Marlox Thermocouples

Marlox Thermocouple 1 | Marlin Manufacturing

Metal Sheathed – Inert Oxide Insulated

Marlox is metal sheathed, inert oxide insulated thermocouple cable from marlin manufacturing Corporation. Available within ANSI/ASTM calibratioin tolerances and with various types of sheath alloys. Marlox can be ordered as complete fabricated assemblies or in random lengths. Drawn to final size and fully annealed standard Marlox, single or dual thermocouple element, is moisture-proof, pressure resistant, accurate, bendable and weldable. Quality control procedures insure that all thermocouple material is tested for adequate insulation resistance. All certified Marlox stock is checked for ANSI/ASTM limits of error conformance by lot sampling in our quality control metrology laboratory, which is certified traceable to the National Institute of Standards and Technology (NIST) and ISO 17025 NVLAP accredited (Lab Code 2000512-0). Post assembly certified traceable calibration is available upon request.

For more information regarding Calibration Services – Click Here!

THERMOCOUPLE DO’s:

DO check in place.
DO replace at established, proper intervals.
DO have good connections throughout the circuit.

THERMOCOUPLE DO NOT’s:

DON’T reinsert at different immersions. (Avoid decreasing the immersion).
DON’T use for accurate measurements at lower temperatures after being exposed to higher temperatures.
DON’T use in defective protecting tubes.
DON’T insulate with used insulators.
DON’T use oils and solvents on or in T/C’s or T/C assemblies.

For more information regarding General Installation, Operation and Maintenance of Thermocouples click here!

General Selection Parameters

The conditions of measurement determine the type of thermocouple used. Temperature, atmosphere, protection, response, and service life should be considered. The following descriptions serve as a guide to selection.

Thermocouple Type

Select the thermocouple type that will be capable of operating in your application temperature range.

Type T (Copper vs Constantan)

Type T is used for service in oxidizing, inert or reducing atmospheres or in vacuum. It is highly resistant to corrosion from atmospheric moisture and condensation and exhibits high stability at low temperatures; it is the only type with limits of error guaranteed for cryogenic temperatures.

Type J (Iron vs Constantan)

Type J is used protected or unprotected in vacuum, oxidizing, inert or reducing atmospheres. Iron element oxidizes rapidly at temperatures exceeding 1000°F, and therefore heavier gauge wire is recommended for longer life at these temperatures.

Type E (Chromel^TM vs Constantan)

Type E may be used protected or unprotected in oxidizing, inert or dry reducing atmospheres, or for short periods of time under vacuum. Must be protected from sulfurous and marginally oxidizing atmospheres. Produces the highest EMF per degree of any standardized metallic thermocouple.

Type K (Chromel^TM vs Alumel)

Type K is used protected or exposed to oxidizing, inert or dry reducing atmospheres. Exposure to vacuum is limited to short time periods. Must be protected from sulfurous and marginally oxidizing atmospheres. Reliable and accurate at high temperatures. (HOSKINS MFG. CO.™)

Type N (NICROSIL vs NISIL)

Type N is used protected or exposed to oxidizing, inert or dry reducing atmospheres. Exposure to vacuum is limited to short time periods. Must be protected from sulfurous atmospheres.

Thermocouple Wire Alloys	Temperature Range (°F)	Order Code Standard Grade	Standard Grade	Special* Grade
			Initial Calibration Tolerance
Copper (+) vs. Constantan (-)	-32 to +270 +270 to +660	1T	±1.8°F ±0.75%	±0.9°F ±0.4%
Iron (+) vs. Constantan (-)	32 to 530 530 to 1400	1J	±4.0°F ±0.75%	±2.0°F ±0.4%
Chromel^TM (+) vs. Constantan (-)	32 to 600 600 to 1600	1E	±3.0°F ±0.5%	±4.0°F ±0.4%
Chromel^TM (+) vs. Alumel (-)	32 to 530 530 to 2300	1K	±4.0°F ±0.75%	±2.0°F ±0.4%
Nicrosil (+) vs. Nisil (-)	32 to 530 530 to 2300	1N	±4.0°F ±0.75%	±2.0°F ±0.4%
* Accuracy of Marlox Thermocouples

Marlin products are manufactured to specifications in conformance with Initial Calibration Tolerance of ANSI/ASTM E230. Standard grade wire is used in manufacturing all Marlin thermocouples for temperature above 32°F; special grade thermocouples for use at sub-zero temperatures, and thermocouples with certified traceable calibrations are available upon request. To order a special grade Initial Calibration Tolerance Thermocouple use a designation; e.g.,2T,2J,2E,2K,2N.

