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Type 330 - PN16-35

16 - 35
Product description Technical data Video



The ACI level indicator Type 330 is an easy to mount fitting for the industrially proven borosilicate sight glass plates according to DIN 7081. The base flange of Type 330 is set into the wall of a container or pipe and is fixed all-round with a welding seam. The base flange has an indentation for glass and seals, which are held by a cover flange. Type 330 only needs a very low torque for the fixing screws, whilst still achieving very reliable sealing.

Type 330, like most of our fittings, is available in a range of materials, including standard types of container steel such as S235, or standard stainless-steel alloys such as 1.4571 or 1.4404, but high-performance materials such as Hastelloy or duplex alloys are available on request.

For the sealing, we use tried and tested high-quality flat seals from well-known manufacturers such as KlingerSIL C4400 or novaphit MST. It is also possible to supply pure PTFE seal plates and soft seals such as NBR or EPDM directly.

The industry norm DIN 7081 includes the use of sight glasses of different lengths in the Transparent” and “Reflex” versions. Transparent glass means simple, smooth glass plates. This type can, should the operating conditions require it, be fitted with protective layers made of mica or other materials such as KEL-F. We recommend the reflex type, if operating conditions allow it, for use with clear, colourless liquids. Due to the grooves contained in this type, the meniscus in the liquid phase can be seen clearer than with the transparent variety.

Read on for technical data and detailed views.


Base and top frame: 

  • 1.4571; 1.4404, 1.4462, RSt 37-2 / H II / Other materials on request


  •  A4-70


  • depending on the application


  •  Reflections -or- Transparent glass according to DIN 7081 or DIN 8903


  • Rectangular Sight Glass as level indicator for visual inspection of tanks, boilers and silos

Nominal size:

  • size from 140 mm up to 1000 mm 
  • Other sizes on request

Nominal pressure:

  • PN 16 or PN 40
  • For operating pressures up to max. 35 bar depending on the model


  •  temperature: 100 ° C or 243 ° C
  • depending on the glass and seal selection.

Special Feature:

  • Lloyd’s Register Design Approval available


  • Optional versions are possible.

Gasket selection:

  • PTFE (200°C)
  • FKM (200°C)
  • NBR (100°C)
  • C4400 (150°C)
  • Silicone (200°C)
  • EPDM (140°C)
  • Graphite (320°C)

Installation instructions:

After welding in the base flange, check whether the sealing surfaces have warped! If necessary, rework must be carried out. The operating pressure does not apply to the base frame, which must be checked together with the pressure device according to AD data sheet B9!

BL = overall length / SL = visible length

BL SL Concealed view Kg(16 bar) Kg(35 bar)
140 79 0 2,8 3,4
170 124 0 3,2 4,0
220 174 0 4,0 5,0
250 204 0 4,6 5,7
300 264 0 5,3 6,7
310 264 0 5,6 7,0
350 304 0 6,3 7,8
370 324 0 6,6 8,2
400 354 0 7, 8,9
500 454 1x46 9,1 11,4
600 574 1x46 10,7 13,4
620 574 1x46 11,1 13,9
700 654 1x46 12,5 15,7
740 694 1x46 13,2 16,5
800 74 1x46 14,2 17,8
930 884 2x46 16,7 20,9
1000 954 3x46 18,2 22,8

Contact form
Type 334 - PN3
Type 334 - PN3
Type 334 - PN3
Material: Base flange: 1.4571, 1.4404, 1.4435, 1.4462, 1.4539, 1.4541, 2.4602, 2.4610, P265GH, Alloy , Super Duplex Cover flange: 1.4571, 1.4404, 1.4435, 1.4462, 1.4539, 1.4541, 2.4602, 2.4610, P265GH, Alloy , Super Duplex Screws: DIN 912, A4-70 or special materials Glass plates: Borosilicate glass similar to DIN 7081 (other materials available) Shape: oval rectangular sightglass fitting for welding in or on Nominal size: from 270 to 760 mm Nominal pressure: for operating pressures up to 3 bar (Vacuum version available on request) Option:  Optional versions are possible. Temperature: 100°C or 243°C depending on glass and gasket selection. Gasket selection: PTFE (200°C) FKM (200°C) NBR (100°C) C4400 (150°C) Silicone (200°C) EPDM (140°C) Graphite (280°C) Rectangular level indicator sight glass for visual observation of fluid levels in vessels, boilers and silos. Intended for welding into the tank wall. Provides a large field of observation. It can also be used as a level indicator (liquid level indicator). The successor to the type 350 sight glass fittings. SHORT DESCRIPTION - RECTANGULAR LEVEL INDICATOR TYPE 334 The ACI tank sight glass type 334 is a light construction, which offers a considerably enlarged sight opening compared to our type 330 at a rather low operating pressure up to max. 3 bar. Due to this design the type 334 combines the functions of our round tank sight glasses like the type 318 and our level indicators for tank wall mounting type 330. Like our other sightglasses, the tank sightglass type 334 may not only be equipped with the highly resistant and industry-proven borosilicate glass, but also with quartz glass or the particularly robust and scratch-resistant sapphire glass for your most demanding applications. For sealing, we use flat gasket materials from well-known manufacturers, which we select based on your individual requirements. We use the proven C4400 aramid fibre gaskets from KlingerSIL for many applications. At high temperatures, we rely on novaphit MST from Frenzelit, and in chemically demanding applications such as strong acids, the sight glass is sealed with pure or expanded PTFE. The tank sight glass type 334 is delivered hand-tight pre-assembled at the factory. After welding in the base flange, the gaskets supplied are fastened together with the sight glass through the cover flange, whereby even very low tightening torques are sufficient to achieve sufficient contact pressure. If unexpectedly a damage of the sight glass should occur during operation, our competent team of technicians and merchants will be at your disposal at any time to provide replacement as quickly as possible. Read on for technical details or watch the product video above in the slider.
Type 410
Type 410
Type 410
Material: Base and top frame:  1.4571; 1.4404, 1.4462, RSt 37-2 / H II Screws:  A4-70 Seals:  depending on the application Glass:  Reflections -or- Transparent glass DIN7081  Shape: longitudinal rectangular sightglass fitting with weld ends Ø 20 x 2,6 for pressures up to max. 35 bar Nominal size: 170- 930 mm (other size on request) Nominal pressure: PN16 or PN40 Temperature: 100 °C or 243 °C depending on the glass and seal selection. Option: Optional versions are possible. SHORT DESCRIPTION - REFLEXION LEVEL GAUGE WITH WITH FRONTALLY WELDED END The ACI filling level indicator Type 410 has a closed casing and welded supports at the ends with which the fitting can be installed into your existing system as required. Type 410 is fully assembled before delivery and is subject to a pressure test, so that the filling level indicator is immediately ready to use after proper installation. As a viewing window, we use high-quality, chemical-resistant borosilicate glass according to DIN 7081. These glass panels are available as “transparent” and “reflex” types. The transparent type has a smooth surface and can be protected if required by a mica layer against aggressive media or high temperatures. The “reflex” type has internal indents that make the meniscus of the fluid phase significantly more visible in the case of clear and colourless media, due to the different refraction of light, than most transparent glass panels. We recommend this version especially for operation with water or alcohol. For sealing, we use as standard high-quality flat seal materials such as KlingerSIL C4400, Frenzelit novaphit or Garlock Gylon. Soft seals made of silicon, EPDM or NBR are also available from us directly. Contact our competent sales team and we will be sure to find the perfect solution for your special application.