MEDICAL GAS SYSTEMS
strategic test plan which allowed us to run a series of simultaneous metered leaks, taking both static and flow pressures at key locations identified at the planning phase. By simulating the stress across the entire site, and comparing it with our initial calculations, we established that a full occupancy of COVID-19 patients could require a 40% increase in flow capacity up to 3,500 L/min.
We reported back to the hospital’s Estates team regarding the areas that needed upgrading to get the most from the system. The Trust was then able to upgrade its oxygen VIE capacity, while we modified the oxygen supply pipeline mains to specific risers within the hospital. While results will differ depending on a huge range of factors, this doesn’t diminish the importance of benchmarking hospitals’ oxygen pipeline performance.
Four key considerations
For Trusts considering how to approach testing their own system, there are four key considerations when testing whether their oxygen flow is sustainable at peak usage.
Firstly, it bears repeating that you need to make sure your oxygen flow test is run simultaneously across your entire site. It is also important to have your CAD drawings up-to-date; these are a critical part of understanding the layout of the medical gas pipeline system, and identifying key test points to measure the stress across your system.
Your testing provider should also have significant experience, and use the right equipment. Analogue testing guns used for commissioning are insufficient. Your provider should be well versed in using equipment such as digital gauges and metered leaks. Finally, your test should conclude with a full report that outlines
A close-up view of the Amal jet flow probes, and documentation of standard flow rates according to simulated outflow.
the weaknesses in your system, and recommended actions you can take to address them.
Building resilience through mini-ring mains
Older, radial systems have consistently struggled to deliver the pressure required by the increased demand over the last 12 months. Where VIEs were operating at capacity, many hospitals increased pressure in the system as an interim measure. Often a radial system with several VIEs will include a manifold, which will back up the system if the pressure drops too far. As with every pipeline, however, the size of the pipework will always dictate the volume that can be delivered safely.
HTM 02-01 usually ensures that the system can supply at safe levels during times of increased demand, but the additional stress placed upon wards by COVID-19 patients has highlighted weaknesses in a number of designs. As hospitals evolve, departments are moved, and new wards are added. These changes can place additional stress on the medical gas system, where the pipes and mains are now having to deliver flows that they weren’t designed to handle.
Adding a linked main
A testing gauge inserted into an oxygen valve to measure flow pressure.
66 Health Estate Journal June 2021
One method of increasing flow capacity with a rising main is to put another linked main into that block – so that when there is a high level of need, additional flow capacity can be generated simply by opening up a valve. Depending on test results, we may also suggest adding more resilience with additional linked branches to create a mini- ring main effect. With more branches closer to the source of supply, pressure can be more consistently distributed throughout the system. The NHS Nightingale hospitals were built with ring main systems for exactly this reason, and newer medical gas pipelines usually follow the same design. COVID-19 will never go away completely,
so system resilience will now permanently become a greater consideration, and ‘while one size does not fit all’, the design of both new and existing oxygen pipeline systems will likely be forever altered to reduce the likelihood of them being at risk of becoming overwhelmed again.
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Anthony Mitten
As managing director at MIG Medical Installations, Anthony Mitten has completed more than 600 healthcare engineering projects throughout Europe, Asia, and the Middle East, over the past 10 years. A specialist in healthcare engineering and construction, he says he and his team have ‘played a key role in the UK’s response to COVID-19’ – ranging from helping to deliver oxygen systems within 14 days, to the supply, installation, testing, and commissioning, of medical gas pipelines. His team also specialises in fitting out wards and operating theatres, modular hospital buildings, and containerised solutions, including treatment clinics and self-contained manifold and plant pods.
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