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Gauge Glass/Level Sight Glass Used in Industry Pipe

Gauge glass also named sight glass or level gauge glass. According to the application requirement for pressure and temperature, different material is used. Each type max working temperature is shown below.

  • Soda-lime glass (window glass) widely used for lower cost, working temperature up to 230 °C.
  • Borosilicate glass particularly useful for applications in aggressive environments (acids, alkali, water vapor), working temperature up to 350 °C.
  • Aluminosilcate glass have similar properties to borosilicate glass, but with better chemical resistance and higher permissible operating temperature of up to 600 °C.
  • Quartz glass has long range light transmittance (from ultraviolet to infrared), and its operating temperature is up to 1100 °C.

Classification:

  1. Round Sight glass:
    • Description
      It is mainly used to observe the level of the boiler or other equipment filled with liquid, also can be used as watching glass window for thermal and chemical reaction.
    • There are four pieces of different sizes sight glass.
      GG-01: Different dimension round sight glass with clear surface and well grinding edge finish used in flange.
      There are two pieces of round sight glass with hole in the center.
      GG-02: Round sight glass with a hole in the center make it convenient to clear the surface of the glass.
      There are two pieces of round sight glass of 10.18 mm and 30.47 mm thickness.
      We can produce wide range dimension of round sight glass.
    • Dimensions of round sight glass.
      Special requirement is available, such as dip hole in center, polishing edge and so on.
    • Dimensions of round sight glass
      Items Diameter (mm) Thickness (mm) Permissible operating pressure (bar)
      RSG-1 30 15 200
      RSG-2 35 7 25
      RSG-3 40 12 50
      RSG-4 45 10 40
      RSG-5 45 12 50
      RSG-6 50 10 25
      RSG-7 50 12 40
      RSG-8 55 10 25
      RSG-9 60 10 16
      RSG-10 60 12 25
      RSG-11 60 15 40
      RSG-12 63 8 8
      RSG-13 63 10 16
      RSG-14 63 12 25
      RSG-15 63 15 40
      RSG-16 70 12 16
      RSG-17 70 15 25
      RSG-18 80 10 10
      RSG-19 80 12 16
      RSG-20 80 15 25
      RSG-21 80 20 40
      RSG-22 90 10 8
      RSG-23 95 15 16
      RSG-24 100 10 7
      RSG-25 100 15 16
      RSG-26 100 20 25
      RSG-27 100 25 40
      RSG-28 113 15 10
      RSG-29 125 15 10
      RSG-30 125 20 16
      RSG-31 125 25 25
      RSG-32 125 30 40
      RSG-33 135 25 25
      RSG-34 150 15 8
      RSG-35 150 20 10
      RSG-36 150 25 16
      RSG-37 150 30 25
      RSG-38 175 20 10
      RSG-39 175 25 16
      RSG-40 175 30 25
      RSG-41 200 20 8
      RSG-42 200 25 10
      RSG-43 200 30 16
      RSG-44 250 25 8
      RSG-45 250 30 10
      RSG-46 265 30 8
  2. Transparent level gauge glass:
    Transparent (smooth) level gauge glass is used to observe the liquid level of the boiler or other liquid tanks. Due to the boiler water high temperature and pressure working environment, borosilicate or aluminosilcate glass is used to meet the requirement.
      There is tree piece of thick strip gauge glass with clear surface and polishing edge.
      GG-03: Strip gauge glass are used in industry to observing the flow of liquid and liquid level.
      There is tree piece of strip gauge glass of heavy thickness.
      GG-04: Thick strip gauge glass make it can withstand acid, alkali, high temperature and high pressure.
    • Types:
      According to the width and thickness of the glass, mainly four types are classified.
      • type A: width 30 mm, thickness 17 mm.
      • type B: width 34 mm, thickness 17 mm.
      • type H: width 34 mm, thickness 22 mm.
      • type TA 28: width of 27.6 mm, 16.8 mm.
    • Dimensions:
      There is a drawing of transparent level gauge glass to describe the length, height and width.
      GG-05: Transparent level gauge glass drawing, the L, W and H in following chart are according to this picture.
