Hach-Lange HACH 5500 sc SiO2 Installation - Manual (Page 10)

Figure 6 Sample and drain lines
1 Sample in (single-
stream)
4 Non-adjustable
pressure regulator
(set at 4 psi to protect
analyzer)
7 Case drain
2 Shut-off valve 5 Sample bypass drain
3 Y-strainer with filter 6 Chemical drain
Sample line guidelines
Select a good, representative sampling point for the best instrument
performance. The sample must be representative of the entire system.
To prevent erratic readings:
• Collect samples from locations that are sufficiently distant from points
of chemical additions to the process stream.
• Make sure that the samples are sufficiently mixed.
• Make sure that all chemical reactions are complete.
Connect the sample stream
Install each sample line into the center of a larger process pipe to
minimize interference from air bubbles or bottom sediment.
Figure 7
shows examples of good and bad installation.
Keep the sample lines as short as possible to prevent the accumulation
of bottom sediment. The sediment can absorb some of the analyte from
the sample and cause low readings. The sediment can later release the
analyte and cause high readings. This exchange with the sediment also
causes a delayed response when the analyte concentration in the
sample increases or decreases.
Figure 7 Sampling methods
1 Air 2 Sample flow
Set the bypass flow rate
N O T I C E
Do not loosen the screw by more than 4 turns for the multi-stream.
10 English