Modern electro-pneumatic pressure regulators, such as Proportion-Air’s QBX Series, can compensate for any movements or changes downstream of the system because of the integrated electronic control system. The regulator monitors those changes and makes pressure adjustments as necessary to ensure the pneumatic system continues to perform as desired.
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And because the electronics are integrated into the regulator, it provides a single, compact and easy-to-install device that can benefit many applications.
Manual regulators remain a good option for those applications which are completely static – the inlet and output pressures stay the same – and do not require a high level of accuracy.
Lister said electro-pneumatic control is the better option if any of the following are required by an application:
“If any of those are needed, that’s where electro-pneumatic control will really shine,” he said.
Lister said electrical and hydraulic options are the biggest competition to electro-pneumatic control. While there are some applications in which those technologies do fit better, there are a wide variety of others for which electro-pneumatic is the right solution.
He said in the past, electrical control was typically better for providing the precision required of positioning applications. But with Proportion-Air’s two-loop QB2X pressure regulator, it is possible to get as good as, if not better, control over electrical.
With the QB2X, you can integrate a position sensor with an air cylinder and plug the sensor directly into the QB2X to allow for position control without having to utilize another PLC.
“Using the second loop technology, you can control speed, torque, or whatever you’d like,” said Lister. “If there's a sensor out there for it, we can hook it up to the QB2X.”
Hydraulic control is typically for those applications with high force requirements, typically in the tens of thousands of psi. However, Lister said Proportion-Air does have electro-pneumatic components, including the QBX pressure regulator, which are capable of achieving higher pressures. The company’s GX unit directly drives up to 1,000 psi.
For higher pressures, ratio regulators are available for the QBX which increase the amount of pressure that can be controlled. “We’ve controlled up to 7,500 psi,” he said. “We know from the process and part availabilities we can go up a little over 20,000 psi but no one has really had the application for that yet.”
Applications with space or size constraints may also factor into the ability to use electro-pneumatic control. “If you don’t have compressed air or ways to fit hoses in, then you can use electrical for [applications] that need some precision,” said Lister. “Sometimes it is not worth putting a whole compressor in if there is just one little part that you need the precision on.”
READ MORE: Advanced Electropneumatic Positioning Achieves Dynamic Force Control
Determining the applications for which electro-pneumatic pressure regulators like Proportion-Air’s QBX are best suited is difficult because they control process variables. “That’s such a wide variety of things,” said Lister. “It’s like asking what’s the best benefit for a screw? It really depends on what you’re using it for; the benefits really vary wildly.”
He said the pressure regulators are commonly used in automation related applications, and have proved particularly beneficial for manufacturing semiconductors, medical devices, and automotive components.
One example he provided was controlling steam temperature for tire curing. Ensuring the correct temperature is reached and maintained throughout the curing process is critical to creating a safe and high-quality tire.
The company’s pressure regulators aid with other parts of the tire manufacturing process as well where intense heats or specific pressures are required such as tire balancing, uniformity testing and tire inflation.
READ MORE: A Primer on Pneumatic Pressure Regulators
The improved performance and extended capabilities provided by electro-pneumatic control in these, and other applications are helping drive further interest in the technology as well as the use cases for it. “It’s interesting to see how just being able to control a small amount of air can affect so many things,” said Lister.
Electrification and automation of systems are among the industry trends helping drive increased use of electro-pneumatic technologies due to the precision and efficiency provided as well as the fact there are more electronics being incorporated with mechanical components.
In recent years the development of machines capable of doing multiple things have become available for the manufacturing sector which Lister said is a good use case for electro-pneumatics. “Now you can have one regulator that's controlling [a robot] gripper arm and you can change the pressure of that gripper arm [based on] whether you're picking up a little plastic die or a big metal ball,” he said. “You can use the same gripper and the same Proportion-Air regulators like the QBX.
“As we’ve seen manufacturing grow pushed by the reshoring effort, we’ve been really involved in what we call retooling America, trying to get [the country] back up to speed like we once were, and like countries all over the globe are doing right now,” he said.
Continued improvements in sensor and valve technology in the coming years will lead to further improvements in the capabilities of electro-pneumatics as well. “And we’re going to be right there on the cutting edge of that. [We have] R&D labs where we’re just constantly testing out new parts and trying to reach new levels of control and performance for everybody,” he concluded.
