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2 INSTALLATION
2.1 Mounting
a) Dimensions of the flange and fixing holes are shown in Fig.
1 together with overall dimensions of the complete system.
b) Since the associated measuring instrument has to be set
up with the electrode immersed in standardising solutions,
the electrode system should not be bolted into place until
the standardisation procedure (see under OPERATION)
has been carried out. Correct alignment of the fixing holes
for the installation should however be checked before
standardisation.
c) It is important to ensure that the system is so positioned as
to ensure a positive head of 300 to 600mm (12 to 24in) of
salt bridge solution relative to the liquid being measured.
2.2 Electrical Connections
The connecting cable is fitted with a waterproof coaxial plug or
tagged ends.
a) Remove the protecting end cap (supplied with the versions
fitted with coaxial connectors) and retain it for future use. It
will be required if the electrode assembly is removed or
otherwise disconnected from the measuring instrument.
b) Ensure that any dirt or grease in the plug and associated
socket connected to the measuring instrument is removed
by carefully wiping with a rag moistened with a suitable
solvent e.g. propanol.
c) Connect the plug and socket and make watertight by
overlapping the rubber sleeves provided.
d) For electrodes with cables terminating in tagged ends,
connect the individual tags to the input terminal block of the
pH meter, as described in the instruction manual for the pH
meter.
2
3 PREPARATION FOR USE
3.1 Activation of Electrodes
Before use, depending on the type of electrode assembly a
period of activation may be required. Full details are given in
the booklet provided with the electrode assembly.
3.2 Assembly of the System
a) Remove the split rubber bung from the cap on the upper
end of the system.
b) Fit the smaller of the ceramic plugs to the side of the
electrode system tube (See Fig. 1) using the special
wrench supplied in the accessory kit. If the sample causes
blockage of the ceramic, replace the plug with the larger
one, which will allow a higher flow of salt bridge solution.
c) Thread the coaxial cable from the electrode assembly up
through the bottom end of the system so that it passes out
through the cap on the upper end.
d) Remove the neoprene cap from the salt bridge solution
entry tube of the reference element (at the upper end of the
electrode assembly).
Note. There should be a minimum of delay between
carrying out this step and the filling of the system with salt
bridge solution (see below).
e) Screw the electrode assembly into the system and tighten
firmly until it is flush.
f) Unscrew the cap on the upper end of the system. There is
no need to remove it from the coaxial cable.
g) Holding the system upright, fill with salt bridge solution
(saturated potassium chloride) until the level can be seen
to be near to the top of the transparent section. Add a few
grammes of KCl crystals to keep the solution saturated.
h) Place the screw cap on the upper end of the system.
i) Fit the coaxial cable into the split rubber bung and place it
in the cap.
3.3 Standardisation pH
This consists of setting up the associated measuring
instrument to read correctly with the electrode in the system
immersed in suitable standard solutions. The procedure is fully
described in the appropriate instrument manual.
Note. When using a glass electrode assembly the check
reading to be expected is between 6.7pH and 7.3pH.
When the standardisation procedure has been carried out,
complete the installation of the system.
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