GOETZE 851 gunmetal angle safety valve, threaded

The 851 is GOETZE’s general-purpose threaded safety valve in gunmetal: the counterpart of the stainless steel 451 for water, air, neutral gases and steam where a copper alloy body is adequate. It covers 1/2” to 2” and set pressures from 0.5 to 50 bar, with the same bonnet logic as the rest of the range: open bonnet for neutral media, bellows for non-neutral media and back pressure up to 4 bar, gastight bonnet, and the double gastight bellows version for flammable or toxic media.

The valve is TÜV type tested for steam, gases and liquids, ASME UV stamped, CRN registered and approved by the main classification societies, which makes it a stock item for boiler makers, pump packages and shipyards. Connections are BSP or NPT; seals range from NBR to metal-to-metal for temperatures from −60 °C to +225 °C.

Three variants serve building and heating technology: the 851bG for solar and district heating primary circuits above 120 °C, the 851bH for hot water heating systems to 120 °C under TRD 721 and EN 12828, and the 851bHF for combined heating and cooling circuits down to −40 °C.

Selection data we need

Medium and state, set pressure, required discharge capacity, operating pressure and temperature, back pressure, inlet and outlet size and thread type, seal material and bonnet version. For heating systems, the boiler output. For a replacement, the type code and nameplate data are enough.