Protection Tubes - Ceramic

 

Alumina | Mullite porcelain | Zirconia

Ceramic thermocouple protection tubes are available in a variety of sizes and materials with Alumina, Mullite, and Zirconia being the most commonly used. Ceramic thermocouple protection tubes are typically used to protect Platinum thermocouple elements at high process temperatures above 2200°F.

When choosing a ceramic protection tube material, careful consideration should be taken into account in regards to its unique thermal shock characteristics and physical strength.

Alumina Thermocouple protection tubes

Alumina has a maximum service temperature of 3450°F or 1900°C in both oxidizing and reducing atmospheres. Alumina thermocouple protection tubes are considered to have better mechanical strength (twice the tensile strength of Mullite) and better chemical resistance than Mullite thermocouple protection tubes. Alumina thermocouple protection tubes also have excellent abrasion resistance. Secondary metal tubes can be added for additional protection from mechanical damage. Alumina protection tubes are considered to be gas tight so they make excellent primary protection tubes. All tubes, which are used in horizontal installations and at elevated temperatures, should be supported to prevent mechanical breakage. Alumina tubes can be for primary and secondary protection tubes on Noble Metal (Platinum based) thermocouples. Alumina has a very low silica content so they will not contaminate Platinum thermocouple elements above (2200°F or 1200°C) as a Mullite protection tube.

Composition - 99.8% Aluminum Oxide.

Alumina tube Specifications

  • Maximum Service Temperature of 3450°F or 1900°C
  • Excellent Mechanical Strength
  • Excellent for Noble Metal Thermocouples
  • Tube sizes from 3/16" to 1 7/8" O.D.
  • Available with Couplings, Hex Fittings, Steel Fittings, Sleeves, or Threaded Nipples.
  • Available with Cemented Support Collars.
  • Tolerance for O.D. +/- 5% or .025"
  • Tolerance for Tube Length +/- .062"

Mullite Porcelain Thermocouple protection tubes

Mullite Porcelain has a maximum service temperature of 2900°F or 1590°C. It is considered to be superior to Alumina for thermal shock resistance. Mullite protection tubes should be used with care, since they have poor mechanical shock resistance. Secondary metal outer tubes can be added for protection from any mechanical damage. Mullite Thermocouple protection tubes are considered gas tight a high temperatures. All Mullite protection tubes, which are used in horizontal installations and at elevated temperatures, should be supported to prevent breakage. Mullite tubes should not be used for primary protection tubes on noble metal thermocouples (Platinum based) if the temperature will exceed 2200°F (1200°C). Above these temperatures the silica in the Mullite can contaminate the platinum thermocouple elements if there is not enough air circulation in the tube.

Composition - 63.5% Aluminum Oxide, balance is Silicon Dioxide.

Mullite tube Specifications

  • Maximum Service Temperature of 2900°F or 1590°C
  • Excellent Thermal Shock Resistance
  • Tube sizes from 3/16" to 1 7/8" O.D.
  • Available with Couplings, Hex Fittings, Steel Fittings, Sleeves, or Threaded Nipples.
  • Available with Cemented Support Collars.
  • Tolerance for O.D. +/- 5% or .025"
  • Tolerance for Tube Length +/- .062"

zirconia Thermocouple protection tubes

Zirconia has a maximum service temperature of 4172°F or 2300°C in oxidizing, reducing atmospheres, and vacuum environments. This material is yttria (10.5%) stabilized. Zirconia is chemically inert and has excellent corrosion resistance. Zirconia thermocouple protection tubes should not be used in contact with Alumina above 1112°F (600°C). Zirconia is gas tight, but above 1112°F (600°C) Oxygen will permeate through its wall structure. To prevent thermal shock. heat or cool at a rate less than 302°F (150°C) per hour.

Composition - 89.5% Zirconia, 10.5% Yttria.

