CLIMET INSTRUMENTS CI-90A, Operator'S Manual

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CI-90A User’s Manual
Page 4
NOTE:

When returning the CI-90A for servicing, keep the accessories in a
safe place at your facility. No accessories are needed during
calibration or repair.
1.4 Overview of CI-90A features
The CI-90A (CLiMET Instruments 90A) is a microbial air sampler that can capture
biologically active particles (bacteria, fungi, etc.) onto a petri dish loaded with nutrient
agar. This sample can then be incubated so that the captured microbes can grow into
colonies. The colonies formed after incubation are counted to determine the
concentration of CFU’s (colony forming units) present in the sampled air.
The CI-90A is a fully self-contained unit, operating on battery power or AC power for
sampling convenience. It has a stainless steel enclosure that makes it suitable for
applications requiring a sterile wipe down. The standard flow rate is 100 liters per
minute (100 LPM), requiring only 10 minutes to take a full 1 cubic meter sample. The
built-in battery can provide approximately 8 hours of continuous sampling (pump
running) on a single charge. The CI-90A interfaces with the user through a 4x20
character LCD display and a keypad overlay. It comes with a thermal printer for printing
labels that will document critical information about the sample. These can then be
attached to the petri dish holding the sample, and any associated documentation to
provide a hard paper trail. This reduces the chance of errors due to lost or incorrectly
identified samples. The unit also has a blower with automatic flow control to ensure
accurate sample volumes. The sample air is filtered before being exhausted through the
bottom panel to ensure the sampled environment is not contaminated.
The CI-90A has menu options that allow the user to set up a UNIT ID name to identify
the CI-90A used, a USER ID name to identify the user who took the sample, and a SITE
(LOCATION) ID to identify where the sample was taken. In addition, the user can
specify the sample volume to be taken, the time delay to allow the user to exit the area,
the number of labels to print, the flow out of tolerance alarm, the beep on completion of
sample, the security options, and the date/time.
1.5 Interpreting the Results
The Petri dishes are incubated for a period of time to allow the entrapped microbes to
grow into colonies large enough to observe macroscopically. By counting the number of
colonies, one can get an idea of the concentration of microorganisms in the sample
volume. Unfortunately, a simple count doesn’t translate directly into concentration.
A statistical analysis of the system considers a variety of things such as the following:

There is no way to tell if a colony had one or more Colony-Forming Units
(CFUs) prior to incubation

Each perforation is uniform and equally likely to pass a CFU to the media

The more colonies that are observed, the more likely it is that more than one
CFU was present before incubation in any given colony
The Feller Correction in the Appendix provides the accepted method to compensate
for the undercounting that results. The graph below shows that as the number of colonies