Adjustment of Electric Gate Valve Torque Limiting Mechanism

Electric gate valves are widely used in various working environments, especially in pump stations, pipeline systems, and other fluid control settings. To ensure the safe operation of electric gate valves under different working conditions, the proper setup and adjustment of the torque limiting mechanism is essential. The main purpose of the torque limiting mechanism is to limit the excessive torque generated during the opening and closing of the valve, preventing motor overload, valve damage, or wear of the sealing surface. This article discusses the torque limiting mechanism of electric gate valves, detailing its working principle, adjustment methods, and applications in different environments.

Working Principle of the Torque Limiting Mechanism

The torque limiting mechanism in electric gate valves is typically used to limit the torque generated by the electric actuator, ensuring the valve’s safety and long service life. When the valve is closed, a pressure difference (such as water or air pressure) causes an imbalance in pressure across the valve disc, resulting in varying operating torque. The torque limiting mechanism sets a reasonable torque value that automatically limits the motor’s torque during the valve opening or closing process, preventing mechanical damage caused by excessive torque.

Adjustment Principle of the Torque Limiting Mechanism

Depending on the valve's operating environment, the torque limiting mechanism must be adjusted appropriately. The torque requirement of the valve varies with different water or air pressure differentials.

1. Locations with Low Pressure Differential

If the electric gate valve is installed in an environment with a low pressure differential, the torque limiting mechanism should be set to a lower torque value. This helps prevent motor overload while ensuring smooth valve operation.

2. Locations with High Pressure Differential

In environments with a significant pressure differential, the torque limiting mechanism should be set to a higher torque value. For example, when the electric gate valve is installed on the discharge pipeline of a pump station, the pressure increases after the pump starts, which increases the torque required to open the valve. Therefore, the torque limiting mechanism must be adjusted to ensure the valve can open under higher pressure conditions.

Specific Steps for Adjusting the Torque Limiting Mechanism

For adjusting the torque limiting mechanism on the electric gate valve, the following steps should be followed.

Remove the Side Cover: Begin by removing the side cover of the electric valve’s housing to expose the torque limiting mechanism.
Loosen the Adjustment Nut: Loosen the set screw in the adjustment nut to release the spring tension. Relax the adjustment spring and set it to its loosest position.
Tighten the Adjustment Nut: Next, adjust the set screw in the adjustment nut so that it aligns with the shaft slot. Ensure that the top of the screw is accurately aligned with the shaft slot. If not, slightly rotate the adjustment nut to the correct position.
Secure the Adjustment Nut: After completing the adjustments, tighten the set screw to secure the adjustment nut.
Reinstall the Side Cover and Test the Valve: Finally, reinstall the side cover, open the valve, and perform a test. If the torque limiting mechanism activates, it indicates that the spring is too loose and needs to be adjusted to the proper tightness. Continue adjusting until the valve opens and closes normally, with the torque limiting mechanism no longer triggering.

Impact of Operating Environment on Torque Limiting Mechanism

The adjustment of the torque limiting mechanism varies depending on the operating environment, primarily influenced by changes in water or air pressure differential.

1. Torque Limiting in Pump Stations

In pump stations, electric gate valves are typically used to control the discharge pipeline. After the pump starts, the discharge pressure increases, and the valve must overcome a higher pressure difference to open. Therefore, the torque limiting mechanism needs to be set to a higher value to ensure the valve can open under higher pressure. Additionally, due to the high and unstable water flow velocity at the pump outlet, the valve disc may move forward and backward due to water flow impact, causing wear on the sealing surface and potentially leading to leakage. Therefore, it is critical to ensure that the valve is fully opened and closed in the pump station to avoid partial openings that could damage the sealing surface.

2. Adjusting Torque in High Pressure Differential Environments

In environments with a large pressure differential, such as the inlet and outlet of pipelines, the torque limiting mechanism needs to be adjusted based on the actual operating pressure. In such cases, the torque required to open and close the valve is higher, and the torque limiting mechanism must be properly set to prevent valve damage while ensuring safe operation.

Usage Suggestions and Precautions

When using electric gate valves and their torque limiting mechanisms, the following important suggestions and precautions should be observed to ensure proper valve operation, extend service life, and avoid system failures.

1. Avoid Over-Adjustment

When adjusting the torque limiting mechanism, avoid setting the torque too low, as this may prevent the valve from fully closing, leading to water or gas leakage.

2. Do Not Use Electric Gate Valves to Regulate Flow

Electric gate valves are not suitable for flow regulation. Frequent adjustments may accelerate the wear of the sealing surface and shorten the valve’s service life. The main function of electric gate valves is to open and close fluid flow, not to control flow rates.

3. Sealing Surface Protection

In high water flow velocity environments, especially near pump stations, the sealing surface of electric gate valves is vulnerable to damage from water flow impact. To prolong the valve's service life, ensure that the valve is fully opened when in use and prevent impacts caused by water flow.

Conclusion

The torque limiting mechanism in electric gate valves plays a key role in ensuring normal valve operation, protecting the motor from overload, and extending the valve's service life. Proper torque setting and adjustment not only help avoid valve damage but also ensure the safe and stable operation of the system. In practical applications, users should adjust the torque limiting mechanism according to the environment's pressure differential to ensure optimal performance of the electric gate valve under various working conditions.