Sheath Alloy

304 Stainless Steel (18% Chromium – 8% Nickel)

A general purpose, economical, readily available sheath material that has good corrosion and oxidation resistance.
Maximum operating temperature is 1650°F.

310 Stainless Steel (24% Chromium – 19% Nickel)

A material that has improved resistance to corrosion as compared to 304SS and the best resistance to oxidation of the “300” series stainless steels.
Maximum operating temperature of 2100°F.

316 Stainless Steel (16% Chromium – 10% Nickel)

A material that has superior corrosion resistance as compared to 304SS or 310SS with improved oxidation resistance and a higher hot strength than 304SS.
Maximum operating temperature is 1700°F.

InconelTM600 (72% Nickel – 17% Chromium)

A material that is readily available and has outstanding resistance to oxidation, corrosion and scaling. Should not be used in the presence of sulfur above 1600°F. (TMInternational Nickel Company)
Maximum operating temperature is 2100°F.

Temperature Recommendation

The temperature limits for continuous duty, grounded junction thermocouples are shown for available sheath sizes and thermocouple calibrations. Exposed junction thermocouples should be used at lower temperatures for equivalent service life.

LIMIT TEMPERATURE °F CONTINUOUS DUTY
Sheath Diameter (Inches)	Nominal Tube Wall Thickness (Inches)	Wire Gauge AWG		ANSI Thermocouple Type
Sheath Diameter (Inches)	Nominal Tube Wall Thickness (Inches)	Single TC Element	Dual TC Element	J	T	K	E
0.020	0.003	38	_	700	400	1600	800
0.032	0.004	34	_	700	400	1600	800
0.040	0.006	33	_	700	400	1600	800
0.062	0.009	28	30	700	400	1600	800
0.125	0.017	22	24	700	400	1600	800
0.187	0.025	20	21	900	500	2000	1000
0.250	0.033	16	18	1000	600	2000	1100
0.3125	0.041	16	_	1000	600	2000	1100
0.375	0.052	15	_	1100	700	2000	1200
0.500	0.070	10	_	_	_	_	_
DIM. TOLERANCE: Up to 0.062 ±0.001"; 0.125 to 0.500 ±0.003"

Sheath Size

Use the thermocouple size that will withstand the rigors of your application but with minimal effect on it.

MARLIN CODE	SHEATH SIZE DIAMETER (Inches)	MARLIN CODE	SHEATH SIZE DIAMETER (Inches) 010 0.010 187
010	0.010	187	0.187
020	0.020	250	0.250
032	0.032	312	0.312
040	0.040	375	0.375
062	0.062	500	0.500
125	0.125	-	-

Junction Type

All junctions are welded by the tungsten inert gas method to insure performance and to prevent contamination of marlox thermocouples.
Exposed Junction
Bare thermocouple wires are welded to form a junction that extends beyond the sheath for a distance equal to the sheath diameter. Used where fast response is required and contamination is not a factor.
Grounded Junction
The thermocouple junction is welded directly to the sheath. Provides good thermocouple protection against pressure, moisture and mechanical damage yet retains good response characteristics.
Ungrounded Junction
The junction is electrically and mechanically insulated from the sheath for long life characteristics under maximum corrosion, thermal shock, and vibration conditions.
Dual Element Junction
Dual element Marlox provides two circuits for simultaneous response from a single thermal point. Exposed, grounded or dual ungrounded are available. In Marlox 0.125″ diameter and up the dual element ungrounded thermocouple junctions are insulated from the sheath and each other. Smaller diameter Marlox dual ungrounded junctions are insulated from the sheath but not from each other.
Weld Pad Junction
The junction is used as a means of attaching Marlox to surfaces such as boiler tubes and pipes to provide efficient surface temperature measurement. Standard construction utilizes grounded or ungrounded junction Marlox welded to an alloy pad (1″ x 1″ x 1/8″) of the same composition as the sheath. Tube skin perpendicular and parallel pad arrangements are available.

