Debunking “Conventional Wisdom” In Actuator Selection and Deployment: Pneumatics

Pneumatic or electric? This choice can make or break many applications, and a wrong answer can cost a business tens of thousands of dollars every year. But how do you make the right choice?

The choice of pneumatic or electric cylinders involves an evaluation of performance, component costs, system costs, and productivity gains. The two technologies are so different that one cannot be a drop-in replacement for the other. Each has inherent advantages and disadvantages.

In this post, we’ll be covering the advantages and disadvantages of pneumatic cylinders.

Pneumatic actuators provide high force and speed at low unit cost in a small footprint. Force and speed are easily adjustable and are independent of each other. The typical pneumatic application employs over-sized cylinders as a safety factor. This is common because pneumatic cylinders are inexpensive and stepping up to the next larger diameter is feasible and practical. Prices for non-repairable rod-type cylinders range from $15 to $250 depending on body diameter, stroke and options.

Pneumatics are most economical when the scale of deployment matches the capacity of the compressor. Small compressors are efficient and economical when used to power a small number of pneumatic devices. Large compressors are efficient and economical when powering a large number of pneumatic devices. Unused compressor capacity is very costly. Time that a compressor sits idling at no load is also costly.

While pneumatic component costs are low, maintenance and operating costs can be high, especially if a serious effort has not been made to quantify and minimize the costs. Maintenance and operating costs include replacement cylinder costs, air line installation and maintenance, and electricity for the compressor. According to the Department of Energy, 24% of the annual cost of compressed air is due to maintenance, equipment and installation, while 76% is due directly to the cost of electricity for the compressor.

Typically, compressor efficiency is lower when the compressor is partially loaded. Furthermore, if during the work week, the compressors are left powered on at no load, a substantial amount of electricity is wasted. Waste is increased by inadequate maintenance (air leaks) and non-essential use of the compressor. Over-sized compressors and cylinders, common today, are costly to operate.

Determination of the operating cost per pneumatic device deployed in a facility can be eye opening, especially if cost calculations have not been done for a while and the scale of operations has shrunk. If there are 500 pneumatic devices using a compressor, cost per device may average $100 per year, but if there are only 50 devices then cost per device increases ten times to $1,000.

For an in-depth conversation about pneumatic vs. electric technologies, including a detailed cost comparison, please view the whitepaper at https://bit.ly/1P4TdNM.