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2. Installation
2.1 Calibration
When installing the sensor, it should be remembered that it is measuring instrument, and should be
treated with care. Before installation the sensor and control unit should be inspected for transit
damage, the gap faces of gap sensors must be parallel. Before installation, the equipment should be
calibrated, if possible, using a representative sample of the liquid in which it is to be used. The head
amplifier unit should be wired to the control unit, which should be connected to its power supply.
Wiring instructions are given in section 2.4.
When the mains supply to the control unit is switched on, either the green ‘normal’ light or the red
‘alarm’ light should be on, the amber ‘fault’ light should be off. The lid of the head amplifier unit is
removed by undoing the four screws or Allen bolts. Care should be taken not to damage the sealing
gasket, which should be replaced with the lid. When using integral head amplifiers, the sensor must
not be unscrewed from the head amplifier unit as this is likely to damage the internal wiring (and may
violate ATEX approval).
The marine head amplifier ***S*PM has one gain potentiometer for each sensor attached. It is factory
calibrated for the side range of liquids carried on tankers. It is advisable to check the function of the
system before final installation, using a sample of the liquid. The gain potentiometers are covered by
a screw cap, which should be replaced after re-calibration.
The industrial head amplifiers ***S*PI, MEP*AI and MEP*XI have a gain switch, which is illustrated in
Figure 2.2 (i) and 2.2 (iii).
Figure 2.1 - Head
amplifier internals
i) ***S*PI
ii) ***S*PM
iii) MEP*AI and MEP*XI