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3.0 GENERAL DESCRIPTION AND INSTALLATION
IMPORTANT
The P7/IS Controller, Holder and Electrode products must only be installed by suitably
trained personnel who have the necessary experience in installation, connection and
commissioning of instrumentation in explosion-hazardous areas, and are familiar with the
relevant codes of practise.
The units contain NO USER SERVICEABLE PARTS. Each product carries an
identification label, which shows its type and other important information.
1. The P7/I.S. is a conductivity operated level controller having approved intrinsically
safe electrode circuitry, which complies with the latest European Harmonised
Standards.
2. The P7/I.S. controller must be installed in the ‘safe’ area in a control panel or other
protective housing. To comply with the certification, only approved Hawker level
sensing electrode holders bearing the approved label, may be used in the
‘hazardous’ area.
3. The maximum operating temperatures must be taken into consideration when using
single and multiple systems in different enclosure configurations i.e. panels.
Adequate spacing, ventilation or cooling should be provided. Ambient operating
temperature ranges other than -20°C to +40°C will be indicated on the product
label. The equipment is intended to be used only in dry, clean and well-controlled
environments.
4. The certificate stipulates that the controller must always be housed in its enclosure,
even when fitted in a control panel. Separate conduit entries must be used for I.S
and mains/high voltage circuits.
5. The output relay gives the user a single pole volt free changeover contact, which its
Load must not exceed 100VA
Current must not exceed 5amps
Voltage must not exceed 250V
The volt free contact is for ‘safe’ area use
6. The P7/IS controller requires the connection of a mains earth to its (earth)
terminal for safety and not for functionality. It should be noted that all other
terminals including the electrode circuitry P1, P2 and G are electrically isolated from
the earth terminal.
7. The electrodes are certified for use in specific zones, check before specifying or
installing. The electrode circuitry is electrically isolated from earth.
8. The maximum number of Holders, which may be installed in any one tank, sump or
vessel, depends on the gas classification for the hazardous area in which the
systems are installed. See system section and drawing 2920.
