The quality of the air is determined by the different types of air sampling devices including hesse's tube, well centrifuge, tube sampler, etc.,

1. AIR SAMPLING
DEVICES
ASSISTANT PROFESSOR
DEPARTMENT OF MICROBIOLOGY

2. INTRODUCTION
• Air can harvest many different kinds of
microorganisms.
• Monitoring air quality is an essential criterion in
quality control in laboratories.
• Air quality monitoring can be done either by
collecting air samples or passively by settled plate
methods.
• The microbial air sampler is a way to collect air
samples for active air quality monitoring.

3. TYPES
AIR SAMPLING DEVICES
BASED ON MEDIUM
LIQUID
MEDIUM
SOILD
MEDIUM
BASED ON SIZE
SETTLING
UNDER
GRAVITY
AIR
CENTRIFUGE
FILTRATION
IMPINGEMENT OF
LIQUIDS
IMPINGEMENT ON
SOILDS

4. SETTLING UNDER GRAVITY
• Method used for collecting the air with particles by gravity.
• Eg: Hesse’s Tube
1
• Hesse’s tube  horizontal glass tube + layer of
solid medium at the bottom
2
• Air pass through the tube & particles with
microbes
3
• Analysis of Microbes

5. AIR CENTRIFUGE
• Developed by Wells – 1993.
• The air containing particles are centrifuged on to the culture medium.
SAMPLE AIR PASSED THROUGH TUBE &
ROTATED ON ITS LONG AXIS
BACTERIA PRESENT IN THE PARTICLES
SETTLE ON THE MEDIUM
ANALYSIS

6. FILTRATION
• Simple method for collecting air.
• The filter can be made up of glass
fibre, sand, alginate wool etc.,
• The recovery of organisms from
the filter is not easy
Tube
sampler

7. FILTRATION
TUBE SAMPLER:
1
• Tube with inlet at the top and
outlet at the bottom
• Sand layer used as filter
2
• Sterilize the tubes
• Air is passed through it
3
• Particles deposited on
the medium
• Analysis

8. • RAISED IMPINGER • BEAD – BUBBLER DEVICES
IMPINGEMENT INTO LIQUIDS

9. IMPINGEMENT INTO SOLIDS
SOLIDS
HOLLAENDER &
DALLA VALLE
SAMPLER
SLIT SAMPLER SIEVE SAMPLER

10. A. HOLLAENDER & DALLA VALLE
SAMPLER
• Brass container with removable
bottom.
• Lower portion contain agar
medium.
• Air passes through the funnel.
• The air borne microorganisms are
impinged on the agar medium.
• Simple, portable and efficient
method.

11. B. SLIT SAMPLER
• Has an enclosed chamber.
• Air drawn into the sampler
through the slit and the
particles get impinged on the
medium.
• The plates are incubated at 37C
for 24 hours.

12. C. SIEVE SAMPLER
MULTISTAGE SEIVE SAMPLER
SINGLESTAGE SEIVE SAMPLER
• Simple & efficient
method.
• The particles are
separated based on
size.

13. D. ELECTROSTATIC PRECIPITATION
• Litton Air Sampler.
• The air is allowed to pass
through the electrodes.
• The charged particles fall on the
rotating disc which is later fed
into the collecting fluid.

14. QUICK RECALL
• What is meant by air sampling?
• Techniques involved based on medium?
• Types of methods employed based on size?
• Example of settling under gravity.
• Two example of impingement into liquids.
• Principle of Sieve sampler.
• Electrostatic precipitation is based on what?
14

15. THANK YOU