Shut-off valve is a commonly used shut-off valve, mainly used to connect or cut off the medium in the pipeline. In the pipeline system, the time for not operating the shut-off valve is very small, so regular maintenance is required.
A small amount of packing leakage can be solved by simply tightening the packing gland nut. But when the packing is damaged, replace the packing. When changing the packing, make the valve fully open for the upper seal to work (generally possible under pressure). When changing, install the appropriate packing in the stuffing box, and tighten the packing gland nut, and regularly check later to prevent the gland nut from loosening.
When changing the valve flap parts, lift the valve stem, remove the valve cover, and then install a new valve flap on the new clamping frame, turn the valve stem until the valve flap is disengaged from the clamping frame, use the new valve flap And the clamping frame is replaced and installed in the valve, the operation of the valve flap is convenient.
In order to grind the valve disc, a small amount of abrasive is applied to the valve disc, and then, grinding is performed. The grinding method is to place a shaft pin on the valve disc nut groove and the hole of the stem support head, place the component in the valve body, unscrew the connecting sleeve, and then grind alternately in forward and reverse directions. Use the valve stem as a grinding tool, put in abrasive materials and grind, the grinding should not be excessive. When grinding is complete, clean the abrasive and then lubricate the threads.
The valve stem axis of the globe valve is perpendicular to the sealing surface of the valve seat. The opening or closing stroke of the valve stem is relatively short, and it has a very reliable cut-off action, making this valve very suitable as a medium for cut-off or adjustment and throttling. Once the valve flap of the globe valve is in the open state, there is no longer contact between its valve seat and the sealing surface of the valve flap, and it has a very reliable cutting action. Therefore, this valve is very suitable as a medium for cutting or adjusting Stream usage.
Once the gost globe valve is in the open state, there is no contact between its valve seat and disc sealing surface, so its sealing surface wears less mechanically, because most of the valve seat and valve of the globe valve The flap is relatively easy to repair or replace the sealing element without removing the entire valve from the pipeline, which is very suitable for the case where the valve and the pipeline are welded together. The flow direction of the medium through such valves has changed, so the flow resistance of the stop valve is higher than that of other valves.
Commonly used globe valves are as follows: 1) Angle globe valves; in angle globe valves, the fluid only needs to change direction once, so that the pressure drop through the valve is smaller than that of conventional structure globe valves. 2) DC type globe valve; in DC type or Y-shaped globe valve, the flow path of the valve body and the main flow path form an oblique line, so that the degree of damage to the flow state is smaller than that of the conventional globe valve, so the pressure loss through the valve is also corresponding Is too small. 3) Plunger stop valve: This type of stop valve is a variant of the conventional stop valve. In this valve, the valve flap and valve seat are usually designed based on the plunger principle. The valve flap is polished so that the plunger is connected with the valve stem, and the sealing is achieved by two elastic sealing rings sleeved on the plunger. The two elastic sealing rings are separated by a collar, and the sealing ring around the plunger is pressed tightly by the load applied to the valve cover by the valve cover nut. The elastic sealing ring can be changed and can be made of various materials. The valve is mainly used for "opening" or "closing", but a special form of plunger or special collar is also available to adjust the flow rate.

Gost Globe Valve

The flow direction of gost globe valve china is determined by the operating conditions, but in most conditions, the flow direction is almost below the spool. Put the letter in the direction of the flow, he has a constant resistance but enough to overcome. For the flow under the spool, the valve is relatively easy to close and the fluid pressure and flow rate change less and less. In addition, the flow under the spool is easy to open because the fluid pushes the bottom of the spool.
The manual shut-off valve can be adjusted to flow characteristics of percentage type, linear type or quick opening type. The flow characteristics determine the expected flow rate representation at a certain position of the valve. In this way, the user can determine the flow rate by the linear position of the manual handwheel. If the spool head is in the throttle position (between fully open and fully closed), the flow moves to the flow opening of the valve seat due to the pressure drop. In the throttle position, the spool head extends slightly into the seat ring to provide corresponding flow at a particular position with given flow characteristics. When retracted and away from the valve seat, a larger flow rate can be achieved. If it extends further toward the valve seat, a smaller flow rate is formed. As the stream moves through the valve seat, the fluid pressure decreases and the speed increases. After the fluid enters the lower part of the stop valve, the flow area increases again, the pressure recovers and the flow rate decreases.
When fluid enters the valve seat or valve spool area, an important design consideration is the table area of the valve body. In a rational state, the flow circulates freely along the valve core and valve seat, so that the flow can enter the valve seat from every direction. If the table area is too narrow in any area (for example, on the back of the cock), the speed may increase, causing noise and abrasion, or turbulence downstream. There are unequal forces acting on the spool head. If the spool head is not guided by the valve seat, it may cause slight deflection of the spool head.
When the forge steel globe valve is closed, the axial force of the handwheel acts on the cock. The force on the surface of the spool exerts pressure on the slightly mismatched angle of the seat ring without allowing any flow through the closing element. In the fully open position, the entire valve seat area is opened to the flow for flow.