JUNCTION TYPE	ORDER CODE
Single Thermocouple Element Marlox	-
Exposed	1X
Grounded	1G
Ungrounded	1U
*Weld Pad, Grounded	-
Perpendicular	1A
Parallel	1B
Tube Skin	1C
Dual Thermocouple Element Marlox
Exposed	2X
Grounded	2G
Ungrounded	2U
*Weld Pad, Grounded	-
Perpendicular	2A
Parallel	2B
Tube Skin	2C

Marlox Transition and/or Extension Types

Marlox Transition Extension Type Sensors | Marlin Manufacturing

The Marlox transition is an exclusive development from Marlin Manufacturing Corporation. After the wire extension has been spliced to the sheathed thermocouple wire, the transition is molded with a thermoset compound. This transition exhibits the characteristics of high strength and resistivity and protects the splice against moisture, vibration and mechanical damage and also incorporates a strain relief for the wires that obsoletes springs and adapters. Standard transitions can be used in ambient temperatures to 400°F (205°C). High temperature transitions are available for use in ambient temperature to 800°F (425°C).

MARLOX TRANSITION DIMENSIONS
Marlox Size Diameter (Inches)	Transition* Size Diameter (Inches)	Transition Length "L" Dimension (Inches)	Wire Extension Gauge (AWG.)
			SINGLE	DUAL
0.020	0.190	0.875	28	N/A
0.032	0.190	0.875	28	N/A
0.040	0.190	0.875	28	N/A
0.062	0.190	0.875	24	28
0.125	0.250	1.000	20	24
0.187	0.312	1.000	20	24
0.250	0.437	1.000	16	20

*Same diameter transitions are available in 0.125″ diameter and larger Marlox.
*Dual element transitions are available in 0.062″ diameter and larger Marlox.

EXTENSION TYPES

Marlin Code	Extension Types
XXX	NONE
MTO	TEFLON INSULATED 260°C (500°F)
MGO	FIBERGLASS INSULATED 482°C (900°F)

NOTES:

For SS Flex Armor Cable over Extension, add “3” to code: e.g. “MG3”
For SS Overbraid over Extension, add “1” to code e.g. “MG1”

TRANSITIONS
Extensions include transitions for use to 205°C (400°F)
For Hi-Temp transition 425°C (800°F) use “H” to code e.g. “HGO”
For transition “same size” as Sheath O.D. use “E” to code e.g. “EGO”
For “Probe Handle” transition use code “P” e.g. “PT7” (good for 350°F – not available in hi-temp).

Teflon-Teflon: Teflon insulates individual conductors followed by an overall teflon jacket. Superior abrasion and moisture resistance. Resists most acids and vapors. Recommended operating temperature -90°F to 500°F.

Glass-Glass: Glass yarn is applied over each conductor then impregnated with silicone varnish plus both conductors are covered with a braid of glass yarn also with silicone varnish. Fair resistance to abrasion and moisture. Recommended operating temperature to 900°F. Varnish is destroyed above 400°F.

Glass-Glass with Stainless Steel Overbraid: Same as Glass-Glass with added abrasion resistance.

Stainless Steel Armor Tubing: Can be used over any wire extension for added mechanical damage and abrasion resistance.

