In this expert guide the indoor air quality specialists at WTS consider the use of LEV airflow indicators and how they can be used to manage ventilation performance, maintain air quality and improve environmental safety. The guide looks at why airflow monitoring is important and how best to achieve it, Local Exhaust Ventilation testing and what to do if things go wrong.
What is Local Exhaust Ventilation?
Local Exhaust Ventilation, usually abbreviated to LEV, is a popular method of extracting fumes and dust from air before staff or customers get the chance to breathe them in. Once the ventilation system has been installed, one of the key aspects is to keep it running effectively and efficiently by monitoring LEV airflow.
LEV airflow indicators
If you are an employer, under UK health and safety law it is your responsibility to make sure that your Local Exhaust Ventilation systems are operating properly to protect your staff and others from harm. One of the main reasons for a LEV system failing is that the airflow through the ventilation unit isn’t what it should be. This might be because dust or other particles are building up in the system, the ducting suffers from reduced flow rates or has become damaged in some way. It is highly recommended that LEV units include airflow indicators (pressure gauges) as these will flag up potential problems before the unit breaks down completely.
In the UK employers have a legal responsibility to test LEV systems thoroughly every 14 months
LEV airflow indicators fitted to your exhaust ventilation systems will also reassure you that the units are operating as they should be, keeping the flow-rates maintained and providing high quality air for your business, helping to protect your people.
Alternative ways to monitor LEV airflow
However, airflow indicators aren’t the only way of monitoring ventilation rates. Alternative methods include manual checking using an anemometer, smoke tracer or dust lamps. However, indicators are the only technology which will provide automatic notification when a problem is detected with your Local Exhaust Ventilation system and so are the preferred method of monitoring airflow.
Retro-fitting automatic LEV airflow detectors to existing extract systems is not a legal requirement. However, you should have some other way of checking if the ventilation system is producing adequate airflow.
What to consider when selecting an airflow indicator
If you do decide to invest in LEV airflow indicators, prioritise fitting based on factors including cost, risk of exposure, how well other sorts of checks are working and the whether the airflow is set manually or automatically.
Airflow indicators are a much more reliable and effective way of measuring the speed of air being drawn into a Local Exhaust Ventilation system than estimating it manually. A well-designed indicator will allow you to see at a glance whether airflow is acceptable or not.
Although LEV airflow indicators are usually the best way to verify sufficient airflow through extractor hoods, this is not always the case. If you have a very simple system made up of a fan, filter, duct and hood, a manometer which measures pressure across the filter can often be sufficient. You don’t need to invest in expensive, top of the range airflow indicators when the risk to people is considered to be very low.
If on the other hand the exhaust ventilation system is installed to deal with hazardous substances or in situations where the business could incur hefty losses if the system shuts down unexpectedly, it’s usually a good idea to buy a LEV airflow monitor that incorporates an indicator alarm which sounds if airflow drops below acceptable levels.
Irrespective of the type of airflow indicator you choose, you should be able to read the display very easily. A common design is with a pointer to green for adequate airflow, and red for poor airflow.
It’s tempting to try to cut costs with other ways of measuring airflow, such as strips of paper or plastic hung in front of the unit. These methods are not accurate and are very easily broken too – they are not recommended.
Local Exhaust Ventilation maintenance and testing
When it comes to LEV maintenance and testing, employers have a legal responsibility to test systems thoroughly every 14 months. Many businesses think that having a sticker attached to the airflow equipment with the testing date is also a legal requirement. It’s not – but it’s the cheapest and simplest method of keeping on top on what has been tested and when.
How to record LEV airflow tests
The UK’s Health and Safety Executive recommends using labels or stickers to record when LEV airflow was tested, and to record the results. Wherever the label is placed, it should be easily visible to anyone using or maintaining the ventilation unit.
What to do if Local Extract Ventilation systems fail testing?
Other Health and Safety Executive guidelines recommend that any LEV system which fails testing should also be clearly labelled to indicate this. The best way of doing this is by using an obvious red “fail” sticker or label placed where it can easily be seen.
Local Exhaust Ventilation examiners should also provide a report detailing the reasons for the failure and giving options to remedy the situation. After the LEV unit has been repaired, arrange to have it tested again to make sure the performance has improved to acceptable levels.
Again, you don’t have to use “fail” labels if you don’t want to. Depending on the needs of the business and the risks involved, you might choose another way to identify faulty equipment, as long as it is very clear to everyone which equipment needs to be repaired.
Specialist LEV testing and exhaust ventilation inspection solutions
WTS offer a comprehensive range of LEV testing and exhaust ventilation inspection solutions to support business owners and operators. Our experts can provide advice and support to help you identify the most appropriate strategies for the on-going management of your LEV systems.
With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained technicians, in-field specialists and consultants we can offer professional, cost effective indoor air quality solutions across the whole of the UK and internationally.
Contact us today to learn how our expert LEV testing and inspection solutions can help you keep your staff and other people safe.
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