Torr

[furryfrog]

Happy new year to you all

Does anyone have any charts on achievable Torr levels at certain ambient temperatures.

Thanks

[nike123]

Happy new year to you all

Does anyone have any charts on achievable Torr levels at certain ambient temperatures.

Thanks

Same to you!

Every Torr is achievable (if you speak about vacuum), only difference is in time and lowest possible vacuum suction pressure by vacuum pump.

[Thermatech]

Did we not all cover that on 2078 refrigerant handling.

[Grizzly]

Happy new year to you all

Does anyone have any charts on achievable Torr levels at certain ambient temperatures.

Thanks

Do you actually mean it as you say it?
Or do you mean at what pressure will any water boil off, for a given temperature.
IE. Steam Tables!
Grizzly

[DjP67]

May have missed that section when he fell asleep LOL

[brunstar]

here is the chart guys

[furryfrog]

Thanks for the chart.

The situation i am in is i am vacuuming out a screw chiller.
The oil has been removed due to moisture content.
A refrigerant sample test came back as OK.
I put a vac pump on overnight and returned in the morning of a reading of 35 Torr. Done a 20min drop test and rised to 39 Torr.
Only about 75% - 80% of the oil was removed due to the size of the circuit.
I realise the oil left in the system will contain a certain amount of moisture.
The ambient overnight was between -2 C and -7 C
I have carried out a triple vac and left vac pump on over the weekend
So the question is - what Torr should be achievable under those ambient conditions?

[nike123]

Thanks for the chart.

The situation i am in is i am vacuuming out a screw chiller.
The oil has been removed due to moisture content.
A refrigerant sample test came back as OK.
I put a vac pump on overnight and returned in the morning of a reading of 35 Torr. Done a 20min drop test and rised to 39 Torr.
Only about 75% - 80% of the oil was removed due to the size of the circuit.
I realise the oil left in the system will contain a certain amount of moisture.
The ambient overnight was between -2 C and -7 C
I have carried out a triple vac and left vac pump on over the weekend
So the question is - what Torr should be achievable under those ambient conditions?

Again, every Torr is achievable, only difference is in time and lowest possible vacuum suction pressure by vacuum pump.

Higher ambient temperature = shorter vacuuming time
Lover vacuum pump pressure = shorter vacuuming time
Shorter and/or biger Vacuum hoses = shorter vacuuming time
Removed valve cores = shorter vacuuming time
Higher pump CFM = higher pressure diference= shorter vacuuming time

Your achived vacuum should be like this:

http://www.refrigeration-engineer.com/forums/showthread.php?t=14826&highlight=vacuum

1 Torr is 1000 microns

[nike123]

Thanks for the chart.

The situation i am in is i am vacuuming out a screw chiller.
The oil has been removed due to moisture content.
A refrigerant sample test came back as OK.
I put a vac pump on overnight and returned in the morning of a reading of 35 Torr. Done a 20min drop test and rised to 39 Torr.
Only about 75% - 80% of the oil was removed due to the size of the circuit.
I realise the oil left in the system will contain a certain amount of moisture.
The ambient overnight was between -2 C and -7 C
I have carried out a triple vac and left vac pump on over the weekend
So the question is - what Torr should be achievable under those ambient conditions?

If you are moisture free than you should achieve at least 1-0,5 Torr. If you have moisture at -7 your pressure should stay at 2,5 Torr at that temperature. If you have leak, pressure will rise above 2,5 Torr

[Grizzly]

Thanks for the chart.

The situation i am in is i am vacuuming out a screw chiller.
The oil has been removed due to moisture content.
A refrigerant sample test came back as OK.
I put a vac pump on overnight and returned in the morning of a reading of 35 Torr. Done a 20min drop test and rised to 39 Torr.
Only about 75% - 80% of the oil was removed due to the size of the circuit.
I realise the oil left in the system will contain a certain amount of moisture.
The ambient overnight was between -2 C and -7 C
I have carried out a triple vac and left vac pump on over the weekend
So the question is - what Torr should be achievable under those ambient conditions?

furry Frog.
I think you already know that you are going to struggle because from what you tell us it appears that you are trying to dry out the oil. Not the system.
I will try and find some more info on required pressure to boil off the water.
The problem as I see it is you and us are talking about removal of moisture from a refrigerant system not it's oil.
I know a deep or triple evac will remove some moisture from the system oil.
But that is not their primary purpose.
You don't tell us what oil it is?
Which would seriously affect how to proceed.
Basically is it is mineral it will contain a certain amount of water.
If it is synthetic change ALL of oil.
Trying to dry out part of the system oil is extremely difficult.
Which as you imply is made even more difficult given the (for us) low ambient temperatures.
Does the system have a oil heater, switch it on it will help.
What degree of contamination within the oil have you got.

