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Type approval of UV disinfection units
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Type approval from the Norwegian Institute of Public Health
Type approval is intended to ensure that UV disinfection units meet minimum requirements.
Only biodosimetrically tested UV units that give a minimum reduction equivalent dose of 40 mWs/cm2 should be used by Norwegian water treatment plants.
- List B: Type approved, biodosimetrically tested UV units with a minimum reduction equivalent dose (RED) of min 40 mJ/cm2
Water treatment plants that have UV disinfection units that are type approved should eventually replace these with biodosimetrically tested equipment:
- List A: Type approved UV units with calculated capacities based on a theoretical model with an integrated dose of min 30 mJ/cm2
Documentation needed for type approval of UV disinfection units
A type approval from the Norwegian Institute of Public Health for an UV disinfection unit is based on the following requirements for UV dosage.
It must be documented that by treatment of the water in the disinfection plant, a Reduction Equivalent Fluence (Dose) of minimum 40 mWs/cm2 (40 mJ/cm2), at a wavelength of 253.7 nm, is delivered, based on a biodosimeter test.
This fluence will ensure:
- a 6-log-reduction of health-related water transmittable bacteria,
- a 4-log reduction of most health-related water transmittable viruses,
- a 2-log reduction of most bacterial spores and parasites, based on current knowledge about their tolerance to UV light.
- This demand is fulfilled if, at a given flow and UV-transmittance of the water, the minimum reference irradiance (in W/m2) does not fall below the required target value that was determined at the type test.
Documentation needed for type approval application with UV dose measured by biodosimetric tests
- Test reports and certificates from biodosimetric tests performed in accordance with the Austrian ÖNORM M 5873-1 or M 5873-2, the German DVGW Technical Standard W294 part 1-3, USEPA Ultraviolet Disinfection Guidance Manual (performed after the same criteria as ÖNORM and DVGW),
- Or equivalent biodosimetric tests done by a skilled test laboratory with experience of performing these tests
- Use of Bacillus subtilis ATCC 6633 spores or MS2 bacteriophage as the test organism. This has a relevant resistance to UV light, to give capacities related to a fluence/UV dose of 40 mWs/cm2 (40 mJ/cm2).
- NB If the UV unit is equipped with medium-pressure lamps, the biodosimetric tests have to be performed with doped quartz sleeves to prevent wave lengths shorter than 240 nm.
- For tests other than ÖNORM and DVGW, the test criteria have to be accepted by us (Norwegian Institute of Public Health) for use as documentation for application for Norwegian type approval.
When applying for type approval, the following documentation must always be included for each model type, in table form:
1) Descriptions of the UV arc tube (lamp), type and make. Information concerning UVC radiated effect in Watts (W) at 254 nm (low-pressure lamps) (and in the area 240-290 nm for medium-pressure lamps), for new lamps and at the end of the lifetime. Total lamp length (without holders), i.e. length of the lamp glass and effective lamp length i.e. length of UV lamp between the central entrance of the radiation chamber, plus the diameter of the UV tube and quartz sleeve (see fig. l). Lifetime curve for the lamps (intensity reduction related to operation time (hours), for the lamp in question, as well as recommended time (hours) for lamp exchange, intensity reduction (%) with passage of light through the quartz sleeve and the description of the UV monitor (type, specification etc).
2) Specification of the materials that will be in contact with water.
3) A drawing showing the location of the arc tubes (lamps) in the radiation chamber and the location of the UV monitor and the position of the entrance and exit of the chamber (see fig. 1 and 2). The drawing should include all internal and external measurements of the radiation chamber, the diameter of the entrance and exit of the chamber and the distance between these centres (see figure 1). A description of the UV monitor, type and make. A figure showing the sensitivity of the UV monitor at different wavelengths.
A = Effective length of lamp; centreline inlet to centreline outlet
B = Outer diameter of quartz tube
C = Internal diameter of chamber
4) A description of how the UV intensity and dimensionable capacity are estimated, as well as the calculated UV intensity at different locations in the radiation chamber. A table of the dimensionable capacity of the unit with various water qualities (UV transmission values in 5 cm cuvettes). The maximum hydraulic capacity stated by the manufacturer should also be stated.
5) A drawing and description of the control system.
6) An instruction (in Norwegian) for operation, control and maintenance.
7) Documentation concerning any tests performed with the equipment, (e.g. inactivation tests for various microorganisms)
NB Please ensure that all relevant information is submitted for each type of UV disinfection unit that is to be approved to avoid delays.
NB Please note that the working hours taken to process an application for type approval will be invoiced at 1 230 NOK per hour, plus VAT.