
Ceramic Thermocouple 
Protection 
Tubes
Tube Length
For Metric Sizes 
and Molten Metal 
Applications, 
See OMEGATITE
at omega.com
®
 650 
Tube Length
Tube Length for 
Tube Length for 
11
⁄
16
1
 and 
⁄
2
" or under
1
1
7
⁄
8
"
3
⁄
4
"
7
⁄
8
"
1
13
⁄
16
"
2
Open-end tubes 
also available.
Typical Physical Properties
Properties  OMEGATITE® 450  OMEGATITE® 300 
Composition  99.8% Al2O3  85% mullite 
       15% glass
 Water Absorption  0.00 0.00 
 Specific Gravity KP/CM3  3.85 2.8 
 Gas Permeability  Gas tight  Gas tight 
 Compressive Strength (psi)  >300,000 >190,000 
 Tensile Strength (psi)  30,000 18,000 
 Transverse Strength (psi)  55,000 27,000 
 Coefficient of Linear Thermal Expansion 
  24 to 250°C (75 to 480°F)  6.2 x 10-6  3.3 x 10-6 
  24 to 500°C (75 to 930°F)  7.4 x 10-6  4.0 x 10-6 
  24 to 1000°C (75 to 1830°F)  8.5 x 10-6  5.0 x 10-6 
  24 to 1500°C (75 to 2730°F)  9.8 x 10-6 -
 Approximate Thermal Conductivity 
 (BTU)(in)/(hr)(ft2)(°F)  
   24°C (75°F)  230 40  
   800°C (1470°F) 60 25
 Maximum Service Temperature  1950°C (3540°F)  1750°C (3180°F) 
 Dielectric Constant (1MC)  9.29 5.80 
 Dielectric Strength (volts/mil)  >230 250 
 Volume Resistivity (ohm cm)  1013 10 
 Te Value (Volume Resistivity of 1 mega Ω cm)  800°C (1470°F)  800°C (1470°F) 
 Hardness (Mohs Scale)  9 7.5 
 Fabrication Methods  Cast Cast
13
Tube Length
2"
3
Typical Chemical Analyses
Al2O3 SiO2 MgO Na2O CaO Fe2O3 Cr2O3 TiO2 MnO ZrO2 K2O
 OMEGATITE® 450 99.8 0.070 0.050 0.005 0.030 0.025 <.003 0.004 0.001 -  <0.001 
 OMEGATITE® 300 60.0 38.0 0.2 0.2 0.1 0.5 - 0.5 - - 0.700
Note: All properties are average for test specimens. Tests were performed according to ASTM specifications.
A-139

Ceramic Thermocouple Protection Tubes
 To Order Visit omega.com/ptra_ptrm for Pricing and Details
      PTRA  PTRM 
    Dimensions: inches    OMEGATITE® 450  OMEGATITE® 300
 Inside Outside           
 Diameter  Diameter  Tube Length*  Model Number  Model Number 
   12 PTRA-11618-12  PTRM-11618-12 
1
⁄16 
    24 PTRA-11618-24  PTRM-11618-24 
   12 PTRA-564532-12  PTRM-564532-12 
5
⁄64 
    24 PTRA-564532-24  PTRM-564532-24 
   12 PTRA-53214-12  PTRM-53214-12 
5
⁄32 
    24 PTRA-53214-24  PTRM-53214-24 
   12 PTRA-31614-12  PTRM-31614-12 
3
⁄16 
    24 PTRA-31614-24  PTRM-31614-24 
   12 PTRA-316516-12  PTRM-316516-12 
3
⁄16 
    24  PTRA-316516-24 PTRM-316516-24 
    12 PTRA-1438-12  PTRM-1438-12 
1
⁄4 
    24 PTRA-1438-24  PTRM-1438-24 
   12 PTRA-516716-12  PTRM-516716-12 