Fitting or Mounting Type

MARLIN CODE	MOUNTING FITTING
XX	None
W1	Spring Loaded Epoxy Sealed Fitting Provides NPT mounting for terminal head and process connection for bearing applications. For 3/16" diameter T/C's only. Select immersion that allows at least a 1/4" interference for spring loading.
S1	Spring Loaded O-Ring Sealed, SS Fitting Provides NPT mounting for terminal head and process connection for bearing applications. For 3/16" diameter T/C's only. Select immersion that allows at least a 1/4" interference for spring loading. T/C element may be easily removed from fitting by bayonet mounting.
MARLIN CODE	*COMPRESSION FITTING SS Fittings
A1	1/8 NPT
A2	1/4 NPT
A4	1/2 NPT
Field Positionable Immersion Length
*Not readjustable with metal ferrule. NOTES: C1=Stl. B1=Brass Ferrules: Metal Standard (Non-readjustable) "T" for Teflon (Readjustable) e.g. T1 "L" for Lava (Non-reuseable) e.g. L1.
MARLIN CODE	FIXED IMMERSION SS Fittings
F1	1/8 NPT
F2	1/4 NPT
F3	3/8 NPT
F4	1/2 NPT
F6	3/4 NPT
F8	1 NPT
Fixed Immersion Length* *Must be specified.
MARLIN CODE	FIXED DOUBLE FITTINGS (Back to Back Threads)
D2	1/4 x 1/4 NPT
D4	1/2 x 1/2 NPT
D6	3/4 x 3/4 NPT
Stainless Steel, NPT thread sizes that are brazed to the sheath. Generally used with terminal heads this arrangement provides a process connection.

MARLIN CODE		SUPPORT FITTINGS
Stl.(1)	SS
XX	XX	None
12	42	NIPPLE "C" DIM=2"
15	45	NIPPLE "C" DIM=5"
16	46	NIPPLE "C" DIM=6"
23	53	NIPPLE/UNION "C" DIM=2-5/8"
26	56	NIPPLE /UNION "C" DIM=5-3/4"
33	63	NIPPLE/UNION/NIPPLE "C" DIM=3"
36	69	NIPPLE/UNION/NIPPLE "C" DIM=6"
(1)Galvanized Steel Standard. NPT Size specified by Weatherproof Head Size.

