High pressure flow sight glass Type 520 | ACI Industriearmaturen GmbH

High-pressure flow sight glasses Type 520

Short description - high-pressure flow sight glass fitting

The ACI high-pressure flow sight glass fittings of Type 520 have a solid casing that is manufactured of various materials, starting with high temperature constructions steel P250GH (1.0460), as well as stainless steels such as 1.4541, 1.4571 or acid-resistant special steels such as 1.4539. According to the pressure level, flanges according to DIN EN 1092-1 are welded on and tested as part of the AD2000 guideline. On request, other materials such as nickel-based alloys like Hastelloy can also be supplied for the greatest wear. The fittings are usually made with two viewing windows, which makes it possible to observe the processes from two sides, as well as an illumination of the process medium.

The standard model has a sight glass manufactured specially for your use, made of thermally hardened borosilicate glass 3.3 or highly temperature-resistant quartz or sapphire glass. The sealing is ensured using flat seals selected especially for your use, according to temperature and chemical load, for example made of graphite (novaphit MST XP) or mica-based seals.

Owing to the solid casing, our Type 520 flow sight glass can be fitted with ducts for measuring devices or additional process connections (e.g. female thread).

In the standard version, Type 520 is designed for up to 160 bar in relation to DIN EN 1092-1. If your process requires a higher operating pressure, simply make an enquiry. The sight glass casing and the glass panels can (depending on the size) be suitable for up to 1000 bar operating pressure.

Type 520 is pre-assembled at the factory and is subject to a pressure test under a 1.5-fold nominal pressure.

Watch the animation video or look at the tecnical data.

Technical data


1.0460 / 1.4301 / 1.4306 (F304L) / 1.4404 (F316L) / 1.4410 (Super Duplex) / 1.4435 (F316L) / 1.4462 (F 51) / 1.4529 (Alloy 926) / 1.4539 (Alloy 904L) / 1.4541 (F321) / 1.4547 (F44) / 1.4550 (F347) / 1.4571 (316Ti) / 1.4828 / 1.4841 / 1.4876 ( Alloy 800H) / 1.4878 / 1.7335 / 2.4068 (Alloy 201) / 2.4360 (Alloy 400) / 2.4375 (Alloy K500) / 2.4602 (Alloy C-22) / 2.4605 (Alloy 59) / 2.4610 (Alloy C-4) / 2.4816 (Alloy 600) / 2.4819 (Alloy C-276) / 2.4856 (Alloy 625) / 2.4858 (Alloy 825) / 3.7035 (Titan)

Nominal size:

DN 15 to DN 200 (The design is order-related. Not every nominal pressure is possible at any size)

Nominal pressure:

PN63, PN100, PN160, PN250, PN400


The design is order-related.


With borosilicate glass up to max. 280 ° C
With quartz glass up to 500 ° C
(Higher temperatures on request)


Straight through flow sight glasses
Optionally available in three-way or four-way shape.


Optional versions are possible.

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High pressure flow sight glass Type 520