R-11 PT Chart and Refrigerant Profile

Where you will find R-11

R-11 (CFC-11) was the standard refrigerant in low-pressure centrifugal chillers. Any R-11 machine still running in the US predates the 1996 production ban, so it is decades old. Many were converted to R-123 or replaced. Check the chiller nameplate, which states the refrigerant and the charge.

R-11 is a low-pressure refrigerant: it boils at 74.7°F at sea level, so the evaporator of an operating chiller runs in a vacuum. At 40°F saturation R-11 reads 15.6 in Hg vacuum. The condenser runs just above atmospheric: 8.9 psig at 100°F. Use a gauge or transducer that reads inches of mercury accurately and convert with the pressure converter when the chiller controls show psia or kPa.

Charging R-11

R-11 is a single-component refrigerant and a liquid at room temperature and atmospheric pressure, so it is handled as a liquid. There is no glide; one PT column covers the evaporator and the condenser. No manufacturer charging procedure is quoted here; follow the chiller maker’s service manual for charge amount and method.

Because the low side is below atmospheric pressure, a leak there pulls air and moisture into the machine instead of letting refrigerant out. Rising condenser pressure above the saturation value for the condenser temperature can indicate non-condensables. Compare the gauge against the chart with the PT calculator. For refrigerant-side diagnosis the subcooling calculator and superheat calculator work as with any pure refrigerant, but chiller targets come from the manufacturer.

Oil and compatibility

BITZER lists mineral oil and alkylbenzene for R-11. Chemours states that the oils used with CFC-11 (mineral or alkylbenzene) also work with R-123, so a conversion to R-123 does not require an oil change on that basis. Everything else a conversion requires comes from the chiller manufacturer’s retrofit instructions. The refrigerant oil types guide covers the oil families.

Safety, handling and recovery

A1 under ASHRAE 34: lower toxicity, no flame propagation. R-11 is named as an example of a low-pressure refrigerant in 40 CFR 82.152 (saturation below 45 psia at 104°F; R-11 is 10.6 psig, 25.3 psia). Servicing, maintaining or disposing of low-pressure appliances requires Type III or Universal certification under 40 CFR 82.161, and the certificate does not expire.

Recovery: for low-pressure appliances, 40 CFR 82.156 requires evacuation to 25 mm Hg absolute before opening or disposal. At sea level that is close to 29 in Hg vacuum, much deeper than the high-pressure requirements. Venting is prohibited; sales are restricted to certified technicians; and as an ozone-depleting refrigerant, appliances with 50 lb or more fall under the leak repair rules of 40 CFR 82.157.

Cylinders: R-11’s legacy container color was orange. Since January 1, 2020 new containers are light green-gray RAL 7044 under AHRI Guideline N-2017, with the legacy color only on the label; recovery cylinders are gray with a yellow top. See cylinder colors.

Status and replacements

CFC-11 is a Class I controlled substance with an ODP of 1.0, the reference value for ozone depletion. US production and import ended January 1, 1996 under 40 CFR 82.4, apart from essential or critical uses. Existing R-11 chillers may keep running and be serviced with recovered, recycled, reclaimed or pre-1996 stockpiled refrigerant. Its AR4 GWP is 4,750; as a CFC it is controlled under the ozone rules, not the AIM Act HFC phasedown.

Replacement and conversion routes:

• R-123 was the main conversion refrigerant (EPA SNAP: acceptable for retrofit and new centrifugal chillers). It is itself an HCFC on its way out: since 2020 newly produced R-123 may only service equipment built before 2020, and allowances reach zero in 2030.
• R-514A (Opteon XP30) is SNAP-acceptable for retrofit and new centrifugal chillers, B1, GWP 7.
• R-1233zd(E) is SNAP-acceptable in new centrifugal chillers only.
• HFC-245fa and R-1224yd(Z) are also named as R-11 alternatives (BITZER); EPA lists HFC-245fa as acceptable for retrofit but unacceptable in new chillers except under narrowed use limits.

Retrofitting a decades-old R-11 machine versus replacing it is an engineering decision; get the chiller manufacturer’s conversion data before committing. GWPs are compared on the GWP chart.

Common questions

What replaced R-11 refrigerant?

R-123 was the main replacement in low-pressure centrifugal chillers, both in new machines and in conversions. New low-pressure chillers now use R-1233zd(E), and R-514A is listed for new and retrofit chillers; R-123 itself has been limited to pre-2020 equipment since 2020 and loses its last allowances in 2030.