Posted By Charlie Gunter
Although oxygen is not flammable it is a supporter of combustion. Oxygen enriched atmospheres present a hazard in that substances not normally considered highly flammable become so.

Does anyone have any thoughts on how the new regulations might affect oxygen and in particular, would places where oxygen was used or stored need to be zoned?

Posted By Adrian Watson
Dear Charlie,

Afraid so, you've got to assess them under DSEAR.

Reg 5. - (1) Where a dangerous substance is or is liable to be present at the workplace, the employer shall make a suitable and sufficient assessment of the risks to his employees which arise from that substance.

(2) The risk assessment shall include consideration of -

(a) the hazardous properties of the substance;

(b) information on safety provided by the supplier, including information contained in any relevant safety data sheet;

(c) the circumstances of the work including -

(i) the work processes and substances used and their possible interactions;

(ii) the amount of the substance involved;

(iii) where the work will involve more than one dangerous substance, the risk presented by such substances in combination; and

(iv) the arrangements for the safe handling, storage and transport of dangerous substances and of waste containing dangerous substances;

(d) activities, such as maintenance, where there is the potential for a high level of risk;

(e) the effect of measures which have been or will be taken pursuant to these Regulations;

(f) the likelihood that an explosive atmosphere will occur and its persistence;

(g) the likelihood that ignition sources, including electrostatic discharges, will be present and become active and effective;

(h) the scale of the anticipated effects of a fire or an explosion;

(i) any places which are or can be connected via openings to places in which explosive atmospheres may occur; and

(j) such additional safety information as the employer may need in order to complete the risk assessment.

Reg 7. - (1) Every employer shall classify places at the workplace where an explosive atmosphere may occur into hazardous or non-hazardous places in accordance with paragraph 1 of Schedule 2 and shall classify those places so classified as hazardous into zones in accordance with paragraph 2 of that Schedule; and that Schedule shall have effect subject to the notes at the end of that Schedule.

Schedule 2

1. Places where explosive atmospheres may occur

A place in which an explosive atmosphere may occur in such quantities as to require special precautions to protect the health and safety of the workers concerned is deemed to be hazardous within the meaning of these Regulations.

A place in which an explosive atmosphere is not expected to occur in such quantities as to require special precautions is deemed to be non-hazardous within the meaning of these Regulations.

2. Classification of hazardous places
Hazardous places are classified in terms of zones on the basis of the frequency and duration of the occurrence of an explosive atmosphere.

Zone 0
A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.

Zone 1
A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is likely to occur in normal operation occasionally.

Zone 2
A place in which an explosive atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapour or mist is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Zone 20
A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is present continuously, or for long periods or frequently.

Zone 21
A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is likely to occur in normal operation occasionally.

Zone 22
A place in which an explosive atmosphere in the form of a cloud of combustible dust in air is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Most places, eg o2 gas stores where o2 is not used but some large leaks are possible would be classified as zone 2.

Regards Adrian Watson

Posted By Stuart Nagle
Oxygen in itself is not a dangerous substance per se.

In cylinders under high pressure it could become dangerous when exposed to certain conditions that may arise, such as fire, and in the case of DSEAR it would I think be more likely to be where and how it was used and the likelyhood of leaks into atmospheres where the potential risk due to leakage were increased, i.e. fire & explosion.