Products - Ceramic Thermocouple Protection Tubes         Return to Product Index

Alumina has a maximum service temperature of 3450°F (1900°C) in both oxidizing and reducing atmospheres. Alumina is considered to have better mechanical strength (twice the tensile strength of Mullite) and chemical resistance than Mullite. Alumina tubes also have excellent abrasion resistance. Secondary metal tubes can be added for additional protection from mechanical damage. Alumina tubes are considered gas tight so they make excellent primary protection tubes. All tubes, which are used in horizontal installations and at elevated temperatures, should be supported. Alumina tubes can be used for primary and secondary protection tubes on noble metal (platinum based) thermocouples. Since they have a very low silica content, they will not contaminate platinum elements above 2200°F (1200°C) as a Mullite protection tube. Composition - 99.8% Aluminum Oxide.

Mullite has a maximum service temperature of 2900°F (1590°C). It is considered to be better than Alumina for thermal shock resistance. Mullite tubes should be used with care, since they have poor mechanical shock resistance. Secondary metal tubes can be added for protection from mechanical damage. Mullite tubes are considered gas tight at high temperatures. All tubes, which are used in horizontal installations and at elevated temperatures, should be supported. Mullite tubes should not be used for primary protection tubes on noble metal (platinum based) thermocouples if the temperature will exceed 2200°F (1200°C). Above these temperatures the silica in the Mullite can contaminate the platinum element if there is not enough air circulation in the tube. Composition - 63.5% Aluminum Oxide, Balance Silicon Dioxide.

Zirconia has a maximum service temperature of 4172°F (2300°C) in oxidizing, reducing, and vacuum environments. This material is Yttria (10.5%) stabilized. Zirconia in chemically inert and has excellent corrosion resistance. Zirconia 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 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.

Easy to order:                          
    1)  State quantity
    2)  Give part number
    3)  Specify length " * " 
         
Special lengths available on request and multiples of 6 inches (152.4 mm) stocked.

Ceramic Tube links to Alumina & Mullite items on this page:

    Plain End                                    No  Bushing, Collar, Coupling,  Nipple, or Fitting
    Bushing (forward) - "B"              Bushing on open end
    Bushing Reverse - "RB"              Reversed Bushing on open end
    Collar - "C"                                 Collar on open end
    Coupling - "CP"                          Coupling on open end, also target tubes
    Fitting - "F"                                 Fitting on open end
    Hex Fitting - "HX"                       Hex Fitting on open end
    Nipples, Close - "NC"                 Close nipple on open end
    Nipple, Sleeve - "SL"                  Metal Sleeve on open end
    Nipples, Space  - "N"                  Space Nipple on open end
    Nipple, Special (brass) "NL"       Special Brass Nipple, 7/8 inch fine thread, on open end 

For any tubes open both ends, any construction, place "OBE" (open both ends) in the catalog number.

Example:  P11F-OBE-12

PLAIN END
Alumina for use up to 1900 C or 3450 F and Mullite for use up to 1590 C or 2900 F. 
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
OD ID OD ID
AP03-*
AP04-*
AP05-*
AP06-*
AP07-*
AP08-*
AP11-*
AP12-*

AP14-*
AP16-*
AP20-*
AP30-*		 P03-*
P04-*
P05-*
P06-*
P07-*
P08-*
P11-*
P12-*

P14-*
P16-*
P20-*
P30-*		 3/16
1/4
5/16
3/8
7/16
1/2
11/16
3/4

7/8
1
1 1/4
1 7/8		 1/8
5/32
3/16
1/4
5/16
3/8
7/16
1/2

5/8
3/4
1
1 5/8		 4.8
6.4
7.9
9.5
11.1
12.7
17.5
19.1

22.2
25.4
31.8
47.6		 3.2
4.0
4.8
6.4
7.9
9.5
11.1
12.7

15.9
19.1
25.4
41.3		 None  PLAIN,
 open one end,
closed other end 

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BUSHING (forward)       
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.

 
AP07B-*
AP08B-*
AP11B-*
AP12B-*

AP14B-*
AP16B-*
AP20B-*
 
P07B-*
P08B-*
P11B-*
P12B-*

P14B-*
P16B-*
P20B-*
 
7/16
1/2
11/16
3/4

7/8
1
1 1/4
 
5/16
3/8
7/16
1/2

5/8
3/4
1
 
11.1
12.7
17.5
19.1

22.2
25.4
31.8
 
7.9
9.5
11.1
12.7

15.9
19.1
25.4		   BUSHING, outside thread-NPT BUSHING (forward)
 on open end,
closed other end 
3/4
3/4
3/4
3/4

1
1
1 1/4

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REVERSED BUSHING
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.

 
AP07RB-*
AP08RB-*
AP11RB-*
AP12RB-*

AP14RB-*
AP16RB-*
AP20RB-*
 
P07RB-*
P08RB-*
P11RB-*
P12RB-*

P14RB-*
P16RB-*
P20RB-*
 
7/16
1/2
11/16
3/4

7/8
1
1 1/4
 
5/16
3/8
7/16
1/2

5/8
3/4
1
 
11.1
12.7
17.5
19.1

22.2
25.4
31.8
 
7.9
9.5
11.1
12.7

15.9
19.1
25.4		   BUSHING, outside thread-NPT BUSHING (reversed)
 on open end,
closed other end 
3/4
3/4
3/4
3/4

1
1
1 1/4

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COLLAR
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.



