Wednesday, 2 September 2015

The Rags to Riches Tour Rolls On

Last month we were talking about why we at RABScreens have called our latest campaign the Rags to Riches tour. We said that installations can cost as little as price of 500kgs of surgical rags and yet provide an ROI of less than 6 months in most cases.


The Rags to Riches Tour has been presenting a previously unknown product to the NHS Estates and their engineering departments. The RABScreensexternal air intake filter is now being used by many NHS Estates to reduce contamination and energy consumption, plus extend filter life and improve maintenance by reducing time expended.

We have received instructions from as far afield as Belfast, Truro and Newcastle and continue to survey hospitals all over the country.

But what about  Health Technical Memorandum 03-01 Part B (HTM 03-01) which recommends the maximum (12mm) and minimum (6mm) opening that should be used on insect mesh which is normally found directly behind the weather louvre (see picture). 


Air intake weather louvres at most major hospitals lead into a larger supply air plenum from which multiple AHU intakes draw in the ambient air.

This insect mesh is not always easy to remove and that makes cleaning difficult. In one example we saw the mesh removal and reinstallation took at least 10 man hours. This is a shameful waste of a valuable labour resource.

Compliance issues mean that this task must be completed. However with a shortage of staff and other, more important PPM’s falling behind, the waste of energy caused by the blanket covering of vermin screens is the least of an Estate Managers problems. 

The pressure drop of insect mesh with a 15mm opening is 19.37 at 1.5m/s face velocity. 

Vermin screens add to the cost of running AHU plant which has been sized to cope with the combined resistance of louvre and mesh + a significant factor to allow for debris build up. 

Debris should be cleaned on a regular basis to prevent this resistance which causes fan motors to use more power.

The solution at this particular NHS Trust has been to completely remove the difficult to maintain mesh. Instead we fitted a RABScreen BHC air intake filter. 

It has a much lower resistance and a much higher particulate capture rate to prevent smaller insects (fruit flies, mosquitoes etc.) from entering the plenum. To reduce maintenance times a drop in framework was installed. This allowed maintenance personnel to remove, vacuum and replace all panels within ONE HOUR. It is now a realistic monthly PPM task.

And the added bonus? At 2.0m/s face velocity this new system only creates a resistance of 12.45 pascals so that the fans will draw higher volumes of cleaner air which will protect filters and reduce energy costs by more than £10,000 per annum for every 15kW motor it protects. 

Unlike the rags, RABScreen external filters will last for 10 years and continue saving money for all of that time. If you don’t believe it then talk to us about a free trial today.

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