Circular Sight Glass Fitting Type 391 - PN16 - PN 40

with pipe adapter for welding onto pipelines

Sight Glass Fitting Type 391

The ACI Type 391 is a round tank sight glass with a pipe adapter intended for welded installation on an existing pipe or small pressure vessels.

As with our other sightglasses, a sightglass made of chemically highly resistant borosilicate glass to DIN 7080 or similar is clamped between two high-quality stainless steel flanges and proven quality gaskets.

Exploded_view_type_391_with_labelling_of_the_individual_parts

Our type 391 sight glasses are made of the high-quality stainless steel 1.4571 (316Ti) that our customers have appreciated for years. The glass material used is borosilicate glass 3.3 according to DIN 7080 (or similar), which has proven itself in the industry.

The fitting is sealed with flat gaskets adapted to your requirements from an extensive range of materials. In addition to the widely used fiber gaskets (e.g. KLINGERSIL® C-4400), PTFE (Garlock GYLON®, Frenzelit novaflon®), NBR, graphite (e.g. Frenzelit novaphit®) and many other branded gaskets are available for special applications.

You can find more information about gasket materials in our Help Center.

If the maximum operating temperature of 280°C does not meet your requirements, or if process conditions pose a problem even for the highly resistant borosilicate glass, an FEP or mica protection screen specially adapted to the fitting offers additional protection against steam and aggressive chemicals, such as alkalis up to a pH value of 14. 

As with other of our sightglass fittings, our Type 391 can be optionally equipped with SGW type wipers or lights. 

More technical details about our sightglass fitting type 391 can be found further down this page!

Technical details

Flange material:

  • Base flange:
    1.4571 (factory standard)
  • Cover flange:
    1.4571 (factory standard)
  • Other materials on request ¹

Shape:

  • with pipe adapter for welding 
    onto medium-carrying pipes

Temperature:

  • up to 280 °C with borosilicate glass
    according or similar to DIN 7080

Sight glass:

  • Borosilicate glass according or similar to DIN 7080

Nominal size:

  • DN 100 up to DN 350
    (depending on nominal pressure)

Options:

  • Wiper SGW with PTFE or silicone wiper blade
  • LED lights for EX- and Non-EX-areas
  • PLEXIGLAS® - impact protection
  • Stainless-steel perforated plate - impact protection
  • FEP protective screen (for higher pH-values)
  • special desgins are possible
² depending on environmental variables

Gaskets:

  • Fiber; (KLINGERSIL® C-4400)
  • PTFE, FKM, NBR, Silicone, EPDM
  • Graphite; (Frenzelit novaphit®)
  • or according to customer requirements

Nominal pressure:

  • PN 16 | PN 25 | PN 40

Screws:

  • A2-70
  • A4-70

¹ Optional materials:

1.0460 / 1.4301 / 1.4307 (F304L) / 1.4404 (F316L) / 1.4410 (Super Duplex) / 1.4435 (F316L) / 1.4462 (F 51) / 1.4529 (Alloy 926) / 1.4539 (Alloy 904L) / 1.4541 (F321) / 1.4547 (F44) / 1.4550 (F347) / 1.4571 (316Ti) / 1.4828 / 1.4841 / 1.4876 ( Alloy 800H) / 1.4878 / 1.7335 / 2.4068 (Alloy 201) / 2.4360 (Alloy 400) / 2.4375 (Alloy K500) / 2.4602 (Alloy C-22) / 2.4605 (Alloy 59) / 2.4610 (Alloy C-4) / 2.4816 (Alloy 600) / 2.4819 (Alloy C-276) / 2.4856 (Alloy 625) / 2.4858 (Alloy 825) / 3.7035 (Titan)

Section_view_type_391

L = acc. to order (Standard: L = 70 mm)

D = Nominal size of the medium-carrying pipeline / vessel

PN DN Da [mm] Di [mm] A [mm] s [mm] Weight [kg] *
16 100 220 107 114,3 3,6 10,5
125 250 132 139,7 4 14,5
150 285 160 168,3 4,5 18,6
200 (PS max. 10 bar(g)) 340 207 219,1 6,3 28,2
300 (PS max. 6 bar(g)) 460 310 232,9 7,1 55,7
350 (PS max. 6 bar(g)) 520 340 355,6 8 78
25 / 40 100 235 107 114,3 3,6 14,8 (PN 40)
125 270 132 139,7 4 21,1 (PN 40)
150 300 160 168,3 4,5 27,5 (PN 40)
200 375 207 219,1 6,3 52,6 (PN 40)

* Weight depending on size of D

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Sight glass fitting with welding adapter type 391 - PN16-40
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