Chemtrac HydroAct 4, Руководство пользователя

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52 Chapter 3. Sensors
using the cleaning brush. The sapphire window and the external flow cell design make brush cleaning
a safe and effective method for removing tough contaminants.
Several methods may be used to clear a blocked flow cell. One of the most effective tools is a small
can of compressed air. Remove the tubing from both sides of the flow cell and blow the air through
the flow cell from the top of the flow cell (opposite direction from the flow). If compressed air is not
available run the liquid sample in from the top of the flow cell and increase the flow rate. The flow cell
windows are sapphire, which is scratch resistant, but it is not recommended that pieces of wire or other
objects be used to clear blockages. Once the blockage is removed, a light can be shone through the
sensor to allow visual inspection. The flow cell opening is large enough to see through when clear.
The particle counter can still count particles with a dirty flow cell, but the accuracy may be
diminished.
3.1.6.1 Syringe Cleaning
Fill a large syringe with cleaner (diluted to manufacturer’s recommendation) and attach it to the top
flow cell barb with a short piece of tubing as shown in the following diagram. Squeeze the syringe to
introduce the cleaner into the sensor and let it sit for a few minutes and then inject some more and let
that stand a few more minutes. Finally, force the remaining cleaner rapidly through the flow cell. The
rapid flow should remove most buildup that has occurred in the sensor and bring the cell condition
back up to an acceptable level. Non-brush cleaning is not a replacement for occasionally cleaning with
a brush.
3.1.6.2 Brush Cleaning
Remove the tubing from the sensor’s fittings. Insert brush from top of sensor until it rests snugly in
the flow cell as shown in the following diagram. Move the brush in and out of the flow cell using short
strokes. Brush again from the other side of the sensor. Once cleaning has been performed, reattach
flow lines and allow a minute or so for the flow cell to flush out. Verify that the cell condition indicator is
back in the 90% range. If it is not, repeat the procedure.
The small size of the brush makes it easy to bend or damage. Do not force the brush into
the flow cell. It should fit into the flow cell with light pressure.
The cell condition indicator is not valid if the sensor is not full of water and clear of air bubbles.
3.1.6.3 Replacing Tubing
As the tubing becomes dirty, it will restrict flow through the sensor and can also contribute to higher
counts (especially if the tubing is disturbed), so sensor tubing should be replaced as it becomes visibly
fouled. It is not necessary to replace the Flow Control Weir drain tubing or the drain tubing on the
bottom of the Drain Cup. Weir Inlet tubing should be replaced occasionally to help reduce the potential
for vibration or any kind of movement on the tubing to release particles. Ensure that sample flow has
been stopped, any pressure build up has dissipated and liquid has drained prior to disconnecting any