IKA A 11.7 Filling Funnel, stainless steel, for A 11 basic, 0003048700

Bulk material mechanics and gravimetric mass flow

In analytical sample preparation, the introduction of granular, crystalline or particulate solids into the grinding chamber requires precise control of bulk material behaviour. The IKA A 11.7 feed hopper is geometrically designed to channel the gravimetric mass flow of the sample material into the IKA A 11 basic analytical mill. The specific slope angle of the hopper overcomes the internal friction (angle of repose) of most dry solid matrices and reliably prevents physical bridging (blockage) at the inlet. This guarantees a continuous, jam-free and, above all, loss-free feed of the sample into the rotor’s active kinetic comminution zone.

Thermodynamic compensation and cryogenics

High-speed impact grinding generates significant frictional heat, which inevitably leads to structural denaturation, molecular degradation or melting of the matrix in temperature-sensitive samples (exothermic reaction). The IKA A 11 basic is designed and approved for cryogenic grinding. The A 11.7 feed hopper serves as an essential thermodynamic lock component in this process: It enables the safe, controlled and metered introduction of extremely cold cooling media – specifically dry ice pellets (solid carbon dioxide at -78.5 °C) or liquid nitrogen (LN2 at -196 °C) – directly into the grinding chamber. The extreme thermal shock stresses (temperature gradients) to which the material is subjected during cryogenic dosing are compensated for by the molecular structure of the stainless steel, without the hopper becoming brittle (cold fracture).

Tribological resistance and electrostatic properties

When feeding highly abrasive materials (such as quartz sand or ores), a plastic hopper is subject to immediate tribological wear. The A 11.7 is manufactured entirely from solid, corrosion-resistant stainless steel. This single-material design not only prevents mechanical abrasion (carry-over) but also eliminates triboelectric charging. Plastic hoppers tend to build up significant static charge when dry dusts rub against them, causing the powder to agglomerate physically on the walls. The earthed stainless steel insert immediately dissipates these electrostatic charges, ensuring a residue-free sample flow and enabling complete thermal sterilisation in an autoclave after analysis.

Technical details

• Product type: Analytical feed funnel
• Process function: Gravimetric mass flow control of bulk materials
• Thermodynamic benefit: Dosing of cryogenic media (dry ice, liquid nitrogen)
• Material: Solid, highly wear-resistant stainless steel
• Tribology: Absolutely abrasion-resistant against hard, mineral matrices
• Physical advantage: Prevents triboelectric (static) charging of powders
• Compatibility: Exclusively compatible with the IKA A 11 basic analytical mill
• Hygiene and sterilisation: Fully thermally autoclavable and solvent-resistant

Contents

• 1 x IKA A 11.7 feed hopper (stainless steel)

(Important note: The IKA A 11 basic analytical mill and cryogenic cooling media are not included in the scope of delivery!)

Individual requirements & accessories

The A 11.7 feed hopper is purely an infrastructural accessory. It is of greatest process-related significance during cryogenic sample preparation. When dispensing liquid nitrogen (LN2) into the mill via this hopper, the thermodynamic expansion characteristics of cryogenic gases must be strictly observed. To ensure compliance with laboratory safety regulations (Occupational Safety), we recommend the use of cryogenically certified protective gloves and eye protection when handling these media. Please contact our procurement service at any time for assistance with the safe configuration of your cryogenic grinding process.