Selection criteria for pipeline and valve fittings of nitrogen machine equipment:

1, by copper or stainless steel combustion resistance to contact with oxygen body; Made of gasket refractory or flame retardant materials, such as graphite asbestos packing, polytetrafluoroethylene, expanded graphite; Strict degreasing of valve, strict air tightness test; Large diameter oxygen valve set pressure small bypass valve.

2, when the working pressure is greater than o.impa, do not use the gate valve. Because the grid groove is easy to rust, the loose relationship, the valve squeezes the chute rust operation, carries iron pounds, particles impact the friction wall, easy to cause fire and explosion accidents. In addition, the double gate valve is also easy to lose weight, but also bring safety risks.

3, the valve material should be consistent with the listing requirements in Table 9-5.

For the working pressure/MPA material < 0.6 body, the valve cover is made of malleable cast iron, ductile iron or cast steel nitrogen machine valve material, carbon steel or stainless steel stem, valve stainless steel > 0. 6 ~ < 10 Stainless steel, copper alloy or combination of stainless steel and copper base alloy (preferred copper base alloy) > 10 All copper base alloy Note: 1 o.impa working pressure or flow control valve material, should be stainless steel or copper alloy or a combination of both. 2 The packing of the valve should be treated with asbestos or PTFE graphite, or expanded stone walls. The working pressure is greater than 1.0MPa, the oxygen pressure reducing valve should choose a small bypass valve with a diameter of > 150mm and uniform pressure, so the pressure before opening the valve opens a small bypass valve, the outlet side is a step slow, reduce the inlet, the lateral pressure difference, avoid the flow speed is too fast, the formation of adiabatic compression, overheating, resulting in explosion accidents. The higher the pressure, the larger the diameter, the more dangerous, the more should use the oxygen valve and the bypass valve pressure is small. Normal operation, working pressure is greater than 1. OmpA oxygen, large diameter valve > 150mm, should use pneumatic control valve, remote operation, can avoid injury accidents, can reduce labor intensity.