Laboratories and research facilities in schools, universities and hospitals are subject to the disposal of various concoctions of waste chemicals. Therefore it is important that the chemical waste drainage system should be specified in a manner that will ensure the system is capable of handling all chemical combinations emptied into it.
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’ and determine the most appropriate for the job. Firstly, it is important to know what volume and type of affluent is being disposed of, whether it be acids, solvents and detergents through to blood samples, retroviruses and radioactive wastes. It is also important to know how corrosive or dangerous the waste is and what temperature it will be disposed at. Consideration of the possibility of dual containment should also be considered. These factors should be used as a benchmark for good working practice and will help to ensure the material chosen is ‘fit for purpose’. 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. A 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 however, have long since replaced glass as the material of choice for chemical drainage. Yet, it is important to stress that not all plastic chemical drainage systems offer the same standards and performance benefits. 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 what can and can’t be put down a sink, 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 like the Vulcathene chemical drainage system has been installed in laboratories worldwide for more than 50 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.
As with any application in design, build, refurbishment and maintenance contracts, specifying the most appropriate system can be a complicated process. But when it comes to the handling of chemical drainage systems, the priority should be on selecting both the material and system that are proven to address the specific job in hand. Compromising by just one element could mean potential project failure, soaring budgets or legal wrangling between working parties. It could also mean risks to children, students and employees’ health or wellbeing, risks that specifiers, contractors or public sector clients should not be willing to take.