190 psi.

[pbulldog]

Ok, air dryer guys. Question of adjusting a new txv. I replaced a compressor in a Pneumatech ad-1000 today. Reportedly it has been changed twice before. Mechanical problem, it was running but not pumping. After changeout, check to see why it failed, and find it flooding the comp. I can tell the power element on both the txv, and the hot gas valve have been changed in the past. A red tag on the txv warns against adjusting it. It wants you to order an oem. The book says factory set at 8-10 deg. superheat. Taking into account the hot gas pressure control, how do I adjust the txv? Both condenser fans are pressure controled. Do I try to control the load, or run it wide open? I should mention the hot gas enters right after the txv. I think.

On refrigerated air dryers you should always set hot gas bypass valve with no load. The valve is there to prevent low suction and freezing, depending on refrigerant, presuming Pneumatech i think uses R-22 on that size dryer. Suction should be set to about 65-67 psig. The tx valves on dryers should be factory set, we sometimes set superheat a little lower on these machines. I would say that flooding would probably be caused more by faulty hot gas valve...

[Dr.phil]

On refrigerated air dryers you should always set hot gas bypass valve with no load. The valve is there to prevent low suction and freezing, depending on refrigerant, presuming Pneumatech i think uses R-22 on that size dryer. Suction should be set to about 65-67 psig. The tx valves on dryers should be factory set, we sometimes set superheat a little lower on these machines. I would say that flooding would probably be caused more by faulty hot gas valve...

That's what's bugging me. Txv is suposed to be factory set. I think it is the txv, because the pressure is in the green.

[pbulldog]

what is your suction pressure? is hot gas vavle opening? are fans coming on? is it OEM txv..we have used none oem valves and not had any problems with the way the are regulating flow..does dryer have control board with alarms and set points?

[Dr.phil]

what is your suction pressure? is hot gas vavle opening? are fans coming on? is it OEM txv..we have used none oem valves and not had any problems with the way the are regulating flow..does dryer have control board with alarms and set points?

Suction pressure is 68psi. Like I said both power elements on the txv and the hot gas valve, but not the bodies, have been replaced, along with two compressors. By another co. Now I need to get to the bottom of it. Maybe I'm overthinking this. I can shut off the compressed air flow to double check the hg valve.

[pbulldog]

has heat exchanger froze up? This hot gas valve is solenoid style and controlled from board?

[Dr.phil]

No solenoid, just a valve with an equalizer. Didn't let it run long enough to freeze the evap. Compressor was flooding so bad I shut it off. Compressed air temp was 105f. This unit was added to the system when capacity was added. System has three 200hp and a 150hp compressor. The main dryer is a 3300.