Escaping air:Major drain on resources

Escaping air is often the biggest single source of wasted energy associated with a compressed air system, but the problem does not always stem from faulty piping, fittings and joints. Inefficient condensate drains can also be a major contributor says Richard Moore, at Parker Hannifin's domnick hunter Industrial division





If not managed properly, compressed air systems can be extremely expensive to operate efficiently, accounting for a high percentage of a factory's overall costs.




Accordingly, action must be taken to increase the efficiency of these systems to cut energy consumption and costs. Ultimately, this means eliminating the problem of air leaks, which essentially dissipate considerable amounts of energy to the atmosphere.




On the other hand, it is vitally important to remove contamination from compressed air systems using efficient filtration and separation devices. However, these practices produce large quantities of condensate as a by-product of the processes, even in the smallest compressors. Even minimal quantities of this often oily and acidic substance can have a significant and detrimental effect on downstream equipment and processes which can bring production to a costly standstill.




As a result, this by-product must be drained away from the system for legal disposal. Traditionally, manual or open valves, disc and steam trap drains, timed drains and mechanical float drains are used to remove condensate.




However, these devices are all too often purchased on a price only basis, with little or no consideration for maintenance and running costs.Unfortunately, there are hidden costs in the operation of most of these common drain types, which are regularly overlooked. In particular, these products can continuously discharge compressed air as part of the condensate removal process, contributing to excessive energy wastage. As a consequence, what at first appears to be a good purchase can actually turn out to be the most expensive option.




For example, a system using a single timed drain could lose approximately 0.062m3/min of air. Over a full year of continuous operation this equates to an air loss of approximately 32,498m3. In energy terms, this drain would consume 3581kW of energy every year. The scale of the problem grows dramatically when you multiply these figures by the number of drains in each compressed air system.




Other options are available to address the problem of condensate removal; however, these can also introduce additional energy inefficiencies. For example, manual valves are often left open to discharge condensate continually, discharging significant volumes of system air at the same time. These open valves reduce system pressure, which can hinder effective operation of downstream equipment. Similarly, disc and steam trap drains discharge compressed air through normal operation, and worse still, even if no condensate is present. They also emulsify condensate preventing easy onsite separation.




Leading manufacturers have been working to develop a new generation of condensate drains that act as an alternative to older designs, which can purge tens of thousands of cubic metres of compressed air a year.




Among recent developments is the ED3000 series level sensing drains from Parker Zander that have been designed to cut energy wastage. These devices are easy to install and feature no mechanical sensor parts, as well as being suitable for use with all types of compressed air condensates, including aggressive oil free types.

The ED3000 series models use electronic sensors to detect condensate, and discharge only when it is present, increasing the overall efficiency of the compressed air system. The devices store condensate removed from the compressed air system in a drain bowl and, when the liquid reaches a pre-determined point, the solenoid valve automatically opens for a set duration to eject nearly all of the contents, while allowing a minimum amount to remain in the bowl after the valve has closed, conserving valuable compressed air.




It is vital to cut unnecessary energy consumption using the latest devices to enable carbon dioxide emissions to be reduced and cost savings realised. A relatively small investment in an efficient condensate drain can ultimately eliminate the wastage of expensive compressed air.