Document ID: chunk:federal_register_of_legislation:F2023L01529:body:0:p35
Version: federal_register_of_legislation:F2023L01529
Segment Type: other
Provision Reference: 
Character Range: 98209–101084

shall limit the differential between the enclosure internal pressure and the barometric pressure to a maximum value of ±5hPa.

        The enclosure shall be capable of latching to a fixed volume.  A variable volume enclosure shall be capable of accommodating a change from its "nominal volume" (see Annex 7, Appendix 1, paragraph 2.1.1.), taking into account hydrogen emissions during testing.

       4.3. Analytical systems

       4.3.1. Hydrogen analyser

       4.3.1.1. The atmosphere within the chamber is monitored using a hydrogen analyser (electrochemical detector type) or a chromatograph with thermal conductivity detection.  Sample gas shall be drawn from the mid-point of one side-wall or roof of the chamber and any bypass flow shall be returned to the enclosure, preferably to a point immediately downstream of the mixing fan.

       4.3.1.2. The hydrogen analyser shall have a response time to 90 per cent of final reading of less than 10 seconds.  Its stability shall be better than 2 per cent of full scale at zero and at 80 per cent ± 20 per cent of full scale, over
       a 15-minute period for all operational ranges.

       4.3.1.3. The repeatability of the analyser expressed as one standard deviation shall be better than 1 per cent of full scale, at zero and at 80 per cent ± 20 per cent of full scale on all ranges used.

       4.3.1.4. The operational ranges of the analyser shall be chosen to give best resolution over the measurement, calibration and leak checking procedures.

4.3.2. Hydrogen analyser data recording system

        The hydrogen analyser shall be fitted with a device to record electrical signal output, at a frequency of at least once per minute. The recording system shall have operating characteristics at least equivalent to the signal being recorded and shall provide a permanent record of results.  The recording shall show a clear indication of the beginning and end of the normal charge test and charging failure operation.

       4.4. Temperature recording

       4.4.1. The temperature in the chamber is recorded at two points by temperature sensors, which are connected so as to show a mean value. The measuring points are extended approximately 0.1 m into the enclosure from the vertical centre line of each side-wall at a height of 0.9 ± 0.2 m.

       4.4.2. The temperatures in the proximity of the cells are recorded by means of the sensors.

       4.4.3. Temperatures shall, throughout the hydrogen emission measurements, be recorded at a frequency of at least once per minute.

       4.4.4. The accuracy of the temperature recording system shall be within ±1.0 K and the temperature shall be capable of being resolved to ±0.1 K.

       4.4.5. The recording or data processing system shall be capable of resolving time to ± 15 seconds.

       4.5. Pressure recording

       4.5.1. The difference p