Biocontamination control techniques in Purified Water System

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Purified water most used in medication as a raw material, ingredients or as a solvent. It’s also used for equipment’s cleaning in pharmaceutical industries.

Purified water must be made devoid of contamination from microbes and various parameters of air must be monitored regularly.

Purified Water should be used, reserved and distributed in a way so that there is no place for contamination. A number of parameter required to set/designed carefully. In Purified water system Reynolds number play a vital role to monitoring the microbial activity in the pipeline.

Reynolds Number

The Reynolds number is the ratio of inertial forces to viscous forces within a fluid which is subjected to relative internal movement due to different fluid velocities. Reynolds Number is used to define water flow. It generally used for determine the water flow is laminar or turbulent.

The concept of Reynolds number was introduce by Sir Geroge Stokes in 1851, but the Reynolds number was named by Amold Sommerfeld in 1908.— It was popularized in 1883 by Irish innovator Osborne Reynolds to maintain the standards of purified water system.

If Reynolds number is less than 2300 that means the flow of water is laminar, if number is over 4000 that means flow of water is turbulent.

If water flow in pipeline is laminar type it may cause formation of biofilm & it can be avoided having turbulent flow in water distribution system.

Reynolds Number Calculation:

There are in general three types of fluid flow in pipes

Laminar

Turbulent

Transient (Between two states)

If Reynolds number is low, it means water flow is laminar (smooth & constant)

If Reynolds number is high, it means water flow is turbulent (chaotic)

If Reynolds number in between, it means water flow changes with time

The Reynolds number can be used for a number of water flow situations, as well as items moving through fluids.

R = ρVD /µ

R = Reynolds number (unit less)

V = Free stream fluid velocity (m/s)

D = characteristic distance/ pipe diameter

ρ = Fluid density (kg/m³)

µ = Fluid viscosity

Turbulent water flow prevents the formation of biofilm. Usually a speed above 1.2m/s or a Reynolds number greater than 10000 is advisable to maintain. It will help to minimize the chance of bio-film formation in purified water system.

In a circular pipe, the length is the diameter of pipe. The boundaries between the types of flow are

  • laminar when Re < 2300
  • transient when 2300 < Re < 4000
  • turbulent when 4000 < Re

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