Principle of Operation These tubular gauge glass valves represent years of experience in the manufacture of gauge valves and offer variety of types of connections to suit all requirements. All have forged bodies with stainless steel trim. All carbon steel parts are rust proofed inside and out. The highest quality borosilicate tubular glass is furnished as original equipment. Material specification Customized suiting to the service (fluid) and temperature.Available in SS 304/ SS 316/ pp/ pvc/ hdpe/ pvdf/ ptfe etc.