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electric ball valves

Electric ball valves are used to control the flow of liquids and gases. By rotating a ball with a bore a quarter turn, flow is allowed or blocked. An electric motor provides the rotational motion.  They are generally used as reliable shut... Read more Read more

electric ball valves

electric ball valves | Tameson

Electric ball valves are used to control the flow of liquids and gases. By rotating a ball with a bore a quarter turn, flow is allowed or blocked. An electric motor provides the rotational motion.  They are generally used as reliable shut off valve, but can also be used for flow control in some cases. They are energy efficient, they only consume energy during the opening or closing of the valve. Its robust construction provides consistent performance and durability. 

Electric valve actuator selection criteria

  • Torque
  • Response time
  • Control method
  • Voltage
  • Mounting
  • Fail-safe
  • Modulation
  • Material
  • IP protection grade (IEC 60529)
  • ATEX certification

Torque

Ball valves are quarter turn valves, they need to rotate 90° to fully open or close. A certain amount of torque is needed to open or close. It is important to ensure that the actuator delivers enough torque for your situation. There are two types of torque that must be kept in mind:

  • Breakaway torque: when a valve is fully opened or closed, a certain amount of torque is needed to start moving. The breakaway torque generally is 30% higher than the run torque. 
  • Run torque: this is the amount of torque needed to keep rotating. 

Take into account that torque can increase after long periods of standstill and is strongly dependent on medium type, pressure, temperature and wear. At Tameson, we created combinations that follow these rules and thus will have no torque related problems.

Response time

The response time is the time needed to rotate the valve 90 degrees. The response time is affected by the internal gearing and the motor power. The response time is a critical application specification together with the torque specification.

Electric control method

Electric actuators are generally controlled using a 2-point or 3-point control:

  • 2-point control actuators (open-close): This control consists out of 3 wires, +, -, and a control wire. When there is a current over the control wire the valve will open. The motor is only powered during opening and closing.
  • 3-point control actuators (open-close): This control consists out of one negative and one positive wire. The two positive wires are control wires. Powering one of the 2 control wires can either open or close the valve. The motor is only powered during opening and closing.
  • 4-20 mA control actuators (modulating): This control consists out of out of one negative, one positive and two control wires. The two control wires are used for the modulating 4-20 mA signal. This control allows the user to set the valve at any position between 0 and 90 degrees.

Voltage

Electric ball valves are available in a wide variety of voltages in AC or DC. Some actuators accept a voltage range and detect AC and DC power. Make sure that your power supply conforms to the specifications of the actuator.

Mounting

It is important to know how the actuator is mounted on the ball valve. We sell both brand specific and standardized ball valve actuator combinations. A commonly used mounting standard is the ISO 5211 standard. Under this standard there are different flange types. These types vary by maximum flange torque, number of screws, dimension, studs or bolts. 

Fail-safe

Standard electric ball valves require a power supply to open and close. If the power fails, the valve remains in the latest position. Certain actuators have a fail-safe safety feature built in. The fail-safe feature opens or closes the valve in case of a power failure. The fail-safe system typically uses a spring mechanism or a battery to operate. Backup battery systems are often called battery safety return (BSR) in which a battery powers the valve to close or open. The BSR’s charging time depends on the battery and actuator size. 

Manual override

In some actuators a manual override is implemented. This is used as a safety precaution if the electrical system fails. It can also be used during commissioning or testing.

Position feedback

Limit switches

Limit switches define the end positions (normally 90°). Once the actuator reaches a limit switch the power supply to the motor shuts down. Some actuators have additional limit switches that can be used for position feedback. Sometimes the limit switches can be adjusted, we do not recommend doing this. Adjusting the limit switches is only advised if it is needed for the application. 

Modulation

For certain applications it is desirable to have a modulating actuator control, often referred to as DPS (digital positioning system). DPS enables accurate valve position control between fully opened and fully closed. 

Material

The valve material must be suitable for your situation. If you choose the wrong valve material they might get damaged. Tameson offers high quality materials as a manufacturer.

Valve housing materials

The most common housing materials for these kinds of valves are brass, stainless steel and PVC.

  • Brass: this material is used for (drinking) water, oil, air, gas and many other media. Demineralized water or chloride solutions (e.g. seawater) may cause dezincification which damages the valve. 
  • Stainless steel: this material is used for corrosive media and in aggressive environments. It is suitable for seawater, swimming pools, high temperature media and a large amount of chemicals. 
  • PVC: They are suitable for water, but also popular for most of the salt solutions, bases, acids and organic solvents. PVC is not suitable for media with temperatures exceeding 60 °C, aromatic hydrocarbons and chlorinated hydrocarbons. These valves have a lower pressure rating than brass or stainless steel.

Valve sealing materials

Most valve seats are made of PTFE (Teflon). It has a very good chemical resistance, low friction and a high melting point of approximately 330 °C. 

IP protection grade (IEC 60529)

It is important to look into the needed IP (Ingress Protection) class for your application. The IP rating specifies the degree of protection against water, dust and other environmental hazards.