Hach TU5200 Basic User Manual page 16

• When collecting a sample from a water tap in a distribution system or treatment plant, turn the
water on for at least five minutes, then collect the sample. Do not adjust the flow because this can
add particles.
• When collecting a sample from a body of water (e.g., a stream or storage tank), collect at least one
liter (1 quart) and fully mix before taking an aliquot for measurement. If the quality of the sample
source is not constant, collect samples at many locations at different depths as necessary. Then,
mix the samples together to prepare one sample for measurement.
• Fill the container. Let the container overflow with the sample and then immediately put the cap on
the sample container so that there is no headspace (air) above the sample.
• Write the sample information on the container.
• Start analysis as soon as possible to prevent temperature changes, bacteria growth and settling.
Prevent vial contamination
Do not to touch or scratch the glass of the sample vial. Contamination or scratches on the glass can cause
measurement errors.
The glass must stay clean and have no scratches. Use a no-lint cloth to remove dirt, fingerprints or
particles from the glass. Replace the sample vial when the glass has scratches.
Refer to Figure 4 to identify where not to touch the sample vial. Always keep the sample vials in the
vial stand to prevent contamination on the bottom of the vial.
Figure 4 Sample vial overview
1 Measurement surface—Do not touch.
Prepare a sample vial
Chemical exposure hazard. Dispose of chemicals and wastes in accordance with local, regional and
national regulations.
Always put a cap on the sample vial to prevent spills in the vial compartment.
Refer to the illustrated steps that follow to prepare a sample vial for measurement. Measure the
sample immediately.
Note: If there is contamination in the sample vial after it is rinsed with the sample, clean the sample vial. Refer to
Clean a sample vial on page 21.
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