Hach-Lange 9187 sc - Manual (Page 12)

10
Installation
3.1.2 General Installation Considerations
• Place the analyzer in an accessible location.
• Keep the sample tubing as short as possible to minimize lag time.
• Do not place the probe next to a heat source.
• Ensure that there is no air intrusion into the sample supply line.
• Sample pressure must be sufficient to ensure a continuous supply to the probe. A
minimum pressure of approximately 0.1–2 bar (1.4–28 psi) is sufficient to provide the
correct flow rate. A stable flow rate of 200–250 mL/min is critical. Erratic flow rates will
create erratic measurements.
3.2 Choosing the Sample Line Location
Note: Erratic readings will occur if a sample is drawn from a location that is too close to points of
chemical additions to the process stream, if mixing is inadequate, or if the chemical reaction is
incomplete.
Selecting a good, representative sampling point is important for optimum instrument
performance (
Figure 4 ). The sample analyzed must be representative of the condition of
the entire system.
Install sample line taps into the side of larger process pipes to minimize the chance of
ingesting sediment from the pipe line bottom or air bubbles from the top. A tap projecting
into the horizontal center of the pipe is ideal.
Figure 4 Sample Line Location in the Process Stream
3.3 Connecting the Sample Stream
Sample inlet and drain connections are made on the Analyzer Flow Cell. Refer to
Specifications on page 3 for flow rates.
The sample inlet requires 6.3 mm (¼ in.) OD tubing. The connections are made with a
quick connect fitting. Use the 6.3 mm (¼ in.) supplied tubing adapter in the electrode kit.
Cut all tubing so the ends are squarely cut and not angled.
1. Push the tubing into the influent of the flow analyzer ( Figure 5 ).
2. Push the supplied drain tubing onto the nipple beside the influent.
3. Ensure there are no bends in the tubing to prevent back pressure.
Poor
Sediment (Typical)
Air (Typical)
Poor Good Best