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8 Necessary Technical Factors that Need to Be Considered When Purchasing Valves 3

  • 2021-05-09 19:21

3. Variable speed transmission box of butterfly valve

    3.1 The material of the box body and the internal and external anti-corrosion requirements are consistent with the valve body principle.

    3.2 The box body should have sealing measures, and the box body can withstand 3 meters of water column immersion after assembly.

    3.3 The adjustment nut of the opening and closing limit device on the box body should be inside or outside the box, but special tools are required for operation.

    3.4 The design of the transmission structure is reasonable. It can only drive the valve shaft to rotate when opening and closing, without causing it to move up and down, and the transmission parts will bite properly, and no separation and slippage will occur when opening and closing with load.

    3.5 The variable speed transmission box body and the valve shaft seal cannot be connected into a leak-free whole, otherwise reliable measures to prevent leakage should be provided.

    3.6 There is no debris in the box, and the gear bite part should be protected by grease.


4. Valve operating mechanism


    4.1 The opening and closing direction of the valve during operation should always be closed clockwise.

    4.2 Since the valves in the pipe network are often opened and closed manually, the number of opening and closing revolutions should not be too much, even for large-diameter valves, it should be within 200-600 revolutions.

    4.3 In order to facilitate the opening and closing operation of one person, the maximum opening and closing torque should be 240N-m under the pipeline pressure condition.

    4.4 The opening and closing end of the valve should be a square tenon, with standardized dimensions, and face the ground so that people can directly operate it from the ground. Valves with roulette are not suitable for underground pipe networks.

    4.5 Display panel of valve opening and closing degree

    4.5.1 The scale line of the valve opening and closing degree should be cast on the gearbox cover or on the shell of the display panel after changing the direction, all facing the ground, and the scale line should be painted with phosphor to show eye-catching;

   4.5.2 The material of the indicator disc needle can be made of stainless steel plate under good management, otherwise it is painted steel plate, do not use aluminum skin;

    4.5.3 The indicator disc needle is eye-catching and securely fixed. Once the opening and closing adjustment is accurate, it should be locked with rivets.


If the valve is buried deeply, and the distance between the operating mechanism and the display panel is ≥1.5m from the ground, an extension rod facility should be provided, and it should be firmly fixed so that people can observe and operate it from the ground. In other words, the opening and closing operations of valves in the pipe network are not suitable for downhole operations. 

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