Terminal Type

MARLIN CODE	TERMINAL TYPE
B10	1" Bare Leads
B30	3" Bare Leads Thermocouples w/Extensions
M12	Miniature Plug Max Sheath Diameter 0.125"
M15	Miniature Plug Thermocouples w/Extensions
P51	Standard 2-Pole Plug Max Sheath Diameter 0.250"
P11	Standard 2-Pole Plug w/External Strain Relief Max Sheath Diameter 0.375"
P12	Dual Standard 2-Pole Plug w/External Strain Relief Max Sheath Diameter 0.375"
P15	Dual Standard 2-Pole Plug w/External Strain Relief Thermocouples w/Extensions
P31	Standard 3-Pole Plug w/External Strain Relief Max Sheath Diameter 0.375"
P32	Standard 3-Pole Plug w/External Strain Relief Thermocouples w/Extensions
NOTES FOR ABOVE CONNECTORS: Connectors for use to 205°C (400°F)For other options, please consult the factory.
500	Single Element Micro Connector Head Max Sheath Diameter 0.250"
504	Dual Element Micro Connector HeadMax Sheath Diameter 0.250"
400	Mini Weatherproof Head Thermocouple w/Double Fitting Thermoset Plastic
402	Mini Weatherproof Head Thermocouple w/Mounted Head Thermoset Plastic
Does not require terminal block 1/4 NPT Conduit
241	Weatherproof Head Thermocouples w/flexible Extension for Thermowells Cast Aluminum w/wire Grip Fitting 1/2 NPT Probe Mount - 3/4 NPT Conduit
TERMINAL BLOCKS for Weatherproof Heads Rigid 4 Wire
204	Weatherproof Heads Thermocouples for Bearing Applications Thermocouple w/Double Fitting Cast Aluminum 1/2 NPT w/Single Block
206	Weatherproof Heads Thermocouples for Bearing Applications Thermocouple w/Double Fitting Cast Aluminum 3/4 NPT w/Single Block
214	Weatherproof Heads Thermocouples w/Mounted Head Cast Aluminum 1/2 NPT w/Single Block
216	Weatherproof Heads Thermocouples w/Mounted Head Cast Aluminum 1/2 NPT w/Dual Block
TERMINAL BLOCKS for Weatherproof Heads Rigid 2 Wire for Single Element TERMINAL BLOCKS for Weatherproof Heads Rigid 4 Wire for Dual Element
224	Weatherproof Heads Thermocouples for Bearing Applications Thermocouple w/Double Fitting Cast Aluminum 1/2 NPT w/Dual Block
226	Weatherproof Heads Thermocouples for Bearing Applications Thermocouple w/Double Fitting Cast Aluminum 3/4 NPT w/Dual Block
TERMINAL BLOCKS for Weatherproof Heads Rigid 2 Wire for Single Element TERMINAL BLOCKS for Weatherproof Heads Rigid 4 Wire for Dual Element
294	Weatherproof Heads Thermocouples for Bearing Applications Cast Aluminum Probe Mount 1/2 NPT - 3/4 NPT Conduit
TERMINAL BLOCKS for Weatherproof Heads B12S Spring loaded 4 wire.Max Sheath diameter 0.187".
274	Weatherproof Head Cast Aluminum (1/2 NPT)
276	Weatherproof Heads Cast Aluminum (3/4 NPT)
278	Weatherproof Heads Cast Aluminum (1 NPT)
374	Weatherproof Heads Cast Iron (1/2 NPT)
376	WeatherproofHeads Cast Iron (3/4 NPT)
378	Weatherproof Heads Cast Iron (1 NPT)
TERMINAL BLOCKS for Weatherproof Heads Spring Loaded 4 Wire
120	Explosion proof Head Thermocouple w/Double Fitting Cast Aluminum 1/2 NPT Probe Mount - 3/4 NPT Conduit
TERMINAL BLOCKS for Explosionproof Heads Rigid 4 Wire for Single or Dual Element
122	Explosionproof Head Thermocouple w/Mounted Head Cast Aluminum 1/2 NPT Probe Mount - 3/4 NPT Conduit
TERMINALBLOCKS for Explosionproof HeadsRigid 4 Wire for Single or Dual Element
124	Explosionproof Head 1/2 NPT Probe Mount - 3/4 NPT Conduit
TERMINAL BLOCKS for Explosionproof Heads Spring Loaded 4 Wire
104	General Purpose Head w/Block Thermocouple w/Double Fitting Cast Aluminum 1/2 NPT Single Element Only 2-Wire Terminal Block
114	General Purpose Head w/Block Thermocouple w/Mounted Head Cast Aluminum 1/2 NPT or 3/4 NPT Single Element Only 2-Wire Terminal Block
106	General Purpose Head w/Block Thermocouple w/Double Fitting Cast Aluminum 3/4 NPT Single Element Only 2-Wire Terminal Block

Specialty Marlox^® Items

Marlin offers thermocouples utilizing noble metals and exotic materials for the sheath, thermocouple wires and insulation. These thermocouples are fabricated utilizing hard-fired refractory oxides and incorporate the highest manufacturing syandards to insure performance and to prevent contamination.

High Temperature Metal-Sheathed Thermocouples

Thermocouple Types:

Platinum-Rhodium vs Platinum

Recommended for use in inert or oxidizing atmospheres or for short periods of time in vacuum. Easily contaminated, these elements must be protected from the effects of reducing atmospheres and contaminating vapors.

Tungsten vs Tungsten-Rhenium

Recommended for use in vacuum, high purity hydrogen and high purity inert atmospheres only.

Thermocouple Type	Maximum Operating Temperature	Maximum Exposure Temperature	Recommended Environment
Pt-10% Rh/Pt ANSI Type S	2700°F 1482°C	3100°F 1704°C	Oxidizing, Inert
Pt-13% Rh/Pt ANSI Type R	2700°F 1482°C	3100°F 1704°C	Oxidizing, Inert
Pt-30% Rh/Pt-6% Rh ANSI Type B	3100°F 1704°C	3220°F 1770°C	Oxidizing, Inert
W-5% Re/W-26% Re Type (C)	5000°F 2760°C	5430°F 3000°C	Vacuum, High Purity Hydrogen, & Inert

Pt-Platinum, Rh-Rhodium, W-Tungsten, Re-Rhenium

SHEATH SIZE - WIRE GAUGE
Sheath Diameter Inches	0.062	0.125	0.187	0.250
Wire Gauge B & S	30	30	24	24

Sheath Alloys:

Platinum

Virtually non-oxidizable, soluable only in acids generating free chlorine. Halogens attack it at high temperatures. Malleable. Recommended for use in oxidizing or inert environments. Maximum operating temperature 3000°F.

