Storing hazardous liquids correctly
11 December 2014
The incorrect storage or poor management of liquids can have far-reaching consequences and although oil storage regulations are some of the most heavily publicised, it is all too easy to forget that many liquids pose a potential threat to health, safety and the environment. In this article, Andrew Lawrence of Empteezy Group looks at major challenges faced by businesses in this area, as well as providing advice on storage and handling good practice.
As a starting point, the following questions need to be answered to generate the information required to help ensure products are stored correctly and safely:
· What are the liquids?
· Is there a fire, explosion or vapour release risk associated with any of the liquids?
· Is there a requirement to store any of the liquids separately?
· How many litres of each product do you want to store?
· Will bulk storage be involved, or use drums and/or intermediate bulk containers (IBCs)?
· Will the liquid be stored indoors or out?
· If indoors, are there any access issues with regard to the location?
· If outdoors, are there surface water drains or a water course in the vicinity?
· How will the liquids be delivered to site?
· How will they be moved around the site?
The Material Safety Data Sheet (MSDS) for the liquids used will provide much of the detail required to answer the first three questions , and the chemical manufacturer can provide advice on issues such as segregation of liquids, possible explosion risk and vapour release hazards.
Determining the amounts of product in what types of containers (e.g. 205 litre drums, 1,000 litre IBCs, bulk tanks, etc.) required on site is fundamental in ensuring there is no product storage or handling incident. Empty containers, which are likely to have residues in them, must also be stored correctly.
The location of the storage area must be considered with great care to minimise the risks of damage to the environment, and the health and safety of employees and the public. It must be located in a place that will ensure there is no pollution of air, land, surface or ground waters if there is a spill.
It goes without saying that storage containers (bunded stores, spill pallets, etc.) must be designed with environmental protection in mind. This means that the bund and any storage units or spill pallets must be able to contain at least 110% of the volume of the largest container or 25% of the total volume stored - whichever is greater - and they must be made of a material that is compatible with the chemical to be stored.
Drums and IBCs also need to be protected when they are being moved around the site. Bunded trolleys or mobile spill pallets are ideal, but they need to be properly secured onto the trolley or pallet before setting off.
If a bund is unprotected, rainwater will collect in it and reduce its capacity. Also, the contents must be checked before disposal to ensure contaminated water is not discharged. It is against the law to discharge anything that could harm or interfere with the treatment or disposal of sewer contents.
Bunded storage of drums
To allow rainwater from bunds to enter surface or ground water the site operator needs an Environmental Permit or registered exemption in England and Wales, discharge consent or groundwater authorisation in Northern Ireland or an authorisation under the Controlled Activity Regulations (CAR) in Scotland.
Even the water from emergency safety showers is controlled as it may be contaminated. It can be disposed of in the foul sewer with permission from the relevant water company or authority, but otherwise will need to be collected and disposed of in a suitable manner. Contaminated water is considered to be hazardous/special waste.
Areas where there are smaller amounts of chemicals such as laboratories, test rigs, workshops or vehicles also need to be considered. The same rules apply and storage in a laboratory cabinet is a common solution, with flammable chemicals held in a fire-proof steel cabinet. The cabinet also needs to be secured to the floor and/or wall to prevent it toppling over.
Where different chemicals are stored together, segregation issues become a factor.
Chemicals should never be left on the floor, even on a temporary basis, and should never be stored above eye-height or on top of cupboards or cabinets. Where necessary, Personal Protective Equipment should be worn.
A full inventory of the chemicals on site must be available at all times, and should be kept somewhere it can be accessed easily out of hours for use by spill responders or outside agencies.
It is also important that staff are fully trained and know how to deal with any spills that may occur, and that there is a comprehensive pollution incident response procedure in place. If large volumes of liquids are stored the installation of a spill alarm should be considered. Where hazardous substances are involved, a major accident prevention policy should be drawn up under Control of Major Accident Hazards (COMAH) Regulations.
All sites should have spill kits, containment equipment and drain sealing products suitable for the type and quantity of chemicals stored and used on site. It is always better to try and keep any spill on the surface.
Locate equipment remote from but accessible to any area that poses a risk and ensure its location is marked on the site plan (again available to staff or outside agencies) and that their location is easily visible.
· Never hose a spill down the drain: it could cause a much worse pollution incident.
· If you cause pollution, you could be prosecuted and fined.
When considering the storage of flammable liquids, over and above all the elements outlined above, there are strict adherences concerning separation distances. This is the distance the flammable liquids must be stored from occupied buildings, boundaries, process units, flammable liquid storage tank, or sources of ignition.
· Up to 1,000 litres - 2 metres
· 1,000 to 100,000 litres - 4 metres
· Above 100,000 litres - 7.5 metres
With these distances maintained, a standard single skinned, fully bunded storage unit can be used to hold flammable liquids. Where they are not, the storage unit must be one-hour fire rated to comply with UK legislation.
The safe storage of flammable liquids in process areas, workrooms, laboratories and similar working areas requires additional careful and informed consideration. The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) require risks from the indoor storage of Dangerous Substances to be controlled by elimination or by reducing the quantities of such substances in the workplace to a minimum and providing mitigation to protect against foreseeable incidents.
Potential threat types
There are three elements required for a fire to start: Heat, Oxygen and Fuel. If you eliminate any one of these elements, you eliminate the fire.
· Heat can be any ignition source which generates heat, such as a mechanical spark, static electricity, a naked flame such as from welding equipment, etc.
· Oxygen is all around us
· Fuel can be any flammable or combustible liquid, remember flammable vapours are a significant hazard too.