      Dimensions of transparent level gauge glass
      Items TYPE A TYPE B TYPE H TYPE TA 28
      L W H L W H L W H L W H
      TLGG-1 115 30 17 115 34 17 - - - 113 27,6 16,8
      TLGG-2 140 30 17 140 34 17 140 34 22 - - -
      TLGG-3 165 30 17 165 34 17 165 34 22 163 27,6 16,8
      TLGG-4 190 30 17 190 34 17 190 34 22 188 27,6 16,8
      TLGG-5 220 30 17 220 34 17 220 34 22 218 27,6 16,8
      TLGG-6 250 30 17 250 34 17 250 34 22 248 27,6 16,8
      TLGG-7 280 30 17 280 34 17 280 34 22 278 27,6 16,8
      TLGG-8 320 30 17 320 34 17 320 34 22 318 27,6 16,8
      TLGG-9 340 30 17 340 34 17 340 34 22 338 27,6 16,8
      TLGG-10 - - - 370 34 17 - - - - - -
      • Glasses are all made strictly according with DIN7081.
      • Gaskets and mica sheet can also be provided together.
    • Working temperature and pressure
      Borosilicate glass can withstand up to 400 °C, 180 bar. Aluminosilcate glass can work up to 660 °C, 180 bar.
  3. Reflex gauge glass:
    Reflex gauge glass are used to read the water level of the boiler or tank. It have 3, 4 grooves longitudinal printed on the glass. The grooves in water can help increase the angle of refraction, so the visibility of the liquid level is much better then without grooves.
    With the grooving increases the angle of refraction which makes the visibility of the liquid level is much better than when using smooth glass.
    A pieces of reflex gauge glass with one groove is on the ground.
    GG-06: The reflex gauge glass with one groove makes the liquid level clear.
    Two pieces of reflex gauge glass with three grooves of different dimension is on the ground.
    GG-07: The reflex gauge glass with more grooves can be supplied together with gasket to seal and buffer the extrusion.
    • Types
      • type A - width 30 mm, thickness 17 mm.
      • type B - width 34 mm, thickness 17 mm.
      • type H - width 34 mm, thickness 22 mm.
      • Type C - width of 20 mm, thickness 12 mm.
      • Type D - width 25 mm, thickness 15 mm.
    • Dimensions:
      There is a drawing to describe the length, height and width of the reflex gauge glass.
      GG-08: Reflex gauge glass drawing, the L, W and H of reflex gauge glass in the following chart are according to this picture.
      Dimensions of reflex gauge glass
      Size TYPE A TYPE B TYPE H
      L W H L W H L W H
      RGG-1 95 30 17 95 34 17 - - -
      RGG-2 115 30 17 115 34 17 115 34 22
      RGG-3 140 30 17 140 34 17 140 34 22
      RGG-4 165 30 17 165 34 17 165 34 22
      RGG-5 190 30 17 190 34 17 190 34 22
      RGG-6 220 30 17 220 34 17 220 34 22
      RGG-7 250 30 17 250 34 17 250 34 22
      RGG-8 280 30 17 280 34 17 280 34 22
      RGG-9 320 30 17 320 34 17 320 34 22
      RGG-10 340 30 17 340 34 17 340 34 22
      RGG-11 - - - 370 34 17 - - -
      • Glasses are all made strictly according with DIN7081.
      • Gaskets and mica sheet can also be provided together.
    • Working temperature and pressure
      Borosilicate glass can withstand up to 400 °C, 180 bar. Aluminosilcate glass can work up to 660 °C, 180 bar.
Chemical and physical properties
1. Chemical composition SiO2 AL2O3 B2O3 Na2O + K2O
80.00% 2.8% 12.8% 3.8%
2.Chemical Durability Water-resistance Acid-resistance Alkali resistance
<0.5 mg/cm2 <0.5 mg/cm2 <80 mg/cm2
3.Thermal stability △T150 °C, temperature <260 °C
4.Bending strength ≥1100 kgf/cm2
5.Hydraulic power -10°C, 16 kg/cm2
6.Transmittance ≥90 %/mm2
7. Appearance
  1. Air bubble:
    Diameter ≤0.5 mm, in 10 mm × 10 mm area the quantity ≤3.
    Diameter from 0.5 mm to 1.5 mm dispersive air bubble, there is less than2 on the sight plane and less than 5 on the No-sight plane. Bubble distance > 40 mm. The air bubble of diameter from 1.5 mm to 2 mm ≤3 on the No-sight plane. Their distance > 40 mm.
  2. Do not contain slag and scrap etc.
  3. Stripe: don't have palpable filaceous and pectinate stripe on the sight plane.
  4. Cockle: In the side face, don't have the cockle of depth > 1 mm.
  5. Crack: don't have crack anywhere.

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