Introduction to technical performance of hydraulic control valves
The hydraulic control valve is a water pressure control valve, which consists of a main valve and its attached conduit, pilot valve, needle valve, ball valve and pressure gauge.
When using a hydraulic control valve, first of all, pay attention to the selection. Improper selection will cause water and air leakage. When using the hydraulic control valve, the displacement of the hydraulic control valve must be selected according to the hourly steam consumption of the equipment multiplied by the selection ratio of 2-3 times for the large amount of condensed water. In order to ensure that the hydraulic control valve can discharge condensate as soon as possible while driving, the temperature of the heating device can be quickly increased. The hydraulic control valve does not have enough energy to discharge, which will cause the condensed water to be discharged in time and reduce the thermal efficiency of the heating equipment.
When the hydraulic control valve is selected, the hydraulic control valve cannot be selected with the nominal pressure, because the nominal pressure can only indicate that the hydraulic control valve body is subjected to the pressure level, and the hydraulic control valve has a large difference between the nominal pressure and the working pressure. Therefore, the displacement of the hydraulic control valve should be selected according to the working pressure difference. The working pressure difference is the difference between the working pressure before the hydraulic control valve and the back pressure of the hydraulic control valve outlet. Selecting the hydraulic control valve requires accurate and unobstructed steam-blocking drainage, high sensitivity, improved steam utilization, no leakage of steam, reliable working performance, high back pressure rate, long service life and convenient maintenance.
[Main technical performance of the valve]
Strength performance
The strength properties of a valve are the ability of the valve to withstand the pressure of the medium. Valves are mechanical products that withstand internal pressure and must therefore have sufficient strength and rigidity to ensure long-term use without cracking or deformation.
Sealing performance
The sealing performance of the valve refers to the ability of the sealing parts of the valve to prevent the leakage of the medium. It is an important technical performance index of the valve.
There are three sealing parts of the valve: the contact between the sealing surface of the opening and closing parts and the valve seat; the joint of the packing with the valve stem and the stuffing box; the connection between the valve body and the valve cover. The leak in the former place is called endoleak, which is commonly referred to as the lack of tightness, which will affect the ability of the valve to cut off the medium. For shut-off valves, internal leakage is not allowed. The latter two leaks are called leaks, that is, the medium leaks from the valve to the outside of the valve. External leakage can cause material loss, pollute the environment, and cause accidents in severe cases. For flammable, explosive, toxic or radioactive media, external leakage is not allowed, so the valve must have a reliable sealing performance.
Flow performance
When the medium flows through the valve, pressure loss (both pressure difference before and after the valve) is generated, that is, the valve has a certain resistance to the flow of the medium, and the medium consumes a certain amount of energy in order to overcome the resistance of the valve. In terms of energy conservation, when designing and manufacturing valves, it is necessary to reduce the resistance of the valve to the flowing medium as much as possible.
Motion performance action sensitivity and reliability
This refers to the sensitivity of the valve to the corresponding changes in the media parameters. For valves with regulating functions such as throttle valves, pressure reducing valves, regulating valves, etc., as well as valves with special functions such as safety valves and traps, their functional sensitivity and reliability are important technical performance indicators.
Opening and closing force and opening and closing torque
The opening and closing force and the opening and closing torque refer to the force or moment that must be applied when the valve is opened or closed. When closing the valve, it is necessary to form a certain sealing pressure between the opening and closing parts and the sealing surface of the bearing seat, and at the same time overcome the between the valve stem and the packing, between the thread of the valve stem and the nut, and at the end of the valve stem and The friction of other friction parts must be applied with a certain closing force and closing torque. During the opening and closing process, the required opening and closing force and opening and closing torque are changed, and the large value of the Zui is in the closed moment. Or open the initial moment of zui. When designing and manufacturing valves, it is important to reduce their closing force and closing torque. The opening and closing speed opening and closing speed is expressed by the time required for the valve to complete an opening or closing action. Generally, there is no strict requirement for the opening and closing speed of the valve, but some working conditions have special requirements on the opening and closing speed. If some requirements are quickly opened or closed, in case of accidents, some requirements are required to be slowly closed to prevent water hammer, etc. This should be considered when selecting the valve type. °C is less than t less than 120 °C valve.
Precautions and features in the use of knife gate valves:
The opening and closing member of the knife-type gate valve is a gate. The direction of movement of the gate is perpendicular to the direction of the fluid. The knife-type gate valve can only be fully open and fully closed, and cannot be adjusted and throttled. The gate has two sealing faces. The two sealing faces of the common mode gate valve of Zui form a wedge shape. The wedge angle varies with the valve parameters, usually 50. The gate of the wedge knife gate valve can be made into a whole body. The rigid ram can also be made into a ram that can produce a small amount of deformation to improve its processability and compensate for the deviation of the sealing surface angle during the machining process. This ram is called the elastic ram knife type gate valve when closed, the sealing surface It can be sealed by only the medium pressure, that is, the sealing surface of the shutter is pressed against the valve seat on the other side by the medium pressure to ensure the sealing of the sealing surface, which is self-sealing. Most knife-type gate valves use forced sealing, that is, when the valve is closed, the external force is forced to press the gate to the valve seat to ensure the sealing of the sealing surface.
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