 
AP03C-*
AP04C-*
AP05C-*
AP06C-*

AP07C-*
AP08C-*
AP11C-*
AP12C-*

AP14C-*
AP16C-*
AP20C-*

 
 
P03C-*
P04C-*
P05C-*
P06C-*

P07C-*
P08C-*
P11C-*
P12C-*

P14C-*
P16C-*
P20C-*


 
3/16
1/4
5/16
3/8

7/16
1/2
11/16
3/4

7/8
1
1 1/4


 
1/8
5/32
3/16
1/4

5/16
3/8
7/16
1/2

5/8
3/4
1


 
4.8
6.4
7.9
9.5

11.1
12.7
17.5
19.1

22.2
25.4
31.8


 
3.2
4.0
4.8
6.4

7.9
9.5
11.1
12.7

15.9
19.1
25.4		 COLLARS COLLAR
on open end,
closed other end 
O.D. inches Width inches
11/16
11/16
11/16
11/16

11/16
1
1
1 1/4

1 1/4
1 7/8
1 7/8		 3/8
3/8
3/8
3/8

3/8
3/8
3/8
5/16

5/16
5/16
5/16

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COUPLINGS-Target Tubes
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.



 
AP03CP02-*
AP04CP02-*
AP05CP04-*
AP06CP06-*
AP07CP08-*
AP08CP08-*
AP11CP08-*
AP11CP12-*
AP12CP08-*

AP14CP08-*
AP16CP12-*
AP20CP16-*
AP30CPT20-*
AP30CPT24-*


 
P03CP02-*
P04CP02-*
P05CP04-*
P06CP06-*
P07CP08-*
P08CP08-*
P11CP08-*
P11CP12-*
P12CP08-*

P14CP08-*
P16CP12-*
P20CP16-*
P30CPT20-*
P30CPT24-*


 
3/16
1/4
5/16
3/8
7/16
1/2
11/16
11/16
3/4

7/8
1
1 1/4
1 7/8
1 7/8


 
1/8
5/32
3/16
1/4
5/16
3/8
7/16
7/16
1/2

5/8
3/4
1
1 5/8
1 5/8


 
4.8
6.4
7.9
9.5
11.1
12.7
17.5
17.5
19.1

22.2
25.4
31.8
47.6
47.6


 
3.2
4.0
4.8
6.4
7.9
9.5
11.1
11.1
12.7

15.9
19.1
25.4
41.3
41.3		 COUPLINGS COUPLING
on open end, 
closed other end
 
NPT inches Length inches
1/8
1/8
1/4
3/8
1/2
1/2
1/2
3/4
1/2

1/2
3/4
1 
1 1/4
1 1/2		 3/4
3/4
1
1 3/16
1 1/2
1 1/2
1 1/2
1 5/8
1 1/2

1 1/2
1 5/8
2
2 1/2
2 1/2

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NIPPLES, CLOSE
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.



 
AP03NC-*
AP04NC-*
AP05NC-*
AP06NC-*

AP07NC08-*
AP08NC08-*
AP11NC08-*
AP11NC12-*
AP12NC08-*

AP14NC08-*
AP16NC12-*
AP20NC16-*


 
P03NC02-*
P04NC02-*
P05NC04-*
P06NC06-*

P07NC08-*
P08NC08-*
P11NC08-*
P11NC12-*
P12NC08-*

P14NC08-*
P16NC12-*
P20NC16-*


 
3/16
1/4
5/16
3/8

7/16
1/2
11/16
11/16
3/4

7/8
1
1 1/4
  

 
1/8
5/32
3/16
1/4

5/16
3/8
7/16
7/16
1/2

5/8
3/4
1
 
 
 
4.8
6.4
7.9
9.5

11.1
12.7
17.5
17.5
19.1

22.2
25.4
31.8


 
3.2
4.0
4.8
6.4

7.9
9.5
11.1
11.1
12.7

15.9
19.1
25.4		 CLOSE NIPPLE CLOSE NIPPLE
 on open end, 
closed other end
 
NPT inches Length inches
1/8
1/8
1/4
3/8

1/2
1/2
1/2
3/4
1/2

1/2
3/4
1 		 7/8
7/8
7/8
1

1 3/16
1 3/16
1 3/16
1 5/16
1 3/16

1 3/16
1 5/16
1 1/2

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NIPPLES, SPACE 
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.