Platinum 10% Rhodium

Has the character of platinum with increased resistance to corrosion and higher heat strength. Suitable for oxidizing or inert environments. Maximum operating temperature 3100°F.

Tantalum

A reactive and refractory metal. Reactive because it will oxidize above 550°F and refractory because of its extremely high melting point. Suitable for use in inert or vacuum environments. Hard and tough with good ductility. Maximum operating temperature of 4500°F.

Molybdenum

Oxidizes at elevated temperatures. Relatively good hot strength. Suitable for inert, vacuum or reducing environments. Maximum operating temperature of 4000°F.

Molybdenum 50% / Rhenium 50%

Ductile with high hot strength. Suitable in vacuum, hydrogen, nitrogen, cracked ammonia and inert atmospheres. Maximum operating temperature of 4000°F.

Sheath Material	Approximate Melting Temperature	Maximum Operating Temperature	Recommended Environment
Platinum	3217°F 1770°C	3000°F 1650°C	Oxidizing, Inert
Platinum 10% Rhodium	3362°F 1850°C	3100°F 1705°C	Oxidizing, Inert
Tantalum	5425°F 2996°C	4500°F 2482°C	Vacuum
*Molybdenum	4730°F 2610°C	4000°F 2205°C	Vacuum, Inert
*Moly 50% Rhenium 50%	4424°F 2440°C	4000°F 2205°C	Vacuum, Hydrogen Nitrogen, Inert Cracked Ammonia

REFRACTORY OXIDE INSULATORS

The resistivity of metal oxides decreases with increasing temperature. Above 3600°F only Hafnia retains sufficient resistivity for most applications.

Insulator Material	Approximate Melt Temperature	Maximum Recommended Temperature
		Hard-Fired	Swaged
Magnesia MgO	5070°F 2800°C	N/A	3400°F 1870°C
Alumina Al2O3	3650°F 2010°C	3200°F 1760°C	3000°F 1650°C
Hafnia HfO2	5126°F 2830°C	4000°F 2200°C	N/A

Random Length Marlox® Thermocouple Cable

Marlox is available for your fabrication from our stock. Ends are cut square and moisture sealed.

Standard Marlox is single element (2 wire) or Dual Element (4 wire) thermocouple construction with magnesium oxide (MgO) insulation compacted into a metal sheath.

Sheath Size Diameter (Inches)	NominalTube Wall thickness (Inches)	Wire gauge B & S		MaximumStock Length (FT.)
		Single T/C Element	Dual T/C Element
0.010	0.0015	44	-	50
0.020	0.003	38	-	100
0.032	0.004	34	-	150
0.040	0.006	33	-	200
0.062	0.009	28	30	500
0.125	0.017	22	24	375
0.187	0.025	20	21	175
0.250	0.033	16	18	100
0.312	0.041	16	-	60
0.375	0.052	15	-	45
0.500	0.070	10	-	30

DIM. TOLERANCE: Up to 0.062 ± 0.001″;0.125 to 0.500 ± 0.003″
Furnished in Coils: 0.010″ to 0.312″
Furnished in Straight Lengths: 0.375″ to 0.500″

When Ordering Please Specify:

Sheath Alloy

304 Stainless Steel
310 Stainless Steel
316 Stainless Steel
Inconel 600
901
100

ANSI Calibration Type

Type J (Iron/Constantan>
Type K (Chromel/Alumel)
Type T (Copper/Constantan)
Type E (Chromel/Constantan)
Type N (Nicrosil/Nisil)

Length in Feet