Why Use a Pneumatic Actuator?
Pneumatic controls have been the go-to tool for process controls and HVAC for most of the past century at the very least. This long history has made them cheap, reliable, and well understood. There’s few applications where a pneumatic system hasn’t already been used at least once.
During the mid 1800s, Pneumatics were the hot new thing, alongside steam engines and industrial machinery at-large. On their own, they were being used for power tools, mail delivery tubes, and even a gigantic pneumatic tube subway. When combined with other fields, manufacturing and the early automation industry however, air became the first control system. Over 100 years ago, compressed air ran the world’s earliest centralized heating systems and controlled our factories.
Prior to modern electronics, air was the best way to give a machine logic. It doesn’t require advanced materials like transistors do, it just needs person-scale pieces of metal and fittings. For a clever engineer, switches could be tied together to create IF, OR, AND, ELSE, gates that could control anything. It didn’t require an advanced degree, just the very common tools necessary to cast or machine a basic part. Air is simple and in large part it just works.
Why Did Pneumatics Take Off?
Pneumatic systems were one of the first major actuation and control systems because it was simple, fast, easily retrofitted into existing facilities, failed cleanly, and was incredibly rugged. The first compressors were similar to existing pump technologies. The air pressure could push and move just about anything at the time. The built in capacity for logic made it flexible. Air was free and ‘safe’, a leak or a failure wouldn’t flood a factory. It was simple, anyone who could work on the furnace or steam engines could work on the pneumatic controls.
At the time, nothing could compete with air either. Hydraulics would have been in their infancy and likely couldn’t perform any of the logical work air’s logic gates did. There wasn’t much machinery that could immediately take advantage of hydraulics for what of them did exist. Everything revolved on the spinning output of a steam engine, hydraulics as we know them today wouldn’t make that any better in an affordable way. Electronics, even in 1900, weren’t ready for primetime either. The first transistor wouldn’t be created for years, let alone something manufactureable at scale.
Are Pneumatics Still Relevant Today?
Pneumatic systems, for building automation, process controls, and everything else are over a century old. We have better technology now, don’t we? How can this old stuff still be useful when we have hydraulic actuators that can crush buildings, electric motors that take cares from 0-60 in a terrifying 2 seconds, and advanced control systems that let me change the office temperature half a degree from an airplane on the other side of the world?
The intervening century plus since the first pneumatic tools came about have been incredibly eventful. The widespread popularity of pneumatic actuators and logic gates in those early days lead to a manufacturing and R&D boom. We’ve made them reliable, durable, predictable, safe and CHEAP. In the right applications, pneumatics absolutely trample all the competition.
Consider that a high performance hydraulic actuator and all the required parts might weigh in at a good $40,000+. A competing pneumatic system would probably be just a few thousand dollars and could potentially actuator faster and have better built-in safeties. Just think about pneumatic logic systems, a hacker can’t remote access a pneumatic safety system to disable it. It’s hardware that’ll always function or at the least, can always fail-safe.
Beyond that yet, a pneumatic system can handle similar weights to hydraulics, as long as you’re not aiming to pneumatically launch the space shuttle. It’ll handle massive valves and heavy building controls, it’s just got some practical limits where it’s own inefficiencies start to really hold it back on the massive-scale lifting and pushing.
So, let’s get a tally:
- Incredibly affordable
- High performance/cost ratio
- Low Maintenance
- Can be more secure in terms of cyber-security
- Can be safer
- Fails cleaner
- Is simple, well documented, and well understood
- A Century+ of R&D has created robust designs for all applications
- Can be combined with modern electronic systems
Those are some really, really compelling reasons to use a pneumatic system. It can save a penny and bring the performance.