GBT4706.32-2024 Safety of household and similar electrical appliances Part 32: Special requirements for heat pumps, air conditioners and dehumidifiers Appendix KK (Normative) A2L Hot surface ignition temperature test method

GBT4706.32-2024 Safety of household and similar electrical appliances Part 32: Special requirements for heat pumps, air conditioners and dehumidifiers Appendix KK (Normative) A2L Hot surface ignition temperature test method

Appendix KK

(Normative)

A2L Hot Surface Ignition Temperature Test Method

KK.1 General Requirements

The ignition temperature of the hot surface of A2L refrigerant should be determined according to Appendix KK. The refrigerant should be sprayed onto water set at the test temperature

On a flat surface.

The experimental system consists of a hot plate, a spray test tube, and a glass cover. Figures KK.1, KK.2, and KK.3 show the composition of the experimental setup.

Note: This method is a modified version of ASTM D6668 "Standard Test Method for Distinguishing Combustion Grades F=0 and F=1". ASTM testing is for automobiles

Designed for compliance testing of automotive fluids at 815 ℃. This appendix focuses on liquefied refrigerants and defines the maximum non ignition temperature.

KK.2 Test Equipment Requirements

The hot plate should have the following characteristics. The hot plate should be composed of stainless steel flat plates with the following dimensions:

Diameter: 50 mm ± 2.0 mm

Thickness: 6+% mm

Surface texture: ISO1302

The hot plate should be placed horizontally. The heater should provide uniform heating to the flat plate. All surfaces except for the test surface should be able to withstand

815 ℃ ceramic fiber board for insulation. The insulation layer should ensure that steam is not ignited by parts outside the top surface of the hot plate.

The spray system consists of a liquid supply device, two valves (with a liquid volume of 1.0cm3 ± 0.2cm3 between the valves), and a pipeline group that guides the spray

Cheng. The spray pipe from the valve to the end should have the following dimensions:

Length: 250 mm ± 5.0 mm;

Outer diameter: ≤ 4mm;

Inner diameter: 1.6 mm ± 0.1 mm;

Use a K-type thermocouple with independent wires to spot weld on the back side of the center surface of the hot plate.

Borosilicate or quartz glass cylinders should have a length of 230mm ± 10mm and an inner diameter of 70mm ± 10mm. The glass cylinder should be supported

Support it vertically with a gap of 2.5mm ± 0.2mm between its bottom edge and the top of the insulation.

KK.3 Program

The experimental environmental conditions should be set at 23 ℃ ± 3 ℃ and a relative humidity of (50 ± 5)%. During the experiment, between the glass cylinder and the hot plate

Establish a constant air flow rate. The airflow dilutes the vapor to form an optimal concentration (approximate equivalent) for ignition on the hot surface.

The experiment should be conducted in the fume hood of the laboratory. The testing device, including the top of the glass cylinder, should be located in the laminar flow of the laboratory fume hood

Zone, so that the airflow inside the glass cylinder will not be disturbed.

The end of the spray refrigerant pipeline should be placed 40mm ± 10mm above the hot plate and pointed towards the center of the hot plate. The pipeline should be vertical

On a horizontal tablet.