PSA D45 1714 Hoses for Cooling Lines - Refrigerant Permeability

The purpose of the method described in the standard “PSA D45 1714 Hoses for cooling lines - Refrigerant permeability” developed by the Peugeot automobile company is to determine the refrigerant permeability of rubber or plastic hoses installed on vehicles equipped with air conditioning systems by following two conditions:

• Case 1: Complete testing (360 hours) must be performed for material approval
• Case 2 (for PSA only): For functional testing to characterize rupture or binding integrity, testing can be limited to weighing after 24 hours and 96 hours

While testing, a sealed hose of known dimensions, filled with refrigerant, is kept at a certain temperature for a certain period of time. The weight change allows the permeability per unit of surface in contact or per length to be determined.

The main equipment used in these tests includes:

• The refrigerant tank is a 510 cm3 plus/minus 25 cm3 glued or fixed tank with a screw valve body.
• Slugs are used to ensure the tightness of valves.
• Halogen leak detector.
• The oven is ventilated and has a thermostat with a capacity of 100 degrees plus/minus 2 degrees or 80 degrees plus/minus 2 degrees.
• The precision scale is equipped with a plate that allows weighing long pieces (minimum 1 m) to 100/1 grams.
• Slide caliper is used to measure part diameter to 1/10 of a millimeter.
• The ruler is graduated in millimeters to measure part length.
• The refrigerant is, for example, tetrafluoroethane or tetrafluoropropene compound contained in the tank.
• The glue is resistant to high test temperatures and ensures the sealing of the end of the hose on the tank and the cap on the valve. The glue must allow the sample and lids to be removed to recover the tank.
• Refrigerant filling equipment is equipment that allows creating vacuum and filling refrigerant, such as a filling station, double boiler or cryostat-connected vacuum pump, and provides an accuracy of 5 kg/m3.

Test samples should be representative of the scale to be characterized. In order to ensure this representation, the basic characteristics of the population examined must be revealed. Selection criteria for test samples should be specified in accordance with the standard “PSA A10 0156 Writing test or measurement reports”. If in doubt about sampling, PSA Group should be contacted to find out the directives to be followed.

Tests can be run in two different ways:

• In the first method, eight samples are taken from the same batch of hose. Six should be used to determine permeability (two in the minimum compression set, two in the nominal compression set, and two in the maximum compression set). Two samples are also used to determine the weight change of the flexible part.
• In the second method, four samples are taken from the same batch of hose. Three should be used to determine permeability (one at the minimum compression setting, one at the nominal compression setting, and one at the maximum compression setting). The other sample should be used as a reference sample to determine the weight change of the flexible part.

Both methods are described in detail in the standard annex. The appendices should be consulted for the accuracy of the samples and dimensions to be measured, for calculating the compression set and for information on obtaining the desired compression set in the sample.

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