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9305
Thermocouple
Input
card
Model
DRC-91C/93C
adjustment
trimpots
are
(Chromel)
as
t h e
positive
accessible through the cover.
thennoelement
(EP) and
a
Cu-Ni
Place the cover on top of the
alloy (constantan) as the negative
cover
clips
and
start
the
thermoelement
(EN).
This
screws.
Carefully move any
thermocouple
has
the
highest
misaligned
cards
to
their
sensitivity
of
the
three
ASTM
proper position and tighten the
standard
thermocouple
types
cover screws.
Replace the top
typically used for low temperature
panel
and
three
top
panel
applications, types E, K, and T.
screws.
The E thermocouple is the best
choice for temperatures down to
about
40
K .
It is recommended for
9305.4 SENSOR ATTACHMENT
use
in
oxidizing environments, or
in
sulphurous
or
reducing
Thermocouple leads are attached to
atmospheres. It should not be used
the
Terminal
Block
by
aluminum
in
environments
that
promote
screws.
Be sure to tighten the
corrosion.
terminal screws carefully.
Loose
connections will result in unstable
readings and control.
The leads
must be connected with the proper
The
ASTM
designation
type
K
polarity
or the
9305
will
not
indicates
a
thermocouple pair
operate properly.
The positive
consisting
of
a
Ni-Cr
alloy
terminal of the terminal block is
(Chromel)
as
t h e
positive
marked with a plus sign and should
thennoelement
(KP) and
a
Cu-A1
correspond
with
the
positive
alloy
(Alumel) as
the negative
thennoelement listed for each type
thermoelement (KN).
It should not
of thermocouple in Section
9305.5.
be used in sulphurous or reducing
atmospheres,
or
in
environments
that promote corrosion.
9305.5.4
Type T Thermocouples
9305.5.3
Type
K
Thermocouples
9305.5
NOTES ON
THERMOCOUPLES
Lake
Shore's
9305
Thermocouple
Input
C a r d
supports the Chromel vs.
The
ASTM
designation
type
T
G o l d ,
E,
K,
and
T
type
indicates
a
thermocouple pair
thermocouples.
consisting of Cu (Copper) as the
positive thermoelement (TP) and a
9305.5.1
Gold-Chromel Thermocouples
Cu-Ni alloy
(Constantan) as the
negative thermoelement (TN)
.
This
The
Gold
Chromel
thermocouple
type of thermocouple may be used in
consists of a Gold(Au)-0.03 at.%,
vacuum as well as oxidizing or
or
0.07
at.% Iron(Fe) alloy as the
reducing environments down to about
negative thermoelement and a Ni-Cr
90
K .
At temperatures below
80
K
alloy
(Chromel) as the positive
the thermoeletric properties of the
thermoelement (KP). This type of
positive
thermoelement
(TP) are
thermocouple can be used at very
very dependent on the impurity of
low temperatures, even below
10
K.
iron.
9305.5.2
Type
E
Thermocouples
The ASTM
(American Society
for
Testing and Materials) designation
The
9305
Thermocouple Input Card
type E
indicates a thermocouple
h a s the capability of interfacing 5
pair consisting of a Ni-Cr alloy
different
thermocouple types
in
9305-4
COPYRIGHT 6/88
LSCI
9305.6
PRINCIPLE OF OPERATION
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