Pneumatics technology is key to manufacturing processes as compressed air is utilised in everything from cooling to controlling automated machinery on assembly and packaging lines.
Since pneumatics make up a sizable proportion of a plant’s energy consumption, taking the steps to ensure wastage and leaks are minimised, whilst maximising airflow in the system can result in significant cost savings and better plant efficiency.
1. Size your pneumatic components correctly
The old saying ‘pipe size is right size’ is no longer valid as many engineers have realised that large, pipe-sized components are no longer the best choice for running an efficient pneumatic system. For example, a standard airline filter, such as Parker’s P33F particulate filter, uses centrifugal action in the head to prevent water and other particles from contaminating the line.
If the filter is sized too large (according to the pipe size), then the centrifugal action will not be robust enough to remove the water. However, sizing it too small will result in a very noticeable pressure drop.
Finding the exact size of a component for your application is critical for the overall efficiency of the system and will avoid these unnecessary pressure drops.
Another factor to consider is to check whether the piping itself is correctly sized.
2. Rethink the plumbing
In many pneumatic systems, the piping will run down from the main-line header into an application.
This piping is often connected by a quick-coupler connector, which snaps together using a male and female piece. These connectors are essential if you need to couple and uncouple devices a lot.
However, they tend to have high rates of pressure loss which can add to starving the system if it is already running at its maximum.
As well as causing press loss, connectors can also become clogged up with the rust and scale flakes that can build up inside steel pipes.
So, consider replacing steel plumbing with plastic, such as Parker’s Thermoplastic solution or changing to standardised fittings and links made from aluminum instead of steel.
3. Adopt the dual pressure approach
Most applications are still using a single pressure circuit – with a single supply pressure and dual exhaust approach. This setup provides optimal exhaust conditions, but still may not always be the best and most efficient setup for many industrial applications.
An alternative technique is known as the dual pressure approach, best suited for applications where the same force is not required for the extend and retract conditions.
For example, a cylinder might need to be extended to move a load at 80 PSI, but the same force is not needed to reset the cylinder. Through the use of two regulators, the cylinder can be run at 80 out and 30 back in a dual pressure model to make the system more efficient.
There are several ways to achieve those two pressures, and some are more efficient than others, but the basic principle of higher pressure out and lower pressure on retract remains the same in all cases.
4. Change filters
Another obvious way of optimising efficiency is to replace dirty elements. Typical commercial primary filters in a pneumatic circuit are designed to filter out particles as small as five microns from the air. Many of the filters commonly employ a spinning action to filter out any water droplets.
Initially, the particulate filter might be sized for two or three pounds of pressure differential. This provides enough back pressure for the correct amount of airflow in and water filtered out.
However, when contamination starts to coat not only the outside of the element but also the inner surfaces, part of the orifice is bound to get closed up, effectively dropping the three-pound differential steadily. Finally, it might get to the point where five to 10 PSI is lost simply because the element is dirty.
A lot of users will try to take the element out and give it a clean to get the system back in service. This is not a good idea because a lot of the contaminants are on the inside and simply can’t be reached.
Instead of simply replacing the relatively inexpensive part, they are running the system on a clogged filter that costs more to run every month because the compressor is labouring to make up the extra pressure drop.
One of the main reasons Parker moved from a sintered bronze or fibre paper type of filter to a white sintered plastic element, as featured on the Parker P3L Lite Particulate Filter, was to give a clear visual indication that when they look dirty, they should be replaced.
5. Clean, dry air
One of the main principles of compressing air is to take the surrounding air and jamming it into a small container, but this air also brings with it a multitude of water, dirt and everything else that’s in the environment around the compressor.
When you compress air, you also heat it up, and the act of compression is part of the gas loss. This results in the air wanting to hold on to that water until it cools off again.
As the air cools off, water condenses in the system’s pipes, which is where water comes from inside the system. There are many different mechanisms that reduce the amount of water going downstream into the pneumatic system, but one of the main starting points would be a dryer, which will cool the air and allow the water to condense and fall out of it.
Putting a dryer into the system, such as Parker’s P3TJ Dry Air System, won’t eliminate all of the water in it, but it will remove the bulk of it. Particulate filters then come into play at the point of use to clear out the remainder of water and dust in the system.
Simply living with water in the system as a fact of life creates a lot of problems with equipment rusting and other environmental issues.
All of these points have to be considered in order to optimise energy conservation and boosting air flow. It’s also important to remember that as plants scale up, so does every part of the pneumatic system need to be upscaled to cope with the demand.