Ozone Resistance Test Chamber Cable Testing Equipment ASTM D470 Standard

Overview:

According to IS 10810 (Part 13), IEC 60811-403, ASTM D 470, IS 3400 (Part 20): 1994, ISO 1431-1/1994 and ASTM 4575 for estimating the resistance of elastomeric and polymeric materials of cables to ozone attack. The test device shall include a test chamber, an ozone generator with a high-voltage power supply and controller, an air dryer/purifier, a flow meter control, a temperature control chamber, a glass instrument, a specimen carrier for chemical testing, and an ozone detection device

 Technical parameters:

1) The test chamber should be made of ozone-non-reactive material, preferably stainless steel.
2) The chamber should have a volume of at least 60 litres and should be a refrigerated oven with both heating and cooling
3) The temperature of the test chamber should be controlled by an electronic digital temperature indication controller using the
PT-100 sensor.
4) The required temperature range is 10°C to 80°C, and the control accuracy is better than ±1°C
5) The inner chamber should be accessible through a door with an appropriate closing mechanism and sealing to prevent partial
pressure loss or adverse effects on ozone concentration levels throughout the test.
6) The door must have a device or interlock mechanism to prevent accidental opening during the expected duration of the test.
7) The access door should be equipped with an observation window made of tempered glass and should be sealed to prevent partial
pressure loss or adverse effects on ozone concentration during the test.
8) The inner chamber can be equipped with a light source for intermediate observation of the sample.
9) The inner chamber can be equipped with a rack or rack for placing the sample, the material of the rack should not react with
ozone, preferably stainless steel, and the rack should be designed in such a way that it minimizes the effect on the introduction,
circulation, exchange or emission of the air-ozone mixture.
10) Require devices to generate, measure, and control the concentration and partial pressure of the air ozone stream, and prevent
ozone stratification when the air ozone stream is introduced into the chamber.

Ozone generator:

1) The ozone generation source should be located outside the test chamber and the foreign matter in the gas stream must be
adequately filtered.
2) The ozone generator should have concentric electrodes, separated by a thin glass dielectric, with a voltage applied between the
electrodes.
3) The generator can be powered by a high-voltage transformer with a maximum voltage range of 20-30 kV and a current output of 8
mA with voltage change control. The accuracy of the high-voltage transformer should be ±1%.
4) The ozone generator assembly should be installed in a wooden case to ensure the complete safety of the operator.
5) The ozone concentration should be measured directly using an ozone meter or ozone analyzer/ozone detector device, the ozone
concentration in the test chamber should be 25 to 500 pphm (parts per million) or ppb (parts per billion), and the ozone meter
should have an optional range of 25 to 500 pphm/ppb
6) In addition to the ozone detector/ozone analyzer, all accessories required for the chemical method should be provided for
verification.

 Air Supply:

1) The air source should come from the environment or compressed air supply, and be fully filtered or filtered and an air dryer is
required to remove moisture from the air
2) A humidity indicator consisting of a reusable humidity indicator gel should be provided.
3) The flow rate of the air with the required ozone concentration should be between 280 l/h and 560 l/h, and the air pressure
should be kept slightly higher than the atmospheric pressure.
4) Flow meter with control: should be able to adjust the air flow very finely in the range of 2 to 20 l/min.

Circulating fan:
1) To circulate the ozone mixture, an electric fan should be provided that can maintain a constant speed throughout the test.
2) The velocity measured from 50 mm at the leading edge of the fan blade on the side of the wind chamber shall not be less than
0.6 m/s.
3) The fan motor shall not be located indoors. The fan motor should have an extension shaft or drive mechanism to isolate the
motor from the inner cavity.
4) The fan blades should be embedded in the wind chamber and separated or closed with a protective net or grid cage.

Glass instruments:
1) Collect ozone gas and determine the ozone concentration by chemical analysis.

Specimen bracket:
1) A mechanical rotating bracket of sufficient size should be installed in the test chamber and a grip should be installed on it
or a frame for fixing the specimen should be installed.
2) The specimen should be moved at a speed of 20 mm/s to 25 mm/s in a plane perpendicular to the air flow, in such a way that the
same specimen reaches the same position in the test chamber every 8 min to 12 min.