Hanna Instruments HI 8510 - Manual (Page 15)

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• Consent contacts (HI 8710 and HI 8720):
these contacts (max. 2A, 240 V) are used
for reduction and oxidation reactions when
the pH controller works in conjunction with
an ORP controller and vice versa.
In these applications, the consent contacts
of both meters are connected together to
link the ORP and pH controllers, so that
ORP dosage will occur only if the actual
pH value is correct. This feature avoids
overdosages which may lead to undesirable
pollution.
For HI 8710, the "Consent" contacts can
be left open if the instrument is used
independently as pH controller only.
For HI 8720, the "Consent" contacts should
be shorted if the instrument is used inde-
pendently as ORP controller only.
• Alarm contacts (HI 8710,
HI 8711 and HI 8720): if the
pH or ORP measurement is
not within the set value
tolerance, the alarm contact
is closed.
Note: All external cables connected to the rear
panel should be ended with cable lugs.
FUSE
ACID
FUSE
FUSE
BASE
FUSE
FUSE ALARM
FUSE
• The HI 8710 models are single dosage
controllers with acid/alkaline selection.
If acid dosage is needed
(e.g. in chromium VI
reduction), leave open the
ACID/BASE selection
terminals (see picture), while
for alkaline dosage (e.g. in
cyanide oxidation), make a
short circuit across the
ACID/BASE selection
terminals with a jumper wire.
• The HI 8720 models are single dosage
controllers with oxidant/reductant selection.
If oxidant dosage is needed
(e.g. in cyanide oxidation),
leave open the OX/RED
selection terminals (see
picture), while for reductant
dosage (e.g. in chromium
VI reduction), make a short
circuit across the OX/RED
selection terminals with a
jumper wire.
• Set contacts (HI 8710 and HI 8720): these
contacts (max. 2A, 240 V)
are used to connect the
dosing pump, and act only
as a switch for the power
to the drive.
• Acid contacts (HI 8711):
these contacts are used to
connect the dosing pump
for acid, and act as a switch
for the power to the drive.
• Base contact (HI 8711):
these contacts are used to
connect the dosing pump
for base, and act as a
switch for the power to the
drive.
OPEN: ACID
SHORT: BASE
OPEN: ACID
SHORT: BASE
OPEN: OXD
SHORT: RDX
OPEN: OXD
SHORT: RDX
FUSE
SET
FUSE