This system detects failure of bellows of any high pressure silane or hydrogen valve. The detection system is filled with 5 psig nitrogen. Nitrogen is provided to detect bellows failure during reactor vacuum prior to hydrogen backfill.
In case of bellows failure, high pressure process stream (silane or hydrogen) will leak through the tubing in the valve’s bonnet into the leak detection system. As a result, the pressure of the detection system will rise. The system and all valve secondary packing are rated for at least 185 psig. Since the pressure on both silane and hydrogen headers will not go higher than 185 psig, bellows failure will not mechanically impact the system. However, in order to prevent silane or hydrogen from flowing into and contaminating the nitrogen header, the detection system is equipped, in series, with a check valve and an interlock valve, which will automatically close if the system pressure reaches 8 psig.