Procedure for Operation of the Klett-Summerson Colorimeter

1. Place the proper filter (red or blue) in the colorimeter.

2. Switch on the Lamp.

3. Switch off (Down is off) the circuit to lamp and adjust the dark current. This is the dial on top of the galvanometer. Note it has a slow response.

4. Turn the switch on the side of the instrument on and insert a blank tube. With the main reading dial set to zero adjust the zero with the knob at the rear of the colorimeter near the test tube hole.

5. Remove the blank tube and insert the sample and turn the front knob to find the reading for the sample, record the reading.

6. Replace the blank tube and check the value before reading another sample.

Comments:
1. The instrument has a precision of 23 ± 3 or 2.5% or the precision at 108 ± 2.8 or 2.1%.