Document ID: chunk:federal_register_of_legislation:F2023L01529:body:0:p44
Version: federal_register_of_legislation:F2023L01529
Segment Type: other
Provision Reference: 
Character Range: 122098–125018

the enclosure's introduction to service, after any operations in the enclosure which may affect the integrity of the enclosure, and at least monthly thereafter.  If six consecutive monthly retention checks are successfully completed without corrective action, the enclosure leak rate may be determined quarterly thereafter as long as no corrective action is required.

       2.3.1. The enclosure shall be purged until a stable hydrogen concentration is reached.  The mixing fan is turned on, if not already switched on. The hydrogen analyser is zeroed, calibrated if required, and spanned.

       2.3.2. The enclosure shall be latched to the nominal volume position.

       2.3.3. The ambient temperature control system is then turned on (if not already on) and adjusted for an initial temperature of 293 K.

       2.3.4. When the enclosure temperature stabilizes at 293 K ± 2 K, the enclosure is sealed and the background concentration, temperature and barometric pressure measured.  These are the initial readings CH2i, Ti and Pi used in the enclosure calibration.

       2.3.5. The enclosure shall be unlatched from the nominal volume.

       2.3.6. A quantity of approximately 100 g of hydrogen is injected into the enclosure.  This mass of hydrogen shall be measured to an accuracy of ±2 per cent of the measured value.

       2.3.7. The contents of the chamber shall be allowed to mix for five minutes and then the hydrogen concentration, temperature and barometric pressure are measured.  These are the final readings CH2f, Tf and Pf for the calibration of the enclosure as well as the initial readings CH2i, Ti and Pi for the retention check.

       2.3.8. On the basis of the readings taken in paragraphs 2.3.4 and 2.3.7 above and the formula in paragraph 2.4. below, the mass of hydrogen in the enclosure is calculated. This shall be within ±2 per cent of the mass of hydrogen measured in paragraph 2.3.6. above.

       2.3.9. The contents of the chamber shall be allowed to mix for a minimum of 10 hours.  At the completion of the period, the final hydrogen concentration, temperature and barometric pressure are measured and recorded.  These are the final readings CH2f, Tf and Pf for the hydrogen retention check.

       2.3.10. Using the formula in paragraph 2.4. below, the hydrogen mass is then calculated from the readings taken in paragraphs 2.3.7 and 2.3.9. above.  This mass may not differ by more than 5 per cent from the hydrogen mass given by paragraph 2.3.8. above.

       2.4. Calculation

       The calculation of net hydrogen mass change within the enclosure is used to determine the chamber's hydrocarbon background and leak rate. Initial and final readings of hydrogen concentration, temperature and barometric pressure are used in the following formula to calculate the mass change.

       Where :

                     MH2 = hydrogen mass, in grams

                     CH2