Low emission valve

摘要

A low emission valve assembly for use with volatile fluids and incorporating a pair of independent inner and outer metal bellows mechanical seal assemblies with means to compensate for thermal expansion of a liquid between the seals and which means transmits product pressure within the valve to the seals, so that the inner seal floats with a near zero pressure differential from outside to inside. The compensating means can be a pressure responsive bellows arrangement or a pressure response diaphragm arrangement.