[DIN low lift safety valve]——According to the opening height of the safety valve disc, it can be divided into a low lift safety valve and a full-lift safety valve. The opening height of the full-lift safety valve is ≤0.25d0 (minimum discharge throat diameter ).
The low lift safety valve is divided according to the structural form, which can be divided into plumb type, lever type, spring type and pilot type (pulse type); according to the valve body structure, it can be divided into closed type and non-closed type. The closed safety valve means that the discharged medium is not leaked, and all discharged along the outlet to the designated place. It is generally used in toxic and corrosive media. For air and steam safety valves, non-closed safety valves are mostly used. The selection of safety valve products should be determined according to the actual sealing pressure. For spring-loaded safety valves, there are springs with several working pressure levels within a nominal pressure (PN) range. In addition to indicating the safety valve model, name, medium and temperature, the valve body sealing pressure should be indicated when ordering. , Otherwise it is supplied according to the maximum sealing pressure.
The installation and maintenance of the low lift safety valve should pay attention to the following items:
(1) All safety valves should be installed vertically.
(2) There should be no resistance at the outlet of the safety valve to avoid pressure.
(3) The safety valve should be specially tested before installation, and its official tightness should be checked.
(4) The safety valve in use should be inspected regularly.
The safety valve installation should meet the following requirements:
(1) Boilers with a rated evaporation capacity greater than 0.5t/h must be equipped with at least two safety valves: boilers with a rated evaporation capacity less than or equal to 0.5t/h must be equipped with at least one safety valve. Dividable
Safety valves must be installed at the outlet of the type economizer and steam superheater.
(2) The safety valve should be installed vertically at the highest position of the boiler and header. Between the safety valve and the drum or header, there shall be no outlet pipes and valves for taking steam.
(3) The low lift safety valve must have a device to prevent the heavy hammer from moving by itself and a guide frame to limit the lever's deviance. The spring-type safety valve must have a device to lift the handle and prevent the adjustment screw from being twisted casually.
(4) For boilers with rated steam pressure less than or equal to 3.82MPa, the safety valve throat diameter shall not be less than 25mm: for boilers with rated steam pressure greater than 3.82MPa, the safety valve throat diameter shall not be less than 20mm.
(5) The cross-sectional area of the connecting pipe between the safety valve and the boiler should not be less than the cross-sectional area of the inlet of the safety valve. If several safety valves are installed together on a short pipe directly connected to the drum, the cross-sectional area of the short pipe should not be 1.25 times the exhaust area of all safety valves.
(6) The safety valve should generally be equipped with an exhaust steam pipe, which should lead directly to a safe place and have sufficient cross-sectional area to ensure smooth exhaust. The bottom of the safety valve exhaust pipe should be equipped with a cavity and a drain pipe connected to a safe place. Valves are not allowed on the exhaust pipe and the drain pipe.
Scope of application
A41H type are used for the equipment and pipeline of the petroleum gas air water etc medium what are working temperature are less than ≤300℃ A41Y-P/R type are used for the equipment and pipeline of the quality with corrode medium what the wirking temperatrue are less than 200℃ Take for extra pressure devices Flange connecting dimentsions of comply with Standard series first of JB/T...94