Fluidisation
systems

A fluidisation nozzle – also called an aeration nozzle – injects air directly into a bulk material and loosens it so that it keeps flowing. Fluidisation (also spelled fluidization) works in three steps: the nozzles introduce air into the product, the bulk material is fluidised so that caking and bridging are prevented, and discharge stays consistent. Without aeration, poorly flowing materials form bridges in the silo cone and discharge stalls. RATEC fluidisation nozzles in sintered metal and silicone are used in silos and storage tanks, vessels, conveyors, chutes and pipes, and in packaging and filling – for example with flour, sugar, grain, fertiliser, cement or plastic granules.

Targeted aeration prevents bridging, caking and blockages, giving a uniform, trouble-free material flow in silo and conveying systems. In addition, the optimised air distribution of RATEC fluidisation systems reduces air demand and saves energy, less dust build-up and fewer blockages minimise explosion risks, and robust, abrasion- and corrosion-resistant materials make the nozzles durable and low-maintenance. Installation is modular, from inside or outside. In chemical and pharmaceutical processes, optimised air flows also mean less dust formation with powders and granules, and when filling big bags, containers or cartons the aeration stays uniform.

Fluidisation nozzles are mainly made of sintered metal or silicone, complemented by aeration bars for poorly flowing products. In sintered metal, RATEC supplies the KBDS-25 sintered nozzle for a Ø21 mm bore, the KBSS-25, -50 and -80 socket fittings (Ø1″, 2″ and 3″) and the KSS-80 flanged fitting (DN 80) for larger nominal diameters. The silicone range comprises the standard nozzles KBD-30, -60 and -100 (Ø30, 60 and 100 mm) for internal mounting, the external-mounting versions KBD-60A and -100A, and the high-temperature versions KBD-30H, -60H and -100H for up to +200 °C. A stainless steel aeration bar in 500 or 1,000 mm length completes the range.

Sintered metal nozzles suit high mechanical loads and abrasive bulk materials, while silicone nozzles provide flexible, self-closing aeration in silos, vessels and conveying systems. RATEC sintered aeration is made of highly porous stainless steel (1.4305/1.4404 or 1.4301/1.4404) with high air permeability and strength, runs silently and is ideal for chemicals and pharma. On silicone nozzles, the silicone sleeve opens under air pressure and closes automatically when the pressure drops, so no product stays trapped in the nozzle. They operate at 1–6 bar from −60 °C to +80 °C, or up to +200 °C in the high-temperature version. The aeration bar is rated for up to 250 °C and 6.0 bar, with higher ratings on request.

Yes – fluidisation nozzles can be supplied in ATEX-compliant versions for potentially explosive atmospheres and with FDA-compliant materials for food and pharmaceutical applications. All RATEC silicone fluidisation nozzles are FDA-compliant as standard, made of silicone and stainless steel 1.4305, and therefore suitable for food and pharma; an ATEX-compliant version is available on request. For sintered aeration, both an ATEX-compliant version and FDA-compliant, product-contacting materials are optional – on request for almost all RATEC fluidisation systems. For the aeration bar, special materials, other sizes and higher temperature and pressure ratings are available on request.

For poorly flowing bulk materials, an aeration bar helps: it releases air along its entire length and combines fluidisation with mechanical discharge by impulse flow. The RATEC aeration bar in stainless steel (1.4301/1.4571, air connection G1/2″) is easy to retrofit into existing silo systems, works with almost every product and cleans itself well thanks to the high air flow. Besides fluidisation and discharge, it is used for drying or fogging of products, degassing or inerting in Ex areas, and preheating for further processing. For retrofitting individual nozzles, the silicone version KBD-A with external mounting bolts can be installed from outside.

A silicone fluidisation nozzle costs roughly EUR 60 to 115 net per piece, depending on size and design. At RATEC, standard and high-temperature nozzles cost less than EUR 100 even as single units, while nozzles for external mounting are slightly more. Volume pricing applies from 10 pieces, and installation instructions in German and English are always included. The cost of a complete silo aeration system depends mainly on how many nozzles your silo needs, as well as on material, temperature and any ATEX or FDA requirements. Sintered metal nozzles and aeration bars are quoted individually after a short clarification. All prices exclude VAT and are ex works.

Start by clarifying four points: the bulk material (product, flow behaviour, abrasiveness), the installation point (silo, cone, vessel, conveyor), temperature and pressure (operating conditions, air supply) and requirements such as ATEX, FDA or mounting from inside or outside. On this basis RATEC advises you on the best material and nozzle configuration and finalises the design together with you. RATEC fluidisation systems are used in the food industry (e.g. flour and sugar), pharmaceuticals, the chemical, building materials (e.g. cement) and recycling industries, and in packaging and filling. Contact us