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Top 10 interesting facts to improve your knowledge & safety concerning MEWPs & the effect of wind forces
1. Wind Speed Rating
MEWPs are generally designed to operate in wind speeds not exceeding a maximum of 12.5 m/s or 28 mph, unless marked different. NOT all MEWPs are designed to be wind speed rated for outdoor use. Lighter indoor MEWPs might include Push Around Vertical (PAV) and smaller electric Scissor Lifts (Mobile Vertical). Always refer to the MEWP’s identification plate / operations manual.
See the MEWP’s identification plate or operations manual to confirm max permissible wind speed.
2. How Many Persons?
Under BS EN280:2001+A2:2009 (Mobile elevating work platforms – Design calculations – Stability criteria – Construction – Safety – Examinations and tests), wind forces are assumed to act horizontally at the centre area of the MEWP and ‘persons’ and equipment on the work platform. Never lift more persons on a platform than stated, even if it is within the Safe Working Load (SWL).
Never lift more persons on a platform than stated, even if it is within the Safe Working Load (SWL).
3. Operating on Inclines
MEWPs are generally designed to work on inclines but usually of small tolerances (1º – 3º on many ‘mobile’ type platforms). Manufacturers do develop and include safety systems to indicate, limit and prevent operation beyond these points. However, it is important to understand that wind forces acting along the same direction of incline as a MEWP could give it a greater impetus to destabilise.
Wind forces acting in the same direction of incline as a MEWP may be cause of greater instability.
4. Localised Wind Effect
On days where the wind is strong, MEWPs should not be operated between gaps in buildings or structures where those winds can be funnelled and concentrated, whipping up turbulent forces that have the potential to destabilise an exposed MEWP. Caution should also be taken when operating MEWPs near to aircraft slip streams at airports and high sided vehicles on roads and motorways.
Care should be taken when operating MEWPs between buildings where winds can be funnelled.
5. The Wind Chill Factor!
Wind chill (a cause of hyperthermia), should be assessed prior to operating MEWPs. An ambient temperature of 10º C is considered to be cool but not unpleasant. However, at this temperature in winds of 8.9 m/s or 20 mph, the face and Hands can experience a wind chill temperature of 0º C. This can impair judgment, lead to confusion, poor co-ordination and changes to normal behaviour.
Always wear warm clothing if operating MEWPs in winds where there is possible risk of wind chill.
6. Increase with Height
It is very important to realise that wind speed can increase with height and may be 50% greater at a height of only 20 metres above ground level. Though a MEWP and its occupants may initially be sheltered at low level, as the MEWP elevates above the surrounding buildings, structures and even through the tops of tree canopies, it will be exposed to a higher strata and the full force of the wind.
Wind speed can dangerously increase with height and may be 50% greater at a height of 20 mtrs.
7. Making a Large Sail
It is essential that great care must be given to the Handling of building cladding, sheet materials, panels and other such-like materials when operating MEWPs in windy, gusty conditions. Such materials act as projecting sails, effecting the ability to handle them safely and compromises the stability of a MEWP. This also applies to the hanging of flags and banners from elevated platforms.
Care must be taken when handling cladding, sheet materials or panels in windy, gusty conditions.
8. Silly ‘Willy’ Waving!
Willy Waver: (An unbearable male show-off. British slang). We’ve all seen MEWPs left stuck up in the air while we drive up and down the motorways or left abandoned on supermarket carparks, regardless of the prevailing weather conditions. Yet guidance is clear, when not in use MEWPs should be Stowed (i.e. lowered to their parking position). Anything else is just blatant advertising!
Guidance is very clear, when not in use MEWPs should be lowered down to their parking position.
9. It’s a Strong Breeze
The only truly accurate way to record wind speed is from the platform of a MEWP using an Anemometer. Many will readily agree that relying on the limited visual Beaufort Scale, is not in the least bit practical for MEWP operators. Standards specify a design wind speed for MEWPs to be a minimum of 12.5 m/s or 28 mph. That’s no more than a strong breeze, see conversion table below:
The only truly accurate way for measuring wind speed is from the platform using an Anemometer.
10. Wrath of the Gods!
Anemometers get their name from the ancient Greek word ‘Anemoi’ (Greek: “Aνεμοι, translating to “Winds”). In Greek Mythology the Anemoi were Gods of the Wind, each ascribed to a compass point, seasons and weather conditions, represented as gusts of winds or personified as winged men. Chief of the Anemoi was Boreas, God of the north winds and harbinger of the cold winter air!
Mythical maybe, but ignore the force of the wind and you may well confront the Wrath of the Gods!