Flow sight glass with double glazing type 531D

Short Description - Flow sight glass with double glazing and welding ends type 531 D

The ACI double-glazed flow sight glass type 531 D is based on the same proven design as the type 530 D and is therefore also considerably lighter than comparable valves with cast housings. As with Type 530 D, only high quality materials are used in a tightly controlled process from quotation to delivery to ensure that the fitting meets your requirements.

The double-glazed with opposing viewing windows of type 531 D offer increased safety compared to single-glazing and allow the observation and illumination of the flowing medium. In the standard configuration they consist of proven borosilicate glass in accordance with the DIN 7080 standard. If these highly resistant glasses do not meet your requirements, we manufacture special glasses made of borosilicate glass in accordance with DIN 7080, quartz glass or corundum or sapphire glass specially designed to meet your requirements. If an even higher level of safety is required, we also have sight glasses with safety double glazing such as type 586 in our product range.

Sealing is provided by quality gaskets from renowned suppliers, which we select according to the requirements of your individual application. Apart from the widely used fibre gaskets such as KlingerSIL C4400, we also use graphite gasket sheets with and without metal inserts, pure or expanded PTFE, or mica composite gaskets under extreme operating conditions.

Simply contact our team of experts with your requirements and let them advise you on the possibilities that our product range offers you for your plant!

Also have a look at the product video of the Type 531D.

Technical data


WN 1.4539, 1.4541, 1.4571, 1.4404, P235GH, P265GH and many more.


Borosilicate glass DIN 7080
Soda-lime glass DIN 8902
quartz glass

Graphite (other materials available)


Flow sight glasses with welding ends as welded construction

Nominal size:

DN50- DN400

Nominal pressure:

PN10, PN16, PN25, PN40, PN63


280°C with borosilicate glass DIN 7080
150°C with soda lime glass DIN 8902
up to 500° with quartz glass

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Sight glass double glazing Type 531 D