The Chemical Trap

The Chemical Trap

Our Building Services Brand Manager, Des Dolan, discusses the importance of safe disposal of chemical waste from laboratory applications with education environments.

As the half way point of the £4.4 billion Priority School Building Programme (PSBP) is reached, there are still near to 300 school rebuild and refurbishment projects planned before 2021. As part of this funding, science departments are seeing significant investment to bring laboratory facilities into the 21st century.

Laboratories and research facilities in schools produce various concoctions of chemicals, which all need disposing of safely. There are strict regulations in place to prevent improper disposal of certain chemical waste down drains, to the local authority refuse collection or into the atmosphere.

However, before considering disposal methods, it is vital to ascertain if the chemicals that are being used, or will be produced, are hazardous. The Hazardous Waste Regulations 2005 provide guidance on classifying hazardous waste and outline the correct disposal procedure for different classifications of hazardous waste. COSHH also exists to require employers, by law, to control substances that are hazardous to health.

Chemical waste classified as hazardous requires separate and safe storage and collection and disposal by a dedicated company. As a costly method of disposal, schools look to keep the quantity of hazardous waste to a minimum. There are a wide variety of chemicals that can be disposed of within a safe chemical drainage system, including concentrated and dilute acids and alkalis, alcohols containing salts and hypochlorite solutions.

Leaks of any chemicals could be potentially extremely harmful to students, the public and the environment and so it is vital that the selected chemical drainage system is capable of handling all chemical combinations that could be emptied into it. However, not all chemical drainage systems are the same and it is vital to ensure the most appropriate system is selected for the specific application.

On considering material selection for a chemical drainage system, there is a range of criteria that should be considered to ensure the material is ‘fit for purpose’. Firstly, it is important to know what volume and type of chemical is being disposed of, whether it be acids, solvents or detergents. It is also important to know how corrosive the waste is and what temperature it will be disposed at, as a dual contained system may need to be considered. These factors should be used as a benchmark for good working practice and will help to ensure the most appropriate material is specified. If not, the material is likely to fail, potentially compromising health and safety of users of the laboratory and leading to possible expensive closures and repairs.

The types of materials used for chemical drainage purposes have changed over time. Traditionally, cast iron was previously used because of its innate strength, density and ability to work at high temperatures. However, the material’s tendency to corrode makes it unsuitable for today’s complex chemical drainage needs. An alternative to cast iron, Borosilicate Glass, remains an excellent chemical and heat-resistant material and is often recommended in bottle traps and dilution/recovery vessels, especially where strong chemical solutions and large amounts of organic solutions are used. However, its fragility makes it difficult to handle, and its relative expense has meant that it has become less favoured for complete chemical drainage systems.

Coupled with the technical advancements in plastic chemical drainage systems, these now offer more diverse and varied one-stop-shop options. Purpose-designed and engineered plastic systems have long since replaced glass as the material of choice for chemical drainage.

However, it is important to stress that not all plastic drainage systems are suitable for chemical drainage applications. For example, those specifiers looking to address the disposal of detergents, in particular non-ionic detergents should take particular notice of how certain plastics perform under distress from these types of solvent. Crystalline polymer materials like Vulcathene offer a very high resistance to attack. However, amorphous polymers, including PVC-U, PVC-C and ABS, can be softened by these chemicals and in some cases lead to stress cracking, which is greatly increased when there is a possibility of the drains drying out.

Although there are guidelines for laboratory users to follow in terms of which chemicals can be disposed of within a drainage system, there is currently no specific British or CEN Standard for the performance of a chemical waste drainage system and standards relating to domestic waste are not valid. So those requiring technical guidance should look for systems that offer assurances in the form of independent testing and approvals by bodies such as the BBA (British Board of Agrément). Tried and tested options, such as the Vulcathene chemical drainage system, have been installed in laboratories worldwide for more than 60 years and offers specifiers and end users the confidence that they are choosing a purpose-designed pipe system that will last and won’t be compromised over its lifetime.

In addition to addressing the appropriate material solution for the safe conveyance of chemical drainage, specifying the right system should also be about the versatility the system offers all parties. From an installation point of view, systems should provide an easy, fast but secure jointing procedure that helps keep on site costs to a minimum. From a specification point of view, a system that offers a comprehensive range of pipe fittings and complementary bench items such as wastes, sinks, drips cups, anti-siphon traps and dilution vessels makes for a more integrated design process. For end users, maintenance systems that offer demountable joints that can be altered and added to without damage to the original system can help address all future maintenance and expansion requirements without costly implications.

To ensure schools fulfil their health and safety obligations and protect the students, employees and public as far as possible, safety needs to be the number one priority when specifying chemical drainage systems. It is crucial that both the material and system selected are proven to offer a safe solution for disposing of chemical waste.


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