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Swagelokdielectric union

Series 174A Bronze body safety relief valves for pressure protection only of all types of hot water heating boiler equipment. Pressure range 30 to 150psi (2.1 - 10 bar) with corresponding high ratings from 650,000 to 14,370,000 BTU/hr. Female inlet and outlet connections. Sizes 3⁄4" - 2" (20 - 50mm).

WattsDielectric Union

174A Boiler Pressure Relief Valves are used in hot water heating and domestic supply boiler applications to protect against excessive pressures on all types of hot water heating supply boiler equipment

Dielectric Unions are used in commercial and residential applications to prevent accelerated corrosion and deterioration in the piping system due to galvanic and stray current. It is installed between pipes made from dissimilar metal. We offer dielectric unions in a range of configurations, sizes, and materials.

As thermal expansion conditions develop, pressure builds up to the setting of the relief valve. This will cause discharging of small quantity of water. Should operating controls fail, permitting runaway firing, the boiler water may reach steam temperatures. The valve will then open to discharge steam at the rate or faster than the boiler can generate it, thus restoring system pressure to a safer level.

• Water seal of high temperature resisting material isolates spring working parts from water during relief.* Specifications Boiler Relief Valves An ASME Section IV certified pressure relief valve shall be installed on each boiler as noted. The valve shall have a BTU rating in excess of the BTU rating of the boiler’s heating output. Each hot water space heating boiler shall be equipped with a pressure relief valve set to relieve below the maximum boiler working pressure. The valve shall feature a raised seat and non-mechanical disc alignment. Working parts and spring shall be isolated from any discharge by a high temperature resistant material.* Valve shall be a Watts Series 174A, 374A or 740.