circular manhole sight glass Type 325

Short description -Round sight glass fitting for screwing onto a manhole

ACI manhole sight glass Type 325 can be used to close entry or inspection ports of tanks, silos and other vessels

The ACI manhole sight glass Type 325 is – unlike commonly used manhole covers – equipped with a sight glass fitting compatible with the established sight glass standard DIN 28120, allowing observation of the interior even with closed inspection port.

The central window is made from the proven MAXOS ® borosilicate glass according to DIN 7080, which is resistant against most chemicals and high temperatures. For operating temperatures above 280°C or alkaline process media, we recommend installation of a mica sheet to protect the glass surface. For very high temperature, the manhole sight glass Type 325 can be equipped with high performance glass material like quartz or sapphire glass.

As gasket material, we rely on high quality material like KlingerSIL C4400, Frenzelit novaphit MST or Garlock Gylon. Soft sealing materials like silicone, NBR and EPDM are also available preinstalled in your device.

Similar to our sight glass Types 320 and 321, Type 325 is optionally available for delivery with preinstalled wiper mechanisms, spray nozzles and light fixtures based on LED or halogen light.

Read on for more technical information and detailed views of our sight glass Type 325!

Read on for more technical information, detailed 3D views and our product video!

Technical specifications


Flanges: P250GH, P265GH, 1.4306 (F304L), 1.4404 (F316L), 1.4462 Duplex (F51), 14539 (Alloy 904 L), 1.4541 (F321) , 1.4571 (F316Ti) or according to customer specifications

Borosilicate Glass DIN 7080
Soda Lime GlassDIN 8902

Seals: to application


depending on material combination up to 900 ° C


Round sight glass fitting for screwing onto a manhole


DN250 bis DN800

Nominal Pressure:

PN6, PN10, PN16 or on request


a) With windscreen wiper
b) With spray device
c) double glazing
d) double glazing + heating element
e) With LED or halogen lights, also ATEX certified
g) with O-ring seal (suitable for vacuum)
h) High temperature version with quartz glass
i) Plexiglas impact protection window (5mm)
j) Other special versions on request

Take a look at the animation video, here you can see the structure of our tank sight glass - type 325 perfectly.

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