Duralox 997 Ceramic Pyrometry Tubes

Duralox stands for durable Aluminium Oxide and is a registered trade name of Jyoti Ceramic Industries Pvt. Ltd. It stands for Aluminium Oxide ceramic compositions content 90 to 99.7% & above percentage of Al2O3 in its residue.

Pyrometry Sheaths

The main feature of Duralox 997 Re-crystalized Alumina is its very high degree of chemical inertness, it offers a high degree of protection against reactive slags or furnace gasses and its low silica content ensures that there is no contamination of rare metals such as platinum by silicon a frequent cause of loss of calibration in thermocouples.

Tubes

Duralox 997 re-crystallized Alumina tubes pass good electrical resistivity as well as high thermal conductivity at high temperatures. When supported adequately, they can be used up to a temperature of 18000C + (3272 0F) and are suitable for molybdenum and tungsten wound tube furnaces, particularly for processes requiring a tube of an impervious nature.

Single and Multibore Insulators

Duralox 997 Re-crystallized Alumina can be used up to a temperature of 1800 0C. It is particularly suitable for use as an insulator for rare metal thermocouples, because of its low silica content ensures that there is no contamination of rare metals such as platinum with silicon. Duralox 997 alumina one end closed thermocouple protection tubes are fired vertically at around 1750 0C temperature in oxygen atmosphere in microprocessor controlled state-of-the-art kiln. After sintering, 100% thermocouple sheaths are tested under air pressure @ 4 bar to ensure gas tightness.

Duralox 997 Re-crystallized Alumina Ceramic is fine grained, non porous, dense and impervious to all acids except hydrofluoric acid. Duralox 997 is exceptionally high purity Alumina Ceramic, containing 99.7% Al2O3 and SiO2 less that 0.05% in its residue.

Physical Strength : Duralox 997 Alumina is extremely hard with high mechanical strength and resistant to abrasion & corrosion and good thermal conductor at high remperatures.

Imperviousness : Duralox 997 Alumina products are fired at extremely high temperature around 1750 0C which ensures impermeability under severe & critical conditions.

Good Electrical Resistivity : Duralox 997 Alumina maintains good electrical resistivity at high temperatures.

High heat Conductivity : Duralox 997 Alumina products are considered as high-tech products and are manufactured with advanced technology, therefore maximum density is ensured with minimum wall thickness. This makes the highest possible heat transfer.

Stability at high temperature and chemical Inertness : Duralox 997 is inert even at high temperatures in reducing atmosphere and flux attack due to low silica content in its residue.

Product Range : Duralox 997 Alumina product range includes solid rods Dia. 0.5mm and above, Pyrometry Tubes with one end closed, both ends open, tubes with single & multibores, thin-wall tubes, capillary tubes, thin & thick ballistic armor tiles, pallets, profiles & custom designed parts.

Amphoteric : Duralox 997 Alumina is highly resistant to acid slugs.

Advantages :

Duralox 997 Re-crystallized Alumina Ceramic offers following advantages over the metals :

  • Continuous high temperature resistance 17500C.
  • Higher thermal stability.
  • Lower thermal expansion.
  • Inert to Hydrogen, Carbon and refractory metals under most server conditions, non-toxic, non-radioactive, non-magnetic and non-aging.
  • Higher electrical insulation.
  • Higher modules of elasticity, hence higher rigidity.
  • Greater hardness and wear resistance.
  • Higher abrasion corrosion and oxidation resistance.
  • Higher compressive strength.

Typical properties of impervious Re-crystallized 997 Alumina ceramics

Chemical Property
Al2O3 99.7
Alkali 0.05%
Physical Property
Colour Ivory
Density 3.85 – 3.90 g/cm3
Porosity Nil, Gas tight
Hardness on Vicker’s scale 1550 / 1650 Hv5
Hardness on Moh’s scale 9 +
Flexural strength 3000 Kg/cm2
Young’s Modulus 3.5 x 106 kg/cm2
Co-efficient of linear thermal expansion (25 0C – 1000 0C) 8 x 10-6 / 0C
Thermal Conductivity (25 0C) 26 W/m0K
Max. working temp. in oxidizing atmosphere @ no load 1800 + 0C
Dielectric strength (25 0C) (1.5 mm thick) 25 Kv/mm
Volume Resistivity (25 0C) 1014 Ω.cm
Thermal Shock resistance Good 170 0C

Chemical Characteristics of Duralox 997

In Vacuum
Reacts with thoria at about 19900C
Reacts with carbon at about 16500C
Reacts with magnesia at about 19000C
Reacts with zirconia at about 18000C
Reacts with beryllia at about 18600C
In Oxidising Atmosphere
Reacts with magnesia at about 16000C
Reacts with zirconia at about 17000 C
Reacts with thoria at about 19000 C
In inert Atmosphere
No reaction with molybdenum at 18000C
No reaction with nickel at 18000 C
Slight reaction with niobium at 16000 C
Violent reaction with niobium at 18000 C
Slight reaction with titanium at 16000 C
Violent reaction with titanium at 18000 C
Slight reaction with beryllium at 18000 C
Slow reaction with silicon at 14000 C
Violent reaction with silicon at 16000 C
Slow reaction with zirconium at 16000 C
Violent reaction with zirconium at 18000 C

Duralox 997 (DIN VDE 0335) RE-crystallized Alumina Ceramic Protection sheaths for Thermocouples & Sensors.

