The operating temperature range of the Universal Valve is determined by the operating temperature, and the nominal pressure of the Throttle Valve is determined by the operating pressure. The calculated constant pressure value of the Throttle Valve determines the constant pressure range of the spring or lever, and then determines the material and structural type of the Universal Valve based on the medium used, and then calculates the throat diameter of the Throttle Valve based on the relief volume of the Throttle Valve. The following are general rules for selecting Universal Valve.
(1) Hot water boilers generally use unsealed micro-opening Throttle Valve with a wrench.
(2) Steam boilers or steam pipelines generally use unsealed full-open Throttle Valve with wrenches or safety relief valves.
(3) Liquid incompressible media such as water generally use closed micro-opening Throttle Valve. Such as high-pressure water heaters, heat exchangers, etc.
(4) High-pressure water supply generally uses closed full-open Throttle Valve. Such as gas storage tanks, gas pipelines, etc.
(5) Compressible media such as gas generally use closed full-open Throttle Valve.
(6) E-class steam boilers generally use dead weight Throttle Valve. Large displacement and high pressure systems generally use pulse type Throttle Valve.
(7) Large diameter. Such as temperature and pressure reduction devices, power station boilers, etc.
(8) Train tankers, automobile tankers, storage tanks, etc. that transport liquefied gas generally use built-in Throttle Valve. Need to be used in conjunction with the breathing valve.
(9) A hydraulic safety valve is generally used on the top of the oil tank.
(10) Pilot-operated Throttle Valve are generally used for underground drainage or natural gas pipelines.
(11) A safety return valve is generally used on the liquid phase return pipeline at the outlet of the LPG station tank pump.
(12) Systems with negative pressure or that may generate negative pressure during operation generally use vacuum negative pressure Throttle Valve.
(13) Containers or piping systems with large back pressure fluctuations and toxic and flammable materials generally use bellows Throttle Valve.
(14) Systems with a low medium freezing point generally use insulation jacketed Throttle Valve.
The Throttle Valve is an important safety accessory on special equipment, and its installation also has corresponding requirements. Here are some common matters:
① Boilers with a rated evaporation capacity greater than 0.5t/h should be equipped with at least two Throttle Valve; boilers with a rated evaporation capacity less than or equal to 0.5t/h should be equipped with at least one Throttle Valve. Throttle Valve must be installed at the outlet of the separable economizer and the outlet of the steam superheater.
② The Throttle Valve should be installed vertically at the highest position of the boiler and header. No outlet pipes and valves for taking in steam shall be installed between the Throttle Valve and the drum or header.
③ The lever-type Throttle Valve must have a device to prevent the weight from moving by itself and a guide to limit the deviation of the lever. The spring-type Throttle Valve must have a lifting handle and a device to prevent the adjustment screw from being turned casually.
④ For boilers with rated steam pressure less than or equal to 3.82MPa, the throat diameter of the Throttle Valve should not be less than 25mm; for boilers with rated steam pressure greater than 3.82MPa, the throat diameter of the Throttle Valve should not be less than 20mm.
⑤The cross-sectional area of the connecting pipe between the Universal Valve and the boiler should not be less than the inlet cross-sectional area of the Throttle Valve. If several Universal Valve are installed together on a short pipe directly connected to the drum, the passage cross-sectional area of the short pipe should be no less than 1.25 times the exhaust area of all Throttle Valve.
⑥ The Throttle Valve should generally be equipped with an exhaust pipe, which should lead directly to a safe location and have sufficient cross-sectional area to ensure smooth flow of exhaust steam. The bottom of the exhaust pipe of the Throttle Valve should be pretended to have a drain pipe connected to a safe location. Valves are not allowed to be installed on the exhaust pipe or drain pipe.
