Discussion on the use of signal valve for fire hydrant control valve in high-rise buildings

Discussion on the use of signal valve for fire hydrant control valve in high-rise buildings

Abstract: Suggestions of high-rise building fire hydrant control valve USES the signal valve discusses keywords: high-rise building fire hydrant valve control signal valve in accordance with the provisions of the “code for fire protection design of tall buildings”, in the indoor fire hydrant system, water supply pipe application valve is divided into a number of , and valve should be obvious signs.
This is so that the number of hydrant standpipes is not less than one when the pipe is being serviced.
{TodayHot} with the development of modern architecture, the building of various pipelines for beautiful demand should be hidden as far as possible to decorate, therefore, hydrant pipes in the ceiling, tube well, is widespread, but this is a problem, namely the control valve of the open fire hydrant pipe can not get monitoring, to cause fire hydrant can be normal use.
Examples are as follows: “State Grid Control Center of Ministry of Electric Power” project covers a construction area of more than 50,000 square meters, with three underground floors and 27 floors above ground. The building height is over 110 meters. It is a comprehensive intelligent building integrating production command and dispatching, office and conference functions, and its high degree of automation is rare in China.
In the design of the automatic wine spraying system, I used signal valves in front of all water flow indicators, so the status of the system can be displayed in the fire control center, and problems can be found at a clear sight. In addition, the control of the water level of life and fire fighting, and the start and stop of the fire pump are also reasonably monitored. Only the control valve of the fire hydrant system uses ordinary valves in accordance with the specifications *, which has obvious open and close signs, but can not be shown in the fire control center. In addition, these valves are located in the tube well and the ceiling for aesthetic needs, and the quality of the current workers cannot guarantee the reliability of the system.
In the fire protection system in the process of acceptance, although the leadership of the ministry project headquarters, construction units and design units are very seriously, has made the deployment and the early rectification, well rehearsed, but in the process of fire department official actual acceptance, but there is a problem, there is a fire hydrant fire hydrant on the standpipe anyway also can’t let out of the water, and the other four are normal, We can’t find a problem at the fire control center.
After inspection, it was found that the control valves at both ends of the riser were closed because of maintenance, and the workers did not open the valves after maintenance, causing the fire hydrant not to water.
I think, in the case that everyone attaches great importance to, still appear this kind of problem, and usually in the case of easy paralysis more do not know what kind of problem will appear.
This is related to whether the fire hydrant system is the key to the rational use of problems, and the more reliable way to avoid this situation appear is fire hydrant system control valves are set into the signal valve, and valve open to display in the center of the fire control, so that the management personnel inspection, although the cost has increased, however, The ratio of investment to the whole fire hydrant system is still very small, and it can make the whole fire hydrant system safety ** improvement, which I think is worth the investment.
Control valve installation and construction considerations analysis
Control valve installation and construction considerations analysis
Precautions for installation and construction:
Precautions for control valve installation should be taken into account such as easy operation, safety and standardization. The specific contents are as follows:
(1) Installation position and orientation of control valve:
1. According to the design drawings and design documents, the installation location should have enough operation space for installation, operation and maintenance; The location should avoid installation in vibration, humidity, easy to mechanical damage, strong electromagnetic interference, high temperature, temperature changes and corrosive gas places; Installation should be firm and smooth; The installation position should make the actuator of the control valve in the upper part of the regulating mechanism, showing the various installation positions of the direct stroke control valve. Where, the chosen position.
2. The flow direction of the fluid in the control valve the flow direction of the fluid in the control valve should be consistent with the arrow marked on the valve body of the control valve. Special circumstances may not be restricted by these provisions.
3, the control valve connection control valve connection has thread connection, flange connection and welding connection. Threaded connection is used for small caliber control valves. When installing threaded connection control valves, removable movable connectors must be installed at the same time. Flange connection has two kinds of flange connection and clamping connection, the nominal diameter of the connecting flange should be consistent with the diameter of the control valve. Flanges also have different pressure levels, the pressure level of the flange should be consistent with the pressure level of the control valve. The inside diameter of the flange shall be equal to the inside diameter of the pipe. The allowable deviation of perpendicularity between flange surface and pipe axis is. Flange sealing surface should be flush. When connecting the flange, the force should be uniform and suitable to avoid excessive pressure on the part. Avoid welding connections as far as possible. When welding connections, detachable movable connectors must be installed. When the control valve is connected, the inner part of the connecting pipe should not be led into a new protrusion. For example, sealing gaskets, welding joints, etc. should not protrude in the pipe.
4, control valve and upper, downstream cut-off valve, bypass valve connection control valve, downstream cut-off valve and bypass valve should be installed at the same time with the control valve. The length of the pipe section between the upper and downstream cut-off valves and the control valves should consider the pipeline resistance and the effect on the fluid flow state. The length of the straight pipe section is long, which is conducive to the stability of the fluid after the cut-off valve, can make the fluid flow stable, reduce the influence of turbulent flow, reduce noise; The length of straight pipe section is short, and the fluid enters the control valve before it is stable after the cut off valve, which enhances the noise, but the short length of pipe section is beneficial to reduce the pipeline resistance, improve the pressure drop at both ends of the control valve, reduce the distortion of the flow characteristics, and is conducive to the stable operation of the control system. Therefore, should weigh and comprehensive consideration. Usually, the upstream side should have a straight pipe segment of 10D to 20D, and the downstream side should have a straight pipe segment of 3D to 7D. D is the nominal diameter of the pipeline, and the rectifier device should be set if necessary.
