HF scientific MicroTSCM Streaming Current Monitor - Manual (Page 10)

MICROTSCM (07/09) Page 6
REV 2.4
4.0 Installation and Commissioning
4.1 Sample Point
Careful consideration must be given to where in the system the sample will be taken.
Streaming current monitoring requires sampling of the raw water after the introduction of
coagulant. It is critical that that the sample point is far enough from the dosage point to
ensure good mixing. The sample point should be at least 10 pipe diameters away from the
dosing point to ensure ample mixing.
Equally important is the lag time from when a change in dosage occurs to when it shows
up at the sensor. If the sample point is too far from the dosing point, it will take too long
for changes to reach the sensor and control of the loop will not be possible. A lag time not
greater than 10 minutes is recommended.
Figure 3: Typical Installation
4.2 Flow Rate
The absolute minimum flow required is 6 liters per minute (1.5 gpm). The sample is
designed to handle flow rates of up to 10 liters per minute (2.5 gpm). Run the flow as
close to the maximum as possible without overflowing the sample chamber.
Note: The sample flow must be free of large shells or other debris that might clog
the orifices or cause damage to the sensor. Supplying an adequate flow free of
debris is the responsibility of the installer.
Drains MUST be routed to a suitable drain. DO NOT reintroduce this water
back into the process stream.
Suggestion: If meeting the minimum flow rate may be a problem, the optional flow alarm
may be required. HF Catalog #19886. See section 8.3.
To prevent large debris from entering the sample chamber, a 40 mesh screen
strainer is recommended.