Continental Trade Sp. z o. o.

Technical glass

Round sight glasses

Our offer includes sight glasses made of various materials, depending on environmental conditions (temperature, pressure, aggressive media). The properties of various glass materials are described on page Types of materials in chapter Our offer/Technical glass. The basic types of materials used for the manufacture of sight glasses are:

  • soda-lime glass - widely available, cheap, working temperature up to 280 °C, 
  • borosilicate glass - particularly suitable for use in aggressive environments (acids, alkalis, water vapor), working temperature up to 350 °C,
  • aluminosilicate glass -  working temperature up to 660 °C,
  • glass-ceramics  - thermal shock resistant, working temperature up to 750 °C,
  • quartz glass - with a broad spectrum light transmittance (from ultraviolet to infrared), working temperature up to 1100 °C,
  • sapphire products - working temperature up to 2000 °C.

To improve the strength, the machined glass is subjected to toughening and annealing. In order to increase the resistance of sight glasses on the aggressiveness of the working environment and in the use of high temperatures and pressures, additional use of mica shield is recommended. Mica disc working as shields are described here.  If you need this solution - please contact us.

Round sight glasses are delivered separately or in a set with gaskets. Gaskets for sight glasses are described here.

We offer sight glasses manufactured by leading brands such as: Spectraglass, Klinger or Maxos, which guarantees high quality and stability of parameters.  

Dimensions

The method of sizing:

Sight glasses sizing

Diameter
D [mm]
Width
s [mm]
Pressure
[bar]
Notes
24 10 150 disc special size
30 12 150 disc special size
15 200 disc special size
31,6 12,75 150 disc special size
  Aluminosilicate
33 14 150 disc special size
33,12 15,95   Aluminosilicate
34 17 200 disc special size
  Aluminosilicate
35 7 25 disc special size
40 10 40 disc special size
12 50 disc special size
44 10 40 disc special size
12 50 disc special size
45 10 40 acc. DIN 7080
12 50 acc. DIN 7080
50 10 25 acc. DIN 7080
12 40 acc. DIN 7080
55 6,5 6 disc special size
10 25 disc special size
60 10 16 acc. DIN 7080
12 25 acc. DIN 7080
15 40 acc. DIN 7080
20 95 disc special size
63 8 8 disc special size
10 16 acc. DIN 7080
12 25 acc. DIN 7080
15 40 acc. DIN 7080
65 10 12 disc special size
15 40 disc special size
70 12 16 disc special size
15 25 disc special size
75 12 16 disc special size
80 10 10 disc special size
12 16 acc. DIN 7080
15 25 acc. DIN 7080
20 40 acc. DIN 7080
86 12 10 disc special size
90 10 8 disc special size
92 10 8 disc special size
94 12 10 disc special size
95 10 6 disc special size
15 16 disc special size
100 10 7 disc special size
12 10 disc special size
15 16 acc. DIN 7080
20 25 acc. DIN 7080
25 40 acc. DIN 7080
105 15 16 disc special size
110 12,5 10 disc special size
20 25 disc special size
113 15 10 disc special size
115 15 10 disc special size
120 10 4 disc special size
15 10 disc special size
18 16 disc special size
125 15 10 acc. DIN 7080
20 16 acc. DIN 7080
25 25 acc. DIN 7080
30 40 disc special size
130 15 10 disc special size
135 15 8 disc special size
25 25 acc. DIN 7080
140 15 8 disc special size
150 10 2 disc special size
15 8 disc special size
20 10 acc. DIN 7080
25 16 acc. DIN 7080
30 25 acc. DIN 7080
160 20 12 disc special size
170 15 5 disc special size
20 10 disc special size
175 20 10 acc. DIN 7080
25 16 acc. DIN 7080
30 25 acc. DIN 7080
200 20 8 acc. DIN 7080
25 10 acc. DIN 7080
30 16 acc. DIN 7080
210 25 10 disc special size
250 20 4 disc special size
25 8 acc. DIN 7080
30 10 acc. DIN 7080
265 30 8 acc. DIN 7080
Note: if in the column Notes otherwise stated, borosilicate glass "extra hard" is used 

Round sight glasses are delivered separately or in a set with gaskets and mica shield.

If you can not find the size - please contact us.

