Localised Fume Extract Arms
Localised fume extract arms (also known as snorkel extracts) are the perfect solution for efficient capture of fumes at source. Their compact size, ease of movement, low-cost and low extract volume make them ideal LEV solutions for bench top experiments.
Fumair are UK agents for the complete range of extract arms and LEV equipment manufactured by Alsident System.
Alsident System extract arms are self-supporting with internal threaded stays and springs. This construction results in a point of extract which is easy to position to the source of the pollutant, and push out of the way when not in use. Unlike traditional fume hoods or enclosures an fume extract arm allows good all-round access to the work area.
All Alsident extraction arms are made of high-quality shock proof polypropylene and anodised aluminium. Threaded stays, springs and inner fixing are made of acid-resistant stainless steel ensuring long durability in aggressive environments. Joints are self-lubricating and maintenance-free.
Alsident fume extract arms are available in a large number of lengths, diameters and materials, including chemical resistant polypropylene and anti-static conductive polypropylene for use in ESD and ATEX environments.
As well as the extract arms, Fumair can supply and install the complete extract duct, fan and control system.
We can advise & design custom enclosures and LEV systems
We can test & commission LEV systems. Our Service engineers are P601 trained and will carry out a "Thorough Examination" to the HSE COSHH requirements.
What is a LEV system
A Localised Extract Ventilation (LEV) System - is a control measure designed to reduce exposure in the workplace to airborne contaminants such as dust, fumes and gases as required by COSHH (Control of Substances Hazardous to Health).
Air is extracted from the work area in such a way that the contaminants are captured and/or contained. They are then either filtered from the airstream and returned to the workplace or ducted to atmosphere and dispersed.
by law, LEV systems must be tested and inspected every 14 months by a competent person.
Fumair have the equipment, skills and experience to ensure your LEV is meeting the legal requirements set out in COSHH, HSG258 and other relevant standards, and performs efficiently and effectively.
Fumair can provide airflow monitors and alarm systems, as recommended by COSHH, providing real-time indication of airflow and audible/visual warning in the event of a significant drop in airflow performance or airflow failure.
Airflow Monitors by Fumair
Every LEV and fume cupboard should come with some sort of airflow monitoring device.
The Digital Fumeguard & Flowmaster are the perfect complement to any extract device
Capture Arms / Capturing Hoods
A capturing hood is the most common form of LEV.
With a capturing hood, (also known as a Capture hood, or captor) the process, source and contaminant cloud are outside of the hood.
The capture hood has to have sufficient airflow to capture and draw the passing contaminated air into the hood.
Due to the containment work process is taking place outside of the hood it is important that all work is carried out within the effective capture distance of the hood. The effective capture distance varies depending on the process being carried out along with the minimum capture velocity to ensure the airflow can carry the debris.
Capturing hoods can vary from small on tool extraction also known as Low Volume High Velocity (LVHV) which are found on the tips of soldering irons, to Alsident arms and Neederman arms used for welding and fumes to rim or lip extraction on large industrial processes.
A receiving hood like a capturing hood also has the process taking place outside of the hood. The difference is that a receiving hood relies on the process propelling the contaminant cloud towards the hood. This can be in a process such as grinding or a hot process. (Another type of receiving hood is a push pull system where air is blowing into the receiving hoods direction). Receiving hoods can be moveable and static.
The face velocity should be a minimum of 0.40m/s unless a lower face velocity can be proven to be effective.
A well designed receiving hood should be large enough to collect the whole plumb if above a hot process. The area of the hood should also be 40% larger than the process being carried out. Keeping the hood as close as possible to the process is also a key consideration as well as a 20% higher extraction flow than the incoming contaminant. The users breathing zone should not be able to interrupt the space between the process and the hood.
Capture Arms / Capturing Hoods
An enclosing hood is the most effective form of control and usually the preferred method as the process takes place inside a set area. A full enclosure completely encloses the process, while a partial enclosure gives access during the process, for example fume cupboards, where the user can place new items inside.
The size of enclosing hoods vary depending on the processes taking place. Some are small bench mounted enclosures such as glove boxes in labs, or blasting enclosures, while others are large enough the operator is inside with the process (with these breathing apparatus is essential) car paint spray booths and large abrasive-blasting rooms are a good example.
The advantage of these types of enclosures are the process is contained and always within the capture distance with little chance of the users breathing zone coming in contact with the contaminated air (if the LEV is functioning correctly). These type of enclosing hoods are also less effected by drafts and user error. However it should be remembered that the users body can create wakes, and eddies potentially placing contaminated air into the users breathing zone. Steps should be made to reduce this happening such as the use of downdraught booths, moving the the source deeper inside the booth or putting a barrier between the users breathing zone and the contaminant source.
LEV Effectiveness Scale
Total Enclosure - Highest form of protection as user is outside and the containment is contained.
Almost Full Enclosure
Partial Enclosure, Down flow Walk-in Booth
Recieving Hood, Walk-in Booth
Capturing Hood - Lowest form of effectiveness as it has a very localised capture area.
A fully functioning LEV system should contain, capture or receive the contaminant cloud within the LEV hood and conduct it away.
The greater the degree of enclosure of the source, the more likely it is that a control will be successful at protecting the user.
Some form of monitoring system should be in place to monitor the performance of the LEV. (this can be an airflow monitor).