Design and installation

• Pages: 33-36

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7. Design and installation

7.1. General principles

7.1.1. Plant and equipment should be designed and installed to contain or

minimise the risks from chemicals used at work, e.g.:

(a) by reducing the release of harmful or flammable chemicals, including the vapour

and dust from such chemicals;

(b) by preventing the spread of fire and explosion in the workplace.

7.1.2. Containment of a hazard is best achieved by fully enclosing processes

involving the use of chemicals. Full enclosure of processes can be more easily achieved

where plant and equipment are automated or operated remotely. This should be a

primary consideration during the design of plant and equipment and the process to be

used. Bulk storage, with fixed pipework transfer suitably designed and fit for the

purpose, should be used in preference to small container storage, where appropriate.

7.1.3. To reduce leaks, where particularly hazardous chemicals are used,

enclosed plant and equipment should be fitted with extraction systems, which should be

designed to ensure a slight negative pressure within the plant and equipment, where the

process allows. Extraction systems should vent to a safe place, or contaminated air

should be filtered or treated to ensure that exposure limits or other established criteria

for the control of the working environment are not exceeded.

7.1.4. Working areas, plant and equipment should be so designed and installed

as to avoid unnecessary exposure of workers to hazardous chemicals; this should

include the provision of local exhaust ventilation, ensuring that cleaning can be kept to

a minimum, and facilitating maintenance and cleaning procedures.

7.1.5. To further reduce risks from hazardous chemicals, plant, equipment and

storage should be separated from other processes, from incompatible chemicals or other

chemicals which may cause a hazard in the event of fire, from premises off site and

other areas outside the control of the employer and, in the case of flammables, from

fixed sources of ignition.

7.1.6. To prevent the spread of fire and explosion the following safety

engineering techniques should be considered:

(a) design and construction to contain the effects of an explosion;

(b) limiting the effects of a fire or explosion by means of suitably sized and designed

pressure-relief vents, explosion-relief panels, etc., which vent to a safe place;

(c) methods that prevent or reduce the spread of fire, such as the use of non-

combustible or fire-resistant materials of a specified standard;