THE GREAT MULLARD MAGIC BLOG — gas in valves

When a valve is manufactured, it undergoes a process called evacuation where successive pumping operations remove air from the envelope prior to sealing.   However, even after evacuation, a small amount of gas remains - one part per one-hundred-thousand-million - as Cilla would have agreed, 'That's NORRA lorra, lorra gas!'    More gas may be released from the metallic components that comprise the electrode cage of a valve, gas that is trapped within the interstices of the metal structure especially if a valve is run under arduous operating conditions such that it gets extremely hot. Valve manufacturers include a component...