T-T Flow offer actuated valve packages for reliable flow control in a variety of applications, sourcing electric, pneumatic and hydraulic actuators from leading manufacturers. This is complimented by our actuator fitting service from T-T HQ in Cheshire, where we assemble, configure and function test actuators so they are delivered ready to install.
A valve actuator is an electric, hydraulic or pneumatically powered device that opens, closes or otherwise adjusts the position of a valve obturator (such as the valve ball, wedge or plug) without direct manual intervention.
Valve actuators are used in applications where the valve is in a hazardous or hard to reach area and requires remote operation, or when manual operation of a large valve poses a health and safety risk to operatives.
Expert Selection & Sizing
Our experts are qualified to size and select electric, pneumatic and hydraulic actuators from Rotork, AUMA, Limitorque, Flowtork and other leading valve actuator manufacturers.
The team’s knowledge, expertise and in-house fabrication facilities enable them to produce actuation solutions for the most challenging industries, including ATEX-rated applications and processes.
T-T provides quarter-turn and multi-turn actuators for precise flow control or on/off duties, coupled with a range of gearboxes (worm, bevel, spur and reversing) and mounting or spool kits suitable for assembly to our range of valves:
Gate valves
Knife gate valves
Eccentric plug valves
Butterfly valves
Penstock valves
Ball valves
Actuator Fitting Services
In our valves workshop, our engineers assemble valves and actuators and complete testing in-house so that your solution is delivered to site ready for installation. We also offer witness testing on-site at T-T HQ for your assurance.
In addition standard local and remote actuation services, T-T Flow also fabricate extension spindles and custom machine drive bushes to suit; providing complete, actuated valve packages from a single source.
Valve Actuator FAQs
What are the different types of valve actuator?
Actuators transform energy from one of three sources into a mechanical motion: electric, hydraulic (liquids – usually oil) and pneumatic (compressed air).
Electric actuators transform electricity from a motor into physical force and are ideal for accurate valve obturator positioning thanks to their consistent and continuous power input. For this reason, electric actuators are often found in precision applications such as food manufacturing or water treatment.
Hydraulic actuators convert pressure from compressed fluids into movement – they can generate the greatest overall force out of the three, but are the slowest to cycle. Because of this, hydraulic actuators are best suited to valves in heavier-duty applications like power plants.
Pneumatic actuators take in air at atmospheric pressure and compress it mechanically to generate a higher pressure, converting this energy into mechanical motion. Pneumatic actuators are fast acting and have short operating cycles, making them suitable for applications such as braking systems.
What is the difference between quarter turn and multi turn actuators?
Multi-turn and quarter-turn refers to the number of rotations an actuator must complete in order to fully operate a valve. Quarter turn actuators only require partial rotation to fully operate (open or close) a valve, whereas multi-turn actuators need multiple rotations.
Whether you need a multi or quarter turn actuator depends on the valve it will be fitted to.
Quarter turn actuators get their name from the quarter turn valves that they are designed to operate, which onl need a 90° turn to actuate and are commonly used for isolation duties due to their fast and simple operation.
Multi-turn actuators are made for valves that require multiple rotations to fully operate, generally used in applications that require precise valve positioning, such as chemical dosing.
What is the difference between on/off duty and modulating actuators?
On/off actuators only have two positions, open or closed. This basic control function makes on/off actuators suitable for use in isolation duties with gate valves, knife gate valves, penstock valves and plug valves.
Modulating actuators allow for more precise flow control and can be positioned at increments between fully open and fully closed to vary flow rate through the valve. Modulating actuators are often used in HVAC systems, irrigation systems and wastewater treatment plants with eccentric plug valves, butterfly valves and ball valves.
Both kinds of actuator can be automated to position the obturator based on input signals such as tank level, flow rate, system pressure or liquid temperature, improving system efficiency.
What is the difference between rotary actuators and linear actuators?
Linear and rotary actuators produce movement in different directions:
Linear valve actuators move in a straight line between two fixed points to create an up and down, back and forth or side to side motion.
Rotary valve actuators convert energy into rotary motion via a shaft, moving in degrees with reference to a central point.
What are the benefits of valve actuation?
Precision – Modulating actuators allow for the obturator to be positioned anywhere between fully open and fully closed based on an input signal, facilitating more fine-tuned control than simply fully open or closed.
Automation – Larger sites with multiple actuated valves can share common communication protocols such as Profibus, Modus and HART to facilitate efficient process automation.
Health and safety – Actuators can generate the force or torque needed to operate large valves and valves in high pressure pipelines, eliminating the risk of injury due to manual operation. Actuators also provide remote valve operation, negating the need for operatives to enter hazardous spaces.
Reliability – Actuators open, close and position valve obturators more reliably than manual operatives as their positioning is based on an input signal.
What information is needed to size an actuator?
A twisting force is needed to rotate the valve stem, this is known as torque and generally expressed in Nm (Newton metres) or lb-ft (pounds-feet).
The torque value together with the number of stem turns (or part turns) is normally needed to size an actuator.
Why are torque values quoted as opening torque rather than closing torque?
T-T Flow will always quote opening torque values in Nm (Newton metres), including any safety factor, based upon a known line pressure.
Sometimes the phrase 'bareshaft torque' is used to refer to a torque value without any safety factor included. Generally, the opening torque will be around 20% greater than the closing torque as more force is needed to remove the obturator from its seat. Mechanical advantage can be gained from using a gearbox.
If in any doubt, please consult the team for further advice.
How to commission a metal seat gate valve?
Here is a simplified overview of how to commission a multiturn actuator to a metal seat gate valve.
Failure to observe the following may result in equipment damage.
Mechanically fix the actuator to the valve or gearbox
Make the electrical connection and ensure actuator powers up correctly
Close the valve obturator manually using the mechanical override (handwheel)
Set the close limit switch
Set the closed trip torque (torque value dependant on actual working pressure)
Fully open the valve obturator manually using the mechanical override (handwheel)
Set the open limit switch
Set the open trip torque (torque value dependant on actual line pressure)
Warning:
Commissioning must be undertaken by competent engineers to avoid equipment damage
Closing on torque seating can result in wedge seizure and equipment damage
Never power the obturator into the seat - in the first instance this must be done manually
In the unlikely events the wedge becomes seized, consult us immediately
Read about some of our most challenging and interesting projects
Actuated Valve Package for £39m Water Treatment Works
T-T Flow® were approached by Southeast Water’s appointed framework contractor for a single source, actuated valve package for a new £39 million water treatment works. The team specified modulating actuators from Rotork, fitting and function testing each valve and actuator before despatch.
Actuated Eccentric Plug Valves for Sustainable Manufacturer
As part of an award-winning food manufacturer expanding their production facilities, T-T Flow® was selected to supply actuated plug valves that would provide reliable isolation and flow modulation in-line with environmental regulations and the company’s B Corp certification.
Actuated Gate Valves for Wastewater Treatment Works
Having been approached by Welsh Water for replacement isolation valves at Beaumaris Wastewater Treatment works, the team sourced, fitted and supplied electrically actuated gate valves specified for long-term isolation duty in the harsh environment.