Dosing unit


Particle and droplet size analysis from aerosols generated by DPI’s, MDI’s, nebulizers, pump and propellant gas sprays with INHALER

The INHALER is a versatile adapter for the investigation and the development of all kinds of metered dose inhalers (MDI), dry powder inhalers (DPI), nebulizers or more recent developments such as superfine mist inhalers (Soft Mist™ Inhaler | SMI). When combined with compact laser diffraction sensor HELOS/BR the system analyses the size distribution of droplet mists and solid aerosols with particles ranging from 0.25 µm to 875 µm.

The central components of the INHALER comprise – alongside a base unit in which the other components are integrated – the measuring chamber and the software-controlled vacuum control unit, which ensures precise control of the volumetric flow. Nebulisers with slanting mouthpieces can be vertically aligned with a tilt compensation feature in the central unit. A large selection of system components allows the system to be adapted to different application conditions and further analysis requirements.

Inlet side | Before the measuring zone

  • Mouthpiece – accurately fitting holders and mountings for applicators | individual mountings can be manufactured from silicone compound
  • Extension cylinder – for adapting the distance between the mouthpiece and the measurement volume (spacer)
  • 90° glass pipe bend – simulation of the throat, horizontal installation position also with pre-separator
  • Pre-separator for DPIs – in order to separate the carrier material from the active ingredient component under measurement (Fine Particle Fraction | FPF)

Discharge side | After the measuring zone

  • Venturi meter – for precise measurement of the air throughput
  • Fine particle collector – for recovery of the active ingredient component from the air flow for further quantitative and qualitative analyses | Reliable separation with ultrafine separation at flow rates of up to 200 l/min
  • Washing bottle – for recovery or separation of all particles at flow rates of up to 60 l/min
  • Vacuum pump – for reliable generation of volumetric flows for the different flow rate and passage conditions required for in vitro simulations | Needle valve for precise control of the volumetric flow from 20 to 200 l/min

The vacuum pump simulates the breath being drawn and creates a vacuum in the INHALER system, which ensures a controlled flow of air. For inhalers with a low flow resistance (typically MDIs or nebulizers) the volumetric flow is determined and controlled via measurement of the differential pressure in the venturi nozzle. In the case of inhalers with a high flow resistance (typically DPIs), control is provided by measuring the absolute pressure. Both the volumetric flow and the ambient temperature, relative humidity and any tilting of the applicator are recorded for every measurement.

Typical Configuration


Aerosols | Sprays
Size range: 0.25 µm - 875 µm
Method: Laser Diffraction

Suited for

Applied for control of

Via an angled connection piece (induction port) it is possible to connect different types of cascade impactors downstream (e.g. Andersen Cascade Impactor (ACI), Next Generation Impactor (NGI)) in order to demonstrate the corresponding correlation between the methods.

The application software allows for integrated or time resolved measurements with up to 2,000 particle size distributions per second for the detection, analysis and presentation of highly dynamic processes, e.g. discharge performance in correlation to pressure drop and/or different flowrates.