Introduction
The sight glass is the service technician’s and driver’s window into the discharge system of a Feldbinder silo trailer. This compact fitting — a small aluminium body housing a borosilicate glass lens — allows visual inspection of whether bulk material is flowing freely, whether any blockage is developing, and whether the discharge is proceeding as expected, all without opening the tank.
On the EUT (horizontal cylinder, fully pneumatic discharge), the ability to observe material flow is genuinely practical: it lets operators detect a slowdown or a material hang-up early. On the KIP (tipping silo), where the pneumatic system works in conjunction with the tank tilting mechanism, the sight glass similarly provides visibility into how the discharge is progressing. The borosilicate glass lens is critical here — it must withstand pressure and the abrasive action of the flowing bulk material while remaining clear. This is why lenses and strainer cones are the key consumables in this category: a scratched or opaque lens loses its function and must be replaced.
PHS Magnum in Chorula near Opole supplies complete aluminium sight glass assemblies as well as replacement lenses and conical strainers as individual spare parts.
Construction and Materials
Aluminium sight glasses in two configurations:
| Design | Feature |
|---|---|
| Thread-thread (3 inch) | Classic design with borosilicate glass lens |
| Thread-flange | Version with flanged connection |
Spare parts:
| Component | Material | Sizes |
|---|---|---|
| Glass lens | Borosilicate glass | DN80 (3″), DN100 (4″) |
| Conical strainer | Stainless steel | DN80, DN100 |
Borosilicate glass provides resistance to pressure and abrasion; stainless steel strainers are suitable for applications with higher cleanliness requirements.
Sizes and Types
- Thread-thread sight glass — 3 inch, with borosilicate glass lens.
- Thread-flange sight glass — flanged connection version.
- Glass lenses — DN80 (3″), DN100 (4″).
- Conical strainers — DN80, DN100, stainless steel.
Compatibility with Feldbinder Silo Trailers (EUT/KIP)
- EUT — sight glass mounted on the discharge system of the horizontal tank; monitors material flow during pneumatic discharge.
- KIP — sight glass on the discharge system of the tipping silo; provides visibility into the discharge process during tipping with pneumatic assist.
Selection depends on the connection design (thread-thread or thread-flange) and the nominal size DN80/DN100, independently of the Feldbinder trailer type.
Role in Feldbinder Silo Trailer Operation
A sight glass tends to go unnoticed until the lens stops doing its job. In Feldbinder service practice, this component plays two distinct roles:
- Operational observation fitting — a clear, functional sight glass lets the driver monitor material flow during discharge in real time, without opening the tank. The harder the material is to discharge (prone to bridging or hanging up), the greater the value of this observation.
- Regular spare part — borosilicate glass lenses and conical strainers are wear items: the glass becomes opaque from abrasion by bulk material, and strainers need periodic replacement. Both are stocked separately as spare parts in DN80 and DN100 sizes.
This logic — complete sight glass assemblies plus individual lenses and strainers — means the fitting can be serviced without replacing the whole body when only the lens or strainer is worn. When selecting, we look at the connection design (thread-thread 3″ or thread-flange) and the nominal diameter.
Common Issues
- Scratched or opaque lens — abrasive bulk material fogs the glass; replace with a borosilicate lens (DN80/DN100).
- Cracked lens — caused by impact or overpressure; requires immediate replacement to prevent leakage.
- Blocked or damaged strainer — replace with a new stainless steel conical strainer.
- Leakage at the connection — verify the correct design (thread-thread/thread-flange) and check the connection seal.
Availability and Delivery
We stock sight glass assemblies, glass lenses, and conical strainers at our facility in Chorula near Opole (4 km from the A4 motorway, approximately 180 km from the German border). Borosilicate lenses DN80/DN100 and conical strainers are typically available from stock.
Delivery by courier throughout Poland and the EU; combined orders with pressure gauges and thermometers are possible. For pricing — ask for a quote.
Related Categories
- Glycerine Pressure Gauges — Pressure measurement instruments for Feldbinder discharge systems.
- Thermometers — stainless steel thermometers 63/100 mm.
- Inter-Flange Gaskets — flange gaskets in EPDM/NBR/Elapac.
- Feldbinder EUT Spare Parts — full range of spare parts for the horizontal silo trailer.
- See also: spare parts hub, silo trailer service — PHS Magnum.
See also: This category in the full PHS Magnum network catalogue (all brands) →
Author: Aleksy Pasternak — Managing Partner PHS Magnum, 20 years in the industry, ISO 9001:2015 internal auditor (DEKRA).
