cascade -90 degree

[edi_197677]

hii all...

i am an assembler work for bio medical frezzer, when i testing with my cascade system
there is a problem at Low Temperature stage system after running a week manifold keiji LP side shown minus pressure and compressor still work but temperature rise to room temperature. High Stage use Prophylene (R1270) and Low Stage Use Ethylene (R1150).
is it and oil cloging the cap tube and something else? now i test for two chamber both added Suction Gas Heat Exchanger and one chamber use POE SW22 Icematic another chamber use AB Oil Zerol TD 150 now still running.

my question is :

1. is it and oil clogging ?
2. anything wrong with the system cause i am not added pentane in system, i heard pentane can solve this problem ? is pentane necessary need on the system, if need charge pentane on system that suitable with the Ethylene (R1150) or not ?
i am still waiting my pentane from jakarta.

anyway any advise are welcome.


thanks ,

Regards,




Edi
Batam Indonesia.

[norseman]

Hello Edi.
It seems like the flow in your low stage is pretty much stopping up. It could be several reason for that malfunction. Since it goes up to ambient temperature, it looks like you can have a certain amount of moisture/water in your system which make a logging in the low stage capillary tube. The oil loggings I have seen would not totally stop the flow, but restrict the flow. Another thing can be that your HX insulation is wet and the ice is building up and by that transfer heat to the capillary tube. The refrigerant would then boil off in the cap. and by that almost stop the flow. I have also seen systems where the capillary is feeded vertically up to the evaporator, but stay wrong at a point a centimer or so below the eva. inlet. Over time, the feed tube/evaporator tube fills up with oil and end up as
a fatty "grease" who prevent the flow to pass. I suppose the unit start up and work a week after it has been off for a while. If the problem is permament, it could be some particles which have entered and blocked the cap.tube.
Seen some filters which drop all "sand" into a capillary to make a full blocking. Since the refrigerant is R1150 Ethene
should it not be a need for an oil return help as Pentane or propane. Never seen that on such kind of systems.
You mention two types og oil. I know that Zerol 150T is a very good ABO oil and used on the systems I work on.
If the POE oil unit fail and the 150T oil work well, you have another thing to think about. As mentioned, if the unit runs for a while and just stop totally like this I would spend a bet on that you have a very high moisture in the system due to it never gets back at higher running temperature.

[edi_197677]

Dear Norseman,

thanks for your answer,

due to your explaination, since r 1150 should not be a need with oil return agent, i will check one more time to my HX piping and insulation system, and during my testing untill today i want to let you know as follows :

a. use POE Oil Icematic SW22 chamber set point -86 Degree and it has work a week and totally running pressure down to minus pressure. but when i turn it of a day then run again, its work as same as before
until a week time its same pressure happened.

b. use Zerol TD 150 chamber same situation happened. at the same time ( i mean less or longer).

anyway i will do your advise before you reply your another advise again,


thanks,
regards,


edi
Batam Indonesia

[jcook1982]

just change both chambers to use Zerol 150 with Pentane.. make sure to flush capillary tubes on both. You can actually use the pentane to remove any clogs when system is recovered of refrigerant. Force the pentane in with a hand oil pump and let it sit for 5-10 minutes then blast it out with nitrogen. Works great. I work on many -80 freezers and -150 chest freezer and this works for us every time.