YSI P 700 IQ Analyzer - Manual (Page 88)

88 ba76133e01 09/2013
P 700 IQ
24 Turn the roll block on the pump head until it agrees with the spin-
dle on the pump drive.
25 Screw in the four knurled-head screws and tighten them step by
step and crosswise.
26 Connect both ends of the pump tube. See Fig. 5-13,  84.
• The upper end of the tube goes to the cell of the optical block
• The lower end of the tube goes to the center connection of V5.
27 Remount the plastic cover from the photometer unit.
28 Reconnect the plug with the P700IQ-PO4.
or
Switch the analyzer on again with the power switch.
Restarting the
measuring operation
29 Carry out the steps 13…20 in section 5.3.4 Maintenance and
cleaning work on the open P 700 IQ,  73.
30 Make sure that the liquids run through the tubes in the correct
direction and that all tube connections are tight.
5.4.5 Cleaning the filter membrane
The time when to clean the filter membrane can be determined empir-
ically based on the negative pressure display on the filtration pump.
• A pulsing negative pressure manometer suggests a normal operat-
ing condition of the filtration unit
• With a delivery height of approx. 2 m and a new filter membrane, the
negative pressure is approx. -0.3 bar.
Every meter of delivery height increases the negative pressure by
approx. -0.1 bar.
If the negative pressure increases by a further -0.3 ... -0.4 bar with
time, the membrane is covered with solid matter from the sample
and has to be cleaned.
• If there is still negative pressure after cleaning, the suction line may
possibly be blocked
Prior to starting the cleaning process, switch off the filtration pump (with
the Start/Stop key, or switch off the whole analyzer).
The mechanical or chemical cleaning of the filter mem-
brane may take some time.
Use a replacement filter unit (FM) during the cleaning pro-
cess to keep the downtime of the analyzer as short as pos-
sible.