In large pumping stations, hydropower stations and long-distance pipeline systems, you will find that hydraulic butterfly valves are widely used due to their characteristics such as high torque output and fast response.
Would you like to know if the hydraulic butterfly valve is suitable for your project? This article will comprehensively introduce hydraulic butterfly valves to help you make judgments in the shortest possible time and provide a reference for subsequent procurement or design.
What is a Hydraulic Butterfly Valve?
The hydraulic butterfly valve is a special type of butterfly valve. It relies on the pressure provided by the hydraulic system to control the opening and closing of the valve disc, thereby controlling the opening or cutting off of the fluid in the pipeline.
Structure of a Hydraulic Butterfly Valve
Valve Body
The valve body is the load-bearing component of the hydraulic butterfly valve. It provides stable support for the entire installation and operation of the valve. The valve body is usually made of pressure-resistant and corrosion-resistant materials such as cast steel or stainless steel.
The valve body is of an overall cylindrical structure. It can be securely connected to the pipeline system through flanges, socket couplings or lug-type structures.
Butterfly Disc
The most crucial component in a hydraulic butterfly valve is the circular butterfly disc. It is installed at the center of the flow channel inside the valve body and is fixedly connected to the valve stem through keyways or threads.
According to your working conditions, the butterfly disc can adopt a central or eccentric structure. The butterfly plate achieves complete opening or closing of the flow channel by rotating 90°.
Valve Stem
The valve stem is a component for power transmission and is made of high-strength stainless steel. The valve stem passes through the upper and lower ends of the valve body and is firmly connected to the butterfly disc.
The valve stem can transmit the torque generated by the actuator to the butterfly disc, allowing it to rotate at a predetermined angle. The valve stem has sufficient torque-bearing capacity. At the same time, its surface will undergo precision machining to reduce friction loss with seals and bearings.
Hydraulic Actuator
The key difference between hydraulic butterfly valves and manual or pneumatic butterfly valves lies in the driving actuator. Hydraulic actuators usually include components such as hydraulic cylinders and pistons. It is the key component for achieving automatic control in the hydraulic butterfly valve.
The hydraulic actuators use hydraulic pressure to convert energy into mechanical torque, which automatically completes valve opening and closing actions.
The Working Principle of the Hydraulic Butterfly Valve
When the valve needs to be operated, the hydraulic pump starts and delivers hydraulic oil through the pipeline to the hydraulic actuator. After the hydraulic oil enters the actuator, it will drive the internal piston or blade to perform linear movement.
This linear motion is then converted into a rotational motion through the mechanical structure within the actuator. This rotational torque will be directly transmitted to the valve stem of the hydraulic butterfly valve.
The rotation of the valve stem drives the butterfly disc connected to it to rotate synchronously within the valve body. By controlling the flow direction and volume of the hydraulic oil, you can make the butterfly plate rotate to a specific angle.
When the butterfly disc is parallel to the direction of the fluid flow, the hydraulic butterfly valve is in the fully open position. When the butterfly disc rotates to be perpendicular to the flow direction, it completely blocks the flow channel and the valve is closed. By stabilizing the butterfly disc at any angle between the two, you can achieve linear regulation of the flow rate.
Types of Hydraulic Butterfly Valves
Hydraulic Counterweight Butterfly Valves
The hydraulic counterweight butterfly valve is additionally equipped with a mechanical counterweight device. This counterweight is usually fixed onto the valve stem. The design of the counterweight helps to improve the stability of valve operation.
After the hydraulic system releases pressure, the counterweight uses its own gravity to assist in resetting the butterfly disc. This can prevent the hydraulic butterfly valve from moving too quickly or getting out of control, avoiding situations such as water hammer and other impacts.
Accumulator Hydraulic Butterfly Valve
The accumulator hydraulic butterfly valve integrates a hydraulic accumulator in the hydraulic actuation system. The function of the accumulator is to store a certain amount of hydraulic energy.
When there is a fluctuation in system pressure or a sudden increase in the demand of the actuator, the accumulator can quickly release the hydraulic energy, ensuring the stable and rapid operation of the butterfly valve. This makes the butterfly valve operate stably and respond quickly.
This design is very important for systems with drastic pressure changes or requiring more reliable closure control. The accumulator hydraulic butterfly valve can better cope with changing loads and improve system stability.
Classified by the Eccentric Structure of the Butterfly Disc
Concentric Hydraulic Butterfly Valve
The structure of the concentric hydraulic butterfly valve is the most fundamental. The rotation center of the butterfly plate coincides with the center of the valve body flow channel and the center of the valve shaft. The structure is symmetrical and simple.
