The piping of your compressed air reticulation system can have a dramatic effect on the efficiency and ultimately the cost of running the system.
The main issue causing decreased efficiency within piping systems is pressure drop. Pressure drop occurs due to friction between compressed air and the wall of the piping. When piping is too small to effectively carry the required flow rate to end use, friction within the pipes increases. If this occurs, end use processes may not receive sufficient pressure to operate properly. In this case, most organisations increase pressure at the compressor in turn decreasing efficiency and increases operating costs. If we increase the discharge pressure by as little as 50kPa, the compressor will require an additional 4% energy input to achieve the higher pressure. It also has the added effect of reducing the volumetric efficiency of the compressor. Over a year this can add many thousands of dollars to your energy costs.
There are 3 distinct areas that must be addressed when designing and installing a compressed air reticulation system to minimise pressure drop.
1) Size of the piping
2) The material of the piping
3) The layout of the piping
Compressed Air Pipe Sizing
When designing a compressed air system it is critical that you correctly size your piping to avoid pressure drop. Sizing of pipe must not only take into consideration current air demand but also any future or expected growth in demand. For example if you set up your system to run 5 air tools and the piping is sized to the exact flow required, if you add any tools or equipment in the future then the piping will become too small, restrict flow and lead to pressure drop. A good rule of thumb is to size piping such that air velocity is maintained below 6m/s.
Compressed Air Pipe Material
There are numerous pipe materials used today such as copper, aluminium, mild steel, plastic and stainless steel.
Piping material can be categorised into two types:
1) Non-Metal (Plastic)
Non-Metal or plastic pipe, as it’s commonly referred to, is popular due to:
- light weight and easy to handle
- Smooth bore which minimises friction losses
- Fast & easy to install (can be easily extended)
- Generally non-corrosive
- Labour costs are reduced due to shorter install times.
Plastic piping is not suitable for some applications:
- Most plastic pipes are limited to 60-90°C temperatures before failing
- Not suitable for high pressure applications
- Are not compatible with some compressor lubricant types such as synthetic oil
- In the case of a pipeline fire plastic piping can melt and spread fire inside the plant.
Can be UV unstableMetal piping is commonly used in specific applications due to:
- Ability to handle higher pressure
- Can withstand high temperatures
- Superior lifespan
It’s important to select compressed air piping manufactured in the material that best suits your application to ensure efficiency and long term reliability.
Compressed Air Piping Layout
The layout of the piping in a compressed air system is crucial in reducing pressure drop and minimising operating costs. The further compressed air travels to its end use the larger the pressure drop will be. Minimising the distance compressed air has to travel through a pipe system is the key to increased efficiency. If this is not possible, maximising the pipe size will reduce pressure drop.
The most common piping layout design is the ‘Ring Main’, the loop design allows airflow in two directions resulting in the volume of compressed air carried in each direction being reduced by up to half in most cases. This significantly reduces pressure drop compared to simply having a long pipe run with multiple branches. The ring main design effectively reduces the velocity of airflow through the system in order to reduce pressure drop. Once the ring main has been installed feed lines can then run to feed required production areas and end-use applications as a sub network.
When planning a new compressed air installation it is critical that compressed air piping design and layout is thoroughly thought out otherwise you will lose capacity, reduce efficiency and ultimately increase your operating costs.
If you would like further information on compressed air piping design or installation contact us on 1300 098 901 or simply complete the ‘Enquiry’ form’ on this webpage.