Practise converting pressure ↔ saturation temperature for common refrigerants using the on-screen chart.
How to use this chart
barg vs bara: gauges read barg (above atmosphere). bara = barg + 1.01325 bar. Use the barg column for gauge readings.
Kelvin: superheat and subcooling are temperature differences, written in K. A 1 K difference is the same as a 1°C difference.
Blends with glide (R404A, R410A): use dew for suction / superheat and bubble for liquid / subcooling. Single-component refrigerants (R134a, R290, R744) have one value.
R448A / R449A: not included. These zeotropic HFO blends have significant glide; use the manufacturer's PT chart for the exact blend [SOURCE NEEDED: manufacturer sheet].
Sat. temp °C
Bubble barg
Dew barg
Bubble bara
Dew bara
R744 rows stop at 30°C: the critical point of CO₂ is about 31°C, above which there is no liquid–vapour saturation.
Sources
Values calculated with CoolProp 8.0.0 (PropsSI, Helmholtz equation of state). Absolute pressure in bar; gauge = absolute − 1.01325 bar (standard atmosphere). Rounded to 0.001 bar for practice. The auditable source file is pt-data-coolprop.json in the same folder; this page embeds a copy. Always confirm against the PT chart on site before charging or setting valves.
Question 1 of 10Score: 0
Your result
Pass mark: 75% (8 out of 10).
Want more practice with gauges, superheat and subcooling? RDA Academy training covers reading PT charts on live systems. Details are on the website: rda-academy.co.uk