Rensair: AGP Clearance in 1.3 Minutes

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ESI claims Rensair air purifier test achieves post AGP clearance in 1.3 minutes

In a statement issued today (5th April) ESI Group has said that in-situ modelling tests it conducted in a hospital dental treatment room have demonstrated that Rensair’s portable, hospital-grade air purifier can achieve clearance in just 1.3 minutes, delivering an air change rate of 12.6 Air Changes per Hour (ACH) when used with no supplementary ventilation.

The statement continued: “Rapid ‘clearance’ – defined as a 99% reduction (log 2 reduction) of particles emanating from the patient – means that only the minimal fallow time is required between patients, enabling pre-pandemic ways of operating and maximum patient throughput.

“The UK government’s updated guidelines on 17th January regarding post AGP downtime for dental practices state that, for 10 or more ACH, a baseline post AGP downtime of 15 minutes is recommended. However, that downtime increases to 20 minutes for a rate of six to nine ACH and to 30 minutes for one to five ACH or where the ventilation rate is unknown.”

ESI Group – experts in predictive physics modelling, virtual prototyping and simulation of product behaviour – conducted the tests in a large dental treatment room (44.7m3, compared to a typical dental practice room at circa 30m3) with three occupants and an integrated ventilation system delivering just five ACH.

ESI concluded that: “When used in isolation, or with the treatment room’s mechanical ventilation notionally turned on, the Rensair device’s air circulation efficiency scales with ACH irrespective of installation location; and rates well in comparison with other commercial portable and wall-mounted units of similar capacity.

“The existing five ACH ventilation demanded the maximum fallow period,” said Christian Hendriksen, co-founder and CEO at Rensair. “With the Rensair unit switched on in addition to five ACH, clearance was logged at just 0.84% of a minute, or just over 50 seconds. Using the Rensair unit alone, when we switched off the existing HVAC system, clearance was achieved 1.3 minutes. Either way, the end result is to shift from maximum to minimum post AGP downtime.”

ESI also analysed the outflow of clean air from the Rensair unit and its subsequent distribution throughout the room. The unit quickly spread purified air at 360 degrees in a uniform, outward ‘radial jet’ motion parallel with the floor.

This enhances room penetration and encourages toroidal circulation of airflow throughout the space, such that clean air bounces off the walls, then the ceiling and then back into the entire room. Importantly, the toroidal flow pressures particles and aerosols downwards, drawing them away from the AGP source and from the dentist’s head, thereby providing greater protection from infectious particles.

“Dental practices should seek evidence of credible, third-party testing before specifying air purification units”, added Hendriksen. “Airflow is critical to performance, but many manufacturers fail to substantiate air circulation claims and do not have the engineering know-how to clean an entire room.”

The full ESI Group report is available upon request, email This email address is being protected from spambots. You need JavaScript enabled to view it.