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Latching system stems HVAC enclosure leaks

11 March 2011

An air conditioning equipment manufacturer has successfully improved the energy and operational efficiencies of its HVAC enclosures, through careful selection of latching systems that have eliminated air leakage past the enclosure door seals

Shildon-based Air Handling Systems (AHS) manufactures bespoke air handling equipment – primarily HVAC enclosures – for the private and public sectors. Its customers include organisations such as Bombardier, the BBC, various NHS Trusts and, more recently, Great Ormond Street Hospital.

For this industry, energy efficiency and optimised operational performance are important requirements, particularly in the case of service buildings such as hospitals, where the demands for hygiene and comfort are high, whilst at the same time there is an increasing emphasis on cost savings and waste reduction. Moreover, any user of such equipment must now have systems in place that comply with Part L Building Regulations and thus benefit from cost savings through energy-efficient installations.

There is, however, an issue with air leakage from HVAC enclosures. Any such leakage implies lost energy and increased costs, so to counteract this, it is imperative to make the equipment as air tight as possible. The current industry standard is DW 143 Class B 1000 Pascal.

When AHS pressure tested its air handling units, it found that the major cause of air leakage was via the sealing of the enclosure doors. Primarily, this was because the latches available at the time failed to properly engage and provide sufficient compression to seal the gasket on the thick door of the cabinets. So AHS turned to fastener specialist Southco for help.

Southco offered a modification of its standard E3 ‘Vise Action’ compression latch. This has additional thread to allow the engagement of the nut at the rear of the latch, and thereby accommodating tight compression for up to 50mm thick doors. The E3 latch has been proven in applications needing a quick, secure, vibration-proof closure – particularly where effective sealing is required. Its smooth operation aligns the pawl behind the frame and draws it up tightly with a single continuous half-turn motion.

The latch’s compression action provides consistent 6.4mm pull-up for environmental sealing of gasket-lined enclosures, and helps reduce or even eliminate noise and rattles caused by vibration. Indeed, this type of over-centre latching resists accidental opening due to shock or excessive vibration. The original Southco Vise Action mechanism combines with numerous body and head styles, all designed to meet specific installation and application requirements.

AHS equipment exceeds the current industry standard to achieve Leakage Class C 1500 Pascal as a minimum. However, for some applications, it has reached Leakage Class D 2500 Pascal. Subject to the same rigid test conditions, the Southco E3 compression latch has successfully passed this same Class D rating.

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