How To Manage Pneumatic System Pressure

For your industrial facility to run optimally, it’s important to manage its pneumatic system pressure. This is usually done by employing pressure control systems, which regulate the amount of pressure travelling around each element of a pneumatic circuit. Setting the correct pressure and maintaining it at a consistent level are important factors in all parts of the system. It will make the whole circuit safer and more energy-efficient, as well as optimise the airflow in individual tools, actuators, and other equipment.

Pneumatic Pressure Control

Every pneumatic component in an industrial system is designed to operate best at a specific air pressure. A manufacturing facility will usually have the input air from the compressor set to an initial pressure of about 110-120 psi. As the air travels through the system, the pressure level will gradually decrease as it encounters friction in moving parts, pressure drops via filters and dryers, plus restrictions or blockages in pipes and fittings. On the other hand, too much air pressure can lead to over-pressurisation in the system, which poses a safety hazard and can lead to equipment damage. 

There are various means of monitoring these variations in pressure, such as solenoid valves, regulators, pressure gauges and safety relief valves. All of these maintain and adjust pressures as needed in a pneumatic system so that all components continue to operate safely. Many modern pneumatic systems have the regulator built into an FRL unit or filter-regulator-lubricator system. 

About Pneumatic Regulators

Air pressure regulators maintain balanced pressure in the compressed air that travels from the filter through a valve into a regulating chamber and out of the outlet vent. The original and most basic pneumatic pressure regulator was a mechanical device consisting of an element that sensed internal pressure plus some frame of reference that indicated force. An input valve allowed pressurised air into a chamber containing a flexible element like a piston or diaphragm that could sense the amount of incoming air pressure. A regulating spring acted as the reference force, maintaining the diaphragm or piston in the position required to counteract the air pressure. 

While air pressure was maintained at the specified level, the piston or diaphragm remained static. If either the incoming or outgoing pressure changed, the spring would force them to move up or down – or in and out – thereby actuating the inlet or outlet valve. Both types of regulators are still in use, though considerably enhanced by technology, including various electro-pneumatic versions that use the same principles. These were designed to convert voltage signals or electrical current into pressure. The force imbalance was generated on a piloted piston or diaphragm using some form of magnetic coil without any additional output control elements. This type of electro-pneumatic regulator had to be carefully calibrated to maintain the expected accuracy and repeatability, using zero and span screws to ensure a consistent performance. 

Diaphragm Or Piston?

Each type of regulator has its own uses, according to an application’s particular requirements, but both have advantages and disadvantages. 

A diaphragm-based regulator is more pressure-sensitive and is a good choice for lower-pressure applications. It’s a simpler mechanism that offers far greater accuracy in controlling outlet pressure. But it’s more delicate and therefore more susceptible to damage.

A piston-based regulator can control higher pressures, as it’s tougher and more damage-resistant. This makes it safer in an over-pressurisation scenario where a diaphragm might rupture. 

You need a thorough understanding of your control requirements before you select a pressure regulator, to improve performance while minimising the risk of damage or accidents. You might also take response time into account, along with repeatability and sensitivity.

Industry 4.0 Pressure Control

Although the original designs of pressure control products are still in use, most people nowadays have adapted their systems to incorporate regulators with internal electronic feedback. Many Industry 4.0 systems, therefore, incorporate pressure sensors and electronic control components, offering greater accuracy and better performance than mechanical versions. Other types of sensors govern control parameters like flow, torque or force.

Electronic pressure controllers are reliable and robustly constructed, offering a high level of precision and repeatability. The pressure is usually controlled by the operation of an inlet valve and an exhaust valve. As usual, the air pressure is regulated by the opening of one or the other of these valves, which are controlled by internal pressure sensors rather than by a mechanical component like a diaphragm. 

The sensors monitor conditions in the chamber and send a continuous stream of signal data to the controller, which interprets it using PID or similar algorithms. This electronic feedback signal is then compared to the input command signal. Any disparity between the two signals triggers a correction signal from the controller, adjusting the airflow by opening one or other of the valves.

You can also get electro-pneumatic regulators that send an external feedback signal to provide two-loop control. This is helpful if you need to maintain air pressure at a point removed from the regulator. An external pressure transmitter sends a primary feedback signal, which is compared to the input from the command signal input. This signal initiates valve actions by commanding the internal control loop.

Choosing The Right Regulator To Manage Your Pneumatic System

When you’re running an application or process that demands consistent performance, you’ll need to know how to manage your pneumatic system pressure. There’s a wide variety of air pressure regulators available today, so you need to apply certain parameters to your selection. Firstly, you’ll want to match your regulator choice to the specific demands of your application, as you’ll find both high- and low-pressure regulators, miniature and speciality versions, and a general-purpose type. Other factors will be based on your primary system characteristics, such as input pressure, approximate flow, pipe size, required outlet pressure and how much precision the application requires. You can then fine-tune your selection between diaphragm or piston types and how complex a sensor array you require.