Refrigerant heel in supply cylinders.

[Miki]

I am trying to reduce R-404A refrigerant heel in supply cylinders (100lb) and exploring whether heating or cooling of cylinders minimizes the heel. Looking at vapour specific density at various temperatures (35F, 80F and 120F), the specific vapour density increases as the cylinder temperature goes up. The way to reduce the heel would be then to cool supply cylinders. I am thinking of using a refrigerator (35F) to store the supply cylinder.

I am not certain how cylinder cooling affects the liquid composition. Will the liquid composition by mass be close to the nominal composition and acceptable for charging, and how does the liquid composition change as the liquid level drops down?

Please advise and comment.

[Andy]

I am trying to reduce R-404A refrigerant heel in supply cylinders (100lb) and exploring whether heating or cooling of cylinders minimizes the heel. Looking at vapour specific density at various temperatures (35F, 80F and 120F), the specific vapour density increases as the cylinder temperature goes up. The way to reduce the heel would be then to cool supply cylinders. I am thinking of using a refrigerator (35F) to store the supply cylinder.

I am not certain how cylinder cooling affects the liquid composition. Will the liquid composition by mass be close to the nominal composition and acceptable for charging, and how does the liquid composition change as the liquid level drops down?

Please advise and comment.

My practical solution is to remove the refrigerant as liquid, but through the vapour port, having turned the cylinder up side down.
BOC cylinders suffer from this problem, the dip tube does not always go the full way down, or gets bent to the one side when people drop the cylinder.

Hope this helps

Kind Regards Andy:)

[mxstar]

If you are charging the full contents of the cylinder to a single chiller then it is OK to extract the last bit out as vapour, even though you are advised to charge blends liquid phase only. The original contents of the supply cylinder should be in the correct blend composition. You will not alter this by transferring the full contents of the cylinder (liquid and vapour) from the cylinder to the chiller you are charging.

What you must not do is remove part of the cylinder contents from the vapour phase when and add this to your chiller.

[Johnny Rod]

I'd go with Andy on this one. By the way, heating cylinders with gas in can be very dangerous, and some have pressure relief devices which might let go and vent the contents for you.