NTC THERMISTORS:
CRYOGENICS
DESCRIPTION:
Cryogenic Thermistor probes consist of bead ther-
mistors hermetically sealed into shock resistant
solid glass rods and come in 2 basic styles. The
CTFP…Type features a very small glass coated
bead extending from the tip of the glass rod while
the CTP…Type features a larger bead sealed with-
in the tip of the glass rod. Both styles are rugged
easy to handle and unaffected by severe environ-
mental exposures including high density nuclear
radiation. The CTFP…units offer ultrafast response
times whereas the CTP…units are more rugged
and at lower cost.
DIMENSIONS:
TYPE CTP60/CTP65/CTP85/CTP100
Figure 1
TYPE CTFP07/CTFP10/CTFP14
Figure 2
APPLICATIONS:
All Cryogenic Type Thermistor probes are designed
for use in the range of 25°C (room temperature)
to -196°C (the boiling point of Liquid Nitrogen).
These units are very stable, exhibit no hysteresis
effects, and rapid temperature cycling from 25°C
to -196°C has no measurable effect on electrical,
thermal or mechanical properties. These units are
well suited for Cryogenic temperature measure-
ment and control applications such as cryogenic
fluid flow, liquid level or temperature sensing in the
25°C to -196°C range. They may be used at tem-
peratures below the Nitrogen Point with suitable
instrumentation.
DATA:
Cryogenic Type Thermistor probes may be exposed
to 300°C for short periods. Units can be exposed
to 105°C for extended periods, however long term
storage at or above 60°C may result in some
resistance change, therefore storage below 60°C
is recommended for best stability.
CODING:
CTP60 B
E
104
R
Tolerance code letter per Table B
Zero-power resistance code from Table
Material System Code Letter (All Cryogenic Thermistors = E)
Probe Length Code Letter B = 1/4", D = 1/2" (for figure 1 only)
Thermistor type (CTP’s or CTFP’s)
BOWTHORPE THERMOMETRICS
Crown Industrial Estate, Priorswood Road
Taunton, Somerset TA2 8QY UK
Tel +44 (0) 1823 335200
Fax +44 (0) 1823 332637
THERMOMETRICS, INC.
808 US Highway 1
Edison, New Jersey 08817-4695 USA
Tel +1 (732) 287 2870
Fax +1 (732) 287 8847
KEYSTONE THERMOMETRICS CORPORATION
967 Windfall Road
St. Marys, Pennsylvania 15857-3397 USA
Tel +1 (814) 834 9140
Fax +1 (814) 781 7969
TABLE A: THERMAL AND ELECTRICAL PROPERTIES:
CRYOGENIC THERMISTOR PROBES
DIMENSIONS:
D (Max. Diameter)
L (Length)
Lead Diameter
Thermal Time
Constant in Still
Air* (Seconds)
Dissipation
Constant
in Still Air
(Milliwatts/K)
Maximum Power
(Watts)
CTP 60
.060
1/4" or 1/2"
.008
CTP 65
.065
1/4" or 1/2"
.008
CTP 85
.085
1/4" or 1/2"
.012
FIGURE 1
CTP 100
.100
1/4" or 1/2"
.012
CRYOGENIC FASTIP PROBES
CTFP 07
.085
1/2"
.012
CTFP 10
.085
1/2"
.012
FIGURE 2
CTFP 14
.085
1/2"
.012
12 Sec.
13 Sec.
16 Sec.
22 Sec.
.1 Sec.
.12 Sec.
.15 Sec.
.60 mW/K
.060 W
.65 mW/K
.065 W
.80 mW/K
.075 W
1.0 mW/K
.100 W
.05 mW/K
.006 W
.09 mW/K
.010 W
.10 mW/K
.014 W
TABLE B: STANDARD TOLERANCES:
Tolerance Code Letter
± % Tolerance at -196°C
RESISTANCE TOLERANCE
K
10
L
15
M
20
N
25
P
30
Q
40
R
50
S
Non-standard (specify value)
STANDARD RESISTANCE VALUES
Resistance in Ohms
at -196°C
100k
240k
510k
1 Megohm
* Resistance is measured in liquid nitrogen.
Standard tolerance is ±50% (tolerance code letter R
at end of code number). For other tolerances, substi-
tute letter from Table B for suffix R at end of code
number. The CTFP07DE105R is 1 Megohm ±50%
when measured in liquid nitrogen.
RESISTANCE RATIO -VS-
TEMPERATURE CHARACTERISTIC
-195.82° = 1.0000
-195° = .97129037
-190° = .75784916
-185° = .54321686
-180° = .37080903
-175° = .24676085
-170° = .16254994
-165° = .10705529
-160° = .07094719
-155° = .04750487
150° = .03221784
-145° = .02216270
-140° = .01547439
-135° = .01096864
-130° = .00789193
-125° = .00576173
-120° = .00426633
-115° = .00320214
-110° = .00243470
-105° = .00187414
-100° = .00145960
-95° = .00114941
-90° = .00091467
-85° = .00073512
-80° = .00059637
-75° = .00048810
-70° = .00040283
-65° = .00033510
-60° = .00028084
-55° = .00023703
-50° = .00020139
-45° = .00017219
-40° = 00014811
-35° = .00012811
-30° = .00011141
-25° = .00009739
-20° = .00008554
-15° = .00007547
-10° = .00006688
-5° = .00005952
-0° = .00005317
+5° = .00004768
+10° = .00004291
+15° = .00003875
+20° = .00003510
+25° = .00003190
Resistance
Code
104
244
514
105
NTC THERMISTORS:
CRYOGENIC THERMISTORS
Type
RL1004-10K-0-S1
For Operation
In Liquid
Oxygen
Nitrogen
RL060628-31.7K-0-S1
Oxygen
Nitrogen
NOTE: Dissipation constant is in still air (mW/K)
Resistance
(Ω)
10K ± 20%
31.5K Nominal
31.7K ± 20%
100K Nominal
Temperature Coefficient
(%/K)
– 8.4
– 10.4
– 8.4
– 10.4
Figure
1
Dissipation
Constant (mW/K)
4
2
3
These cryogenic thermistors are extremely useful for
liquid level detection in various cryogenic liquids. In
this application, the thermistor is slightly self-heat-
ed by passing a small current through the unit. The
heat generated in the unit is more easily dissipated
when the thermistor is immersed in cryogenic fluid
than when the fluid level falls below the thermistor.
The resulting change in thermistor temperature is
easily detected by the change in resistance.
Figure 1
Figure 2
BOWTHORPE THERMOMETRICS
Crown Industrial Estate, Priorswood Road
Taunton, Somerset TA2 8QY UK
Tel +44 (0) 1823 335200
Fax +44 (0) 1823 332637
THERMOMETRICS, INC.
808 US Highway 1
Edison, New Jersey 08817-4695 USA
Tel +1 (732) 287 2870
Fax +1 (732) 287 8847
KEYSTONE THERMOMETRICS CORPORATION
967 Windfall Road
St. Marys, Pennsylvania 15857-3397 USA
Tel +1 (814) 834 9140
Fax +1 (814) 781 7969
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