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.

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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.

• Double-Acting Pneumatic Actuated Ball Valves
  Double-acting uses air to move internal pistons (racks) in two directions, which rotates the actuator pinion 90°. The pinion is connected to the ball valve stem and opens or closes the ball valve as it rotates. Double-acting actuators will return to the normal position when power is lost and can be configured as either normally open or normally closed. In the event that air supply is lost, double-acting actuators will stay in their current position.
• Spring-Return Pneumatic Actuated Ball Valves
  Spring-return uses air to move the internal pistons in one direction and springs in the other. These actuators are normally supplied as an air to open, spring to close operation, but can be supplied as air to close, spring to open. The mechanical springs can be susceptible to spring fatigue, making double-acting a better choice for high-cycle applications. Spring-return actuators will fail to the normal position in the event of either power failure or loss of air supply.
• Double-Acting with Failsafe
  Gemini Valve now offers an industry first double-acting pneumatic actuator with failsafe. This combines the durability of a double-acting actuator with the failsafe normally only offered by spring-return models. The actuator operates in a double-acting configuration until power or air pressure is lost, and springs engage automatically to return the valve to the normal position.

Pros & Cons of Pneumatic Actuators Pros Cons

• Low Cost
• High Durability
• Fast Cycle Time
• Spring-Return Failsafe Available
• Resistant to Overheating & Moisture
• Double-Acting Models Are Up to 70% Smaller Compared to Industry Standard Electric Actuators

• Higher Operating Costs
• Compressed Air Required
• Fast Cycle Time

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.

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 Cons

• Compressed Air Not Required to Operate
• Low Operating Costs
• Minimal Noise
• Flexible Motion Control 
• Slower Cycle Time Than Pneumatic Actuation

• Failsafe Options Not Widely Available
• Generally Higher Cost
• Slower Cycle Time Than Pneumatic Actuation

Power 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:

• NEMA 4: Water-tight and intended for indoor or outdoor use. This rating sets a level of protection against dirt, water and ice. 
• NEMA 4X: Similar to NEMA 4, with an additional level of protection against corrosion.
• NEMA 6: Submersible, with design dependent on the specified conditions and time.  
• NEMA 7: Designed for indoor applications and certain hazardous environments. Capable of withstanding pressure from internal explosions.

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 Source

• Air Supply of 60 to 125 PSI 
• Solenoid Valve Controlled By AC or DC Voltage

• Voltage of 120AC / 24DC / 12DC

Common Component Sizes

• 2.66” x 3.41” x 3.63” (Double Acting)
• 2.86” x 8.11” x 3.63” (Spring Return)

• 7.70” x 6.45” x 4.75” 

Open/Close Speed

• 1⁄2 a Second to 1 Second

• 6 Seconds

Temperature Range

• -20° to 350° F

• -40° to 150° F

Lifespan/Cycles

• 1,000,000 +/- When Used Within Specifications

• 250,000 +/- Application Dependent

Spring-Return Options

• Widely Available

• Not Widely Available

Industry Examples

• Oil & Gas
• Automotive
• Pharmaceutical
• Food & Beverage
• Power Processing
• Chemical Admixtures & Treatment

• Food Service Equipment
• Irrigation
• Vehicle Wash Systems
• Water Treatment Equipment
• Manufacturing Facilities

Pneumatic Actuators

For more Electro Pneumatic Valveinformation, please contact us. We will provide professional answers.

If your facility has access to compressed air, you can explore the following pneumatic actuators: 

• Double-Acting Pneumatic Actuated Ball Valves

These are intended for low to high-cycle applications that require a power outage failsafe and compact design.

• Spring-Return Pneumatic Actuated Ball Valves

This option is designed for moderate-cycle applications that require a failsafe in the event of compressed air or power loss.

• Double-Acting Pneumatic Actuated Ball Valves (with Failsafe)

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. 

Gemini Valve is happy to help you find the perfect ball valves for your project. Just contact us to get started.

Pneumatics|Published Sep 1, |Updated Aug 19, |8 MIN READ

Everything You Need to Know About Pneumatic Systems

Diving into the world of engineering, pneumatics stands as a pivotal concept. It's in our daily devices and at the core of industrial machines. In this concise guide, we'll explore its indispensable role and specifics. Let's explore the world of pneumatics together.

What is Pneumatics?

Pneumatics is a crucial engineering discipline. It involves the use of pressurized gas or air to produce mechanical motion, based on the principles of fluid dynamics and pressure. The use of pneumatics extends from compact handheld devices to large-scale machines, highlighting its versatility. This field has seen significant development and diversification, becoming an indispensable part of modern engineering.

