Tubular sight glass DIN 11851 Type 645 | ACI Industriearmaturen GmbH

Tubular sight glass type 645 with connections according to DIN 11851

Tubular sight glass fitting with connections according to DIN 11851

The heart of the ACI tubular sight glass type 645 is a glass ring made of borosilicate glass 3.3 or acrylic glass which is enclosed between two stainless steel flanges with connections according to DIN 11851. Due to this construction the type 645 enables a 360° observation and illumination of the process medium.

The standard version of the tubular sight glass type 645 is supplied with flat gaskets made of pure PTFE (Teflon®), but we also have soft-material gaskets such as EPDM or NBR in stock. If our standard range of gaskets does not meet your requirements, simply ask us about your special requirements and we will work with you to select the perfect special material.

As flange material we use the highly resistant quality stainless steel 1.4404. These flanges are held together and supported by solid A4-70 grade stainless steel screws to ensure the best possible valve life.

The sight glass can easily withstand a nominal operating pressure of up to 16 bar up to a nominal diameter of DN 150. Larger nominal sizes are available on request.

Since the flange, gasket and glass are precisely matched to each other, the tubular sight glass type 645 is almost completely free of dead space and is therefore also well suited for applications that place high demands on cleanliness.

Our tubular sight glasses are completely assembled in our workshop and subjected to a pressure test at 1.5 times the operating pressure. Maintenance after installation is usually not necessary.

Technical data


Flanges: 1.4404 or 1.4301/7

Screws: A4-70

Glass: Borosilicate glass 3.3

Gasket: Viton, PTFE, EPDM, graphite or according to agreement.

Nominal size:

DN 15-150

Nominal pressure:

PN 16


max. 280°C (depending on gasket selection,
higher temp. on request)


Optional versions are possible.

Request an offer
+49 (0) 2461 91634 00
Offer request Offer
Data sheet download Data sheet
Productvideo Productvideo
Tubular sight glass DIN 11851 Type 645