Reference

HVAC Refrigerant Glossary

Plain-English definitions for the acronyms and terminology that come up in refrigerant sales, service, and compliance work. Bookmark it — your apprentices will thank you.

A

A1: Lower toxicity, no flame propagation. The historical residential refrigerant safety class — R-22, R-410A, R-134A, R-404A all classify as A1. Allows charging without flammability-specific procedures.
A2L: Safety classification under ASHRAE Standard 34 for refrigerants that are mildly flammable with low flame propagation speed (under 10 cm/s). Includes R-454B, R-32, R-1234yf. Requires updated charging procedures (no torch, ventilation) and A2L-rated recovery equipment. Class A means lower toxicity; Class 2L means flammable but harder to ignite than A3 (propane / R-290).
AHRI-700: Industry-standard purity specification for fluorocarbon refrigerants in commerce. AHRI-700 sets maximum allowable contaminant levels for moisture, acid, particulates, non-condensable gas, and high/low boilers. Every cylinder we ship is third-party tested and certified to AHRI-700. The specification is what separates 'virgin' product from reclaimed or recovered.
AIM Act: Federal law signed December 2020 that gave the EPA explicit authority to phase down HFC production and import in the US. The Act mandates a 85% reduction in HFC consumption from baseline by 2036, on a stepped schedule. The 2025 step (down to 60% of baseline) is the trigger that pushed the residential AC industry from R-410A to R-454B / R-32. Service refrigerant remains legal indefinitely.
ASHRAE Standard 34: American Society of Heating, Refrigerating and Air-Conditioning Engineers standard that governs how refrigerants are named (R-410A, R-32, R-1234yf etc.) and classified for toxicity and flammability (A1, A2L, A3, B1, B2, B3). The reference any HVAC code or building code points to when discussing refrigerant safety.
Azeotrope / azeotropic: A blend of two or more refrigerants that boils and condenses at a constant temperature for a given pressure (no glide). R-410A is near-azeotropic — its glide is so small (under 0.3°F) that it can be charged by vapor without significant blend drift. Compare to zeotropic blends like R-407C and R-448A which have measurable glide and must be charged in liquid form.

D

DOT-39: DOT specification for non-refillable steel refrigerant cylinders. Specifies wall thickness, valve, marking, max pressure rating, hydrostatic test requirements. Every cylinder we ship is DOT-39 compliant. Service techs do not refill DOT-39 cylinders; they're single-use shipping containers.

E

EPA Section 608: EPA certification under 40 CFR Part 82 Subpart F required to purchase, handle, or recharge any HFC refrigerant in stationary equipment (residential and commercial HVAC). Type I (small appliances), Type II (high pressure), Type III (low pressure), or Universal (all three). Required by federal law since 1995. Cards do not expire.
EPA Section 609: EPA certification under 40 CFR Part 82 Subpart B required to purchase or handle automotive AC refrigerants (R-134A, R-1234yf). Separate cert from Section 608. Most auto-AC techs hold 609 only; HVAC techs servicing a personal vehicle may need both.
EPA SNAP: EPA program under section 612 of the Clean Air Act that evaluates and lists refrigerant alternatives as 'acceptable', 'acceptable subject to use conditions', or 'unacceptable' for specific equipment classes. SNAP listings are how the EPA legally specified which refrigerants could replace ozone-depleting ones. Now overlaps with AIM Act for HFC phasedown.

G

Glide: The temperature difference between the bubble point (start of evaporation) and dew point (end of evaporation) of a zeotropic refrigerant blend at constant pressure. R-407C has roughly 7°F glide; R-410A under 0.3°F. Glide affects how a system is charged (liquid only for high-glide blends) and how the expansion device must be sized.
GWP: Relative measure of how much heat a refrigerant traps in the atmosphere over a 100-year period vs an equal mass of CO₂. GWP of CO₂ = 1. R-410A GWP = 2,088. R-454B GWP = 466. R-1234yf GWP = 4. R-22 GWP = 1,810. The AIM Act and CARB rules are written in terms of GWP caps for new equipment.

H

HCFC: Older refrigerant chemistry containing chlorine — gives non-zero ozone depletion potential. R-22 is the dominant HCFC in HVAC. Banned from new equipment manufacturing in the US since 2010, banned from import since 2020 under the Clean Air Act. Service refrigerant remains legal.
HFC: Synthetic refrigerant containing hydrogen, fluorine, and carbon — but no chlorine, so zero ozone depletion potential. Includes R-410A, R-32, R-134A, R-404A, R-407C, R-448A. The category of refrigerants the AIM Act phases down because of high GWP.
HFO: Newer-generation refrigerant chemistry with very low GWP (typically under 10) and short atmospheric lifetime. R-1234yf is the most common — replaces R-134A in new automotive AC. Often blended with HFCs to make low-GWP service refrigerants like R-454B (R-32 + R-1234yf).

M

MAP / Minimum Advertised Price: Pricing policy where the manufacturer prohibits dealers from advertising below a set price floor. Common in HVAC equipment but not in refrigerant cylinder distribution — most refrigerant pricing is freely set by distributors.
MO / Mineral Oil: Petroleum-derived compressor oil compatible with R-22, R-12, and other CFC/HCFC refrigerants. Not compatible with HFC blends — system retrofits from R-22 to R-410A or R-407C require flushing mineral oil and recharging with POE oil.

N

Net-30: Standard B2B invoice term. Customer receives goods and an invoice; payment due 30 days from invoice date. We offer Net-30 to approved trade accounts up to a $5K standard credit line, with no early-pay discount and no late-pay surcharge if payment stays current.

O

ODP: Relative measure of how much a refrigerant depletes stratospheric ozone vs CFC-11. CFC-11 ODP = 1.0. R-22 ODP = 0.05. R-410A and other HFCs ODP = 0. The metric the Montreal Protocol uses. Modern refrigerants are essentially all zero-ODP; the AIM Act and current regulatory effort focus on GWP instead.

P

POE / Polyolester: Synthetic compressor oil compatible with HFC blends (R-410A, R-454B, R-32, R-404A, R-407C). Hygroscopic — absorbs water from atmosphere during storage. POE 32, POE 68, POE 100 are common viscosity grades; system OEM specifies which. Required when retrofitting from MO/R-22 to any HFC.

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