These chemical gauge guards should be utilized to isolate and protect pressure or vacuum instruments used on ultra-pure or highly corrosive fluid lines. They can be confidently used with liquids such as demineralized water, sulphuric acid, hydrochloric acid, and caustics. Use caution with chlorine applications and consult factory for recommendations. Utilization of Plast-O-Matic gauge guards offers the added advantage of protection against clogging of instruments caused by suspended solids or highly viscous fluids. Materials Construction: Gauge Guard housings are molded of Glass-filled Polypropylene. PTFE diaphragm. Non-wetted parts: O-ring seals are Buna-N, fasteners and 1/4" instrument connections are stainless steel. 1/2" instrument connections are direct to upper housing material. Liquid used to solidly fill all Plast-O-Matic gauge guards and instruments is a highly refined temperature stable mineral oil that complies with FDA regulations 21 CFR 172.878, 178.3620, and 573.680. 1/2" NPT pipe connection x 1/2" all-plastic connection.