Outer Dia (OD) Inner Dia (ID) Length Up to (L) One Part (ISO pressed)
6 4 1500 -
6.35 4.8 1500 -
7 5 213 YES
8 5 1500 -
9 6 1500 -
9.5 6.35 1500 -
10 6 1500 -
10 6 225 YES
12 8 1500 -
13 9 1500 -
15 6 1500 -
15 10 1500 -
Outer Dia (OD) Inner Dia (ID) Length Up to (L) One Part (ISO pressed)
15 6 1030 YES
15 10 1030 YES
15 10.5 330 YES
17 13 1000 YES
17 13 1500 -
20 8 1000 YES
20 10 1000 YES
20 15 1000 YES
20 8 1500 -
20 10 1500 -
20 15 1500 -
24 18 100 YES

• Pyrometer protection sheaths (closed one end) are available from 100 to 1500 mm long.

Pyrometer Sheaths sizes not shown in above table can be made on request, if found feasible.

Only against specific enquiry, we can offer protection thermocouple sheaths and tubes with open both ends and with flanges, price on request. Please do not fail to specify length of the sheath in your purchase enquiry.

Workable dimensional tolerance are adhered to DIN standards 40680 medium class. Tubes with close tolerances can be manufactured on enquiry. Code RC PS corresponds to Re-crystallized Pyrometry Protection Sheaths. Sheath means closed one end Pyrometer tube.

ISO Pressed closed one end (COE) tubes with collar*

* Price on request.

Confirm collar dimensions, tube OD, tube ID and length.

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Duralox 997 (DIN VDE0335) RE-crystallized Alumina Ceramic, Solid Round, Oval Rods, Single & Multibore Tube insulators (all dimensions are in mm)

Solid Round Rods Single Bore Tubes 2 Bore Insulators 4 Bore Insulators Oval 2 Bore Insulators
Dm (Ø) O Ø / I Ø O Ø / B Ø O Ø / B Ø L / W x B Ø
0.6 to 50 1 x 0.25 2.5 x 0.6 3 x 0.8 3 / 1.5 x 0.8
- 1.35 x 0.6 3 x 0.8 3.5 x 1 4.2 x 2.2 x 1.2
- 1.4 x 0.5 3 x 1 4 x 1 -
- 1.4 x 0.5 3 x 1 4 x 1 -
- 2.5 x 1.3 4 x 1 4.5 x 1.3 -
- 2.5 x 1.5 4.5 x 1 5 x 1.2 -
- 2.7 x 1.7 4.5 x 1.5 5 x 1.3 -
- 3.2 x 1.5 5 x 1.3 6 x 1.3 -
- 4.75 x 1.35 5 x 1.8 6 x 1.5 -
- 4.8 x 3 5.5 x 2 7 x 1.5 -
- 6 x 4 6.4 x 0.8 8 x 2.3 -
- 8 x 5 6 x 2 8.5 x 1.5 -
- 10 x 2.5 6.5 x 1.8 8.5 x 2.5 -
- 10 x 6 6.5 x 2 9.5 x 2.5 -
- 12 x 8 7 x 2 10 x 1.8 -
- 15 x 6 7 x 2.5 10 x 3.1 -
- 15 x 10 - 6.6 x 2 -
- 20 x 8 - - -
- 20 x 10 - - -
- 20 x 15 - - -
* Ø = diameter in mm    O Ø = outer diameter in mm    B Ø = bore diameter in mm

Profiles, solid round & oval rods, tubes and multibore insulators other than above sizes can be manufactured on request. All tubes are open at both ends. Solid Rods and Tubes of length 5 to 1500 mm can be produced depending on outer Diameter. Specify length of Solid Rod, Tube or Insulator in purchase enquiry.

Duralox 997 single and multibore tubes and insulators are used for insulating thermocouple wires suitable for maximum temp 1800 0C according to DIN 43725 standards. Tube sizes other than as above shown in table can be made on request if found feasible. Dimensional tolerances are maintained to DIN 40680 medium class standards.

Dimensional tolerances and allowances are conforming to DIN standard 40680 medium class.

DIN standard 40680 Medium Class.
For Diameters (OD-ID) – Length – Camber – Ovality and Eccentricity
On diameter Tolerances
1 to 5 mm ± 0.2 mm or 4% whichever is greater
5.1 to 40 mm ± 0.3 mm or 2 % whichever is greater
On Length
20 to 150 mm ± 0.5 mm or 2% whichever is greater
151 to 1500 mm ± 2 mm or 1% whichever is greater
Allowance on Camber 0.5% of the length
Allowance on Ovality 0.1 mm or 0.5% of the diameter whichever is greater
Allowance on Bore eccentricity 0.05 mm or 0.5% of the diameter

Tolerances closer than above on request.

Duralox 997 Alumina Ceramic Pyrometry Tubes and Insulators are formed by high pressure extrusion, dry/wet bag isostatic pressing.

We are constantly working for improvement of the product quality, hence the data given in the brochure may change as and when found necessary.

Information contained herein is to the best of our knowledge, true and accurate and is based upon measurements made in our R &D laboratory. Recommendations, suggestions and data are practical guidelines and not guarantees. Actual results may vary with conditions of use and with variations in the methods of manufacture, size and shape of the ceramic part. We disclaim any liability that may be incurred in connection with use of suggestions or data. This publications is not to be taken as licence to operate under or a recommendation to infringe any patents. Observation of all legal regulations and patents is the responsibility of the user.