Is it because you feel cross contamination of water from the oil to the refrigerant could occur.
This may be a situation where you could just recharge the oil and having pulled a deep vac.
Recharge and set to work.
Please tell us more.
Grizzly
Incidentally a 4 Torr rise is not excessive given the ambient temps and my perceived size of the system.
But to be fair I would normally look for better!

[nike123]

Check this thread!
http://www.refrigeration-engineer.com/forums/showthread.php?t=13586&highlight=moisture

[furryfrog]

Thanks for the latest input

The oil is synthetic SW 220
Oil heater is on

The system holds 40 L of oil and there is no way I can get all the oil from the whole system.
I drained of from oil sep, evap and oil lines using OFN

My concern is I know the left over oil in the system will hold onto some moisture so I may not be able to get down to a really good Torr.
I want to - do what I can before putting new oil in (It costs a fortune)
If at the end of this I do another sample in two weeks time and its still got some moisture I realise I need to change the oil again and the dryers etc. At least I know I have done the right thing and can " sleep at night"
PS - The oil sample was 521 - Water PPM, ( serious )
If when I return Monday the difference between what it should be and what it actually is will point to - what needs doing next

[Grizzly]

Thanks for the latest input

The oil is synthetic SW 220
Oil heater is on

The system holds 40 L of oil and there is no way I can get all the oil from the whole system.
I drained of from oil sep, evap and oil lines using OFN

My concern is I know the left over oil in the system will hold onto some moisture so I may not be able to get down to a really good Torr.
I want to - do what I can before putting new oil in (It costs a fortune)
If at the end of this I do another sample in two weeks time and its still got some moisture I realise I need to change the oil again and the dryers etc. At least I know I have done the right thing and can " sleep at night"
PS - The oil sample was 521 - Water PPM, ( serious ) (depends -what the refrigerant is?)
If when I return Monday the difference between what it should be and what it actually is will point to - what needs doing next

Yep you know what you are doing!
Good luck,
You can only do your best and synthetic is a bitch.
IE. leave the cap of a drum of synthetic and it will absorb 10% of its weight in moisture in either 12 or 24 hrs can't remember which?
Grizzly

[psycho]

daft question but why so much moisture?
reminds me off the time that a plate heat exchanger failed on an airdale two cuircuit chiller,obviously lost two compressors,liqiuid line s.g had water visibly in it,anyhow,took a little while to vac at about 3c but i were able to position a few radiant heaters around the chiller,got them on hire from hss but the chiller was in a sort of plant room,big open lourvers,drafty and cold but nice with the heaters blazing

[nike123]

daft question but why so much moisture?
reminds me off the time that a plate heat exchanger failed on an airdale two cuircuit chiller,obviously lost two compressors,liqiuid line s.g had water visibly in it,anyhow,took a little while to vac at about 3c but i were able to position a few radiant heaters around the chiller,got them on hire from hss but the chiller was in a sort of plant room,big open lourvers,drafty and cold but nice with the heaters blazing

If oil has absorbed that much moisture, it is going to be very hard and time consuming to remove moisture (and acid) from system by vacuuming. Only efficient way is oil changes and frequent dryer core changes.

We have here good thread with that subject but I am unable to find it momentary.

[nike123]

This is from other forum:
Quote:
Originally posted by smac

RobY: In reference to your statement that a dryer will pull the moisture out of POE oil very quickly. Do you have any reference literature to explain this. And to what quanities. And how do you size a drier so you know it is all removed? This is very interesting. I was taught by Lennox reps that once POE gets saturated with moisture that the best thing is for it to come out, then replace it with new. Where can I read about this? Thank you.


The statement was based on work I had done at a previous employer where we dosed a R-134a / POE system with water until it was at over 1000 ppm of moisture. We then valved in a fresh liquid line filter drier and took samples every few minutes until the moisture concentration stabilized. It took an hour for most of the moisture to be removed (over 90% of the dose), and within four hours the moisture concentration had stopped changing. I know at one point this was presented to the OEM engineers, but I don't know if it was ever put into a technical bulletin for the aftermarket.

A rough rule of thumb you may want to use is as follows:

If the HFC refrigerant and POE oil are almost saturated with moisture they will contain about 1000 ppm of moisture. That means for every ounce of wet refrigerant or oil, it will contain about 1/2 drop of water. You want to choose a dryer with 1/2 the capacity in water drops at 125 degrees F as the number of ounces of wet refrigerant and oil in the system.

For example, if the system has 48 ounces of wet POE and 5 pounds (80 ounces) of wet refrigerant, then you have 128 ounces of total wet refrigerant and oil. You would need a drier with at least 64 drops of water capacity at 125 degrees F to bring the moisture in the system down to 50 ppm or less, where the POE will be very stable.

At the end of the drying process, the filter drier would be used up and would not be able to handle any more moisture that enters the system. If you want to have a reserve in the drier to safeguard the system, go bigger than the 1/2 factor, or change the first drier after a couple of days.

Rob Yost
National Refrigerants