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Safety valve pressure adjustment and operating procedures

From:Net   Date:2012-3-5

 

Safety valve opening pressure, discharge pressure and adjust the pressure back seat

A safety valve opening pressure adjustment

① valve factory, should be adjusted by one to the user requirements of its opening pressure setting value. If the user made the spring pressure level, the pressure level is generally lower limit shall adjust the factory.

② users will be protected safety valve installed on the device before or during installation, you must re-adjusted at the installation site to ensure the safety valve set pressure value to meet the requirements.

③ In the spring pressure plate level specified range by turning the adjusting screw to change the amount of compression springs can be adjusted on the opening pressure.

④ rotating the adjusting screw until the valve inlet pressure should be reduced to below 90% of the opening pressure in order to prevent rotation of the adjusting screw is rotated, the valve flap, which damage the sealing surface.

⑤ In order to ensure accurate pressure opening, should make adjustments in the medium conditions, such as media type, temperature and other operating conditions as close as practical. Media type change, especially when the media is not the same accumulation state (e.g., in the vapor phase from the liquid phase), opening pressure changes often. Operating temperature increases, the opening pressure is generally decreased. Therefore, the adjustment at room temperature for high temperature, the room temperature should be slightly higher than the set pressure value of the required opening pressure. High to what extent the valve structure and material selection have a relationship should be based on the manufacturer's instructions.

⑥ conventional safety valve for securing additional back pressure of the occasion, when the examination adjusted opening pressure (back pressure is atmospheric pressure at this time), and its value should be setting the required opening pressure minus additional backpressure values.

Second, the relief valve discharge pressure and adjust the pressure back seat

① discharge pressure adjusting valve seat and the back pressure to fully open the valve to achieve a high degree of action test, therefore, only the bulk of the test device or in the relief valve mounted on the equipment to be protected before possible. The adjustment method varies according to the safety valve structure.

② For recoil plate and seat belt adjustment ring structure is the use of seat adjustment ring to be adjusted. Unscrew the adjusting screw ring, screw extending from the exposed person a fine tool like an iron bar, you can toggle adjustment ring on the teeth, so that the adjustment ring turning left. When the adjustment ring to the left for counterclockwise rotation, its elevated position, the discharge pressure and reseating pressure will be reduced. Conversely, when the adjusting ring to the right for clockwise rotation, the position reduced pressure and the discharge pressure back seat will be somewhat higher. Every time adjustment, adjustment: Circle rotation range should not be too large (usually turn to the number of teeth). After each adjustment screw should be screwed on, so that it ends in the adjustment ring groove between two teeth, both to prevent the adjusting ring rotation without a radial pressure on the adjusting ring. For safety reasons, toggle adjustment ring, you should make appropriate to reduce the inlet pressure relief valve (opening pressure should generally be less than 90%) in order to prevent sudden adjustment of valve open, causing the accident.

③ to have upper and lower adjusting ring (guide sleeve and have a seat adjustment ring) structure, the adjustment to be complicated. Seat adjustment ring is used to change the valve flap and the size of the channel between the adjusting ring, thus changing the initial opening the valve when the pressure in the valve chamber and the accumulation of the adjusting ring between the degree of size. When elevated seat adjustment ring, the pressure increases the degree of accumulation, so that the valve opening phase ratio decreases rapidly to a sudden sharp turn. Therefore, elevated seat adjustment ring allows discharge pressure decreased. It should be noted that the seat adjustment ring should not rise too close to the valve. That, the sealing surface could cause leaks at the valve suddenly opened prematurely, but because this time is not sufficient to medium pressure valve in the open position, the valve was then closed, and then the valve occurrence frequency jump. Seat notes: "Circle is mainly used to reduce the proportion valve, open stages and regulate discharge pressure, but also have an impact on the back seat pressure.

The adjustment ring is used to change the flow medium side of the valve flap folded after reflection angle, thus changing the size of the fluid force, in order to adjust the pressure back seat. Increase the adjustment ring, turning angle decreases, the fluid force decreases, so that the back seat pressure increased. Conversely, when lowering the adjustment ring, the back seat pressure is reduced. Of course, the adjustment ring in the back seat pressure changes, but also affects the discharge pressure, which increases the pressure on the adjusting ring so that emissions have increased, reducing the pressure on the adjusting ring so that emissions decreased, but its impact as back seat pressure as obvious.

Third, the safety valve seals

Valve adjustment is completed, should be seal to prevent the adjusted status changed arbitrarily. When the safety valve refurbishment, before disassembling the valve shall be credited to adjust the position of the screw and the adjustment ring for easy adjustment after finishing work. Should again be re-adjusted seals.

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