In its simplest form a pneumatic system uses compressed air to complete work. It starts with a compressed air source which is most often a compressor. A typical compressor will convert electrical energy to potential energy in the form of compressed air. It is this potential energy that is stored and distributed through the air lines for a variety of purposes

One of the most common examples of a pneumatic actuator is the simple air cylinder.  In a cylinder as pressurized air forced into one side of the cylinder, it pushes onto the piston. With the opposite side open to the atmosphere, there is a force imbalance across the piston. This imbalance creates motion. It is this force imbalance and action that is used to do work.

Applications of Pneumatics

Pneumatic systems are diverse in their applications, including:

• Transportation: Pneumatics powers the braking systems in most vehicles.
• Manufacturing: Pneumatic tools are often used in product assembly lines.
• Medicine: Devices like respiratory ventilators and pressure regulators use pneumatics.
• Construction: Many heavy-duty tools, like jackhammers, operate on pneumatic systems.
• Home appliances: Everyday devices like vacuum cleaners and spray cans utilize pneumatics.

5 Benefits of Using Pneumatics

• Reliable/Low Maintenance – A properly designed pneumatic system supplied with clean, dry air is exceptionally safe and requires next to no maintenance. Components are rated for tens of millions of cycles, and the majority of modern equipment no longer needs lubrication.
• Simple- Pneumatic systems are relatively simple. Circuits are base on logic, and their outputs are typically linear or rotary motion.
• Ability to stall–Great for pressing and clamping applications. Pneumatics can supply a constant force indefinitely without the worry of burning out motors or drives.
• Self Cooling-Due to properties of expanding gases, pneumatic actuators cool themselves as they cycle back and forth. No need to worry about overheating.
• Inexpensive- Relative to their hydraulic and electrical counterparts, pneumatic components are much less expensive.

Basic Terminology

Dew Point Temperature at which moisture in the air condenses into water droplets Atmospheric Dew Point Temperature at which moisture in the air condenses into water droplets at atmospheric air pressure Pressure Dew Point Temperature at which moisture in the air condenses into water droplets at working air pressure Relative Humidity Current moisture content in air vs theoretical maximum moisture content Compression Ratio A measure of how much air is compressed Condensation Formation of water droplets from water vapor CFM  Cubic Feet Per Minute L/min Litres per minute SCFM Standard cubic feet per minute Nl/min Normal Litres per minute Standard Conditions

• A generally accepted definition of standard consolidations by which values can be compared
• 7 psia, temp 68 decF, relative humidity 36%

ANR

• Similar to Standard Conditions
• 1 bar, 20 deg C, 65% relative humidity

Mist Separation/Coalescing

• Removal of oil mist from air.

NO vs NC Auto drains 

• NO – Normally open, drains fluid when de-pressurized
• NC – Normally closed, drains fluid only when full

Main Parts of a Pneumatic System

Compressor

A compressor compresses air up to the required pressure. It converts the mechanical energy of motors and engines to potential energy of compressed air. This is where it all begins. Compressors typically feed air into a tank where the air is allowed to cool, removing some of its moisture. Tanks also act as a storage for pneumatic energy and also eliminates pulses generated by piston compressors.  Dryers are typically  connected after the tank to remove the moisture created in the compression process.

FRL – Filter, Regulator and Lubricator (Combination Units)

1. Filters remove particulate from the air,  as small as 5 microns. Some also remove water droplets using centripetal force. Mist Separators or Coalescing filters can be added to remove oil from the air.
2. Regulators control working pressure. Typical regulators have system air working against spring force across a diaphragm. As you adjust the handle on a regulator, you compress the spring more, requiring higher pressure to create a balance. When you need more force, this is what you adjust. Some electro-pneumatic regulators convert an electronic signal to pneumatic pressure settings.  Regulators as the name imply create a stable pressure output.  Most pneumatic systems run at 70-80 psi.
3. Lubricators supply a steady stream of oil droplets into the airlines. Earlier generations of pneumatic components used to require this source of lubrication to work correctly. Today, most parts come from the factory don't require lubricators

Control Valves

1-Directional Control Valves are similar to electronic relays. They convert a small control signal to a larger signal used to move actuators back and forth, rotary actuators to spin CW or CCW or grippers to open or close.

2-Solenoid Valves Solenoid valves are known for their efficient power usage, impressive flow rates, rapid response, and sleek, modern designs. They find wide-ranging applications in industries such as semiconductor, automotive, packaging, medical, specialty machinery, and machine tools.

