Pipe sight glass Type 671

for industrial applicationsmonitoringborosilicate glass

The Tubular sight glass Type 671 is a glass-ring tubular sight glass for intermediate-flange installation between flanges (DIN EN 1092-1), offering 360° visibility for process monitoring. It is suitable for liquid and gaseous media and is available in a wide range of nominal sizes and pressure/temperature ratings.

Key features

• Design: glass ring tubular sight glass with intermediate flange for installation between DIN EN 1092-1 flanges.
• Visibility: 360° visual access for flow and phase monitoring.
• Media: suitable for liquid and gaseous media.
• Standard glass: tempered borosilicate; standard version suitable for operating temperatures up to 280 °C.
• Pressure capability: rated for operating pressures up to 40 barg (depending on DN); larger nominal sizes achieve up to 20–25 barg as specified per size.
• Installation: compact intermediate-flange design suitable for retrofit and confined spaces.
• Sealing: flat gaskets selectable from a wide material range (fiber, PTFE (Teflon®), NBR, novaphit® MST-XP, KlingerSil® C4400 and other brand gaskets).
• Customisation: bespoke designs available; more than 50 sealing materials offered.

Available nominal sizes (DN)

• DN 10, 15, 20, 25, 32, 40, 50, 65, 80, 100, 125, 150

Nominal pressure (PN)

• PN 25
• PN 40

Temperature ratings (standard borosilicate glass)

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

Dimensions and typical technical data per nominal size

• DN 10: Di 13 mm · DF 40 mm · L 134 mm · Weight 1 kg · PS³ 40 barg
• DN 15: Di 18 mm · DF 45 mm · L 134 mm · Weight 3 kg · PS³ 40 barg
• DN 20: Di 23 mm · DF 58 mm · L 134 mm · Weight 3.5 kg · PS³ 40 barg
• DN 25: Di 29 mm · DF 68 mm · L 134 mm · Weight 4 kg · PS³ 40 barg
• DN 32: Di 38 mm · DF 78 mm · L 144 mm · Weight 6 kg · PS³ 40 barg
• DN 40: Di 44 mm · DF 88 mm · L 144 mm · Weight 7 kg · PS³ 40 barg
• DN 50: Di 55 mm · DF 102 mm · L 146 mm · Weight 9 kg · PS³ 40 barg
• DN 65: Di 71 mm · DF 122 mm · L 148 mm · Weight 11 kg · PS³ 25 barg
• DN 80: Di 83 mm · DF 138 mm · L 148 mm · Weight 13 kg · PS³ 25 barg
• DN 100: Di 108 mm · DF 162 mm · L 148 mm · Weight 15 kg · PS³ 25 barg
• DN 125: Di 132 mm · DF 188 mm · L 158 mm · Weight 19 kg · PS³ 20 barg
• DN 150: Di 160 mm · DF 218 mm · L 174 mm · Weight 24 kg · PS³ 20 barg

Materials & sealing options

• Standard glass material: tempered borosilicate glass.
• Seals: flat gaskets available in many materials (fiber, PTFE (Teflon®), NBR, novaphit® MST-XP, KlingerSil® C4400 and other brand gaskets).

Technical specifications & certifications

• Product type: glass-ring tubular sight glass, Type 671.
• Installation: intermediate-flange design for DIN EN 1092-1 flanges.
• Nominal sizes: DN 10–150.
• Nominal pressure: PN 25 and PN 40 (pressure capability varies with DN; see dimensions table for PS³ values per DN).
• Maximum standard operating pressure: up to 40 barg for smaller DN; larger DN up to 20–25 barg as specified per size.
• Temperature range (standard borosilicate): up to 280 °C.
• Media: suitable for liquids and gases.
• Customisation: bespoke designs available; >50 sealing materials possible.
• Certifications / quality approvals: TÜV ISO 9001; TÜV SÜD (2014/68/EU Annex III).