Sight glass for industrial applications Type 335

for vesselslevel indicatormonitoring

The Type 335 longitudinal sight glass fitting is an oval sight glass and level indicator for tank or container wall mounting, designed for enlarged viewing at low operating pressures (up to 3 barg). The borosilicate sight plate is clamped between gaskets and firmly screwed into a metallic base frame to ensure sealing and pressure resistance.

Main features

• Enlarged oval sight opening for improved observation compared with round sight glasses
• Designed for wall mounting (weld‑in or weld‑on versions)
• Sight glass plate: borosilicate glass (similar to DIN 7081) — alternative materials on request
• Standard body material: stainless steel 1.4571 (316Ti); other materials available on request
• Sealing with flat gaskets from a wide selection (including PTFE (Teflon®), NBR, novaphit® MST‑XP, KlingerSil® C4400 and many others)
• Design variants available for increased chemical or thermal resistance (FEP or Halar® coating, mica protection disc, high‑temperature design)
• Nearly dead‑space‑free design and possibility for custom constructions

Options / additional components

• FEP or Halar® coating for chemical resistance
• Mica protection disc for enhanced thermal/steam protection
• High‑temperature versions (see temperature ratings)
• Wide choice of gasket materials (more than 50 options)
• Accessories (e.g., FEP protective screen / coating)

Dimensions / weight (face‑to‑face BL -> sight length SL and weight)

• BL 270 mm — SL 200 mm — Weight 6.3 kg
• BL 340 mm — SL 270 mm — Weight 7.9 kg
• BL 410 mm — SL 340 mm — Weight 9.5 kg
• BL 480 mm — SL 410 mm — Weight 11.1 kg
• BL 550 mm — SL 480 mm — Weight 12.7 kg
• BL 620 mm — SL 550 mm — Weight 14.2 kg
• BL 690 mm — SL 620 mm — Weight 15.8 kg
• BL 760 mm — SL 690 mm — Weight 17.4 kg

Technical specifications

• Nominal pressure: PN 3 (maximum working pressure up to 3 barg)
• Temperature ratings (select per design): 80 °C, 130 °C, 150 °C, 175 °C, 180 °C, 200 °C, 280 °C, 300 °C, 400 °C
• Standard body material: stainless steel 1.4571 (316Ti); other materials on request
• Sight glass material: borosilicate glass (DIN 7081 or per customer specification)
• Face‑to‑face (total) length range: 270 mm – 760 mm
• Applications: suitable for liquid and gaseous media; usable as level indicator at low pressures
• Available protection/coating: FEP protective screens, FEP or Halar® coatings
• Design notes: nearly dead‑space‑free design; custom constructions available; mica protection disc option where borosilicate glass temperature limit is exceeded

Materials & gaskets

• Standard housing: stainless steel 1.4571 (316Ti)
• Sight glass: borosilicate glass (DIN 7081‑like) or alternative glass/protection on request
• Flat gasket options: more than 50 materials including PTFE (Teflon®), NBR, novaphit® MST‑XP, KlingerSil® C4400

Assembly / components

• Screws
• Cover frame
• Glass spacer
• Sight glass
• Gasket
• Base frame