csacade refrigeration r12 & r13

[kool it man]

What is the best way to check the carge on a cascade refer when the evaporator on the r-12 sysytem in part of the condensor of the r-13 system.

right now it looks like the r-12 side is good.

the r-13 side looks low, supervisor called the factory and one of there techs said to shut the system down and let everything go to room temp and to get the charge in so the whole system is at 65 lbs.
I would weigh the charge in but don't have anything on nameplate to go by.

[gasnowman]

have you looked at the properties of R-13? Do you no about static pressure charging(70#@70 degress F). I'm just wondering from your question. Sencond stage is typically used to cool your first stage condensor.

[Variable]

Originally posted by kool it man
the r-13 side looks low, supervisor called the factory and one of there techs said to shut the system down and let everything go to room temp and to get the charge in so the whole system is at 65 lbs.
I would weigh the charge in but don't have anything on nameplate to go by.

Listen to what the factory rep said, understand what this means and the purpose of the expansion tank. Get a R-13 PT chart and look at the numbers. Now the purpose of the expansion tank will make sense. Understand this thoroughly before adding 13. If not, say schrapnel, major hospital stay or the morgue.

If none of this makes sense, get someone else, for your own saftey.

[kool it man]

Originally posted by gasnowman
Do you no about static pressure charging(70#@70 degress F).

I've always either weighed in the charge which I prefer,
or used subcooling with a txv or superheat without txv.

I 've never just shut everything off the r-13 tank to the system let everything balance out to room temp and unhook tank and run unit.

I'm assuming this is what the factory suggested and there is no expansion tank on this system it has two hermatically sealed compressors and i'm talking about maybe 10 oz of r-13 to charge system.

[shaun66]

Ultra low refrigerants are charged by static pressure

the factory rep says 65 psi - that is 65 psi at 72 F

when a cascade unit is at ambient temp (usually after 24 hrs off) there is no liguid present in the low stage, just a vapour charge

[gasnowman]

So you are not familiar with static pressure charging. Who is the manufacturer and model number. As stated you are working with a bomb. I don't know if R-13 is available if so you will pay. This is a low temperature application refrigerant with extremely high pressure. This is why you have 2 hermetically sealed systems and one process ranging from -60 C to say 200 C. You can forget about weight charges,scales,charging cylinders,etc. They may have a web site if manufacturer was known? Your superheat and subcool is not a prefered method with this machine. Is STATIC PRESSURE charging, do you know ??? We would like to help you more, but we need more info KOOL IT MAN. If not please make sure your accidental/life insurance is up to date for your families sake because R-13@ 80 degress Farenheit is 519 pounds psig. HELL LO

[kool it man]

The site has R-13 and they want the unit to get down to -50
farenheit.

I thought there was something different about r-13 when the factory said to static charge it.

thanks for the info and I'll let you know how it goes.

[gerryboy00]

-leak test and repair
-dryer
-vacuum below 100 microns
-propane
-r-13 charge

[DaleP]

Kool it Man - I don't know your history but if you have never worked with a cascade system you could have a long road ahead of you. Charging this equipment is simple for the most part but you MUST be able to look at the entire system to properly work with them. Walking away from this could be a blessing. These systems can eat your lunch and the refrigerant is expensive. Something to think about. If you do go forward with this I hope it all works for you but just beware they are a little tricky. My .02 DaleP

[kool it man]

I'm doing maintenance for this facility, and these are small units used for testing switches to failure at -50 farenheit.

one of the testing chambers had been shut down as no one knew how to fix it, and the second had been sent up by a different facility to use, and it looks like the only problem I've found are leaky shreder valves on r-13 side from prior servicing.

[Paul V.]

Kool it man. Did you get the chamber fixed?
If not what kind of chamber is this.
I work on these things daily and might be able to help you.