Pneumatic actuators

Pneumatic actuators are the workhorses of a pneumatic system, transforming compressed air energy into mechanical motion. They come in various forms, capable of linear, rotary, or reciprocating movement, to suit different applications. Round body and tie rod cylinders offer robust linear motion, rodless cylinders provide a compact solution, rotary actuators enable rotational movement, and grippers are perfect for manipulating objects. Each type serves its unique purpose, ensuring that whatever the task, there’s a pneumatic actuator designed to handle it efficiently.

Pneumatic Tubes

Pneumatic tubes are hollow pipes, made from materials ranging from rubber and nylon to stainless steel, used to transport compressed air in pneumatic systems. They are crucial for ensuring a smooth flow of air between components, similar to how wires function in electrical circuits. The choice of material is vital, with options like polyurethane and polyethylene providing resistance to various environmental factors, including high temperatures and corrosion.

Pneumatic Connectors

Pneumatic connectors provide secure, removable connections between tubing and pneumatic components such as valves and actuators. Typically utilizing push-to-connect fittings, these connectors ensure a tight seal to prevent leaks, while also allowing for easy assembly and maintenance. They accommodate a variety of tubing materials and include silencers to minimize noise from exhausting air.

5 Things to Consider About Pneumatics

1. Air Quality - Moisture– When compressing air, you concentrate all that is in it. Especially includes moisture. Even on cold, dry days, there is sufficient moisture in the air to create a problem. Water in airlines corrodes metal parts they come into contact with, causing valves to seize, damaging seals and other components. It is vital to ensure the air in the system is dry by installing an appropriate air dryer system to remove moisture.
2. Air Quality – Particulate – Keeping air clean is critical to maintaining a reliable pneumatic system. At a minimum, air should filter down to 5 microns. It's recommended filter elements should be replaced every two years or when the pressure drop across the filter exceeds 14 psi.
3. Meter In vs Meter Out –There's an old saying in fluid power "When in doubt, meter out." Metering out is when you control or limit the airflow exiting a component. Metering in is controlling or restricting the airflow entering a part. In most scenarios, you'll want to meter out. Doing so will ensure smooth motion of actuators, especially at low speeds. Metering in can result in a stuttering motion. Why would you meter in? One example would be for single-acting actuators. You can't control the air leaving the cylinder, so you have no choice but to control what's entering it. The spring force acting against the piston will help eliminate the stuttering motion.
4. The proximity of valves to actuators - You'll want to physically mount valves as close as you can to the actuators they control. Minimizing the lengths of airlines to flow through from the valve to control the actuator. Longer tube lengths mean there's more volume needed to fill to reach working pressure. On the retract stroke, that's extra air needs to be vented and has to travel farther to do so. Adding cycle time and needlessly consumes compressed air.
5. Speed– Typically, the most significant factor in limiting the speed of an actuator is the air exhausting from the low-pressure side. As pressure decays, there is less energy available to move air particles through tubing and out through the exhaust port. As stated above, having needlessly long tubing lengths compounds this problem. One solution is a quick exhaust. These get plumbed near the cylinder port. During the high-pressure cycle, these stay closed. During the low-pressure period, they open up and allow air to vent to the atmosphere right at the cylinder port, dramatically reducing restrictions on the exhaust air, increasing speed. Always keep in mind, maximum speed specifications and implementing some form of shock absorption should cylinders be travelling the entire stroke length at high speed.

What do Pneumatics run on?

Pneumatic systems utilize compressed air or inert gases as a power source. The system comprises a network of components, including a gas compressor, transmission lines, air tanks, hoses, standard cylinders, and atmospheric gas.

How is pneumatics used in everyday life?

A Pneumatic device is a tool or instrument that operates using compressed air. Examples range from rock drills and pavement breakers to riveters, forging presses, paint sprayers, blast cleaners, and atomizers. The use of compressed air offers flexibility, cost-effectiveness, and safety.

Why is pneumatic better than hydraulic?

Pneumatic systems offer cost-effectiveness as air, which is the main component, is free. They provide enhanced safety as they can operate in potentially explosive environments and avoid overheating. Additionally, despite being small and light, they offer a relatively higher power output compared to other systems. Furthermore, Pneumatic technology is known to be cleaner.

Which is safer hydraulic or pneumatic?

When it comes to safety in the industrial setting, Pneumatic systems are a more secure choice than hydraulic ones. Compressed air leakage from Pneumatic systems does not pose a contamination risk, since air is not toxic or corrosive. However, it should be noted that certain gases utilized in standalone or mobile equipment may present hazards.

Still have questions after reading our post? Don't leave them unanswered! Contact us today for your pneumatic needs and questions.

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