Actuated Ball Valves
To understand what an actuated ball valve is, it may be best to establish what a ball valve is first. In principle the two are the same, but in operation they are completely different. One is automatic, and the latter is worked by hand.
A Simple Ball Valve
A valve itself is nothing more than a means to control the flow of a fluid or other material--water, oil, gas, etc.--in a pipeline or piping system at particular points. Inside the housing of the valve is a "plug," which can be opened or closed to permit or deny this flow. The plug in a ball valve is spherical, though it is not a true ball, as there is a hole (usually the same diameter as the inside diameter of the pipe to which the valve is fitted) bored through the middle. When a ball valve is open, this bore is in line with the pipe, and allows the fluid to continue upstream. When closed, the bore is perpendicular to the direction of flow, essentially creating a seal against it, therefore stopping the flow. This start/stop action is achieved by moving an external lever, wheel, or other handle attached to the ball inside the housing. This is normally done by hand, earning this common example of a ball valve its title as a shut-off valve.
A Simple Actuated Ball Valve
An actuated ball valve performs this operation by means of a power source--usually an electric or pneumatic actuator. Unlike the shut-off valve, which is normally only utilized for line repairs or other reasons to temporarily stop flow, an actuated ball valve starts and stops flow more periodically, and is automatic. An actuated ball valve is often connected to an entire computer system in a plant that allows for full automation of processes.
Ball Valves as Control Valves
A ball valve can be used as a "control valve" as long as it has an actuator AND a positioner. ( a positioner accepts a control signal, usually a 4 to 20 mA or 0-10 volts). This signal is typically sent from a PLC ( programmable logic controller)or DCS ( distributed control system). In the case of an electric actuator, there is a "board" or "card" that is added to actuator. In the case of pneumatic actuators, you need to bolt a electo-pneumatic positioner to the side of the actuator in order to accept the control signal (4-20 mA). For best control in a ball valve, the ball should a a "V" shape in either a 30,60, or 90 degree V. You can approach a turndown ratio of approx. 15-20:1. A "standard or full ported" ball valve can also be used as a control valve, but this configuration will only approach a 8-10:1 turndown ratio.
Alway remember that any type of valve that you want to use as a "control valve" MUST BE SIZED correctly. This entails inlet pressure to the valve, outlet pressure from the valve, as well as maximum desired flow rate and minimum desired flow rate.
Where to Buy Actuated Ball Valves
Now that you know what an actuated ball valve does, you may want to know where to buy one. The folks at ValveMan can help you with sizing of all of your valves on your project, particularly, the control valves. The ValveMan.com valve store can supply your valve needs. We've been in the valve business for over 50 years, and we sell nothing but valves.
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