1. Classification Currently mass produced safety valves are available in two types: spring type and rod type. There are also impulse-type safety valves, pilot-operated safety valves, safety switching valves, safety decompression valves, and deadweight safety valves. Spring-loaded safety valves mainly rely on the force of springs. Spring-loaded safety valves are closed and non-closed. Generally, flammable, explosive, or toxic media should be closed. Steam or inert gas can be used. In the spring-loaded safety valve, there are also wrenches and without wrenches.
The role of the wrench is mainly to check the degree of flexibility of the valve flap, and sometimes it can also be used as manual emergency pressure relief, as shown in Figure 3. Lever type safety valves mainly rely on the force of the lever weight, but due to the bulkiness of the lever type safety valves, the range of choice is limited. Use a safety valve with radiator when the temperature is high.
The main parameter of the safety valve is the displacement. This displacement is determined by the valve seat diameter and the opening height of the valve disc. The opening height is different, and it is divided into two kinds: micro-opening and full-opening. Micro-opening means that the opening height of the valve flap is 1/40 to 1/20 of the throat diameter of the valve seat. Full-open type refers to the opening height of the valve flap is 1/4 of the throat diameter of the valve seat.
2. The selection of the safety valve determines the nominal pressure of the safety valve according to the operating pressure. The operating temperature determines the operating temperature range of the safety valve. The constant pressure value of the safety valve is used to determine the constant pressure range of the spring or lever, and the safety is determined according to the medium used. Valve material and structure type, and then calculate the safety valve throat diameter according to the safety valve discharge volume. The following are the general rules for the selection of safety valves.
(l) Hot-water boilers are generally not enclosed with a microvalve-type safety valve with a wrench.
(2) Steam boilers or steam pipes are generally not enclosed with full-open safety valves.
(3) For liquids such as water, incompressible media generally use closed micro-relief safety valves or safety relief valves.
(4) High-pressure feed water is generally closed safety valve, such as high pressure feedwater heaters, heat exchangers, etc.
(5) Gas and other compressible media are generally closed safety valves, such as gas tanks, gas pipelines, etc.
(6) E-grade steam boilers generally use static-type safety valves.
(7) Large-diameter, large-displacement and high-pressure systems generally use pulse-type safety valves, such as temperature-reducing decompression devices and power station boilers, as shown in Fig. 8.
(8) Internally installed safety valves such as train tankers, car tankers, and tanks for transporting liquefied gas are shown in Fig. 4.
(9) Hydraulic safety valve is generally used at the top of the tank and it must be used with the breathing valve.
(10) Downhole drainage or natural gas pipelines generally use pilot-operated safety valves, as shown in Figure 6.
(11) A safety return valve is generally used on the liquid phase return line at the outlet of the canister pump of the LPG station.
(12) Negative pressure or vacuum pressure relief valves may be used in systems that may generate negative pressure during operation.
(13) Bellows safety valves are generally used for vessels or piping systems with large back pressure fluctuations and toxic flammability.
(14) The system with a lower freezing point of the medium generally uses a heat-insulated jacket-type safety valve.
The role of the wrench is mainly to check the degree of flexibility of the valve flap, and sometimes it can also be used as manual emergency pressure relief, as shown in Figure 3. Lever type safety valves mainly rely on the force of the lever weight, but due to the bulkiness of the lever type safety valves, the range of choice is limited. Use a safety valve with radiator when the temperature is high.
The main parameter of the safety valve is the displacement. This displacement is determined by the valve seat diameter and the opening height of the valve disc. The opening height is different, and it is divided into two kinds: micro-opening and full-opening. Micro-opening means that the opening height of the valve flap is 1/40 to 1/20 of the throat diameter of the valve seat. Full-open type refers to the opening height of the valve flap is 1/4 of the throat diameter of the valve seat.
2. The selection of the safety valve determines the nominal pressure of the safety valve according to the operating pressure. The operating temperature determines the operating temperature range of the safety valve. The constant pressure value of the safety valve is used to determine the constant pressure range of the spring or lever, and the safety is determined according to the medium used. Valve material and structure type, and then calculate the safety valve throat diameter according to the safety valve discharge volume. The following are the general rules for the selection of safety valves.