Store flammable liquids in a separate area in purpose-made bins or cupboards that are compliant with UK regulations and, when dispensing, ensure there is good ventilation and no sources of ignition. Always keep containers closed when not in use. Whenever possible, use safety containers with self-closing lids and flame arresters and always have the appropriate spill kit available too.
Flammable dust in the atmosphere can, if ignited, explode violently. If such dusts are handled, the areas concerned must be dust-tight and regularly cleaned. Any spills should be vacuumed with intrinsically safe equipment.
Many types of packaging material (plastic foam, polyester wadding, textiles, etc,) give off dense black smoke when they burn so should not be stored close to heaters or electrical equipment which could act as an ignition source.
Gases are often stored at very high pressure and any uncontrolled release can fill a large area quickly, this is particularly true of liquefied gases such as LPG. Cylinders should be kept in a designated area in purpose built stores under restraint to protect the valves from potential impact damage.
Materials that ordinarily burn slowly will burn vigorously in an oxygen-rich atmosphere, so oxygen should be treated in a similar manner to flammable gases. Never use oxygen when compressed air is an option, never use oxygen to sweeten the air in a working area or confined space and never use grease or oil on equipment containing oxygen as they can self-ignite.
Some products have chemicals such as organic peroxides as part of their composition which can explode if not stored and handled correctly. Other substances can react with incompatible materials or contaminants in an explosive manner, for example oxidising chemicals can cause flammable materials to ignite and some substances such as sodium react violently and can ignite when they come into contact with water. Storage and process temperatures should be controlled in line with recommended levels to prevent dangerous decomposition or reactions.
Some questions worth considering when working with flammable substances are:
· Is there good natural air movement in and around where the flammable substances are stored and used? If not, mechanical ventilation should be introduced, which will ensure that any vapours given off from a spill, leak, or release will be rapidly dispersed.
· Have all the obvious ignition sources been removed from the storage and handling areas? Ignition source can be very varied: sparks from electrical equipment, welding or cutting tools, hot surfaces, open flames, static charge etc. An explosion can be caused by the simple action of decanting a flammable liquid from one container to another if they have not been earthed.
· Are the flammable substances kept in the correct type of container? Does it need to be fire rated? Or if there is a spill, will it be contained and prevented from spreading? Dependent on the quantity of product involved and the separation distance, a fire rated storage unit may well be necessary.
· Can a flammable substance be replaced by a less flammable one, or be eliminated from the process completely? Processes and products evolve - supplier(s) may be able to advise on safer alternatives.
· Are flammable substances stored and used in a different area to other processes? By separating them, the risk of an incident is reduced and workplace safety improved.
For practical purposes where flammable liquids are required in a process, there is likely to be a need for a limited quantity to be stored and available in the workplace. It is the responsibility of the employer/duty holder when carrying out the risk assessment to justify the need to store any particular quantity of flammable liquid within the working area.
The guiding principle is that only the minimum quantity needed for frequently occurring activities or an amount required for use during half a day or one shift should be present in the working area. Actual quantities will depend on the work activity and the arrangements for controlling the fire risks.
When not in use, containers of flammable liquids needed for ongoing work should be kept closed and stored in suitable fire-resistant cabinets or bins, which are also designed to retain spills. They should be located in designated areas that are - where possible - away from the processing area and do not interfere with any escape route from the working area.
Flammable liquids should be stored separately from other dangerous substances that may increase the risk of fire or compromise the integrity of the container or cabinet/bin it is stored in; for example, oxidisers and corrosive materials should be stored separately from each other. Other dangerous substances may also be flammable in their own right however, and it will be inappropriate to store these in the same cabinet/bin with flammable liquids. For further guidance on energetic and spontaneously combustible substances, consult HS(G)131 published by the Health and Safety Executive (HSE).
The HSE recommends that the maximum quantities that are stored in cabinets/bins are no more than 50 litres for extremely flammable, highly flammable and those flammable liquids with a flashpoint below the maximum ambient temperature 30ºC; and no more than 250 litres for other flammable liquids with a higher flashpoint of up to 55°C.
These quantities are intended to be viewed as recommended maximums and represent good industry safe practice, rather than being taken as the absolute limits. There can be some flexibility with the limits of the quantities stored, where it is understood that the design of the building and or the pattern of work can sometimes make adherence to these quantities difficult. For example in large or open-plan working areas where the employer/duty holder does identify a need to store quantities in excess of the recommended maximum, they must fully demonstrate the need for this requirement, and the risk assessment should take into account factors including the properties of the materials to be stored or handled, the size of the working area and the number of people working in it, and the amount of flammable liquids being handled in the working area.
In the event of an incident the objective is to ensure that people can safely escape from the working area and in this context, the purpose of storing Dangerous Substances in the appropriate cabinets/bins is to provide a physical barrier to delay the involvement of the stored materials in a fire and provide sufficient time for safe evacuation of staff and the duty holder’s immediate emergency procedures to be implemented.
The onus is always on the operator to ensure products are stored correctly and handling procedures are safe and fully compliant. As such, it is essential that all hazards associated with those products are fully understood. Information from Material Safety Data Sheets and manufacturers’ help desks are invaluable sources for this.
Manufacturers of safety equipment such as fire-rated storage units, earthing wires and flammable liquid transfer containers will all offer specific advice as well, and consultation with local authority, fire brigade and insurance provider is also essential.
This information should help the operator determine the correct system to suit a site’s specific requirements, and when used in conjunction with other measures including good housekeeping, spill kits and training, should substantially reduce the risk of an incident.
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About the author:
Andrew Lawrence is International Business Development Manager at Empteezy Group, an environmental services company based in Livingston, West Lothian, UK.