AP03N-*
AP04N-*
AP05N-*
AP06N-*

AP07N-*
AP08N-*
AP11N08-*
AP11N-*
AP12N-*

AP14N-*
AP16N-*
AP20N-*



P03N-*
P04N-*
P05N-*
P06N-*

P07N-*
P08N-*
P11N08-*
P11N-*
P12N-*

P14N-*
P16N-*
P20N-*



3/16
1/4
5/16
3/8

7/16
1/2
11/16
11/16
3/4

7/8
1
1 1/4



1/8
5/32
3/16
1/4

5/16
3/8
7/16
7/16
1/2

5/8
3/4
1



4.8
6.4
7.9
9.5

11.1
12.7
17.5
17.5
19.1

22.2
25.4
31.8



3.2
4.0
4.8
6.4

7.9
9.5
11.1
11.1
12.7

15.9
19.1
25.4		 SPACE NIPPLE NIPPLE, SPACE
 on open end, 
closed other end
 
NPT inches Length inches
1/4 X 1/4
1/4 X 1/4
3/8 X 3/8
3/8 X 3/8

1/2 X 1/2
1/2 X 1/2
1/2 X 1/2
3/4 X 3/4
3/4 X 3/4

3/4 X 3/4
1 X 1
1 1/4 X 1 1/4		 1
1
1 1/2
1 1/2

2
2
2
2 1/2
2 1/2

2 1/2
3
3

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NIPPLES, SLEEVES
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.

  


AP03N9A6-*
AP04N9A6-*
AP05N9A6-*
AP06N9A6-*

AP07N9A6-*
AP08N9A6-*
AP11N922A6-*
AP11N9A6-*
AP12N9A6-*

AP14N9A6-*
AP16N9A6-*
AP20N9A6-*



P03N9A6-*
P04N9A6-*
P05N9A6-*
P06N9A6-*

P07N9A6-*
P08N9A6-*
P11N922A6-*
P11N9A6-*
P12N9A6-*

P14N9A6-*
P16N9A6-*
P20N9A6-*



3/16
1/4
5/16
3/8

7/16
1/2
11/16
11/16
3/4

7/8
1
1 1/4



1/8
5/32
3/16
1/4

5/16
3/8
7/16
7/16
1/2

5/8
3/4
1



4.8
6.4
7.9
9.5

11.1
12.7
17.5
17.5
19.1

22.2
25.4
31.8



3.2
4.0
4.8
6.4

7.9
9.5
11.1
11.1
12.7

15.9
19.1
25.4		 NIPPLE SLEEVE NIPPLE SLEEVE
 on open end, 
closed other end
 
NPT Thread Length inches
1/4
1/4
3/8
3/8

1/2
1/2
1/2
3/4
3/4

3/4
1
1 1/4		 6
6
6
6

6
6
6
6
6

6
6
6

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NIPPLES, Special (brass) NL
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.




AP11N-*



P11N-*



11/16



7/16



17.5



9.5		 SPACE NIPPLE NIPPLE, SPACE
 on open end, 
closed other end
NPT inches Length inches
3/4 X 3/4 2 1/2

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FITTINGS
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.


AP07F-*
AP08F-*
AP11F-*
AP12F-*

AP14F-*
AP16F-*

AP20F-*

P07F-*
P08F-*
P11F-*
P12F-*

P14F-*
P16F-*

P20F-*

7/16
1/2
11/16
3/4

7/8
1

1 1/4

5/16
3/8
7/16
1/2

5/8
3/4

1

11.1
12.7
17.5
19.1

22.2
25.4

31.8

7.9
9.5
11.1
12.7

15.9
19.1

25.4		 FITTING -NPT FITTING
on open end,
closed other end 
1/2 X 3/4
1/2 X 3/4
1/2 X 3/4
1/2 X 3/4

3/4 X 1
3/4 X 1

1 X 1 1/4

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HEX FITTINGS
ALUMINA MULLITE INCHES MILLIMETERS MOUNTING CONSTRUCTION
O.D. I.D. O.D. I.D.
 

AP03HX-*
AP04HX-*
AP05HX-*

AP06HX-*
   AP06HX12-*
AP07HX-*
AP08HX-*

   AP11HX08-*
AP11HX-*
AP12HX-*

AP14HX-*
AP16HX-*
AP20HX-*

P03HX-*
P04HX-*
P05HX-*

P06HX-*
   P06HX12-*
P07HX-*
P08HX-*

   P11HX08-*
P11HX-*
P12HX-*

P14HX-*
P16HX-*
P20HX-*

3/16
1/4
5/16

3/8
3/8
7/16
1/2

11/16
11/16
3/4

7/8
1
1 1/4

1/8
5/32
3/16

1/4
1/4
5/16
3/8

7/16
7/16
1/2

5/8
3/4
1

4.8
6.4
7.9

9.5
9.5
11.1
12.7

17.5
17.5
19.1

22.2
25.4
31.8

3.2
4.0
4.8

9.5
9.5
7.9
9.5

11.1
11.1
12.7

15.9
19.1
25.4		 HEX FITTINGS - NPT HEX FITTING
 on open end,
closed other end 
11/16
11/16
11/16

1/2 X 1/2
3/4 X 3/4
1/2 X 1/2
1/2 X 1/2

1/2 X 1/2
3/4 X 3/4
1X 1
 
1X 1
1X 1
1 1/4 X 1 1/4

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  © Copyright 2005 Arklay S. Richards Co., Inc.