Throughout the entire stroke of the switch, the butterfly disc remains in contact with the valve seat and generates friction. You can use the concentric hydraulic butterfly valve in conventional working conditions with relatively low pressure and temperature requirements.
Double Offset Hydraulic Butterfly Valve
The axis of the valve disc of the double offset hydraulic butterfly valve is offset in two directions relative to the center line of the valve seat and the center line of the pipeline.
When the hydraulic actuator drives the valve to open, the butterfly disc can quickly separate from the valve seat. The butterfly disc only contacts the sealing surface of the valve seat at the moment of complete closure, which significantly reduces friction loss.
The double offset hydraulic butterfly valve can reduce the requirement for operating torque. Meanwhile, the wedge force generated by the eccentric structure can enhance the sealing effect. Therefore, the double offset hydraulic butterfly valve is suitable for medium and high-pressure conditions that require more durable sealing performance.
Triple Offset Hydraulic Butterfly Valve
The triple offset hydraulic butterfly valve is a high-performance hydraulic butterfly valve further developed on the basis of the double offset structure. It adds an inclined eccentricity of the butterfly disc seal surface relative to the valve axis.
During the entire switching process, the butterfly disc has no contact with the valve seat. It only fits in at the last moment of the closing process.
The sealing of the triple offset hydraulic butterfly valve does not rely on the elastic deformation of the rubber. It uses the huge torque provided by the hydraulic actuator to press the metal sealing ring tightly onto the valve seat. This means that the higher the pressure, the tighter the seal.
The triple offset hydraulic butterfly valve is widely applied in industrial scenarios with extremely high temperatures, high pressures and strict requirements for sealing performance.
Advantages of the Hydraulic Butterfly Valve
Strong Driving Force
The key advantage of the hydraulic butterfly valve lies in its power source. The hydraulic drive system can generate stable and powerful torque, which means it can drive large-diameter butterfly valves or operate stably under high pipeline pressure.
Accurate Control
Due to the precise control of pressure and flow by the hydraulic system, the hydraulic butterfly valve can achieve accurate flow regulation.
By controlling the movement of the hydraulic actuator, you can accurately control the butterfly disc at any angle between fully open and fully closed. The hydraulic actuator has high rigidity and will not drift after being positioned.
This can achieve continuous and linear flow rate changes, which meet the requirements for accurate control of the process.
Compact Structure
The hydraulic butterfly valve retains the simple and compact design of a butterfly valve, which means it occupies relatively little space in the piping system. It is easier to install in spaces with limited space and has a lighter overall weight.
Respond Promptly
The actuator of the hydraulic butterfly valve is controlled by the changes in hydraulic oil pressure. It can complete the action from opening to closing quickly and stably. This action response characteristic makes the hydraulic butterfly valve suitable for systems that require rapid switching of fluid control.
High Adaptability
The hydraulic butterfly valve is suitable for various types of media, including liquids, gases, steam and suspensions. The hydraulic drive method does not generate electric sparks during operation. Therefore, the hydraulic butterfly valve id also suitable for harsh working conditions such as high temperature, humidity, flammability, and explosiveness.
The Application of Hydraulic Butterfly Valves
Water Supply and Sewerage Works
In urban water supply and drainage projects, hydraulic butterfly valves are the key equipment in the water supply pumping stations and the sewage lift pumping stations. It is mainly installed on the outlet pipeline of the water pump.
The hydraulic butterfly valve can prevent the backflow of the medium in the pipeline when the pump is stopped. Meanwhile, the hydraulic butterfly valve is suitable for large-diameter and high-flow pipelines.
It can meet the control needs of large-scale fluid transportation such as centralized water supply and sewage discharge in cities, keeping the stable operation of the water supply and drainage system.
Hydropower Station
At the water intake ports, pressure pipes and tailwater pipelines of hydropower stations, hydraulic butterfly valves are widely used as emergency shut-off valves and maintenance valves.
Hydraulic butterfly valves can be used in conjunction with bypass valves to achieve pressure balance and opening operations in pipelines according to the special requirements of turbine start-up.
And when the unit needs to be shut down or in emergencies, the hydraulic butterfly valve can achieve fast and reliable closure.
Energy Industry
In oil and gas transportation and processing, hydraulic butterfly valves are used to control the transportation paths of crude oil, natural gas, and other fluids. It can withstand medium to high-pressure environments.
Combined with an automated control system, hydraulic butterfly valves can be used for pipeline cutting, process scheduling, and emergency shutdown. Therefore, hydraulic butterfly valves are widely used in oil pipelines, refining equipment, and storage tank systems.