Zirconia tube Specifications

  • Maximum Service Temperature of 4172°F or 2300°C
  • Excellent Corrosion Resistance
  • Excellent Chemically Inert
  • Tube sizes from 3/16" to 1" O.D.
  • Available with Couplings, Hex Fittings, Steel Fittings, Sleeves, or Threaded Nipples.
  • Available with Cemented Support Collars.
  • Tolerance for O.D. +/- 5% or .025"
  • Tolerance for Tube Length +/- .062"
Ceramic Protection Tube | Plain
Plain Ceramic Thermocouple Protection Tube
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Plain Tube)
AP03-* P03-* Not
Available
3/16"
(4.8 mm)
1/8"
(3.2 mm)
Plain Tube
AP04-* P04-* ZP04-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
Plain Tube
AP05-* P05-* Not
Available
5/16"
(7.9 mm)
3/16"
(4.8 mm)
Plain Tube
AP06-* P06-* ZP06-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
Plain Tube
AP07-* P07-* ZP07-* 7/16"
(11.1 mm)
5/16"
(8.0 mm)
Plain Tube
AP08-* P08-* ZP08-* 1/2"
(12.7 mm)
3/8"
(9.5 mm)
Plain Tube
AP11-* P11-* ZP11-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
Plain Tube
AP12-* P12-* ZP12-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
Plain Tube
AP14-* P14-* ZP14-* 7/8"
(22.2 mm)
5/8"
(15.9 mm)
Plain Tube
AP16-* P16-* ZP16-* 1"
(25.4 mm)
3/4"
(19.1 mm)
Plain Tube
AP20-* P20-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
Plain Tube
AP30-* P30-* Not
Available
1 7/8"
(47.8 mm)
1 5/8"
(41.3 mm)
Plain Tube
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Cemented Collar
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Cemented Collar)
AP03C-* P03C-* Not
Available
3/16"
(4.8 mm)
1/8"
(3.2 mm)
1/2" O.D.
3/8" Wide
AP04C-* P04C-* ZP04C-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
5/8" O.D.
1/4 " Wide
AP06C-* P06C-* ZP06C-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
5/8" O.D.
1/4 " Wide
AP08C-* P08C-* ZP08C-* 1/2"
(12.7 mm)
3/8"
(9.5 mm)
5/8" O.D.
1/4 " Wide
AP11C-* P11C-* ZP11C-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
1" O.D.
3/8" Wide
AP12C-* P12C-* ZP12C-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
1" O.D.
3/8" Wide
AP16C-* P16C-* ZP16C-* 1"
(25.4 mm)
3/4"
(19.1 mm)
1 1/2" O.D.
3/8" Wide
AP20C-* P20C-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1 5/8" O.D.
5/16 " Wide
AP30C-* P30C-* Not
Available
1 7/8"
(47.8 mm)
1 5/8"
(41.3 mm)
 
