Tubular Sight Glass type 620 PN10/16 | ACI Industriearmaturen GmbH

Tubular flow sight glass type 620 for a perfect all-round view

SHORT DESCRIPTION - Tubular Sight glass for 360° optical control

The central component of the ACI Tubular Sight Glass type 620 is a glass tube made of borosilicate glass 3.3, which is clamped between two steel or stainless steel flanges. This design ensures a complete 360° view and illumination of the process medium.

The default version of the tubular sight glass type 620 is equipped with flat gaskets made of virginal PTFE. Other materials like novaphit MST or elastic materials like EPDM and NBR are on stock for your order. If our range of gasket materials does not fulfil your requirements, contact us with your special conditions, and together we will find the perfect solution for you.

The flanges are machined from highly resilient stainless steel 1.4571 (AISI 316Ti, X6CrNiNoTi17-12-2), and held together using threaded rods. The rod assembly also supports the flanges lengthwise to prevent excessive forces from acting upon the glass, ensuring a long lifetime of your device.

For less demanding applications, our tubular sight glass Type 620 can be built using flanges made from P265GH. Of course, it is also possible to deliver special materials like Hastelloy, duplex steel or other high performance alloys.

Smaller nominal sizes of type 620 (up to DN50) can withstand an operating pressure of up to 16 bar without restrictions, and up to DN100 an operating pressure of 10 bar is still safe!

Since flange, gasket and glass are well adapted to each other, the tubular sight glass Type 620 contains next to no wake spaces, and is suitable for applications with strict hygiene requirements.

If the installation site is in an area in which manual work is performed, especially if catwalks are situated above the sight glass, we recommend installing a polycarbonate impact protection. This simple optional feature protects the glass tube from falling parts or tools and potentially prevents expensive maintenance or even catastrophic failure of the plant!

Our tubular sight glasses are fully assembled on our factory floor and subjected to a pressure test with 1.5-fold operating pressure. Generally, a regular on-site maintenance is not required.

Read on for more technical information, detailed product views, videos and our online 3D view!

Technical data


1.4571 or P265GH / 1.0425


borosilicate glass 3.3

Viton, PTFE, EPDM or negotiable.

impact protective shell


Tubular sight glasses Type 620 with flanges on both sides to fit flanges according to DIN 2633 and EN 1092 for installation in pipes.

Nominal size:


Nominal size:

DN15-DN150 = PN10/16

DN200- DN300 = PN10

Nominal pressure:

up to DN50 max. 16 bar
from DN65 max. 10 bar
from DN125 max. 8 bar
from DN150 max. 7 bar
from DN200 max. 5 bar
from DN300 max. 4 bar


max. 300°C (depending on gasket selection)


Optional versions are possible.

Table: Dimensions and weights


BL = Overall length / LK = Bolt hole circle / B = Number of bolts / D = Flanges Outer diameter

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Tubular Sight Glass type 620 PN10/16