Type 334 - PN3 | Rectangular sight glass | ACI Industriearmaturen GmbH

Rectangular tank sight glass type 334 - PN3

Rectangular tank sight glass for level indicaton - PN3 (3bar)

The ACI rectangular 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.

Technical data


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


DIN 912, A4-70 or special materials

Glass plates:

Borosilicate glass similar to DIN 7081

(other materials available)

Option: Optional versions are possible.


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)


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)

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Type 334 - PN3 | Rectangular sight glass