Turbidimeters measure turbidity in liquids by determining how much light is transmitted through the liquid. They operate on the principle that particles suspended in water will scatter light. There are several types of turbidimeters including basic/single beam, ratio, four-beam, surface scatter, and transmittance models. The basic/single beam uses one light source and detector, ratio uses multiple detectors, four-beam uses two light sources and detectors to eliminate errors, surface scatter compensates for very high turbidity, and transmittance actually measures light transmittance. Turbidimeters can be benchtop, portable, or online models for different applications.

1. SUBMITTED BY
K.SANJAY
BD230907
TURBIDOMETER

2. Turbitimeter
 Also called as Turbitimeter.
 An instrument for measuring and
comparing the turbidity of liquids by
viewing light through them and
determining how much light is
transmitted.

3. Principle of turbidimeter
 Turbidimeters operate based on the
optical phenomena that occur when
incident light through water body is
scattered by the existence of foreign
particles which are suspended within it.

4. Types
 Basic/Single Beam
 Ratio
 Four-Beam
 Surface Scatter
 Transmittance

5. Types
 Basic/Single Beam
Contains one light source and one 90°
photodetector; simplest and oldest design;
requires frequent recalibration.
Application : Nearly-colorless samples such as
treated water; samples below 40
NTU.(Nephelometric Turbidity Units)
 Ratio
Features single light source with multiple
detectors; turbidity calculated using mathematical
algorithms.
Application : Most colored samples.

6.  Four-Beam
Uses two light sources and two 90° detectors;
measurements taken in multiple 0.5 second pulses;
turbidity is calculated from four separate
measurements; eliminates errors arising from use of
ratio instruments.
Application : Samples up to 100 NTU, as well as very-
low-turbidity samples between 0 and 1 NTU.
 Surface Scatter
Uses an angled light source to extend optical limits
of instrument;
designed to compensate for very high turbidity.
Application : Highly-turbid raw and recycled water;
may be accurate up to 9999 NTU.

7.  Transmittance
Actually measure light transmittance rather than
turbidity
or absorption; uses a straight-on photodetector;
measures transmittance as a percentage of light.
Application : Uncommon design used to measure
filter backwash water to determine filter media
cleanliness.

8. Form factors of Turbidimeters
 Turbidimeters can be grouped into three
form factors:
 Benchtop,
 Portable,
 On-line.

9. Benchtop devices use glass samples and typically
use ratio technology to measure turbidity. Many
devices feature switches to turn off ratio functions
so that they can also be used as single-beam
designs.
Portable designs function similarly to benchtop
types, but are built with rugged features for field
activities, such as sampling upstream from
treatment plants. They are typically battery-
powered.
On-line turbidimeters are affixed to process
streams within treatment plants and often employ
single-beam or four-beam operation. Some
specialized on-line turbidity meters may involve

10. SINGLE BEAM TURBITIMETER

11. RATIO TURBITIMETER

12. FOUR BEAM TURBITIMETER

13. SURFACE SCATTER
TURBITIMETER

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