5
⁄16 
    24 PTRA-516716-24  PTRM-516716-24 
   12 PTRA-51612-12  PTRM-51612-12 
5
⁄16 
    24 PTRA-51612-24  PTRM-51612-24 
   12 PTRA-3812-12  PTRM-3812-12 
3
⁄8 
    24 PTRA-3812-24  PTRM-3812-24 
   12 PTRA-7161116-12  PTRM-7161116-12 
7
⁄16 
    24 PTRA-7161116-24  PTRM-7161116-24 
   12 PTRA-1234-12  PTRM-1234-12 
1
⁄2 
    24 PTRA-1234-24  PTRM-1234-24 
   12 PTRA-5878-12  PTRM-5878-12 
5
⁄8 
    24 PTRA-5878-24  PTRM-5878-24 
   12 PTRA-341-12  PTRM-341-12 
3
⁄4 1 18 PTRA-341-18  PTRM-341-18 
    24 PTRA-341-24  PTRM-341-24 
   12 PTRA-78118-12  PTRM-78118-12 
7
⁄8 1 
    24 PTRA-78118-24  PTRM-78118-24 
   12 PTRA-1114-12  PTRM-1114-12 
  1 1  
    24 PTRA-1114-24  PTRM-1114-24
      300 mm PTRA-5MM7MM-12  PTRM-5MM7MM-12  
  5 mm  7 mm  450 mm PTRA-5MM7MM-18  PTRM-5MM7MM-18 
    600 mm  PTRA-5MM7MM-24 PTRM-5MM7MM-24
 Length: The tube lengths shown are standard lengths for a tube without any fittings. Special lengths are also available. Consult Sales. 
*
Tolerance: ±5%. See omega.com for diagrams with fittings.
Important Ordering Notes
Fittings: When ordering tube with fitting specify the  
fitting number (1, 2, 3) after the model number.
 1⁄2 x 1⁄2" NPT: Fits tubes from 6.0 to 12.5 mm (1⁄4 to 1⁄2") OD 
1.
1
2. 
⁄2 x 3⁄4" NPT: Fits tubes from 8.0 to 19.0 mm (3⁄8 to 3⁄4") OD 
7
3. 
⁄8" x 27NS Brass Ferrule 50 mm (2") long: Fits tubes from 17.5 mm 
(11⁄16") OD tubes to 
Tube with any of the above fittings for an additional cost. 
1
⁄8 18 PTRA-11618-18  PTRM-11618-18 
5
⁄32 18 PTRA-564532-18  PTRM-564532-18 
1
⁄4 18 PTRA-53214-18  PTRM-53214-18 
1
⁄4 18 PTRA-31614-18  PTRM-31614-18 
5
⁄16 18  PTRA-316516-18  PTRM-316516-18 
3
⁄8 18 PTRA-1438-18  PTRM-1438-18 
7
⁄16 18 PTRA-516716-18  PTRM-516716-18 
1
⁄2 18 PTRA-51612-18  PTRM-51612-18 
1
⁄2 18 PTRA-3812-18  PTRM-3812-18 
11
⁄16 18 PTRA-7161116-18  PTRM-7161116-18 
3
⁄4 18 PTRA-1234-18  PTRM-1234-18 
7
⁄8 18 PTRA-5878-18  PTRM-5878-18 
1
⁄8 18 PTRA-78118-18  PTRM-78118-18 
1
⁄4 18 PTRA-1114-18  PTRM-1114-18 
For Protection Tubes 
with Custom Lengths or 
Fittings Please Consult 
Custom Engineering
Ordering Examples: 
PTRM-11618-12, standard tube 
with no fitting. 
PTRM-11618-12-1, standard 
1
⁄2 x 1⁄2" NPT fitting.
tube, 
1
⁄4" OD
Discount Schedule
1 to 10 units ..........Net
 11 to 24 units ........10%
 25 to 100 units .......20%
 101 to 500 units ......30%
Quantity discount applies to 
like tubes. Other sizes,  
materials, and configurations 
by quotation.
A
A-140