Sight window for a food-grade tank
Hygienic requirements, CIP washing and materials that contact the product.
In food vessels the window must not create dead zones and must withstand regular washing and sterilization.
Product-contact materials are selected for the product and the treatment modes; material documents are often mandatory.
Typical conditions
- low pressure, frequent thermal washing cycles;
- CIP/SIP with alkaline and acidic stages;
- requirements to surface finish and cleanliness;
- fatty and protein products — different gasket resistance.
What visibility is required
Level, foam and washing pulsation control. Usually a circular window with lighting is sufficient; an oblong one suits tanks with the level along the axis.
Limits
- gaskets for the product and CIP agents (see the gaskets article);
- a construction without crevices where product accumulates;
- documents for product-contact materials.
Questions for the vessel designer
- which CIP/SIP mode is provided (concentrations, temperatures)?
- which hygienic certificates of materials are required?
- are lighting and a wiper needed?
Which classes to consider
Flanged DIN 28121-type fittings are convenient for maintenance and washing; the final hygienic version is confirmed by the fitting manufacturer.