Three-way flow sight glass type 590

Short description - Three-way flow sight glass type 590

The ACI three-way flow sight glass Type 590 is based on the solid structure of our proven high-pressure sight glass Type 520. Type 590 has an additional process connection and viewing windows adapted to the operating conditions.

As the 3-way sight glass Type 590 makes use of the solid casing structure of Type 520, it is also possible to fit additional connections / measuring connections with a female thread or ducts for measuring probes if required.

For our casing we only use high-quality stainless steel and steel with pressure container approval according to AD2000. Our sight glasses are available for example in the highly corrosion-resistant 1.4571, especially acid-resistant 1.4539, special alloys such as Hastelloy or duplex steels and many other materials. We can also supply special material according to your specific requirements. Simply make an enquiry.

Type 590 has the same proven borosilicate glass DIN 7080 as our other fittings. Insofar as your process conditions allow, we equip our devices with glass according to DIN 7080 for round sight glass panels made of borosilicate glass with thermal prestressing, but glass panels in special sizes similar to to DIN 7080 for increased pressure, quartz and sapphire glass for very high temperatures, or metal-fused “meta glass” are also part of our product spectrum.

To seal our Type 590 sight glass, we use high-quality flat seals by well-known manufacturers such as Frenzelit novaphit MSTXP with TA air approval, KlingerSIL C4400 with DVGW approval, Garlock Gylon or virginal PTFE for chemically challenging applications, as well as mica compound materials for very high temperatures.

Like our other sight glass types with round viewing windows, Type 590 can be equipped with wipers, lighting or other accessories.

Read on for more detailed technical information and take a look at our animation video or our 3D animation.

Technical data


Body made of 1.4571, 1.4404 or carbon steel


Three Way Sight Glass

Nominal size:

DN15-100 (Larger sizes available as special design)

Nominal pressure:

PN16, PN40 (higher operating pressures on request)


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


Optional execution also in vacuum, available with lighting, with metal fused glasses with wiper or test bores


Optional versions are possible.

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ACI three-way flow sight glass type 590