BS ISO 21885:2019 pdf download – Ships and marine technology – Testing specification for stairsteps using electrical resistance trace heating
5 Test method
5.1 Test purpose
The purpose of the test is to evaluate whether or not the heated equipment is capable of preventing the formation of ice and can operate (function) properly when subjected to low temperature operating conditions.
5.2 Test facility requirements
a) The test facility shall have the ability to maintain the specified temperature within the permissible range indicated in 5.3.2, in the available volume.
b) The wind generated by the refrigerating machine installed inside the cold chamber shall not affect the specimen.
c) A wind speed control system installed inside the cold chamber shall allow to generate a wind at constant speed.
NOTE A test specimen installation method will be given with each equipment.
5.3 Test conditions
5.3.1 General The ambient temperature, wind speed, heating media and test-specimen temperature shall be recorded during the test. The test conditions shall be selected based upon the desired performance of the equipment.
5.3.2 Test temperature General The equipment shall be tested at the temperatures agreed upon between the manufacturer and the purchaser. The test temperature shall be observed after the test-specimen temperature is stabiized according to The temperature of the wind delivered to the test specimen shall be within +2。C of the test condition temperature during the steady state. Where, due to the size of the test chamber, it is not feasible to maintain these tolerances, the tolerances may be widened to +3。C down to -25 °C. A temperature sensor shall be installed between the wind generator and the test specimen to measure the ambient temperature. Temperature stabilization
a) Ambient temperature: once the ambient temperature does not change by +2 °C over a period of 30 min, it shall be considered as stabilized.
6) Specimen temperature: once the specimen temperature does not change by +2。C over a period of 60 min, it shall be considered as stabilized. Temperature sensors
a) Spatial resolution of temperature measurements shall be sufficient to identify cold spots on the surface of the test piece. No less than 9 sample points shall be used.
b) Technical evidence shall be provided to identify the coldest spots to be used as sample points.
c) The sample points need not be located within 50 mm of the perimeter, however, 5 sample points shall be located within 20 mm of the leading edge. The remaining sample points shall be located at the coldest spots on the specimen. Any temperature sensor used in the testing shall be calibrated according to its manufacturers’ directions for the planned test conditions.
d) Temperature sensor’s (e.g. thermal imagery or thermo couples) shall be properly adjusted for the emissivity of the material, if applicable, and verified with a secondary measurement.
5.3.3 Test wind The equipment shall be tested at each wind speed, as specified below.
a) Wind sensors shall be installed within 10 cm in front of the specimen and within 10 cm above and below, as applicable.
b) Wind speed control should maintain the flow rate within 10 %. Wind sensors shall be calibrated by an organization acceptable to the competent authority or classification society involved.
5.4 Test specimen requirements
5.4.1 General requirement The test specimen shall be installed inside the test facility as specified in Figure 1, in a manner that does not aid the performance of the specimen.
5.4.2 Shape The heated stairsteps shall consist of two steps of the staircase.
NOTE The stairsteps can be composed of the handrail and the steps installed at regular intervals. Dimension The dimensions of the staircase and steps should be as follows.BS ISO 21885 pdf download.