Manual valve system valve first cited the need to be concerned about the issue of

Manual valve system is a pipeline fluid delivery system control components, it is used to change the access section and the direction of media flow, with a guide, cut-off, regulation, throttling, check, shunt or overflow pressure relief and other functions. Valves for fluid control, the nominal diameter of the valve from a very small instrumentation valve to a diameter of up to 10m of industrial pipeline valves.

A manual valve opening and closing:

1, manual valve is the first of the most widely used valves, its handwheel or handle, is in accordance with the ordinary human power to design, taking into account the strength of the sealing surface and must phase of the closing force. Therefore, you can not use a long lever or long board hand to board movement. Some people are accustomed to the use of plate hand, should pay strict attention to, do not exert too much force, otherwise it is easy to damage the sealing surface, or plate broken handwheel, handle.

2, open and close the valve, the force should be smooth, not impact. Certain impact opening and closing of the first high-pressure valve components have been taken into account this impact and general valves can not be equal to Gunn.

3, for steam valves, before opening, should be pre-heated, and exclude condensate, open, should try to slow, so as to avoid the phenomenon of water shock.

4, when the valve is fully open, the handwheel should be reversed a little, so that the threads are tight, so as not to loosen the damage. For open stem valves, to remember the fully open and fully closed when the stem position, to avoid fully open when the impact on the dead centre. And easy to check whether it is normal when fully closed. If the valve office off, or the spool seal embedded between the larger debris, fully closed when the stem position should be changed.

5, the pipeline for the first time, more internal dirt, the valve can be slightly open, the use of high-speed flow of the medium, to wash it away, and then gently closed (can not be closed quickly, violently closed to prevent residual impurities clamping the sealing surface), open again, and so on for many times, wash out the dirt, and then put into normal operation.

6, always open the valve, the sealing surface may be sticky with dirt, close the above method should also be used to flush it clean, and then formally closed tight.

7, such as handwheels, handles are damaged or lost, should be matched immediately, can not be replaced with a live plate hand, in order to avoid damage to the valve stem quartet, opening and closing, so that accidents occur in production.

8, some media, in the manual valve closed after cooling, so that the valve contraction, the operator should be closed again at the appropriate time, so that the sealing surface does not leave a slit, otherwise, the medium from the slit high speed flow through, it is easy to erode the sealing surface.

9, operation, if you find the operation is too laborious, should analyse the reason. If the packing is too tight, it can be appropriately relaxed, such as crooked stem, should notify the personnel to repair. Some valves, in the closed state, the closure of the thermal expansion of the parts, resulting in difficulties in opening; if you have to open at this time, the bonnet threads can be loosened by half a turn to a circle, to eliminate the stress on the valve stem, and then the plate hand wheel.

Second, precautions:

1, 200 ℃ above the high temperature valve, due to installation at room temperature, and after normal use, the temperature rises, the bolt thermal expansion, the gap increases, so it must be tightened again, called the ‘hot tight’, the operator should pay attention to this work, otherwise prone to leakage.

2, when the weather is cold, the water valve is closed for a long time, should be excluded from the water behind the valve. Steam valve after stopping the steam, but also to exclude condensate. The bottom of the valve, such as silk plug, it can be opened to drain.

3, non-metallic valves, some hard and brittle, some low strength, operation, open and close the force can not be too large, especially not to make violent. Also pay attention to avoid objects knocking.

4, the use of new manual valves, packing do not press too tightly to the degree of no leakage, so as to avoid too much pressure on the valve stem, accelerate wear and tear, and opening and closing effort.