Pneumatic System Efficiency Calculator

It’s no secret that we live in a world of climate change and environmental stresses. Not only nature itself but society is challenging us to press for sustainable development while at the same time maintaining our economic edge. For this reason, manufacturers in all industries are looking for more energy-efficient solutions for production. Improving the energy efficiency of automated and pneumatic systems allows us to reduce the drain on natural resources and develop a responsible attitude towards sustainable development.

Some industrial sectors are taking a while to address their system inefficiencies. Pneumatic systems are a case in point. Pneumatic equipment is very common in industry, owing to its flexible and robust nature, but the systems are often poorly designed. This makes them inefficient in energy consumption, which is a factor not always taken into account by design engineers. Designers of pneumatic systems tend to focus on cost and functionality, meaning that pneumatics are still seen by many as an inefficient technology.

This article will show you how to assess your pneumatic system by calculating its efficiency. If you’re setting out to design or overhaul a pneumatic system, you can calculate how to select the most cost-effective design. We’ll also look at how to implement the most energy-saving measures and tune the system parameters to your application.

How To Estimate Your Airflow Consumption

The first step to improving your energy efficiency is to work out how much energy you’ll be using. In pneumatic systems, this primarily means calculating the air flow rate and total consumption while factoring in pressure and environmental variables like humidity. There are standard formulae you can use to do this, as well as online tools that will perform the calculation when you enter the various parameters of your system. You should then be able to obtain maximum and minimum values for any given system, plus the pneumatic circuit’s total air consumption per cycle. 

You should also look at the various parts of your pneumatic system individually to see what energy savings can be made. These include the drives or actuators, the distribution line and valve system, the FRL unit, etc. You can examine possible gains from reducing mass, leakage and friction, minimising pressure drops and dead volumes, as well as fine-tuning pressure levels and ensuring components are correctly sized. You may be able to find ways of reusing energy and can certainly optimise the parameters of your system, such as cylinder diameter and inlet pressure.

Actuators

First, look at your pneumatic cylinder to determine whether you’ve got the most effective type for your application. If you find that another cylinder type would perform better, make sure that its diameter is correctly specified. Recalculating a cylinder’s diameter is one of the best ways to improve your energy efficiency, as cylinders are frequently oversized. Over-estimating a cylinder’s capacity can easily lead to greater dead volumes and an unnecessary over-consumption of energy, sometimes up to 40%.  

You should be able to calculate the ideal diameter for your cylinder by considering the various parameters that contribute to its performance. These include its intake pressure level, required force and velocity, flow rate and friction. If you correctly evaluate these factors, you should be able to optimise your energy consumption according to the cylinder’s demands. If you’re not equipped with the means to do this, dedicated software is available to evaluate your specific needs and do the calculations for you. Some companies also offer cylinders with energy-efficient specifications, such as non-standard diameters which can save up to 25% of energy used.

Pressure Reduction

Another option for increasing pneumatic system efficiency is to reduce the air pressure levels. It’s not unusual for engineers to produce a system that delivers too much air pressure. Operators will often bump up the pressure in the mistaken belief that this will improve performance. All this consumes more power than is required. You can help keep pressure within optimal limits with a regulator. You can also adjust the pressure levels by reducing them on the return stroke since many applications only need force for the outward stroke. Reducing the air pressure on the return could save up to 28% of energy consumption.

To reduce pressure as much as is feasible within the working requirements of the system, you need to make sure your actuators are as close as possible to the compressed air supply. Also, keep the lengths of tubing and hoses between components as short as possible so that less pressure is needed to move the air between elements of the system. Leakage is also a prime energy-waster, sometimes losing as much as 45% or 50%.

Energy-Saving Controls

Once you’ve reduced your cylinder’s diameter and pressure level, you might look at other methods of optimising energy use. One of these is to use expansion energy for the drive motion and reuse exhaust energy. 

Bridge circuits in a double-stroke cylinder can offer at least 50% savings in compressed air consumption over a standard circuit. The volume of the chamber increases when the piston moves, but the bridge circuit interrupts the compressed air supply. This considerably reduces the pressure in the end positions.

You can also save up to 40% of energy by recovering and reusing exhaust air, by fitting a simple spring. For this technique, you’ll need an appropriately sized air reservoir, so you’ll also need space for that.  

Optimising Your Pneumatic System Efficiency

Choosing the best design for your application is the first step in reducing your energy consumption: you can go all out for smart systems that aim at a 50% saving, or replace your existing cylinders with more efficient ones. If you’re starting from scratch, you’ll find more energy-efficient pneumatic solutions are being created than ever before. You can calculate the appropriate diameter and pressure level of your cylinder and perhaps invest in a pressure reducer or regulator. 

Several manufacturers and suppliers offer tools to help you make engineering calculations; alternatively, the team at Rowse Pneumatics is always happy to offer expert assistance.