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:

Diameter D [mm]	Width s [mm]	Pressure [bar]	Notes
24	10	150	disc special size
30	12	150	disc special size
30	15	200	disc special size
31,6	12,75	150	disc special size
31,6	12,75		Aluminosilicate
33	14	150	disc special size
33,12	15,95		Aluminosilicate
34	17	200	disc special size
34	17		Aluminosilicate
35	7	25	disc special size
40	10	40	disc special size
40	12	50	disc special size
44	10	40	disc special size
44	12	50	disc special size
45	10	40	acc. DIN 7080
45	12	50	acc. DIN 7080
50	10	25	acc. DIN 7080
50	12	40	acc. DIN 7080
55	6,5	6	disc special size
55	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
65	15	40	disc special size
70	12	16	disc special size
70	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
95	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
110	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
135	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
170	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

s - theoretical minimum glass thicknes [mm]
d_m => (d₁+d₂)/2 => average sealing diameter [mm]
d₁ - glass and sealing outside diameter [mm]
d₂ - sealing inside diameter [mm]
p - permisible presure [bar]
δ_bB - 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

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]
Soda lime glass, material acc. to DIN 8902 – up to 150°C
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.

Technical glass

Round sight glasses

The method of sizing:

Safety precautions when using sight glass discs:

Round sight glasses with central hole

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