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Steel Coupling
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Steel Coupling)
AP03CP02-* P03CP02-* Not
Available
3/16"
(4.8 mm)
1/8"
(3.2 mm)
1/8" NPT
3/4" Length
AP04CP02-* P04CP02-* ZP04CP02-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
1/8" NPT
3/4" Length
AP06CP04-* P06CP04-* ZP06CP04-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
1/4" NPT
1 " Length
AP08CP04-* P08CP04-* ZP08CP04-* 1/2"
(12.7 mm)
3/8"
(9.5 mm)
1/4" NPT
1" Length
AP11CP06-* P11CP06-* ZP11CP06-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
3/8" NPT
1 3/16 " Length
AP11CP08-* P11CP08-* ZP11CP08-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
1/2" NPT
1 1/2" Length
AP12CP08-* P12CP08-* ZP12CP08-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
1/2" NPT
1 1/2 " Length
AP014CP08-* P014CP08-* ZP014CP08-* 7/8"
(22.2 mm)
5/8"
(15.9 mm)
3/4" NPT
1 5/8 " Length
AP016CP12-* P016CP12-* ZP016CP12-* 1"
(25.4 mm)
3/4"
(19.1 mm)
3/4" NPT
1 5/8 " Length
AP20CP16-* P20CP16-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1" NPT
2 " Length
AP30CPT20-* P30CPT20-* Not
Available
1 7/8"
(47.8 mm)
1 5/8"
(41.3 mm)
1 1/4" NPT
2 1/2 " Length
AP30CPT24-* P30CPT24-* Not
Available
1 7/8"
(47.8 mm)
1 5/8"
(41.3 mm)
11/2" NPT
2 1/2 " Length
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Steel Fitting
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Steel Fitting)
AP08F-* P08F-* ZP08F-* 1/2"
(12.7 mm)
3/8"
(9.5 mm)
1/2" x 3/4" NPT
AP11F-* P11F-* ZP11F-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
1/2" x 3/4" NPT
AP12F-* P12F-* ZP12F-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
1/2" x 3/4" NPT
AP016F-* P16F-* ZP16F-* 1"
(25.4 mm)
3/4"
(19.1 mm)
3/4" x 1" NPT
AP20F-* P20F-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1" x 1 1/4" NPT
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Steel Hex Fitting
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Hex Fitting)
AP03HX-* P03HX-* Not
Available
3/16"
(4.8 mm)
1/8"
(3.2 mm)
1/8" X 1/8" NPT
AP04HX-* P04HX-* ZP04HX-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
1/4" X 1/4" NPT
AP06HX-* P06HX-* ZP06HX-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
1/2" X 1/2" NPT
AP11HX-* P11HX-* ZP11HX-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
3/4" X 3/4" NPT
AP016HX-* P16HX-* ZP16HX-* 1"
(25.4 mm)
3/4"
(19.1 mm)
1" X 1" NPT
AP20HX-* P20HX-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1 1/4" X 1 1/4" NPT
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Steel Threaded Nipple
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Steel Nipple)
AP04N-* P04N-* ZP04N-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
1/4" NPT
1" Long
AP06N-* P06N-* ZP06N-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
3/8" NPT
1 1/2" Long
AP11N-* P11N-* ZP11N-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
3/4" NPT
2 1/2 " Long
AP12N-* P12N-* ZP12N-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
3/4" NPT
2 1/2 " Long
AP016N-* P16N-* ZP16N-* 1"
(25.4 mm)
3/4"
(19.1 mm)
1" NPT
3 " Long
AP20N-* P20N-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1 1/4" NPT
3 " Long
Note: * Specify the protection tube length (P) in inches.
Ceramic Protection Tube | Alloy Sleeve Nipple
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Sleeve Nipple)
AP04N9-* P04N9-* ZP04N9-* 1/4"
(6.4 mm)
3/16"
(4.8 mm)
1/4" NPT
1" Long
AP06N9-* P06N9-* ZP06N9-* 3/8"
(9.5 mm)
1/4"
(6.4 mm)
3/8" NPT
1 1/2" Long
AP11N9-* P11N9-* ZP11N9-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
3/4" NPT
2 1/2 " Long
AP12N9-* P12N9-* ZP12N9-* 3/4"
(19.1 mm)
1/2"
(12.7 mm)
3/4" NPT
2 1/2 " Long
AP016N9-* P16N9-* ZP16N9-* 1"
(25.4 mm)
3/4"
(19.1 mm)
1" NPT
3 " Long
AP20N-* P20N9-* Not
Available
1 1/4"
(31.8 mm)
1"
(25.4 mm)
1 1/4" NPT
3 " Long
Note: * Specify the protection tube length (P) in inches. Standard Nipple Sleeve is made from Inconel 600.
Ceramic Protection Tube | Brass Nipple
Mgo Thermocouples With Male Plug
Alumina Mullite Zerconia O.D.
Inches
I.D.
Inches
Mounting
(Brass Nipple)
AP11NL-* P11NL-* ZP11NL-* 11/16"
(17.5 mm)
7/16"
(11.1 mm)
7/8"
2 " Long
Note: * Specify the protection tube length (P) in inches.