9. Generators must be arranged so that after-generation cannot produce objectionable results.
10. The holder of carbide-to-water generators must be large enough to take all the gas which may be produced by the introduction of one charge of carbide without undue pressure ensuing.
11. The maximum pressure permissible in any part of the apparatus is 1.1 atmosphere absolute.
12. The temperature in the gas space of a generator must never exceed 80° C.
13. Generating apparatus, &c., must be constructed in a workmanlike manner of metal capable of resisting rust and distortion, and, where the metal comes in contact with carbide or acetylene, it must not be one (copper in particular) which forms an explosive compound with the gas. Cocks and screw connexions, &c., of brass, bronze, &c., must always be kept clean. Joints exposed to acetylene under pressure must be made by riveting or welding except that in apparatus not exceeding 100 litres per hour productive capacity double bending may be used.
14. Every apparatus must be fitted with a safety-valve or vent-pipe terminating in a safe place in the open, and of adequate size.
15. Every apparatus must be provided with an efficient purifier so fitted that it may be isolated from the rest of the plant and with due consideration of the possible action of the purifying material upon the metal used.
16. Mercury pressure gauges are prohibited. Liquid gauges, if used must be double the length normally needed, and with a cock which in automatic apparatus must be kept shut while it is in action.
17. Proper steps must always be taken to prevent the apparatus freezing. In the absence of other precautions water-seals and pressure-gauges must be filled with liquid having a sufficiently low freezing-point and without action on acetylene or the containing vessel.
18. Signal devices to show the position of the gasholder bell must not be capable of producing sparks inside the apparatus house.