Hawker P7/I.S., Operating And Installation Instructions, Page: 15 / 23

Page 15 of 22
5.1.4 Special conditions for safe use
(denoted by an X after the certificate number)
1.
The Holder Type 1G/0 HPE5/IS shall not be used with an input current,
Ι
i, that is in
excess of 100 mA.
2.
The equipment cannot be considered capable of withstanding 500 Vrms. a.c.
voltage test to earth (a requirement of clause 6.4.12 of EN 50020:2002). This shall
be taken into account when the equipment is being installed.
3. Holder Types 1G/0 HPEXXXX/IS and 1G/0 HPE5/IS shall not be directly installed
in any process where the plastic holder or plastic electrode coating might be
charged by the rapid flow of a non-conductive medium, including application,
cleaning, maintenance or other.
4.
In any equipment installation the cap of the Holder Type 1G/0 HPE12/P and the
electrodes of versions of the holders fitted with titanium electrodes shall be provided
with protection from impact or installed such that impacts cannot occur.
5.2
Installation
Electrodes should preferably be mounted vertically in the vessel. Spacing between the
electrodes and their distance from the side of the vessel is dependent on the likelihood of
bridging due to floating matter and the degree of turbulence. For clean application the
distances can be as low as 5 - 8cm but in the case of raw sewage the recommended
distance is 23cm. Using plastic coated electrodes, which are available from stock, can
eliminate bridging, always bare at least 50mm of the coating and have the reference ‘G’
electrode central.
Wall mounted brackets are available for the electrode holders. Where turbulence is
expected, electrodes of long length should be fitted with steady brackets. Both these are
available from stock.
Care must be taken when mounting to ensure that the electrode holder insulators protrude
through the surrounding material e.g. concrete floors. If only the electrodes protrude they
may find a conductive path through the concrete and not the liquid in the vessel.
It is advisable to clean electrode rods and insulators at periodic intervals.
The electrode holder suitability should be confirmed as being correct for the hazardous
location, and must carry the specific certification.
The electrode conductors are electrically isolated from earth. Using a separate ‘G’ probe
as the common probe, and not the vessel or any part of its structure will provide the best
operational performance, and will comply fully with the system certification.
Termination consists of crimp/solder terminals, washers and nut or screw, this may be by
collar or direct to the electrode, depending upon holder type. All connecting hardware is
provided with the holder. The user should ensure a sound connection, which does not
interfere, contact or stress any other connection if present. Adequate clearance must be