FEATURE AIRFUL CONSIDERATIONS
It is important to carefully assess and clean ventilation systems upon returning to the workplace to help limit the risk of transmission, says Carl Davison, Technical Services Manager at Kingspan Technical Insulation.
The National Association of Air Duct Specialists UK (NAAD UK) has issued specific guidance for maintaining ventilation hygiene during the coronavirus pandemic on their website. Its recommendations include, ventilating spaces with outdoor air where possible and keeping ventilation systems on at lower speeds when the building is likely to be unoccupied.
They also recommend carrying out a detailed inspection of the ventilation system, ensuring it meets the cleanliness requirements within BS EN 15780 (Ventilation for Buildings. Ductwork. Cleanliness of Ventilation Systems) and paying particular attention to ensuring grilles on extract vents within toilets and on dampers are clear.
BS EN 15780 identifies Low, Medium and High cleanliness Quality Classes for ventilation systems within different spaces and sets clear criteria to determine whether ductwork needs cleaning.
In most cases, the best place to start is with a visual assessment of all system components by a suitably trained individual. This should help to identify any significant build-ups of dust, microbial or other contamination. If there is any uncertainty about the level of cleanliness, it may be necessary for them to undertake more in-depth testing such as a vacuum test.
For this, a 100 cm2 template is secured in a section of the
ductwork. The open area of the template is then carefully vacuumed with an air pump and dirt collected in a cassette. By measuring the weight of the cassette before and after, an independent laboratory can calculate how much dirt has been collected. Ductwork should meet the following requirements:
Quality class Low
Medium High
Supply ductwork Recirculation or secondary air ductwork
< 4.5 g/m2 < 3.0 g/m2 < 0.6 g/m2
< 6.0 g/m2 < 4.5 g/m2 < 3.0 g/m2
Table 1 – Acceptable cleanliness levels in existing ductwork within BS EN 15780
If you do not already have a regular inspection process in place, it is important to establish one. BS EN 15780 recommends the following inspection periods for ductwork in different areas: High quality class every 12 months, medium quality class every 24 months and low quality class every 48 months.
Other parts of the system (such as the AHU, filters and humidifiers) will need to be checked more regularly (See Table A.2 of BS EN 15780) and inspections should be adapted if regular problem points are identified.
48 | TOMORROW’S FM
Cleaning pre-insulated Ductwork Where cleaning is necessary, it is important to ensure that the tools and processes used are appropriate for the ventilation system being cleaned. NAAD UK recently undertook an independent assessment to determine how best to clean ductwork fabricated from The Kingspan KoolDuct System.
NAAD UK carried out up to 100 passes on different sections including 90-degree angles and t-sections. They determined that the ductwork can be effectively cleaned by a competent technician using a mechanical rotary brush with plastic fibres (polypropylene is recommended) at a speed of up to 900 RPM. For additional protection around areas such as bends, it is also recommended that a plastic ball is fitted to the end of the metal shaft. When working at height, ladders should not be propped against the ductwork.
Maintaining healthy spaces By undertaking an inspection of the ventilation system, maintaining an ongoing inspection schedule and ensuring cleaning measures are appropriate for the ventilation system, facilities managers can limit transmission risk and ensure the system operates effectively over the long- term, creating healthier spaces filled with clean air.
www.kingspan.com/gb/en-gb/about-kingspan/ kingspan-insulation
www.kingspan.com/gb/en-gb/about-kingspan/kingspan-insulation
twitter.com/TomorrowsFM
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70
