Flammable and Explosive Substances

Some gases, liquids and solids can cause explosions or fire. For a fire to start, fuel, air and a source of ignition are needed.
Common materials may burn violently at high temperature in oxygen rich conditions, e.g. when a gas cylinder is leaking.
Some dust from a cloud which will explode hen ignited. A small explosion can disturb dust and create a second explosion severe enough to destroy building. Serious explosions can occur in plant such as ovens, stoves and boilers.
Some materials are explosives and need special precautions and licensing arrangements.
Some flammable liquids and substances are also corrosive or toxic and may pose risk to health.

Before You Start

The supplier’s safety data sheet will help you decide how to handle these substances.

Think about:
1. doing the job another way
2. using liquids with higher flash points. Look at the data sheets – remember a high flash point is safer than the low one.
3. reducing the amounts you keep on site.
4. checking with the supplier about any special precautions which may be needed when certain materials are delivered in bulk.
5. checking containers labels and consignment notes to make sure that goods are supplied as ordered


Storage

Some chemicals react dangerously together. Such classes of material should be stored correctly, e.g. oxidizing substances should be kept apart from flammable ones.
Use the information from the supplier and the package label to decide storage arrangements. Materials can be separated by distance, by a physical barrier or (sometimes) by other non-reactive materials.

Good Storage will:
1. be separate from process areas ( where fire or leakage is more likely to occur)
2. be in a safe, well-ventilated place, isolated from buildings
3. prevent incompatible chemicals being mixed, e.g. by spillage, damage to packaging or by wetting during fire fighting.
4. reduce the risk of damage, e.g. by lift truck, and by ensuring that cylinders are secured and stored upright.
5. prevent rapid spread of fire or smoke, or liquid or molten substances, e.g. by the store being made of fire-resisting material
6. exclude sources of ignition, e.g. static electricity, unprotected electrical equipment, cigarettes and naked flames.
7. include empty drums or cylinders as well as full ones – the risk can be just as great.

Housekeeping

1. remove grease frequently from ducts, such as kitchen ventilators and cooker extractor hoods.
2. keep the workplace tidy and free from old containers etc. Plastic foam crumb and off-cuts are particular hazard
3. contaminated clothing or containers need careful disposal.
4. keep flammable waste secure from vandals.

Flammable liquids

The safest place to store any flammable liquids and substances is in a separate building or in a safe place in the open air. If highly flammable liquids have to be stored inside workrooms you should store as little as possible and they should be kept on their own in a special metal cupboard or bin. Larger stocks should be held in a fire resisting store with spillage retention and good ventilation.

If you run a factory you should :
1. minimize the amount kept at the workplace
2. dispense and use in a safe place with adequate natural or mechanical ventilation
3. keep containers closed e.g. use safety containers with self-closing lids and caps
4. contain spillage e.g. by dispensing over tray and having absorbent material handy.
5. control ignition sources e.g. naked flames and sparks, and make sure that “no smoking” rules are obeyed, specially when spraying highly flammable liquids.
6. keep contaminated material in a lidded metal bin which is emptied regularly.
7. get rid of waste safely , e.g. burn rubbish in a suitable containers will away from buldings. Have fire extinguishers on hand. Don’t burn aerosol cans and don’t “brighten” fires with flammable liquids.


Gas Cylinders

Storage and use:
1. store both fill and empty cylinders in a secure outside compound where possible.
2. store with valves uppermost, particularly where they contain liquid like acetylene.
3. don’t store them below ground level or near to drains or basements – most gases are heavier then air.
4. protect cylinders form damage e.g. by chaining unstable cylinder in racks or on special trolleys.
5. use the right hoses, clamps, couplers and regulators for the particular gas and appliances.
6. turn off cylinders valves at the end of each days work.
7. change cylinder away from sources of ignition, in a well-ventilated place.
8. avoid welding flame “flash-back” into the hoses or cylinders by training operators in correct lighting up and work procedures and by fitting non-return valves and flame arresters.
9. use soap or detergent/water solution, never a flame to test for leaks.
10. before welding and similar work , remove or protect flammable material
11. where possible, position gas cylinders on the outside of buildings and pipe through to appliances or processes.
12. make sure that rooms where appliances, e.g. LPG heaters are used have sufficient ventilation high up and low down which never blocked up to prevent draughts.

Dust Explosions

Do you have a dusty process? Is the dust fammable? examples include aluminum powder, flour, bone-meal, cotton fly, paper dust, polystyrene and fire sawdust.

If so you must:
1. keep plant dust-tight and frequently checked and cleaned.
2. avoid buildup of dust, e.g. reduce the number of ledges and horizontal surfaces on which dust may settle and use exhaust ventilation with suitable dust collectors as necessary.
3. control sources of heat such as welding space heaters and smoking.
4. reduce sparking by using dust-tight electrical equipment, by earthing sources of static electricity and by using magnets to catch any stray pieces of metal before they get into the process.
5. take explosion protection measures, by providing explosion vents or a plant structure strong enough to withstand and explosion.
6. make sure explosion vents discharge safely.

You can reduce the effects of an explosion by using lightweight construction for buildings which house dangerous plant.

Oxygen

Common materials may burn violently at high temperature in the presence of oxygen.
1. never use oxygen to “sweeten” the atmosphere
2. make sure there are no leaks, specially in confined areas, and don’t use oxygen to operate compressed air equipment.
3. keep oxygen cylinders free from grease and other combustible materials and don’t store them with flammable gases or materials.


Transporting Materials

If you transport and deliver materials off site, then you must:

1. ensure the packages are suitable and correctly labeled as required for carriage by road, rail, air or sea.
2. ensure that the vehicle is suitable for the purpose.
3. provide appropriate fire-fighting equipment
4. fit hazard panels/plates on delivery vehicles as required
5. check compatibility of loads
6. provide written information for the driver
7. train vehicles drivers on their duties, the hazard and risk involved and the necessary emergency procedures as required.

Emergencies

Consider what could go wrong:

1. could staff accidentally mix incompatible chemicals e.g. bleach with other cleaners.
2. are you prepared for a large leak or spillage?
3. what about hazardous by-products? Could mixing of waste chemicals in the drains cause a hazardous reaction or pollution?
4. are any special first-aid facilities or equipment required?
5. could emergency water supplies freeze up in winter?

Supplier

Supplier must:
1. provide safety data sheets and other information for users
2. arrange for any necessary testing and research so that substances can be used safely at work
3. choose packaging which provides protection for users and during conveyance and transport
4. provide labels which give adequate information about the risk and necessary precautions

Latest News Occupational Health & Safety

Latest News Occupational Health & Safety