PDA

View Full Version : Drier



Vincent Yu
31-01-2006, 12:01 AM
Hello All,

I have a stupid question. I am working on a small dehumidifier. It is a flooded system. A 7000 BTU/hr Rotary Compressor is used. R22 is the refrigerant and cap tube is used as the metering device. In order to cut the price, some people suggest eliminating the drier from the system. As a refrigeration engineer, I have never designed any systems without driers. So I really do not have any ideas about this issue.

Is it possible that a system works properly for a long time without the drier? If it is possible, what vacuum level should be reached before charging?

Any inputs are welcome.

Thanks
Vincent

wambat
31-01-2006, 12:59 AM
Vincent, If you have a cap tube system you might want to consider this comment from "The News"
Early in the introduction of small, self-contained units using R-22, our company’s techs noticed an increase in the number of units with restricted cap tubes to the point we would not replace a compressor without replacing the cap tube also. When units with R-134a were introduced and the problem of restricted capillaries hit epidemic proportions, we began using Sporlan C-052S driers. This almost eliminated the problem. Sporlan now offers a solid-core drier with an access fitting made specifically for capillary tube applications. We have used those with excellent results. :)
PS: Mark does this meet with your approval :D

Johnny Rod
31-01-2006, 01:57 PM
Moisture content of new refrigerant should be below 10ppm; problems with moisture usually start around 50ppm upwards depending on temperatures. Moisture is saturated in R22 at 615ppm at 0C, so it's (almost) always in solution, but it still causes problems.

I guess you could get moisture in through charging but to be honest I'd have thought a lot of it was from condensation on fittings when you finish charging one and start on the next. Only a suggestion though. Realistically, attempting to dry the refrigerant any further is pretty difficult as the ability of desiccants to absorb moisture decreases with the amount of moisture present.

Interesting reading from Wambat, I think this tells you what you need to know. Are driers expensive for a small one? And how does it compare to warranty costs?

Vincent Yu
31-01-2006, 06:08 PM
Vincent, If you have a cap tube system you might want to consider this comment from "The News"
Early in the introduction of small, self-contained units using R-22, our company’s techs noticed an increase in the number of units with restricted cap tubes to the point we would not replace a compressor without replacing the cap tube also. When units with R-134a were introduced and the problem of restricted capillaries hit epidemic proportions, we began using Sporlan C-052S driers. This almost eliminated the problem. Sporlan now offers a solid-core drier with an access fitting made specifically for capillary tube applications. We have used those with excellent results. :)
PS: Mark does this meet with your approval :D

Wambat,

Could you tell me what evaporating temperature you are talking about?

Thanks
Vincent

Johnny Rod
02-02-2006, 04:06 PM
The only stuff I get to see as virign material is what we supply, which is fine. Have heard the same as yourself but nothing to back it up. What have you seen? The samples I usually get are what ranges from acceptable to filth from peoples' running systems. I also heard from some of our people in the far east that you can't really rely on cylinder or even drum tank labels to get the ID right...

Johnny Rod
06-02-2006, 10:33 AM
I shouldn't be surprised I guess. Also the maximum level for moisture is around 50ppm which is a water drop in a kilo, so it is quite easy to let too much moisture in somewhere along the line. The way the cylinders are filled shold preclude this, but it isn't a perfect world.

Lc_shi
07-02-2006, 04:02 AM
in my opinion,if you do enough work to vacuum and clean the system,it's possible to cancel the drier(absorb moisture and filter dirt).But it's not saving cost due to stricter assembling process.

regards
LC:)