Pneumatic actuators rely on compressed air or gas as the primary power source. These actuators don’t require a motor, but electricity is necessary when paired with an integral solenoid valve which is commonly referred to as a pilot valve.
Remote piloting can also be achieved utilizing the air supply port(s). The solenoid (pilot) valve receives an electric signal which energizes its coil and allows air to flow either in or out of the pneumatic actuator, subsequently opening/closing the ball valve.
Two types of pneumatic actuators are available: double-acting and spring-return. Both utilize a rack and pinion design, which is well known for its reliability and durability.
Electric actuators (sometimes known as motorized or rotary ball valves) are powered by a motor and gear train. These are the most popular choice for ball valve automation. If no air supply is available to power pneumatic devices, electric actuators are used.
The most common motors are supplied in 120AC, 24DC and 12DC voltages. The motor, when supplied with voltage, engages a gear train which produces the torque necessary to cycle the ball valve.
In the case of Gemini Valve’s electrically actuated ball valves, this torque rotates a shaft that is connected to the stem of the ball valve. An external SPDT (Single Pole Double Throw) switch or device is used with the electrically actuated ball valve to control the position, either open or closed.
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With the Gemini Model 600, starting with the ball valve in the closed position and applying power to “terminal 2” on the internal actuator terminal strip, the actuator shaft rotates 90° at which time an internal cam switch shuts off the motor. The ball valve is now in the open position. Using the external SPDT switch, the power is then applied to “terminal 3”, causing the actuator shaft to rotate 90° at which time another internal cam switch shuts off the motor. The ball valve is now in the closed position. This cycling process takes approximately 6 seconds. Gemini’s electric actuator also features a fold out manual override handle to enable the valve to be operated in the event of loss of power.
Pros & Cons of Electric Actuators Pros ConsPower Source
The biggest difference between electric and pneumatic actuators is the driving force of their operation.
Pneumatic actuators require an air supply of 60 to 125 PSI. The solenoid (pilot) valve is controlled by either an AC or DC voltage.
When no air supply is available, electric actuators are used.
Component Size
Double-acting pneumatic actuators are up to 70% smaller in size compared to electric actuators.
Speed
To open or close the valve, pneumatic actuators take 1⁄2 a second to 1 full second, depending on the model. Gemini’s electric actuators take approximately 6 seconds, while other manufacturers can take upwards of 25 seconds or more.
Temperature
Pneumatic actuators are suitable for a wide variety of ambient temperatures, and are rated to operate in temperatures between -20°F and 350°F. Electric actuators can be at risk of overheating in high temperature applications and are often rated between 40°F and 150°F. However, the temperature restrictions will vary depending on the product and the company’s guidelines for rating their products.
Durability & Longevity
High quality rack & pinion style pneumatic actuators can cycle on or off up to 1,000,000 +/- times when used within specifications. Electric actuators have cycles of 250,000 +/- but are application dependent.
NEMA Ratings
The National Electrical Manufacturers Association (NEMA) sets guidelines for the use of actuators in specific environments, like hazardous areas or locations affected by water and debris.
Pneumatic actuators are explosion proof, though care must be taken when paired with a flush mounted solenoid valve. Electric actuators are designed to the following most-common NEMA ratings:
Spring-Return
A safety feature for valve actuators is a spring-return or failsafe option. In the event of a power or signal failure, the spring-return sets the valve to the “safe” position determined by the operator.
Spring-return failsafe options are widely available for pneumatic actuators. However, this feature is not as easily implemented with electric actuators.
Cost
Pneumatic ball valves generally have a lower purchase price than electric ball valves. When used within specifications, they have a longer lifespan and may deliver the best overall value depending on your application.
Pneumatic Actuators Electric Actuators Power SourcePneumatic Actuators
If your facility has access to compressed air, you can explore the following pneumatic actuators:
These are intended for low to high-cycle applications that require a power outage failsafe and compact design.
This option is designed for moderate-cycle applications that require a failsafe in the event of compressed air or power loss.
Use these actuators for high-cycle applications that require a failsafe in the event of compressed air or power loss.
Electric Actuators
If your facility or OEM equipment doesn’t have access to pressurized air, pneumatic actuators won’t be an option. Electric actuators are also popular in applications where a slower cycle time is required. The fast ½ second cycle times offered by pneumatic actuators can be a detriment in high flow applications due to water (or other liquid media) hammer caused by the abrupt stop of media when cycling the valve.
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