100
Source: BP International
Figure 10.6 – Discharge to Atmosphere
10.3 Maintenance, Examination and Testing of Ventilation Systems
Local Exhaust Ventilation LEV is one of the most effective means available of preventing hazardous materials entering the workplace atmosphere.
However, in order to function correctly it must be in good working order. The general features associated with the maintenance, examination and testing of
LEV systems are outlined.
10.3.1 Legal requirements
In some countries there is a legal requirement that control measures are maintained in an efficient state, in efficient working order and in good repair.
For example in the UK, the COSHH Regulations requires that LEV is examined and tested, at least once every 14 months, and that suitable
records are kept for at least 5 years. There is also a requirement to carry out weekly visual examinations.
10.3.2 Regular Maintenance
Maintenance should include: Regular inspection of the plant, including a weekly check for signs of
potential damage, wear or malfunction.
101 Monitoring of performance indicators, e.g. air velocities, static
pressures, electrical power consumption. Routine replacement of components known to have a limited working
life. Prompt repair or replacement of components which are found to be
worn or damaged. The form of inspection will depend on the type and complexity of the plant. A
visual check, at least every week, is essential to identify any obvious faults. This includes checking for:
Incorrect positioning of hoods. Wear, tear and signs of malfunctions or damage to hoods, ductwork
and dust collectors. Other outward signs of malfunction or damage.
The checking should also include the monitoring of any permanently fitted monitoring devices. A simple record should be kept of weekly inspections
together with a written note of faults identified and actions taken to rectify them.
10.3.3 Thorough Examination and Testing
This is a periodic audit of the LEV system and its performance and will normally comprise:
A thorough external and, where appropriate, internal examination of all parts of the system.
An assessment of control, for example, by the use of dust lamps, fixed position air monitoring andor smoke testing.
Measurement of plant performance, for example by static pressure measurement behind each hood or enclosure, air velocity at the face of
the enclosure or point of emission, pressure drop across filters, air velocity measurement in the duct andor power consumption.
Where air is circulated, an assessments of the performance and integrity of the air cleaner or filter.
102 Some LEV systems return filtered air to the workplace and therefore these
systems should receive a particular high standard of maintenance etc.
103
11 ASBESTOS
11.1 Background
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