LEGIONELLA

The problematic

In France, Legionella affects around 3000 people every year. The infection is caused by the Legionella bacteria, leading to death in 15% of cases.

The bacteria is transmitted to humans through the air and by inhalation of contaminated water diffused in air. The responsible germ is a bacillus that lives in fresh water and reaches optimal proliferation when the water is between 35 and 40°C.

Legionella Pneumophila can survive for several months in distilled water and for more than a year in a tap at ambient temperature. Moreover, certain elements used in plumbing (iron, zinc and certain constituents of rubber) stimulate its growth.

bacterie-legionellose-721908

Legionella is present in various application areas, such as :
>> Hot water systems of sanitary installations
>> Hot jet spa and whirlpool baths used for relaxation, balneotherapy and other hydrotherapy treatments
>> Medical equipment for aerosol respiratory treatments
>> Air-conditioning systems
>> Badly insulated cold water systems
>> Air humidifiers
>> Air cooling towers (*)
>> Decorative fountains

Amongst all these sources, sanitary hot water systems and air cooling towers are the most frequent cause of infection.

Establishments concerned:

>> Air-conditioned buildings
>> Hotels
>> Hôtels
>> Campings (showers)
>> Hospitals and medical centers, care homes for the elderly
>> Sports facilities

(*) These towers, usually situated on the roof of buildings, are exterior facilities for cooling hot water systems. They are often found as annexed facilities to refrigerator plants. If the hot water (around 30°C) circulating in the cooling system is not regularly treated, it could very quickly become a hotbed for Legionella which subsequently will spread through the vapour plume into the atmosphere.

Solutions

UVC treatment creates a highly effective ‘anti-bacterial barrier’ against Legionella. It is an excellent complement to anti-scaling, bactericide and biodispersant treatments.

The UV light emitted by the lamps is absorbed by the DNA of the microorganisms, leading to their immediate destruction.

In order to ensure the effectiveness of a UV treatment, it is absolutely necessary to carry out a choc treatment of the pipe circuit before the start of the UV device, i.e.:

>> By thermal disinfection at 60 to 80°C
>> By chlorine disinfection, 100 ppm/h

It is also necessary to analyse the canalisation to make sure all the zones are disinfected and to eliminate the stagnant water areas which could favour the development of bacteria.

Characteristics

The UV dose necessary to eliminate 90% of the Legionella Pneumophila is 12 mJ/cm2.

To perfectly destroy all strains of Legionella and all human pathogenic bacteria, we apply a UV dose of 40 mJ/cm2 to 60 mJ/cm2.

We offer a ‘compact’ range for small flow rates up to 10 m3/h, and an industrial range for larger flow rates, for example in air cooling towers.

To size our equipment we use a modelling software developed by our research department to ensure a UV dose of 40 mj/cm2 at the end of the lamps’ lifespan (Standard NF EN 14897+A1), and so minimizing pressure loss.

>> Maximum service pressure: 8 bar (higher pressure as an option).
>> Power supply: 220-240 V or 400 Tetra V – 50-60 Hz.
>> Inlet/Outlet flanges in grade 316L stainless steel – Type 01A PN 10/16 ≤ DN 150 and PN 10 ≥ 200 (option: PN16)
>> High transparency UV quartz sleeve.
>> Low pressure amalgam UV lamp, guaranteed for 16 000 hrs or 2 years.
>> Electrical cabinet in epoxy coated steel for interior use, or a polyester double door version for exterior installation.

>> UV intensity sensor complying with the DVGW standard, with alarm and pre-alarm, display in W/m2 and alarm for the service life of the lamps.

>> Automatic or manual cleaning with pull handle : deposits are liable to form on the quartz sleeves (TSS -Total Suspended Solids-, scaling…) and reduce the UVC intensity of the lamps. It is therefore essential to clean them regularly.

>> Remote control and alarms (lamp error signal, alarm buzzer):

  • 4-20 mA output, allowing remote processing.
  • Dry contact input: UV lamps on/off
  • Analog input: regulation of UV intensity according to the water flow rate (option).
  • Dry contact output: dry contact for alarm lamp(s), automatic cleaning alarm, alarm and pre-alarm
  • analogic output: UV intensity.

Advantages

>> Low energy consumption due to our low pressure UV lamps
>> Guaranteed lifespan of the lamps 16 000 hrs or 2 years
>> Low maintenance costs: operating costs are reduced to replacement of the lamps and cleaning of the sleeves
>> Lamps can be changed without emptying the stainless steel body
>> Possibility of custom-built reactors to meet specific client requirements
>> Horizontal or vertical installation
>> Manufactured in France
>> UVGERMI tests all its devices in its own test laboratory.