Knowledge/Refrigerants/Glide, and why blends can only be charged as liquid
Glide, and why blends can only be charged as liquid
Glide is how much a refrigerant's temperature shifts as it boils or condenses at one pressure. But the Australian Refrigeration Council (ARC) code doesn't go by glide. Pure refrigerants can go in as vapour or liquid, and blends only as liquid. That covers every blend, glide or not, and R513A is where people get caught.
- Pure refrigerant
- Vapour or liquideither is fine
- Any blend
- Liquid onlyregardless of glide
- Charging per
- AS/NZS 5149.4Section C.2 Handling
- Most glide, new gases
- R454B, 1.52 Kat 25°C saturation
What does the Australian code say?
Clause 6.2, and it's short. All charging must be carried out in accordance with AS/NZS 5149.4, Section C.2 Handling. Note that pure refrigerants can be charged as a vapour or liquid but refrigerant blends can only be charged as a liquid.
That's stricter than some overseas guidance, which often only asks for liquid charging when the blend has real glide. Here it's simpler. If it's a blend, it goes in as liquid. Full stop.
How much glide do the common gases have?
Glide is shown in kelvin (K). A 1 K difference is the same size as a 1°C difference.
| Refrigerant | Glide at 25°C | Blend? |
|---|---|---|
| R32 | 0.00 K | No, pure |
| R410A | 0.12 K | Yes |
| R454B | 1.52 K | Yes |
| R452B | 1.26 K | Yes |
| R513A | 0.00 K | Yes |
| R22 | 0.00 K | No, pure |
| R290 | 0.00 K | No, pure |
| R134a | 0.00 K | No, pure |
| R407C | 5.44 K | Yes, for contrast |
Here's the trap. R513A has effectively zero glide and it's still a blend, so the Australian code still wants it charged as liquid. Zero glide doesn't mean you can charge it as vapour.
If your rule of thumb is "charge as liquid where there's glide", R513A is where that rule of thumb turns into a compliance breach.
Where do these glide figures come from?
We couldn't find a published Australian pressure-temperature or glide chart for these, so we calculated the glide figures above rather than quoting them. The table caption says how, so you can check our working or challenge it.
We checked the method two ways before publishing. Our R407C glide matches the published range. And when we used the same method to work backwards to a charge limit, it matched a published standards figure to the gram.
Treat the three mixtures we built from blend percentages with a bit more caution, and use the manufacturer's data where an exact figure matters.
Working out what the transition means for you?
There's a lot of noise about what's banned and when, and most of it is either early or wrong. What matters is what you buy and stock this year.
Kevin will give you the straight version.
Who this is for: small and medium HVAC contractors in Victoria. If you're a homeowner after a rebate or a repair, you need a licensed contractor, not us, and yours can point you the right way.
Related
- R744 CO2 is a different world: 63 bar at 25 degreesAbove 31°C, CO2 won't condense, so transcritical is normal running for a CO2 heat pump water heater here. Ordinary HVAC gauges aren't rated anywhere near it.
- R410A: what's actually banned, and what isn'tThe phase-down limits bulk gas, not equipment. The equipment ban is narrow and ducted is exempt, the opposite of what a lot of contractors have been told.
- R290 and R454B: where they actually are in the marketR290 air conditioning here is almost all portables, not splits, and the reason is electrical law, not refrigerant law. R454B has only just started arriving.
- Which refrigerant GWP figures count in AustraliaAustralian law uses the IPCC AR4 2007 GWP figures. New Zealand uses AR5. A GWP that doesn't say which set it's from can't back a claim here.
Review date: 1 April 2027. Figures in this area change without much notice and this page carries some that will go stale. Every number above is dated and sourced so you can check it yourself. If you find something out of date here, tell us and we will fix it.