(2) the selection of connection scheme
1. There are many ways to connect the control valve and the upper and downstream cut-off valve, and several common connection schemes. In the figure, the structure of scheme A is compact, occupies A small footprint, is easy to maintain and operate, and the system is easy to empty or drain. But often can not meet enough straight pipe length, resulting in noise enhancement. The structure of scheme B covers a large area, and the control valve can be installed in the lower or upper part, which is easy to meet the operation requirements, but the length of the straight pipe segment is not easy to ensure. The structure of scheme C is suitable for angular control valves, which can reduce the number of elbows and occupy a small area. For the flow direction of the bottom inlet and outlet, there can be a longer upstream straight pipe length. The structure of Plan D is similar to Plan B and occupies a larger area. The structure of scheme E is suitable for angular valves. Compared with scheme C, the length of the straight pipe section on the upstream side is shorter, which is not conducive to fluid stability. The structure of scheme F is a common join structure. It has a large footprint, less pipeline resistance, but less space for operation and maintenance.
2. The connection of the discharge valve, discharge valve and discharge valve, in order to facilitate the disassembly of the control valve, the pressure before and after the valve should be discharged before disassembly, and the discharge valve should be installed between the control valve and the upper and lower cut off valves.
3. Vent valve and drain valve are used to discharge non-condensing gas and condensate entrained in the fluid. When the controlled fluid is gas or steam during installation, the blowdown valve should be installed at the lower part of the control valve set to facilitate condensate discharge. When the controlled fluid is liquid, in order to facilitate the discharge of non-condensing gas, the discharge valve should be installed at the height of the control valve group.
4. Bypass valve. When the control valve is removed for maintenance, the bypass valve can be used to operate the production process. When charged with excessive traffic. When the control valve cannot be adjusted normally, as an emergency measure, the bypass valve can also be used as the parallel connection scheme of the control valve to control the process. To reduce costs, large caliber control valves are equipped with handwheel actuators that can be operated instead of bypass valves. The installation OF the bypass valve should be easy to operate, it and the control valve, downstream cut-off valve together to form a control valve group, therefore, installation should be matched with them, and complete the construction installation at the same time. The nominal diameter of the bypass valve is the same as the nominal diameter of the pipeline, and the pressure class is consistent with the process pressure class.
5. The installation of the actuator is usually directly connected with the valve body of the control valve, but when the hydraulic actuator, long stroke actuator and other actuators are separated from the valve body of the control valve, attention should be paid to the installation of the actuator. The connecting rod and the mechanical moving parts of the actuator should be flexible without loosening or clamping. The connecting rod length should be stable, flexible and reliable in the full stroke range. When connected to a control valve body with thermal displacement in process piping, ensure that the relative position between actuator and control valve body remains unchanged. The handwheel actuator has two kinds of side mounting and top mounting, and the operation space should be left when installing. Hand wheel operation should be flexible, no stuck or torsion phenomenon. The relationship between the rotation direction of the handwheel and the valve opening should be marked. Limit device should be adjusted properly to play a protective role. The hydraulic actuator should be installed lower than the controller, if it must be higher than the controller, the height difference should not exceed 1.0m, and the exhaust valve should be installed at the pipe air collection point, and the check valve or automatic cut-off valve should be installed near the controller.
6, valve positioner installation valve positioner valve position detection device and control valve stem or valve shaft is directly connected, therefore, the installation should ensure that the feedback signal can be correct, timely reflect the valve position signal and changes. Usually, the valve positioner is supplied with the control valve, and the manufacturer completes the connection between the two. When the production process control needs to add the valve positioner, should ensure that the valve positioner valve position detection device action is correct, reliable and flexible. The mechanical clearance of the feedback rod fulcrum should be as small as possible. The SIGNAL LINE OF THE VALVE POSITIONER SHALL BE PROPERLY CONNECTED, AND THE AIR SOURCE LINE AND OUTPUT LINE and INPUT LINE shall be marked with nameplates. The valve position display signal of the valve positioner should be convenient for operation and maintenance personnel to observe.
7. Installation of other accessories, including valve position sensor, solenoid valve, limit switch, actuator, electrical converter, etc., should be installed in accordance with the relevant provisions of the product manual. Small flow control valve should be installed in the upstream filter. When turbulence is severe, a rectifying device should be installed on the upstream side.
8. Installation of connecting pipelines The installation of connecting pipelines should pay attention to the following matters.
1) Signal pipe and air source pipeline generally adopt PVC sheathed copper pipe cable, pipe diameter is sL6Xl or g18Xl
2) The air source pipeline should be close to the control valve.
3) The signal pipeline and hydraulic pipeline should be as short as possible to shorten the signal delay and system time constant.
4) The pipeline should have enough expansion and redundancy, and should not hinder the operation of the actuator.
5) The welding slag shall not be placed in the pipe during pipeline welding. Connecting lines should be cleaned prior to installation to remove dirt such as oil, water and rust. Piping connecting pipelines should be neat and beautiful.