A second and larger version of the Sampling Apparatus for MDIs, capable of sampling at a variety of flow rates up to 100 L/min, is available for use with Dry Powder Inhalers (DPIs).
In the case of the system for DPIs however, an electrically operated, timer controlled, two-way solenoid valve (Critical Flow Controller) is positioned in the line between the collection tube and the vacuum pump to control the air flow supply to the inhaler and to ensure that critical (sonic) flow conditions are maintained during testing.
This allows the time that the test flow is applied to the inhaler to be adjusted to a specific volume, for example 4 litres, thus equating to human inspiration.
This is necessary because unlike MDIs, the majority of DPIs are passive breath-actuated devices which rely on the patient’s inspiration rather than a propellant for dose emission.
The Dose Unit Sampling Apparatus (DUSA) for DPIs utilises the same materials and is of similar construction to that of its MDI counterpart.
For comprehensive product details, specifications and part numbers, please request a copy of our brochure “Quality Solutions for Inhaler Testing”.