INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS
If you are looking for more details, kindly visit Xingyu.
Log In
Are you an
Engineering professional?
Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving . By joining you are opting in to receive .
Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Eng-Tips Posting Policies
pneumatic vs electro-pneumatic valves
thread408- Forum Search FAQs Links MVPsForum
Search
FAQs
Links
MVPs
(Civil/Environmental)
(OP)
5 Jan 21 17:43Having a debate with colleagues whether there is a difference between these two types of pneumatic actuated valves. Can't find a clear definition which would explain the difference, but don't all pneumatic valves have electric solenoids (AC or DC) to control the air flow to the valves cylinder or diaphragm housing (or a positioner if its a modulating valve)? The solenoids require electricity to open or close, so does that not make the whole assembly electro-pneumatic valves (we just refer to them as pneumatic actuated valves or pneumatic valves)? Or is there such thing aa a fully pneumatic valve without requiring electricity of some form to control a solenoid or positioner?
Replies continue below
(Mechanical)
5 Jan 21 17:54Purely pneumatic CVs have pneumatic positioner (without electrical intervention). Electro-pneumatic valve will receive position signal from an electronic control system or positioner and final control element is pneumatic. It is similar to purely hydraulic vs electro-hydraulic control valves(as normally used for steam/gas turbines).
Engineers, think what we have done to the environment !https://www.linkedin.com/in/goutam-das-b30/
(Marine/Ocean)
5 Jan 21 17:54There are valves that are operated entirely by air. They are typically called pilot operated valves.
(Mechanical)
12 Feb 21 07:06i feel definition of pneumatic or electro-pneumatic valves were some what old. As already few experts here expressed, pneumatic valve operates only by means of compressed air and the entire control is done by means of mechanical linkages. An electro-pneumatic valve involves solenoids, motors or any other electrically operated devices to operate the valve and control the valve. However, in present days one can not imagine a pure pneumatic valve to put in any kind of industry, be it cement, chemical, food, manufacturing or any other. Even a presence of solenoid valve in the valve assembly should be treated as electo-pneumatic or electro-hydraulic valve. With this definition, the valve hence forth attracts several other regulations and certifications in addition to mechanical safety. Hope this is helpful!
Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.
If you are looking for more details, kindly visit Electro Pneumatic Valve.
Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.
Click Here to join Eng-Tips and talk with other members! Already a Member? Login
A positioner for a control valve is used to adjust a valve&#;s position based on a desired set point for a process variable, whether it be pressure, temperature, or flow.
Below, we&#;ll talk about why you might want to use them, how the three main types of positioners work, and the options that Kimray provides.
Producers typically install valve positioners on the yolk or top casing of a pneumatic actuator for linear control valves. On rotary control valves, the valve positioner is installed in line with the valve and actuator stems on top of the actuator or on the side of the actuator. Installation depends on what type of actuator one uses.
Affixing the positioner to the actuators allows the positioner to measure the stem travel (linear valves) or degree of rotation (rotary valves). This also changes the position of the valve as required based on the input signal from the instrument controller.
When the process variable differs from the desired set point, the instrument controller sends an electrical or pneumatic signal to the positioner. This varies its pneumatic output to the actuator to move the valve open or closed accordingly. This occurs until the process variable reaches the desired set point.
There are 3 primary types of positioners:
A Pneumatic Valve Positioner receives a pneumatic signal (typically 3-15 or 6-30 psi) from a controller. It then supplies the valve actuator with the correct air pressure to provide an accurate valve stem or shaft position proportional to the pneumatic input signal.
An Electro-Pneumatic Positioner, sometimes abbreviated "EP Positioner," receives an electric signal (typically 4-20mA or 0-10 VDC) from a controller. It then sends a corresponding pneumatic signal to a pneumatic valve actuator.
EP Valve Positioners may also be referred to as &#;analog positioners.&#; This is because the electrical input to the positioner is an analog signal.
Since many processing units use electronics with a 4-20 mA DC signal to modulate control valves, the positioner must convert the electronic current signal into a pneumatic pressure signal.
This is also known as an I/P positioner or transducer, such as Kimray&#;s YAK2.
A Digital Valve Positioner also receives an electric signal from a controller (typically 4-20mA, HART, PROFIBUS, or Foundation Fieldbus), but it&#;s digital as opposed to analog. It then sends a corresponding pneumatic signal to a pneumatic valve actuator.
It also differs from an EP Positioner because it uses a microprocessor to convert the control signal and perform the position control rather than a mechanical beam, cam and flapper assembly found in an EP.
This electrical input allows more advanced capabilities for the user. These digital &#;smart positioners&#; also collect data to automatically alert users about valve performance, diagnostics and maintenance.
The Siemens PS2 is one example of a digital valve positioner. The PS2 can remotely monitor and control any pneumatic valve. We offer it with many different communication protocols and enclosure options to meet customer needs.
The PS2 may be operated manually or electronically. It&#;s simple to program, with only three buttons and a two-line display and it can be calibrated in minutes.
The PS2 also features low air consumption compared to the industry average and only use air when required so you'll quickly reduce costs incurred by air generation, maintenance and material.
One Kimray-designed solution that combines the positioning capabilities we&#;ve talked about in this video and more is the Electric Valve Controller.
The Electric Valve Controller is a compact, easy-to-use, versatile solution for oil and gas automation, including remote monitoring and control of your production.
You can use the Electric Valve Controller for back pressure control, suction control, pressure differential or hi-low gap control all through a simple 3-button interface.
For further information about how a control valve positioner can improve your operation, contact your local Kimray store or authorized distributor.
Are you interested in learning more about Fluid Control Solutions? Contact us today to secure an expert consultation!