10
Figure
3.
The
z
height
of
a
typical
microcuvette
E.
COOLING
WATER
FOR
THE
PELTIER
The
Peltier
element
(or
“thermoelectric
cooler”)
is
a
heat
pump.
When
cooling,
it
transfers
heat
from
the
Turret
body
to
a
heat
exchanger;
when
heating,
electrical
polarity
is
reversed
and
it
transfers
heat
from
the
heat
exchanger
to
the
tower.
When
cooling,
it
is
particularly
important
to
transfer
this
heat
away
from
the
Peltier.
This
is
accomplished
with
flowing
water
through
the
heat
exchanger.
A
source
of
water
(or
other
cooling
fluid)
must
be
connected
to
the
⅛‐
inch
hose
barbs
on
the
back
of
the
Turret
6
.
If
you
purchase
the
BATH
10
from
us,
you
will
get
an
inexpensive
submersible
aquarium
pump,
the
appropriate
fittings
for
connecting
tubing,
and
a
plastic
bucket.
Connect
the
pump
to
the
Turret
6
,
place
it
in
the
bucket
with
water,
and
run
a
return
tube
to
the
bucket.
A
more
robust
pump
is
available
as
the
BATH
100
for
a
higher
price,
although
the
larger
pump
has
a
higher
Wattage
and
tends
to
heat
the
water
when
used
for
extended
periods
of
time.
You
may
also
provide
the
cooling
water
from
another
source,
such
as
a
refrigerated
cooling
bath
or
even
a
tap
for
brief
use.
You
will
need
a
flow
of
100
‐
300
ml/minute.
This
flow
should
require
a
pressure
of
about
3
‐
5
psi
(0.2
‐
0.3
bar).
Do
not
exceed
an
input
water
pressure
of
25
psi
(1.7
bar),
as
damage
may
occur
inside
the
Turret
6
.
The
heat
exchanger
and
hose
barbs
are
brass,
and
the
tubing
inside
the
Turret
6
is
vinyl.
Be
sure
that
any
circulating
fluid
used,
other
than
water,
will
not
corrode
these
materials.
The
temperature
of
the
heat
exchanger
in
the
Turret
6
is
monitored
using
a
thermistor.
If
the
temperature
exceeds
60
°C,
then
temperature
control
is
shut
down
to
prevent
damage
to
the
Peltier
element
and
the
warning,
“check
coolant
flow,”
displayed
on
the
TC
1
temperature
controller.
This
will
happen
if
the
circulating
fluid
gets
too
warm
and/or
is
restricted
in
flow.
The
heat
exchanger
temperature
may
be
accessed
by
computer
through
the
RS
232
or
USB
connections
on
the
back
of
the
TC
1
Temperature
Controller
(see
External
computer
control
below).
Temperature
increases
will
be
faster
when
room
temperature
water
is
used
in
the
circulator.
Temperature
decreases
will
be
faster
when
ice
water
is
used.
Only
water
should
be
circulated
using
the
BATH
10
.
When
using
a
refrigerated
bath,
circulating
pre
‐
cooled
fluids
(such
as
30%
methanol
or
diluted
ethylene
glycol)
at
below
0
°C
will
permit
measurements
below
the
specified
temperature
range.