(l) Hot-water boilers are generally not enclosed with a microvalve-type safety valve with a wrench.
(2) Steam boilers or steam pipes are generally not enclosed with full-open safety valves.
(3) For liquids such as water, incompressible media generally use closed micro-relief safety valves or safety relief valves.
(4) High-pressure feed water is generally closed safety valve, such as high pressure feedwater heaters, heat exchangers, etc.
(5) Gas and other compressible media are generally closed safety valves, such as gas tanks, gas pipelines, etc.
(6) E-grade steam boilers generally use static-type safety valves.
(7) Large-diameter, large-displacement and high-pressure systems generally use pulse-type safety valves, such as temperature-reducing decompression devices and power station boilers, as shown in Fig. 8.
(8) Internally installed safety valves such as train tankers, car tankers, and tanks for transporting liquefied gas are shown in Fig. 4.
(9) Hydraulic safety valve is generally used at the top of the tank and it must be used with the breathing valve.
(10) Downhole drainage or natural gas pipelines generally use pilot-operated safety valves, as shown in Figure 6.
(11) A safety return valve is generally used on the liquid phase return line at the outlet of the canister pump of the LPG station.
(12) Negative pressure or vacuum pressure relief valves may be used in systems that may generate negative pressure during operation.
(13) Bellows safety valves are generally used for vessels or piping systems with large back pressure fluctuations and toxic flammability.
(14) The system with a lower freezing point of the medium generally uses a heat-insulated jacket-type safety valve.
Hitachi Elevator Spare Parts, Hitachi Elevator Parts
Hitachi has been developing and manufacturing elevators and escalators for about 90 years. Social demands on elevators and escalators changed dramatically over time: faster, larger, and barrier-free and required.
History of Hitachi's Elevator and Escalator Business
- 1924Lift manufacturing at the Kameido plant
- 1932First elevator delivered (to Tokyo Electric Power)
- 1937First escalator delivered (to Osaka Railway Department Store)
- 1956Hitachi Building Services Co., Ltd. founded (currently known as Hitachi Building Systems Co., Ltd.)
- 1966Hitachi Elevator Engineering Co ., (Hong Kong) Ltd. founded in Hong Kong
- 1967Construction of an elevator research tower in the Mito plant completed (90m in height)
- 1968300m â„ minute ultra high speed elevator delivered to the Kasumigaseki Building, Japan's first skyscraper
- 1972Hitachi Elevator Engineering (Singapore) Pte. Ltd. founded in Singapore
- 1974Delivery of 540m â„ minute elevators to skyscrapers in Shinjuku
- 1987Hitachi Mito Engineering Co., Ltd. founded
- 1991Siam-Hitachi Elevator Co., Ltd. Founded in Thailand
- 1998Three affiliated companies in China merged to found Guangzhou Hitachi Elevator Co., Ltd.
- 2003Opened Hitachi Building Solution Lab
- 2007Guangzhou Hitachi Elevator Co., Ltd. renamed to Hitachi Elevator (China) Co., Ltd.
- 2008Hitachi Lift India Pvt. Ltd. foundedDelivered the world's highest class ultra fast double deck elevators to the Shanghai World Financial Center
- 2009Introduction of the Company systems leads to the establishment of the Urban Planning and Development Systems Company
- 2010Completed elevator research tower [G1TOWER" (213m in height) for Mito WorksFounded Hitachi Elevator Asia Pte. Ltd. as a general elevators and escalators business company for the Southeast Asia, India, and Middle East regionsCompleted elevator research tower (172m in height) for Hitachi Elevator (Shanghai) Co. Ltd.
-
2011Founded Hitachi Elevator Philippines CorporationDelivered 600m â„ minute elevators to the Al Hamra Mixed-Use Complex in Kuwait.
Hitachi Elevator Spare Parts, Hitachi Elevator Parts
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