KK.1 General
The hot surface ignition temperature of A2L refrigerants shall be determined according to Annex KK. The refrigerants shall be sprayed onto a horizontal flat plate surface which is set at the test temperature.
The test system consists of a hot plate, a spray tube and a chimney. Figure KK.1 , Figure KK.2 and Figure KK.3 display the set-up of the test apparatus.
NOTE This method is a modification of the ASTM D6668. The ASTM test is designed for automotive fluids as a
pass fail test at 81 5 °C. Annex KK is concerned with liquefied refrigerants and defining the maximum no Ignition temperature.

Procedure
The ambient conditions of the test shall be set at 23 °C ± 3 °C and 50 % RH ± 5 % RH. The chimney and hot plate establish a constant air velocity during the test. This airflow dilutes the vapours so that an optimum (near stoichiometric) concentration for ignition develops over the hot surface.

The test shall be performed in a laboratory fume hood. The test apparatus including the chimney
top shall be located in the laminar flow region of the laboratory fume hood so the chimney flow
is not disturbed.
The end of the spray refrigerant line shall be placed 40 mm ± 1 0 mm above the hot plate and
shall point to the centre of the hot plate. The tube shall be perpendicular to the horizontal plate.
Operating steps:
a) The hot plate shall be heated until a steady test temperature is maintained for 5 min. The
plate temperature shall be kept within ±1 5 °C of the set-point during the test.
b) Refrigerant used for the test shall be the nominal composition (NC) in accordance with
ISO 81 7. Refrigerant from the liquid phase shall be trapped between valve 1 and valve 2.
Open valve C to spray the liquid refrigerant onto the centre of the hot plate.
c) Observe and record if ignition (flames) occurs or does not occur within 3 min after release.
NOTE Ignition is considered as being within the chimney above the plate.
Care shall be taken to avoid vapours getting under the insulation, any ignition outside of the chimney is due to ignition on surfaces hotter than the test surface.
d) A minimum of 5 min of ventilation shall be allowed between runs to clear out reaction products and residual refrigerant.
e) Perform a minimum of 5 repetitions trials at each temperature being tested.
f) The temperature of the hot plate shall be set at 800 °C. If ignition occurs, then the plate temperature is to be reduced in increments of 20 °C until no ignition occurs in five trials.
This temperature is to be recorded as the hot surface ignition temperature.