Tunnel dryers for food processing
The parts of the specification an auditor will ask about.
A food-grade tunnel dryer differs from an industrial one in the details an auditor checks: stainless trays and wagons, a welded floor coved to the walls, filtered supply air, and a chamber that can be wet-cleaned between products. The drying itself runs the same 40–100 °C.
Indicative price of an industrial tunnel dryer, Ex-Works (EXW): USD 6,280–41,885
Shipping, customs clearance and local duties are extra. The final price depends on the configuration and is fixed in the written quotation.
What food-grade means in a drying chamber
The heat stage is already food-safe by construction — the exchange is indirect, so combustion gases never reach the product. Everything that remains is about what the air and the product touch after that, and it is decided by material choice and by geometry rather than by temperature.
The rule the whole specification follows is that every surface the product can contact must be cleanable to a wet standard and must not hold water afterwards. That is what drives stainless over mild steel, welded seams over fasteners, and coving over square internal corners.
The specification, item by item
| Item | Specification | Why it is that way |
|---|---|---|
| Trays | SS 304 angle frame, SS 304 woven mesh deck, 900 × 500 × 25 mm | Mesh drains and dries; a solid deck holds a film of wash water |
| Wagons | SS 304 throughout, 23 levels, 46 trays | Wheeled out for cleaning rather than cleaned in place |
| Tray pitch | 70 mm, giving a 45 mm free air channel per level | Below this the load shadows itself and the batch dries unevenly |
| Floor | SS 304 wearing deck, 1.5 mm, seam-welded and coved to the walls | No joint for product or water to sit in |
| Panels | 100 mm rockwool core, non-combustible A1 to EN 13501-1 | Fire rating and a wipeable facing in one build-up |
| Supply air | MERV 8 filtration ahead of the chamber | Dust carried in becomes a foreign body on a dried product |
| Doors | 40 mm fire-rated, stainless hinges, door and drop seals | Seals hold the pressure regime; hinges are the part that rusts first |
Cleaning between products
A chamber that has dried fish and is about to dry mango needs a full wet clean, not a wipe-down. Fish oil carries into the panel facing and into the mesh of the trays, and the aroma transfers to fruit at a level a buyer will reject even when the microbiology is clean.
The practical sequence is wagons out, trays through a wash, chamber surfaces washed and dried, filters changed, then a heat-up cycle on an empty chamber before the first product batch. Allow the better part of a shift. Where a processor runs two products in one season, this cost is the argument for zoning the line rather than sharing chambers.
- Aroma carryover. Fish, garlic, onion and chilli are the four that transfer; fruit and vegetable products are the ones that suffer for it.
- Allergens. Declared allergen changeovers need a documented clean and, for an export buyer, a validated one.
- Temperature step. Moving between fish at 45–50 °C and fruit at 65–70 °C is a recipe change on the PLC, not a mechanical one.
Zoning, and why it is decided before the slab is poured
Product should travel in one direction: intake and washing at one end, drying in the middle, grading and packing at the other, with no path that takes a finished product back through the wet area. This is trivial to design at the layout stage and close to impossible to retrofit once the building is up.
The same is true of running two product families on one site. Genuine separation means separate preparation areas, dedicated chambers, and independent waste and drainage streams. A single-product plant that is later asked to take a second product usually fails its first food-safety audit on exactly this point.
Specifications
| Parameter | Value |
|---|---|
| Batch capacity | 1,500 kg per standard tunnel chamber |
| Working range | 40–100 °C, held to a process setpoint |
| Air velocity | 2.0–3.0 m/s, product dependent |
| Product contact | SS 304 trays, wagons and wearing deck |
| Filtration | MERV 8 on supply air |
| Panel fire rating | 120 minutes; A1 non-combustible to EN 13501-1 |
| Warranty | 12 months from date of shipment |
This is the hygienic side of the industrial tunnel dryers platform. For the products it is built around see industrial mango drying system, fish and seafood drying and fruit and vegetable drying; for how the chamber count is arrived at, see sizing a tunnel dryer.
Where this equipment is used
The same equipment is specified across several product classes. These are the ones it is configured for most often:
industrial mango drying system, fish and seafood drying and fruit and vegetable drying.
Each of those pages carries the drying parameters, cycle times and quality targets for that product class.
Frequently asked questions
Is a tunnel dehydrator the same thing as a tunnel dryer?
Yes — dehydrator is the more common term in food processing and dryer the more common one in engineering, and both describe a chamber that takes a product to a target moisture. On this platform that means 40 to 100 °C at 2.0 to 3.0 m/s, holding a setpoint rather than simply blowing warm air.
Why stainless trays rather than galvanised or plastic?
Galvanised coatings degrade under repeated wet cleaning and shed zinc onto food. Food-grade plastics soften and distort well below the 100 °C top of the working range. SS 304 handles both the wash and the heat, which is why trays, wagons and the wearing deck are all specified in it.
Can the same chamber dry fish and fruit?
Thermally yes — both sit inside the 40 to 100 °C range, at 45–50 °C and 65–70 °C respectively. The constraint is aroma carryover, which survives a casual clean and transfers to fruit at levels an export buyer will reject. Budget most of a shift for a full wet changeover, or zone the line.
Discuss a food-grade drying line
Tell us the products, the season each one runs in and your daily fresh intake, and we will size the chambers and the zoning around them.
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