Vessel sight window vs flow indicator vs level gauge
Why these are different products and why they must not be mixed in one catalog or inquiry.
Short answer
A sight window is built into the wall or cover of a vessel to observe the medium. A flow indicator is installed on piping; a level gauge column is mounted on the side surface for level. Different products, different standards.
The site is dedicated to vessel sight windows; in-line indicators and level gauges are out of scope and are not included in the catalog.
Comparison
| Product | Where it is mounted | Task |
|---|---|---|
| Sight window | vessel wall or cover | observing the medium, foam, colour |
| Flow indicator | piping | presence and pattern of the flow |
| Level gauge column | vessel side surface | measuring the level |
Why the difference matters
Requirements to pressure, documents and mounting differ. An inquiry for a “DN 100 sight glass” in a piping context misleads the vendor.
What to do if in doubt
Describe the observation task and the object in the RFQ sheet — the vendor or designer will determine the product class. For vessel observation use the categories and series of this site.