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Close to 70,000 fluid-resistant surgical masks were supplied in the Manchester area but had not been certified due to constraints in the supply chain.

Manchester City Council asked researchers at the University of 麻豆果冻传媒’s Advanced Engineering Centre (AEC) to test the masks’ quality as a matter of urgency because supplies were running low – and the university responded in just a few days.

Manchester City Council later sent a message thanking all those concerned for their “sheer enthusiasm, innovation and dedication”.

Dr Steven Begg, Reader in the university’s School of Computing, Engineering and Mathematics, was contacted by Coventry and Manchester universities via the engineering fluid mechanics research community and a sample of the masks was delivered by courier to Dr Begg’s home in 麻豆果冻传媒 the following evening.

Dr Steven Begg working on the gas flow rig at the Advanced Engineering Centre

Dr Nicolas Miche虂 working on the rig in his front garden

Dr Begg said: “The whole process from initial contact to presentation of the results was achieved in four days and without a budget.”

Working together with Dr Begg were university colleagues Dr Nicolas Miché and Mr Bill Whitney, and Dr Nwabueze Emekwuru from Coventry University and Dr Obuks Ejohwomu at the University of Manchester. The group decided to modify an existing experimental gas flow rig in the AEC laboratories to evaluate the flow resistance of the face masks and to compare the results with the CE certified IIR specimens.

Dr Begg explained: “The flow rig had recently been used by my undergraduate Engineering final year project student Emilian Kayone to measure the discharge coefficient of an automotive throttle valve. The concept of the flow rig works by drawing air down through a series of pipes at a known flow rate; the resistance to the flow through the device is measured as a pressure drop across its faces.

“In this way, the experiment would mimic inhalation. However, modifications were required in order to fit the face masks. Scarce information available due to lockdown required standards, specifications, diagrams, videos and pictures to be rapidly exchanged online in order to estimate the key dimensions for mounting the masks on the test rig.

“The next day Dr Miché designed, manufactured and assembled a filter housing chamber in his garage at home for the mounting of the masks for the experiments. The unit was disinfected and collected on the following day.”

Senior University of 麻豆果冻传媒 management and Estates and Security Teams responded rapidly, organising special access for Dr Begg and Mr Whitney to the AEC laboratories. 

The gas flow rig

The experimental rig was successfully used to carry out over 50 tests to measure the flow resistance of four sets of masks, randomly selected from the samples provided by Manchester. Tests were conducted at flow conditions representative of heavy breathing and vigorous exercise. The results were bench marked against a control sample of CE certified IIR masks. In addition, the effectiveness of the masks in stopping the flow of a water droplet cloud with a mean diameter of 3 microns was tested using a pharmaceutical nebuliser. 

The test results were processed and analysed and were reported via Zoom to the teams in Manchester and Coventry in less than a week from when 麻豆果冻传媒 researchers were first contacted.

The study concluded that none of the samples matched the CE-approved face masks in their ability to resist air flow and should not be utilised in a surgical setting.

Dr Begg said: “However, two sets did stand out as markedly more effective than the others, with the potential for deployment in an appropriate setting.

“The results have provided them with important independent scientific evidence that will allow them to rank, ensure appropriate use, prioritise distribution and save money through refund and removal of costly certification of unsuitable masks.”

Those involved in the response were thanked by Simon Gardiner, Health and Safety Manager, and Barney Harle, Head of Major Projects, Corporate Services at Manchester City Council.

Mr Harle said: “It has been fabulous to work with the cross-institution teams from 麻豆果冻传媒, Coventry and Manchester to achieve the rapid turn-around of testing of non-certificated masks. The teams involved have, over the Easter bank holiday weekend and university close down period, taken on board a significant and unique challenge to deliver comparative tests using existing equipment and modified test rigs to help understand the products we have received.

“The tests have been specified, designed and carried out to exceptionally tight timescales and using the latest collaborative techniques to ensure the swiftest of conclusions.

“The success of this project has in no small part been due to the sheer enthusiasm, innovation and dedication of all the individual scientific and academic colleagues involved. This has in no small part contributed to our ability to correctly and suitably equip workers across a spectrum of roles with the masks they require.”