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Manufacturing,
Engineering
and
Sales
Since
I938
Phone: 017-527-4385
Fax:
6
1
7-9
04-i
740
E-Mail: sales@asrichards.com
Common
Thermocouple
TYPes
-
Types;
Bn
E,
J,
K, N,
R, S,
T,
C (WsR)
&
P
(Platinel ll)
The Type
R
thermocouple
is
composed of a platinum-13% rhodium
(+)
wire versus a platinum
(-)
wire.
This type
of
thermocouple can
be used in oxidizing
or
inert atmospheres with a service
temperature
range between 0 and
1480"C
(321o 27OO"F).
They should
never be used in reducing
atmospheres.
As
with all
platinum type thermo-
uples,
they should
always
be
protected
with
a
ceramic
protection
tube.
Alumina insulators and
protection tubes
preferred
to prevent silica
contamination
from Mullite
ceramics.
When
Type
R
thermocouples are
continuously
used
at
high
temperatures, the
elements
can develop excessive grain growth
in
time causing
mechanical breakage
to the
thermocouple. ln
most situations platinum thermocouples
should
not be placed in any type
of
metal
tube
or in applications where
metallic
vapors are
present.
The
Type S
thermocouple
is
composed of a platinum-10% rhodium
(+) wire
versus a platinum
(-) wire.
This
type
of thermocouple can be used in oxidizing or inert
atmospheres
with a service temperature range between 0
and
1480'C
(32
1o2700"F).
They should never be used in
reducing
atmospheres. As with all
platinum
type
thermo-
couples, they
should
always be protected
with
a
ceramic
protection
tube.
Alumina
insulators
and
protection
tubes
are preferred
to
prevent silica contamination from Mullite
ceramics.
When Type S thermocouples are
continu-
ously
used
at
high temperatures,
the
elements can develop excessive grain
growth
in
time
causing
mechanical break-
age to
the thermocouple. ln
most
situations
platinum
thermocouples should not
be placed in any
type of
metal
tube
or
in
applications where
metallic
vapors are
present.
The
Type
T thermocouple
is
composed of a copper
(+)
wire versus a
nickel-45%
copper
(-)
wire.
The Type
T
thermocouple
is
frequently
referred
to
as
copper-constantan. This type of thermocouple can be used in
oxidiz-
Tyrpe
ing,
reducing,
or inert atmospheres with a service temperature
range
between -200 and
370'C
(-330 to 700'F).
The
high
temperature
use
of this thermocouple
is
also limited due to rapid oxidation of the copper
element.
The
Type T
thermocouple
is
one
of
the few thermocouples
which
have established limits of error
for
use
in
subzero and cryo-
genic
applications. This
is possible due
to
the Type
T's superior corrosion
resistance
in
moist environments.
The Type
C
or
WSR
thermocouple
is
composed
of a
tungsten-S% rhenium
(+)
wire
versus
a
tungsten-26"/" rhe-
nium
(-)
wire.
This
Vpe
of
thermocouple can be
used in high
temperature vacuum or ineft
atmospheres with a
service temperature range up to
2316'C
(4200'F). lt
has very poor oxidation resistance, which must be taken
into
consideration.
The Type C
thermocouple
is
the
most common tungsten-rhenium form of thermocouple due to
the conductors
being
the least
brittle
at
room
temperature. This characteristic
is
very
important
since
brittle con-
ductors
create
inferior thermocouples.
The Type
P
or
Platinel
116
thermocouple
is
composed of a palladium-55%,
platinum-31"/",
and 14%
gold (+) wire
versus a65"/" gold and 35% palladium
(-)
wire.
TheType
Pthermocouple
is
a
noble-metal
form and should
be
protected
in
the same manner as
a
Type R, S, or
B.
This type
of
thermocouple was developed to approximate the
ype
K curve
at
high
temperatures. lt
can
be
used in oxidizing
or
inert atmospheres with
a
service
temperature
to
1260"C
(2300"F).
When
using
Type
P
thermocouples,
Type
K extension
wire should be
used.
Note:
The thermocouple types we describe in
the Richards Catalog
#
15 are
the
letter designations assigned by
the
lnstrument
Society of
America (lSA) and
adopted
as
an
American
Standard
in
ANSI
MC 96.1. The Type C
and
P letters
are exceptions.
The Type
C
and Type
P
are letter designations commonly used today by thermocouple manufacturers and not
the
lSA.
There are a few
other
more exotic types
of
thermocouples, which have been developed, but since they are rarely
used
we decided
not
to
list
them
in
this
catalog.
lf
you
have any
questions
regarding any
of these other
less
common types of thermocouples, contact one of our sales
engineers
and we
will
be glad
to
assist you.
lTrademark of
Harrison
Alloys,
lncorporated.
2Trademark
of
the Hoskins Manufacturing
Company
3Trademark
of Driver
Harris Company
4Trademark of
Carpenter Technology Corporation
STrademark
of
Kanthal Corporation
oTrademark
of Engelhard
lndustries
Visit
our
Web
Site
At wwW.AsRtcHARDs.coM
@
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