Health and Safety Executive

Chlorine.... its safe use in foundries

Contents

This leaflet gives advice on current good practice

Chlorine is supplied in cylinders or tanks which contain liquid chlorine under pressure. Chlorine gas is blown through molten metal as part of some metal degassing operations. Unused gas is blown out of the molten metal and may require exhaust ventilation control.

The hazards

Chlorine is a very toxic gas and exposure to levels as low as 1 ppm for a few minutes can cause eye, nose, and throat irritation.

Exposure to concentrations above 30 ppm, even for a short period, can be dangerous, causing severe breathing difficulties such as coughing, tightness in the chest and wheezing. It is essential that persons exposed to such levels seek early medical advice and be warned that pulmonary oedema (fluid on the lungs) may occur several hours afterwards.

Breathing even very low concentrations of chlorine can aggravate the symptoms of existing respiratory diseases such as bronchitis and asthma. Workers need to be aware of this possibility. Those with such disorders should be medically assessed prior to placement, and may require ongoing health surveillance.

How to reduce risk

Any worker who is involved with the use, storage or transport of chlorine should be instructed on the associated dangers and necessary precautions. This may include the use of goggles, gloves and aprons and, where necessary, respirators.

Cylinders require careful handling, preferably using purpose-made trolleys or stillages.

Exhaust ventilation equipment should be regularly checked for leaks and damage.

Complying with workplace exposure limits

The workplace exposure limits for a range of chemicals can be found at http://www.hse.gov.uk/coshh/table1.pdf

The (WEL) for chlorine is currently:

  • 0.5 parts per million (0.5 ppm) time weighted average over eight hours,

    or
  • 1 ppm over fifteen minutes.

The occupational exposure standard (OES) for chlorine is 0.5 parts per million (0.5 ppm) time weighted average over eight hours, or 1 ppm over ten minutes.

A worker's exposure should not normally exceed those limits. If it does, action should be taken to reduce that exposure.

Chlorine may be detected by smell at around 1 ppm.

The duty of suppliers

Suppliers have a duty to ensure so far as is reasonably practicable, that chemicals they supply are safe and present no risk to health when used, handled, processed, stored or transported.

They also have a duty to provide the customer with a description of the hazards involved and precautions necessary to overcome these hazards.

This advice usually comes in the form of a product safety sheet, and users are advised always to request copies from suppliers. Advice given in these safety data sheets may form the basis of training and instruction given to employees.

Safe storage

Cylinders should be stored in a safe place in the open air, such as a simple open-sided enclosure, and sited at least 5 m from combustible materials or be separated by a fire-resisting (BS 476) wall.

When stored or in use, cylinders should be secured upright in a position where they cannot b damaged by passing traffic.

Chlorine gas is heavier than air and cylinders or tanks should not be stored or used in basements or near occupied underground rooms where leakages could collect.

Pipework

Pipework and associated equipment used in blowing operations should be examined frequently to ensure that leaks are detected promptly and necessary repairs carried out. Pipework needs to be banded or painted in accordance with BS1710:1984.

Other available information

This leaflet was produced by the Foundries Industry Advisory Committee which advises on the protection of foundry workers from hazards to their health and safety while at work.

General information is available from the HSE infoline on 08701 545500 or from your local HSE office.

Specialist advice is available from HSE's Molten Metals Group at their Cardiff office: Tel: 01222 263000

Further Information

Priced publications

Foundry hazard leaflets (free)

HSE priced and free publications are available by mail order from:

HSE Books, PO Box 1999,
Sudbury, Suffolk CO10 6FS
Tel: 0787 881165
Fax: 0787 313995

This publication may be freely reproduced, except for advertising, endorsement or sale purposes. The information it contains is current at 04/07. Please acknowledge the source as HSE.

Printed and published by the Health and Safety Executive

IAC(L)36(rev) 04/07

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18.09.09