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How It Works
Chart recorders consist of a graph wheel with replaceable graph paper and
ink pens. The pens mark the temperature on the graph paper as the wheel
turns. The current temperature is at the end of the line. Temperatures are
recorded continuously, 24 hours a day. The wheels of the most common
models used for vaccine temperature monitoring make one full rotation every
seven days. The graph paper has Fahrenheit or Celsius scales on it and the
temperature is read where the ink line falls on the scale. Follow manufacturer
instructions for loading the chart to ensure that the chart references the
correct time.
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Chart recorder. |
Graph paper—
two-degree increments. |
Graph paper—range. |
How to Read It
| 1. |
The graph contains two scales: one along the outer border of the
paper that indicates the day of the week and the time; the other
radiating from the center of the graph, like the spokes of a wheel,
that indicates the temperature. The temperature will either be in
Fahrenheit or Celsius. |
Day
and
time scale. |
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Temperature scale. |
Each graph contains two scales.
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| 2. |
To read the temperature for any point of interest along the recorded
ink line, find the nearest graph line that circles the center of the
graph. Follow that circular graph line to the temperature scale. The
temperature is indicated by where the circular graph line intersects
the scale. Temperature scales come in different increments. On some
graphs, the circular graph lines represent 1-degree increments on the
temperature scale. On other graphs, the circular graph lines
represent 2-degree increments. |
Current temperature is 33°F
(end of red line). Each circular graph
line represents 1 degree.
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Current temperature is 48°F
(end of red line). Each circular graph
line represents 2 degrees.
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3.
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To read the day for any point of interest along the recorded ink line,
find the nearest curved line flowing from the center of the graph to
the outside border. Follow the curved line to the outside border to
read the day of the week. Estimate the time of day from the nearest
curved line. The curved lines usually progress in 3-hour increments. |
Nearest curved line to
temperature of interest (current
temperature at end of red line).
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Follow curved line to outside
border to reach the
day and time scale.
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Current temperature falls on the line
halfway between the curved lines “Noon” and “6PM” under “FRIDAY”,
indicating Friday, 3 p.m.
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| 4. |
Record the current temperature on the temperature log. Note any
out-of-range temperatures and the action taken on the back of
the log. |
Front: Temperature Log for Vaccines.
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Note:
 Immediate
action must be taken to correct improper vaccine storage conditions. |
Reverse: Vaccine Storage Troubleshooting Record.
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| 5. |
Some charts (such as the one shown here) may have only a white
band (without circular graph lines) indicating
the recommended temperature range for
vaccine storage. In this case, you must still
document that the temperatures were
checked twice daily and were in range. You
may either: |
Chart with only a white band
(without circular graph lines)
indicating the recommended
temperature range.
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| a. |
Make a mark in the unshaded area of
the temperature log that corresponds
to the position of the line on the chart
recorder graph (an approximation is
acceptable, so long as the recorded
temperature is within the
recommended range); or |
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b. |
Write "graph in range" or some similar notation
in the appropriate column of the temperature log. |
| 6. |
All charts from recording thermometers must be kept with the
temperature logs for a minimum of 3 years. Charts should always be
labeled with the date range before they are place in the chart
recorder and when they are removed. |
| 7. |
Some graphing thermometers have both a recording wheel and a
digital temperature display. The reading from the digital display may
not be the same as the temperature recorded on the chart. In case of
discrepancies, the charted reading on the certified calibrated chart
recorder is preferred over the digital reading, which uses a separate,
uncertified sensor. |
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