How it works
- dose, not contact — UV is measured in millijoules per square centimetre — intensity multiplied by the time an organism spends in the field. A big lamp with a fast flow can deliver less dose than a small lamp with a slow one.
- transmittance — Water absorbs UV. UVT is how much survives one centimetre of path, and it falls fast with organics, iron and colour. Drop UVT from 92 to 75 % and the intensity in the outer annulus collapses — the reactor has not changed, but the dose has.
- the fastest path — Not every organism gets the average dose. The one that takes the shortest, fastest streamline gets the least, and that is the organism that sets your log removal. Validated reactors are certified on the worst path, not the mean.
- ageing and fouling — Lamps lose output over their life and the quartz sleeve fouls. Design for end-of-life output, typically 70–80 % of new, or the plant will fail its dose target long before anyone replaces a lamp.
- what governs it — Dose is intensity times time; intensity depends on lamp power, geometry and UVT; time depends on flow. Drag UVT down and watch the log removal fall away with no change to the hardware — upstream filtration is part of the UV design.
Design parameters
The panel opposite runs the same correlations as the UV-700 design sheet, so the animation and the calculator cannot disagree. Drag any of them and the picture responds.
- Flow — m³/h
- UV transmittance — % / cm
- Lamp UV output — W each
- Lamps — off
- Reactor volume — L
- Lamp age / fouling factor — –
Open the full UV-700 design sheet for the governing equations, the accepted design envelopes and the worked calculation.