
Immersion Temperat ure Sensors
Specifications subject to change without notice.
Catalog No. 11-808-632-01
Figure 2: J-Box Immersion (Standard)
Part #
NSB-10K-2-I-4-M304 (4” probe, 304 SS thermowell)
#20907 – 2/20/19
Overview
The Immersion Temperature Sensor is made for thermowell mounting and temperature measurement in water pipes, water tanks or
cooling tower sump applications. The rigid probe is made of Stainless Steel and made in different lengths for a custom thermowell fit.
Enclosure mounting sty les come in plastic or metal for both NEMA 1 and NEMA 4 applications and are all plenum rated.
Installation and
BB2 Box Immersion
s NSB-10K-2-I-2-BB2 (2” probe, no thermowell)
NSB-10K-2-I-4-BB2 (4” probe, no thermow ell)
NSB-10K-2-I-8-BB2 (8” probe, no thermowell)
NSB-10K-2-I-2-M304 (2” probe, 304 SS thermowell)
s NSB-10K-2-I-2 (2” probe, no thermowell)
NSB-10K-2-I-4 (4” probe, no thermowell)
NSB-10K-2-I-8 (8” probe, no thermowell)
NSB-10K-2-I-2-M304 (2” probe, 304 SS thermowell)
NSB-10K-2-I-4-M304 (4” probe, 304 SS thermowell)
NSB-10K-2-I-8-M304 (8” probe, 304 SS thermowell)
3: BB4 Box Immersion
s NSB-10K-2-I-2-BB4 (2” probe, no thermowell)
NSB-10K-2-I-4-BB4 (4” probe, no thermowell)
NSB-10K-2-I-8-BB4 (8” probe, no thermowell)
able Knockout Plug (Part #NSB-PKP-100)
for the open port in the BB4.

Immersion Temperat ure Sensors
Installation and Operation
Specifications subject to change without notice.
Catalog No. 11-808-632-01
Figure 4: Machined Bar Stock ThermoWell
Part #
Figure 5: Two-Part Welded Thermowell
Part #
#20907 – 2/20/19
Specifications
Sensor: Passive, 2 wire
Thermistor Thermal resistor (NTC)
Temp. Output Resistance Per Order1
Accuracy (std) ±0.36ºF, (±0.2ºC)
Stability 0.036ºF/Year, (<0.02ºC/Year)
Heat dissipation 2.7 mW/ºC
Temp. Drift <0.02ºC per year
Probe range -40º to 221ºF (-40º to 105ºC)
Sensitivity Approximate @ 32ºF (0ºC)
Thermistor Non-linier
Lead wire 22 AWG stranded
Insulation Etched Teflon, Plenum rated
Probe Rigid, 304 Stainless Steel,
0.25” OD
Probe Length 2” or 4”
Mounting ½” NPSM Plastic Threads
Enclosure Types
J-Box (-JB) With eight ½” knockouts
BB2 Box With three ½” NPSM & three ½” drill-outs
BB4 Box With three ½” drill-outs & one ½” open port
Enclosure Ratings
J-Box (-JB)
BB2 Box NEMA 4X,
IP66 BB4 Box IP10
Enclosure Materials
J-Box (-JB) Galvanized steel, UL94H-B
BB2 Box Polycarbonate, UL94V-0, UV rated
BB4 Box Polycarbonate & Nylon, UL94V-0
Ambient (Encl.) 0 to 100% RH, Non-condensing
BB2 & BB4 Boxes -40ºF to 185ºF, (-40º to 85ºC)
J-Box & No Box -40ºF to 212ºF, (-40º to 100ºC)
NEMA 1
(IP44 with Knockout Plug in the open port)
Thermowells
Thermowells are hollow tubes closed off on one end and threaded at the other end. They are permanently placed into pipes, tanks, or
sumps so that the probes on immersion temperature sensors can be inserted into the pipe. The temperature of the pipe’s contents is
transferred through the wall of the thermowell. The thermowell prevents the pipe’s contents from escaping and maintains the pressure
of pressurized pipes.
s ZSI-T-2-MB
ZSI-T-2-MSS
ZSI-T-4-MB
ZSI-T-4-MSS
ZSI-T-8-MSS
Agency RoHS, *CE
JIS C1604-1989
*Thermistors are CE compliant
s ZSI-T-2-WSS
ZSI-T-4-WSS
ZSI-T-8-WSS

Immersion Temperat ure Sensors
Specifications subject to change without notice.
Catalog No. 11-808-632-01
Table 2: Maximum Fluid Velocity versus Insertion Length
Insertion Length (inches)
Maximum Fluid Velocity (Feet per second)
Table 1: Pressure Rating versus Temperature
Temperature in Degrees Fahrenheit
Pressure Rating (Pounds per Square Inch)
Installation and
#20907 – 2/20/19
Thermowells (continued…)
Choosing the correct Thermowell
As part of our ZS Sensor line, Carrier sells 2.5” and 4.5” machined thermowells made of Brass or 304 Stainless Steel (SS) and twopart welded thermowells made of 304 Stainless Steel. The two-part welded thermowells are not as strong as their machined
counterparts. Carrier recommends the use of welded thermowells be limited to small diameter systems in low vibration environments.
Carrier strongly encourages that single-piece machined thermow ells be used when pos si bl e. See the entries for Welded SS in the
following design tables. Additi onal ly , welded stainless steel thermowells should not be used in turbulent flow; ideally they should be
three to five pipe diameters from elbows or transitions.
Thermowell
Material
The values shown in Table 3 are based
on operating temperatures of 350ºF for
Thermowell
Material
Brass
Fluid Type
brass and 1000ºF for stainless steel.
Slightly higher velocities are possible at
lower temperatures.
Welded
304 SS
304 SS
Comparing the Wake Frequency and the Resonant Frequency
Table 2 and Table 3 were developed to insure that there will be no thermowell failures due to application stresses. Thermowell
failures, in most cases, are not due to the effects of pressure or temperature on the well. The calculations necessary to provide
adequate strength, under given conditions, are familiar enough to permit proper choice of wall thickness and material. The values
shown in Table 2 are conservative, and intended primarily as a guide.
Less familiar, and more dangerous, are the vibration effects to which thermowells are subjected. Fluid, flowing by the well, forms a
turbulent wake (called the Von Karman Trail) which has a definite frequency, based on the diameter of the thermowell and the velocity
of the fluid. It is important that the thermowell have sufficient stiffness so that the wake frequency will never equal the resonant (natural)
frequency of the thermowell itself.
If the resonant frequency of the thermowell coincided with the wake frequency, the thermowell would vibrate to destruction and break
off in the piping. Thermowells are also safe if the resonant frequency below the wake frequency or if the fluid velocity is constantly
fluctuating through the critical velocity point. Nevertheless, if the installation is not hampered by the use of a sufficiently stiff thermowell,
Carrier recommends the values given in Table 3 not be exceeded.