Hach-Lange PHOSPHAX sigma Basic User Manual - Manual (Page 97)

English 97
Hose pinch valves
The three hose pinch valves used have different tasks to fulfill. The two
valves in the top of the device (pinch valves Q1 and Q2) alternately feed
sample, air and standard solution to the sample pump. The third valve in
the bottom of the refrigerator (pinch valve QA) alternately delivers
reagent A and air to the reagent pump A. The electrical connection
occurs via a control cable, which is routed from the refrigerator going out
of the back into the PHOSPHAX Σ sigma housing. There it is plugged
into the fan plate behind the photometer baseplate.
As the hose pinch valves do not come directly into contact with reagent,
no cleaning or servicing work is required. For the hose change, the
attached hose holders are pulled off to the front.
Then the hoses in the front valve slot can be directly taken out or
inserted again, for the rear valve slot the center piece is pushed back
beforehand.
Figure 11 Handling of hose pinch valves
Drain tray moisture sensor
The drain tray is designed so that it drains any outflowing liquids
immediately to the moisture sensor, which is located at the very back in
the center. As soon as the two electrodes of the moisture sensor register
a strongly increased conductivity, the measurement operation is
switched off for safety reasons. It can only be started again after the
error (leak at hoses, digestion unit etc.) is rectified, the electrodes are
dry again and the error has been acknowledged in the [STATUS] menu
section Software menu system . The chemicals in the collection tray can
be picked up with soft blotting paper.
Refrigeration system
The durability of the reagents is only ensured at temperatures below
10 °C. For this reason, the device has a refrigerator. This system is easy
to handle and requires no maintenance. Commissioning takes place by
plugging in of the mains connector. To maintain the required temperature
range, the controller on the thermostat of the cooling machine must be in
position 5–6.
N O T I C E
For a long-term shutdown (over 48 hours), the pump cassettes must be released
in order to relieve the dosing hoses — but because of the return flow risk the
hoses should first be removed from the screw caps (canister lids)!
C A U T I O N
Position 6–7, or very cold installation rooms, can cause excessive cooling
(possibly even freezing).
The refrigerator compressor is protected by the PHOSPHAX
® housing and must
not be exposed either to spray water or water jets. The control cables for the
refrigerator valves are routed from the back into the housing of the measurement
device and connected to the fan plate.