HVAC
In the HVAC systems of large commercial and industrial buildings, hydraulic butterfly valves are used to manage the flow of cooling water, hot water and circulating fluids.
By integrating with the automatic control system, hydraulic butterfly valves can accurately adjust the flow rate of pipelines in various areas, thereby improving energy efficiency and environmental comfort.
Common Troubleshooting of Hydraulic Butterfly Valves
The Hydraulic Butterfly Valve Operates Slowly or Gets Stuck.
This is usually due to insufficient hydraulic power or excessive mechanical resistance. You need to check whether the hydraulic pump has weak output and whether there is internal leakage in the system.
At the same time, check whether the valve stem bearing is insufficiently lubricated, whether the packing gland is too tight, and whether there are impurities between the butterfly plate and the valve body.
Internal Leakage of the Hydraulic Butterfly Valve
The most common reason is that the sealing surface has been damaged.
For soft-sealed valves, you should check whether the rubber valve seat is aged or damaged. For hard-sealed valves, check whether the metal sealing surfaces have any erosion, scratches or deformation.
You can also confirm whether the butterfly plate was not fully closed due to improper positioning.
Exterior Leakage of the Hydraulic Butterfly Valve
It mainly occurs in several areas.
Leakage at the valve stem packing usually means that the packing is worn or needs to be re-tightened.
If there is leakage at the connection between the valve body and the end cover or the hydraulic cylinder, it might be caused by the aging of the sealing gasket or the loosening of the fastening bolts.
If the hydraulic pipeline joint is leaking, you need to check the sealing gasket of the joint and retighten it.
FAQs
What is the Two-Stage Closure of the Hydraulic Butterfly Valve?
This divides the complete closure action of the hydraulic butterfly valve into two consecutive stages: the rapid approach to the closed position stage and the slow completion of the closing stage.
In a large part of the opening, such as about 70°, the valve closes at a faster speed to quickly cut off fluid flow. This can minimize the duration of the medium backflow as much as possible.
When the butterfly plate approaches the last small angle of complete closure, such as about 20° remaining, the valve slowly closes. This can reduce the impact of the medium and water hammer effect, prevent pipe bursting and pump reversal, and protect system safety.
Does the Hydraulic Butterfly Valve Require Lubrication?
Hydraulic butterfly valves usually do not require frequent lubrication of the entire internal structure of the valve. The rotating bearings and seals inside the hydraulic butterfly valve have been subjected to long-term lubrication treatment during the manufacturing process.
However, if the valve is not in use for a long time, the working environment is dry, or there is high mechanical friction inside, you also need to apply appropriate lubrication as recommended by the manufacturer.
Is There an Emergency Operation Method When the Hydraulic Butterfly Valve Malfunctions?
Yes. Most hydraulic butterfly valves are equipped with a manual emergency operation device.
In case of hydraulic system failure or power outage, you can disconnect the transmission structure from the hydraulic actuator and connect the manual shaft instead. Then, by shaking the handwheel, the valve stem and butterfly plate are directly driven to rotate, completing the opening and closing action.
Furthermore, after the hydraulic drive is deactivated, the hydraulic counterweight butterfly valve can achieve emergency closure by relying on the gravitational force of the counterweight, without the need for manual intervention.
Does the Hydraulic Oil of the Hydraulic Butterfly Valve need to be Replaced Regularly? And How often should it be Replaced?
Yes. Generally speaking, the replacement period for hydraulic oil is usually between six months and one year. If the working conditions are harsh such as high temperature, high dust, and strong corrosiveness of the medium, you need to shorten the replacement cycle.
Can the Hydraulic Butterfly Valve be Set in the Middle Position to Regulate the Flow Rate?
Yes, but there are limitations. Through the control system, the hydraulic butterfly valve can stop at any intermediate position during the opening or closing process.
However, we do not recommend long-term use for precision throttling. Under high-pressure differential conditions, continuous small opening throttling may cause severe erosion, vibration and noise at the edge of the butterfly disc and the cavitation area.
Final Thoughts
Hydraulic butterfly valves perform exceptionally well in large-diameter and heavy-load conditions due to the high torque and rapid response provided by hydraulic drive.
Target has been deeply involved in the field of hydraulic components for many years. We can provide you with a full range of services about hydraulic butterfly valves, including selection consultation, customized solutions, high-quality product supply, professional installation guidance, and after-sales maintenance.
If you have any further questions about hydraulic butterfly valves, please feel free to contact us！
