General selection principles of valve materials for air conditioning
1. The pressure resistance grade, operating temperature range, corrosion resistance and material of the valve body should not be lower than the requirements of the process connection piping material. The manufacturer’s definitive products should be preferred. Cast steel or forged steel valve body is usually used for selection.
Water vapor or moisture with high water content and flammable fluids, cast iron valve body should not be used.
3. When the ambient temperature is lower than -20 ℃, cast iron valve body should not be selected.
4. Valve internal parts should be able to resist corrosion, fluid corrosion, fluid throttling caused by cavitation damage.
Valve internal parts of the choice of materials
1. Non-corrosive fluid selection of 1Crl8Ni9, 1Crl8Ni9Ti or other stainless steel.
2. Corrosive fluids should be based on the type of fluid, concentration, temperature and pressure, containing oxidants and flow rate to choose the appropriate corrosion-resistant materials. Commonly used corrosion-resistant materials are 1Crl8Ni9Ti, 0Crl8Nil2M02Ti, 20# alloy, Hastelloy and titanium steel.
3. For the working conditions with high flow rate and serious scouring, wear-resistant materials should be selected. For example, 9Crl8 and 17-7PH heat treatment, and chromium-molybdenum steel, G6X and other materials with strong curing oxide layer, toughness and fatigue strength.
4. Material selection for severe wear.
When the fluid flash, cavitation and containing particles, the spool and seat surface should be hardened. When the fluid temperature is too high, the pressure difference is too large, the spool and seat should be surface hardening. For example, the surface weld Stellite alloy.
Third, the regulating valve leakage and flow.
According to the process requirements for leakage, choose the type of valve with different levels of leakage. In general, the leakage of straight-through single-seat valves should be less than or equal to the rated 01% or less, and the leakage of double-seat valves needs to be below 0,1% of the rated c value.
China industrial valves manufacturer
Select flow direction.
1. Ball valves and ordinary butterfly valves do not require flow direction, you can choose any flow direction.
2. Three-way valve, venturi angle valve, double-sealed sleeve valve with balance hole has specified a certain flow direction, generally can not be changed.
3. Single-seat valves, angle valves, high-pressure valves, single-sealed sleeve valves without balance holes, small flow rate adjustment valves, etc. The flow direction of the regulating valve should be selected according to different working conditions.