Flange sight glass Type 520

tempered glass facingfor chemicalsborosilicate glass

The High-pressure sight glass Type 520 is a heavy-duty flow sight glass engineered for industrial high-pressure applications, offering robust corrosion-resistant construction and dual-sided visibility for safe, real-time process observation.

Key features

• Designed for industrial high-pressure use with focus on maximum operational safety and long-term durability.
• Robust body made of corrosion-resistant stainless steel alloys (standard: 1.4571); on request available in nickel-based alloys or Hastelloy® for highly aggressive or thermally stressed environments.
• Two opposing sight windows made of thermally pre-stressed borosilicate glass manufactured to DIN 7080 for clear, safe observation from two sides and for targeted illumination of the medium.
• Flange connection: intermediate flange design for flanges according to DIN EN 1092-1 form B2, enabling standardized integration into piping systems.
• Pressure capability: available for a wide range of pressure ratings up to PN 400.
• Typical applications: chemical, pharmaceutical, food and energy industries where high-pressure, high-temperature or aggressive media are present.

Nominal sizes (DN)

• 25
• 40
• 50
• 65
• 80
• 100
• 125
• 150
• 200

Nominal pressure (PN)

• 63
• 100
• 160
• 250
• 320
• 400

Temperature options

• 80°C
• 130°C
• 150°C
• 175°C
• 180°C
• 200°C
• 280°C
• 300°C

Options

• Double glazing

Dimensions (excerpt by PN / DN)

• PN 63 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 230 / D1 45 / AL1 175 / AL2 140
  • DN40 — BL 260 / D1 45 / AL1 185 / AL2 170
  • DN50 — BL 300 / D1 65 / AL1 211 / AL2 185
  • DN65 — BL 340 / D1 8 / AL1 239 / AL2 220
  • DN80 — BL 380 / D1 80 / AL1 264 / AL2 250
  • DN100 — BL 430 / D1 125 / AL1 324 / AL2 300
  • DN125 — BL 500 / D1 125 / AL1 354 / AL2 350
  • DN150 — BL 550 / D1 160 / AL1 435 / AL2 400
  • DN200 — BL 650 / D1 160 / AL1 505 / AL2 480
• PN 100 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 230 / D1 45 / AL1 175 / AL2 140
  • DN40 — BL 260 / D1 45 / AL1 190 / AL2 170
  • DN50 — BL 300 / D1 65 / AL1 211 / AL2 195
  • DN65 — BL 340 / D1 65 / AL1 239 / AL2 220
  • DN80 — BL 380 / D1 80 / AL1 274 / AL2 250
  • DN100 — BL 430 / D1 125 / AL1 354 / AL2 290
  • DN125 — BL 500 / D1 125 / AL1 397 / AL2 350
• PN 160 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 230 / D1 45 / AL1 175 / AL2 140
  • DN40 — BL 260 / D1 45 / AL1 195 / AL2 170
  • DN50 — BL 300 / D1 65 / AL1 241 / AL2 195
  • DN65 — BL 340 / D1 65 / AL1 296 / AL2 220
  • DN80 — BL 380 / D1 80 / AL1 294 / AL2 250
• PN 250 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 230 / D1 48 / AL1 196 / AL2 150
  • DN40 — BL 290 / D1 48 / AL1 221 / AL2 185
  • DN50 — BL 300 / D1 65 / AL1 255 / AL2 200
  • DN65 — BL 340 / D1 65 / AL1 279 / AL2 230
  • DN80 — BL 380 / D1 80 / AL1 334 / AL2 225
• PN 320 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 230 / D1 20 / AL1 186 / AL2 160
  • DN40 — BL 260 / D1 20 / AL1 201 / AL2 195
  • DN50 — BL 300 / D1 30 / AL1 230 / AL2 210
  • DN65 — BL 340 / D1 30 / AL1 254 / AL2 225
  • DN80 — BL 380 / D1 48 / AL1 289 / AL2 275
• PN 400 (DN / BL / D1 / AL1 / AL2):
  • DN25 — BL 280 / D1 20 / AL1 210 / AL2 180
  • DN40 — BL 320 / D1 20 / AL1 220 / AL2 220
  • DN50 — BL 370 / D1 30 / AL1 240 / AL2 235

Characteristics / specifications

• Denomination / model: Type 520
• Body material (standard): stainless steel 1.4571; other high-performance alloys (nickel-based, Hastelloy®) available on request.
• Glass: thermally pre-stressed borosilicate glass to DIN 7080, dual opposing panes for two-sided observation.
• Flange standard: DIN EN 1092-1 form B2 (intermediate flange design).
• Max. nominal pressure: up to PN 400 (product variants available for PN 63, 100, 160, 250, 320, 400).
• Temperature ratings: multiple temperature options up to 300°C (selection depends on configuration).
• Available options: double glazing and customizable material selections for aggressive or high-temperature media.