BCAS 2018

Technology Guide 38 www.bcas.org.uk Condensate drains in focus Some of the greatest wastages, often up to 10% of the mean demand, are found at the condensate collection points at the inter-cooler, after-cooler, air receiver, coalescing filters and distribution system. BCAS reports. C ompressing Air creates moisture and contaminates which can combine and form emulsion. Often drain traps are unsuited to the duty, or incorrectly installed, and after a short while they fail, causing the contamination to pass on to the usage points. To avoid this problem many traps are found by-passed or valves left cracked open, causing the wastage. Traps without some lubrication can have internal parts rust, causing them to fail. Special oil: water separation systems are needed to comply with the Environmental Protection Act 1990. This act and its implications for the disposal of condensate from compressed air systems are described in the booklet ‘Condensate Disposal’, available from the British Compressed Air Society (BCAS). Condensate drain types Zero air loss drains Zero air loss drains are any condensate drain (also known as a drain trap) that discharges condensate from a compressed air system without discharging (wasting) compressed air. These can be internal float drains as found in water separators and coalescing filters, external float drains or electronic level sensing drains. Properly maintained, any of these types of drains will significantly reduce air loss and improve energy efficiency. Timed solenoid drains Timed solenoid drains use an electronic timer to open and close a solenoid valve and discharge condensate. They will typically lose compressed air during discharge and hence are wasteful of energy. Correctly set up (short duration between discharges and short opening times), the air loss can be minimised however they will need re-setting to match seasonal conditions. Thermodynamic disc traps Thermodynamic Disc Traps are modified steam traps and were once very common due to their low cost. By design they constantly discharge compressed air as well as emulsifying condensate as it is discharged to a point where standard gravity oil / water separators will not work, requiring more costly disposal methods. It is recommended to replace thermodynamic disc traps with more energy efficient solutions. Failure of a condensate drain will result in carryover of liquid resulting in overload of filtration and drying equipment and or contamination of downstream distribution piping and applications. Best Practice for your condensate drains ● Daily checks of condensate drain function are recommended. ● Almost all condensate drains are susceptible to particulate contamination and where necessary, should be protected by strainers. ● Except for timed solenoid drains, condensate discharged from float drains and level sensing drains will be under gravity, not system pressure – do not try to “lift” condensate above the point of drainage or “push” condensate over long distances. ● For condensate discharge piping, use large internal diameter piping and keep pipe lengths short to prevent back pressure. ● Never combine or tee condensate drain lines, always run individual drain lines to a common, open ended or vented condensate manifold prior to feeding into storage vessels or on-site treatment devices. ● Condensate drains require regular maintenance (or replacement in the case of internal float drains). Always follow manufacturers recommended maintenance instructions. Drains