At a glance
Aluminium inspection sight glasses for silo trailers in two designs - thread-to-thread (3 inch) and thread-to-flange - with borosilicate glass. Glass discs (DN80/DN100) and stainless steel conical strainers (DN80/DN100) are offered separately as spare parts, so the most common repair - replacing a scratched or cloudy glass - doesn’t require importing the whole sight glass. A sight glass is selected by connection type and size, not by trailer brand. Popular items off the shelf in Chorula near Opole.
Introduction
The sight glass is an inspection window seated in the silo trailer’s installation — through the borosilicate glass the operator can see whether the material is flowing correctly and whether the tank has been emptied, without opening the manholes. Across the entire network of brands we service at PHS Magnum, this component performs the same function, no matter whose plate the trailer carries. What differs is mainly how the socket is seated and the connection type, while the sight glass itself remains a simple but important viewing instrument while the tank works at operating pressure.
We look at sight glasses from the perspective of a mixed fleet, not a single manufacturer. For us it’s a family of components: two sight glass designs plus two sizes of glass discs and strainers available separately as spare parts. This lets one supply source serve workshops and fleets where trailers of different brands work side by side — and the most common repair, replacing a scratched or cloudy glass, doesn’t require importing the whole sight glass from abroad.
Specification
We offer aluminium sight glasses in the classic thread-to-thread design (3 inch) with borosilicate glass, as well as thread-to-flange sight glasses. As spare parts we carry glass discs and conical strainers separately.
| Component | Material | Size / type |
|---|---|---|
| Thread-to-thread sight glass | aluminium + borosilicate glass | 3 inch, classic design |
| Thread-to-flange sight glass | aluminium | flanged connection |
| Glass disc (spare part) | borosilicate glass | DN80 (3 inch), DN100 (4 inch) |
| Conical strainer (spare part) | stainless steel | DN80, DN100 |
The body of the classic sight glass is made of aluminium — a light, corrosion-resistant material common in silo trailer equipment. The transparent element is borosilicate glass, combining clarity with resistance to scratching and thermal loads, which matters in constant contact with an abrasive cargo. Sight glasses are one of the few inspection equipment categories for which we quote specific numerical sizes of glasses and strainers — DN80 and DN100.
Brand compatibility
A sight glass is selected by connection type and size, which is why one offering covers many silo trailer brands:
- Spitzer (SF/SK) — inspection sight glass in the tank wall of the SF series (non-tipping) and SK (with a lifting tank).
- Feldbinder (EUT/KIP) — sight glass on the discharge system of the horizontal EUT tank and the tipping KIP silo; on food-grade versions full clarity of the glass is essential.
- Kässbohrer (K.SSK/K.SSL) — viewing sight glass in the discharge system with typical connections.
- Other brands — wherever a classic 3-inch thread-to-thread socket or a flanged connection is found, the same range of sight glasses and glass discs fits.
Because the sight glass is a universal instrument, selection is not decided by the trailer manufacturer’s name but by the connection type (3-inch thread-to-thread or thread-to-flange) and — for spare parts — the DN80 or DN100 size. These determine the fit of the glass disc and strainer, so it’s worth stating them when ordering.
Glass disc replacement — work sequence
Replacing a scratched or cloudy glass disc is the most common sight glass repair and usually a simple workshop operation:
- Depressurising the installation — make sure the tank and piping are not at working pressure.
- Unscrewing / detaching the sight glass — the thread-to-thread version is unscrewed by the body, the thread-to-flange version by breaking the flanged joint.
- Replacing the glass and the seal — the glass is selected by size (DN80 or DN100); it’s a good moment to also replace the conical strainer if it is clogged or damaged.
- Reassembly and leak check — refit and check the joint at working pressure.
In the thread-to-flange version the joint is closed off by a flange gasket matched to the DN diameter. The sight glass is one of the discharge system’s inspection instruments alongside glycerine pressure gauges and thermometers - it’s worth inspecting and ordering these components together. You’ll find the full list of categories in the spare parts catalogue.
Chorula warehouse
We stock sight glasses, borosilicate glass discs and conical strainers at our warehouse in Chorula near Opole (4 km from the A4 motorway, approx. 180 km from the German border). Aluminium 3-inch thread-to-thread sight glasses plus DN80/DN100 glass discs and DN80/DN100 stainless strainers are usually available off the shelf, while less typical builds come via direct supply. We ship by courier across Poland, the European Union and the DACH market, and handle grouped orders together with other inspection instruments — pressure gauges and thermometers. To select the right sight glass or spare part — ask for a quote, stating the connection type and size.
Specialist portals
More detailed guidance on matching sight glasses to specific brands is available on our specialist portals: Spitzer and Feldbinder.
Contact
Selection and shipping of sight glasses, borosilicate glass discs and conical strainers - the silo trailer parts warehouse in Chorula near Opole. State the connection type (3-inch thread-to-thread or thread-to-flange) and the DN80/DN100 size, and we’ll prepare an offer and a dispatch date. Ask for a quote.
Related categories
- Glycerine pressure gauges
- Thermometers
- Flange gaskets
- Spare parts catalogue
- PHS Magnum silo trailer service
Author: Aleksy Pasternak — Managing Partner at PHS Magnum, 20 years in the industry, internal auditor ISO 9001:2015 (DEKRA).
