Local Exhaust Ventilation Testing
Background
Many people today are exposed to a variety of substances at work for example chemicals, fumes, dusts, fibres which can under certain circumstances, have a harmful effect on their health.
These 'hazardous substances' can cause harm by too much being taken into the body through breathing, by being absorbed through the skin or swallowed, or by acting directly on the body at the point of contract.
The Health and Safety Executive have set occupational exposure limits for a large number of hazardous substances at work and publishes them in EH40 updated every year. Many work activities involve hazardous substances being handled, produced or processed in ways that result in dust, fumes or gases being given off to the workplace atmosphere. Current legislation requires that exposure to hazardous substances is either prevented or adequately controlled. Local exhaust ventilation is a key part of providing effective means of controlling exposure.
Current regulations including The Control of Substances Hazardous to Health Regulations 1999 (COSHH) require systems to be maintained in an efficient state, in an efficient working order and in good repair. All plant deteriorates with time therefore regular monitoring and testing forms an important part of the proactive maintenance.
Under the COSHH regulations there is a statutory requirement to undertake formal examinations and testing of LEV systems at least once every 14 months. HS(G)37 "An Introduction to Local Exhaust Ventilation" suggests that these checks should be undertake by competent people who are not normally responsible for the system maintenance to get an independent opinion.
Test Protocol
The HBI testing protocol is designed to ensure that the systems are operating effectively and efficiently and
comply with the current legislation on LEV systems.
The assessments are all undertaken in accordance with the procedures detailed in HS(G)37: An Introduction to Local Exhaust Ventilation and HS(G)54: Maintenance, Examination and Testing of Local Exhaust Ventilation.
The performance of each system is verified using a combination of visual and physical checks of each system including all associated ductwork, filtration equipment and pressure gauges. A variety of test equipment is used where appropriate, including pitot tubes, micromanometers, hot ball anemometers and other test equipment, to monitor;
(i) Face velocity
(ii) Static pressure at selected locations through out the system
(iii) Duct dimensions
(iv) Installation of test points in duct
(v) Capture distance
