Safety valve operation and application of law
May 17, 2012
Safety valve before leaving the factory, one by one to adjust the opening pressure setting value to the user requirements.
China safety valve manufacture-Datian Valve, the specialist of China valve manufacture, main product range: pneumatic control valve, electric control valve , ball valve, automatic recirculation valve, gate valve, butterfly valve, globe valve, check valve, choke valve, safety valve, plug valve, diaphragm valve, strainer, pressure reducing valve and valve products.(china heat pump)
1, The safety valve opening pressure adjustment
① safety valve before leaving the factory, one by one to adjust the opening pressure setting value to the user requirements. If the user asked the spring working pressure level according to the general should be the lower limit of the pressure level to adjust the factory.
② users in the safety valve installed at the installation site, the equipment to be protected before installation, re-adjust to meet the requirements to ensure that the safety valve set pressure value.
③ In the spring working pressure level within the nameplate indicate, by rotating the adjustment screw to change the amount of compression spring, you can adjust the pressure on the opening.
④ in the rotation adjustment screw until the valve inlet pressure reduced to less than 90% of the opening pressure to prevent rotating the adjustment screw when the valve is driven to rotate, which damage the sealing surface.
⑤ In order to ensure the accurate opening pressure value, you should make adjustments in the medium conditions, such as medium type, temperature as close as possible to actual operating conditions. Media types to change, especially when the media accumulate state (eg, from liquid into vapor), open the pressure changes often. Operating temperature increases, the opening pressure generally decreased. Therefore, at room temperature to adjust for high temperature, room temperature, set pressure value should be slightly higher than the requirements of the opening pressure value. High to what extent the valve structure and material selection has relations should be based on the manufacturer’s instructions.
⑥ conventional safety valve for a fixed additional back pressure of the occasion, when the opening pressure adjustment in the examination (in this case the back pressure is atmospheric pressure) value minus the opening pressure setting value should be to require additional back pressure value.
2, The safety valve discharge pressure and reseating pressure adjustment
①The adjust valve discharge pressure and reseating pressure, the need for the action test valve to reach the opening height, therefore, possible only in the large capacity of the test device or the safety valve installed on equipment to be protected. The adjustment method varies according to valve structure.
② with the recoil plate and seat adjustment ring structure is the use of seat adjustment ring to adjust. Unscrew the adjustment screw ring, stretching like a thin iron bar tools from the exposed screw, you can toggle the adjustment ring on the tooth, 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 decrease. The contrary, when the adjustment ring to the right for clockwise rotation, the position of lower discharge pressure and back pressure will be higher.
③ with the structure of a regulator under the adjustment ring (the guide sleeve and seat each circle), the adjustment should be complex. Seat adjustment ring is used to change the size of the channel between the valves and valve adjustment ring, and thus change the size of the open valve initial pressure of the chamber between the degree of accumulation in valves and valve adjustment ring. When the increase in seat adjustment ring, the degree of pressure accumulation increases, so that the valve in proportion to open the stage decreases rapidly to a sudden sharp turn. Therefore, the discharge pressure of increased seat adjustment ring can be reduced. It should be noted that the seat adjustment ring should not rise too close to the valve. As a sealing surface at the leak may cause the valve prematurely suddenly opened, but due to media pressure is not enough to the valve in the open position, the valve was then closed the valve, so the frequency jump occurs.
Reproduced in: http://www.bf35.com/news/detail/22917.html