Introduction of plastic globe valve

Introduction of plastic globe valve

The opening and closing part of the plastic globe valve (stop valve, Globe Valve) is a plug-shaped valve disc, the sealing surface is a plane or a conical surface, and the valve disc moves linearly along the center line of the valve seat. The movement form of the valve stem, (common name: dark rod), also has lifting and rotating rod type, (common name: open rod) globe valve refers to the valve in which the closing member (disc) moves along the center line of the valve seat. According to this movement of the valve disc, the change of the valve seat port is proportional to the valve disc stroke. Because the valve stem of this type of valve has a relatively short opening or closing stroke, and has a very reliable shut-off function, and because the change of the valve seat port is proportional to the stroke of the valve disc, it is very suitable for flow regulation. Therefore, this type of valve is very suitable for shut-off or regulation and throttling.

Working principle of plastic globe valve

       Plastic globe valve is the most widely used valve. The reason why it is popular is that the friction between the sealing surfaces is small during the opening and closing process, it is more durable, the opening height is not large, it is easy to manufacture, and it is convenient to maintain. It is not only suitable for The closing principle of medium and low pressure, but also suitable for high pressure plastic globe valve is that relying on the pressure of the valve stem, the sealing surface of the valve disc and the sealing surface of the valve seat are closely fitted to prevent the flow of the medium. The plastic globe valve only allows the medium to flow in one direction, and it is directional during installation. The structural length of the RPP plastic globe valve is longer than that of the gate valve, and at the same time, the fluid resistance is large, and the sealing reliability is not strong during long-term operation.

Operation of plastic globe valve

For plastic globe valves, it is necessary not only to install and maintain, but also to operate. When opening and closing the stop valve, the force should be stable and not impacted. Some parts of the high-pressure globe valve that are opened and closed by impact have already considered this impact force and cannot be equal to the general globe valve. When the plastic globe valve is fully opened, the handwheel should be turned upside down a little to make the threads tight to avoid loosening and damage. When the pipeline is first used, there is a lot of dirt inside, the plastic stop valve can be slightly opened, and the high-speed flow of the medium can be used to flush it away, and then gently close (can not be closed quickly or violently to prevent residual impurities from pinching the sealing surface ), turn it on again, repeat this many times, rinse off the dirt, and then put it into normal work. Normally open plastic globe valve, there may be dirt on the sealing surface, when it is closed, it should be washed clean by the above method, and then officially closed. If the handwheel and handle are damaged or lost, they should be assembled immediately, and cannot be replaced with a flexible wrench, so as to avoid damage to the valve stem in all directions, failure of opening and closing, and accidents in production. Some media cool down after the plastic globe valve is closed to shrink the valve parts. The operator should close it again at an appropriate time, so that the sealing surface does not leave a slit. Otherwise, the medium flows through the slit at a high speed and is easy to be eroded. Sealing surface. During operation, if it is found that the operation is too laborious, the reason should be analyzed. If the packing is too tight, it can be loosened appropriately. If the valve stem is skewed, the personnel should be notified for repair. For some globe valves, in the closed state, the closing part is heated and expanded, which makes it difficult to open; if it must be opened at this time, the bonnet thread can be loosened by half a turn to one turn to eliminate the stress of the valve stem, and then the handwheel is turned.