Tolerances
Diameter (d1):
d1 ≤ 125 mm
125 mm < d1 ≤ 200 mm 
d1 > 200 mm 

± 0,5 mm
± 0,8 mm
± 1,0 mm
   

Thicknes (s):
s ≤ 20 mm
s > 20 mm 


+ 0,5 mm / -0,25 mm
+ 0,8 mm / -0,40 mm 

Flatness (e):
d1 ≤ 100 mm
100 mm < d1 ≤ 150 mm
150 mm < d1 ≤ 200 mm
d1 > 200 mm


0,05 mm
0,08 mm
0,12 mm
0,15 mm 

 

Parallelity (p):
d1 ≤ 100 mm
100 mm < d1 ≤ 200 mm
d1 > 200 mm


0,20 mm
0,25 mm
0,30 mm

Calculation of the glass thickness
Calculation of the glass thickness
Calculation of the glass thickness

 

s     - theoretical minimum glass thicknes [mm] 
dm  => (d1+d2)/2  => average sealing diameter [mm]
   d1 - glass and sealing outside diameter [mm]
   d2 - sealing inside diameter [mm]
p     - permisible presure [bar] 
δbB - min. value of surface comressive stress [N/mm2
S    - safety factor

Safety precautions when using sight glass discs

Safety precautions when using sight glass discs:

  • Whenever a sight glass assembly has been taken apart it is urgently recommended in accordance with DIN 7080/ DIN 8902 that the glass disc and gaskets are replaced by new ones. That is particularly important in the case of pressure vessels and/or aggressive media. The following extract from DIN 7080/DIN 8902 text is verbatim:

Sight glass discs may only be installed by personnel who have been informed fully about the following requirements:

  • care in handling sight glass discs
  • cleaning of recesses, sight glass discs, gaskets and other parts i. e. removal of foreign bodies (e. g. swarf), prior to installation/reassembly
  • even tightening of retaining bolts

Sight glass discs that have been removed after operating use must not be re used.

,,
  • Planned maintenance:
    Sight glass discs should be included in routine maintenance and periodically checked visually or using ultrasound wall thickness measuring means. In the event of damage, a glass disc must be promptly exchanged, with the plant first having been brought to a standstill. The service life of a sight glass, relative to the particular vessel in which it is mounted, should be established by regular and careful visual check of its condition.
    Caution: Completely demineralised water may dissolve glass – especially intensive periodical inspection required!

  • Breakage of a sight glass:
    In spite of careful installation and recommended use, sight glass discs can, on rare occasions, suffer breakage through external influences. In order to prevent the entry of glass particles into products of a critical nature, e. g. foodstuffs, appropriate safety precautions should be taken by the plant manufacturer or user.

Round sight glasses with central hole

Round sight glasses with central hole

Rounded sight glass may be subject to evaporation or covering substance from observed tank. This could have a significant impact on reducing the visibility. In this case it is recommended to use a round glass with wiper. Examples of wipers for round glasses we discuss here.

Installing a wiper, however, requires the use of glass spy hole in the middle. This solution may affect allowable pressure, which can operate under glass with wiper.

There are a rounded sight glassmade of soda-lime glass and of borosilicate glass

Dimensions and properties of rounded sight glasses with central hole are discussed below.

Dimensions and properties of rounded sight glasses with central hole
Dimension 
D x s
[mm]
Viewing Diameter d1
[mm]
Nominal Pressure
[bar]
Notes
Soda lime glass, material acc. to DIN 8902 – up to 150°C Dimensions of rounded sight glasses with central hole
63 x 10
80 x 12
94 x 121)
100 x 15
113 x 151)
125 x 15
141 x 151)
150 x 15
166 x 151)
175 x 15
200 x 15
225 x 15
250 x 15
48
65
801)
80
1001)
100
1251)
125
1501)
150
175
205
225
6
6
6
6
6
6
6
5
4
4
4
2
2
Borosilicate glass, material acc. to DIN 7080 – up to 280°C
63 x 10
80 x 12
94 x 111)
100 x 15
113 x 151)
125 x 15
141 x 151)
150 x 19
166 x 151)
175 x 19
200 x 19
225 x 15
250 x 25
48
65
801)
80
1001)
100
1251)
125
1501)
150
175
205
225
6
6
6
6
6
6
6
6
6
6
4
2
4

1) For screwed sight glass fittings, material acc. to DIN 11851

The diameter of the center hole in the sight glass is 10.5 mm.

Other dimensions on request.

While every attempt has been made to verify the source of the information, no responsibility is accepted for accuracy of data.

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