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cretan
27-07-2007, 10:39 AM
To use a pressure\temp chart,how do you find saturated temp?

taz24
27-07-2007, 11:14 AM
To use a pressure\temp chart,how do you find saturated temp?



On the chart you will find it in two places.
One all the way across the bottom (the evap).
The other all the way across the top (the cond).
The saturation temp is the temp the refrigerant changes state, So in the evap the saturation temp would stay constant and the state of the refrigerant would change from liquid to vapour (evaporate or boil off).
In the cond the hot vapour will condense and change state from vapour to liquid.

The chart shows a perfect system without pressure drops, If pressure drops were included then the saturation temp may vary slightly.

But for normal drawings the pressure drop is shown before or after the evap and cond.

Cheers taz.

US Iceman
27-07-2007, 03:56 PM
If you are using a Pressure-Temperature chart, the saturation temperature is the temperature shown next to the pressure.;)

Taz, it seems like you are describing a Pressure-Enthalpy diagram. That's different from a true Pressure-Temperature chart.

cretan
28-07-2007, 09:53 AM
saturation means the when there is a mixure of liquid and vapor.correct?my pressure chart has "saturated temp" and beside them are the corresponding pressures.how do I use this chart correctly?Thanks!!

paul_h
28-07-2007, 10:15 AM
You connect your gauge up to the evap or suction port and read the pressure off it. Then use the chart to find the closet possible pressure for the refrigerant you're using, follow the line to the left to get your saturation temperature. With that you can work out superheat, (with a thermometer on the evap outlet), also temperature difference of the refrigerant and air/liquid being cooled, two bits of important information.

US Iceman
28-07-2007, 06:26 PM
saturation means the when there is a mixure of liquid and vapor.correct?


Not exactly. The refrigerant can exist as 100% vapor, 100% liquid, OR a mixture of liauid and gas.

If the gas is saturated, removing any heat causes the refrigerant to condense.

If the liquid is saturated, adding any heat causes the refrigerant to boil.

If it is a gas and liquid mixture, the liquid boils if heat is added, and the vapor condenses if heat is removed.

TXiceman
28-07-2007, 07:58 PM
Need to find out if he is looking at a 400 series which will have both a bubble point and a dew point....

Ken

US Iceman
28-07-2007, 11:58 PM
Yep, you're right right Ken. I keep resorting back to my prior experience with the good refrigerants!:D

TXiceman
29-07-2007, 04:10 AM
I was hoping to be retired before we got too deep in to the "alternate" refrigerants....did not make it.

Ken

US Iceman
29-07-2007, 04:18 AM
Perhaps the next round of refrigerants will slowly decompose in the system to ensure continued supply and demand.:rolleyes:

I doubt it will be long before round 2 in the refrigerant problems.

taz24
01-08-2007, 07:53 PM
Perhaps the next round of refrigerants will slowly decompose in the system to ensure continued supply and demand.:rolleyes:

I doubt it will be long before round 2 in the refrigerant problems.


I thought refrigerant already wore out:)
The amount of times I've been asked to top the system up because the gas has wore out or run out.
If I was paid a each time I'd have enough to retire on now.:)

Cheers taz.

US Iceman
01-08-2007, 08:11 PM
If I was paid a each time I'd have enough to retire on now.:)


No doubt. This is where having ethics can hurt you.:rolleyes: