Validating AIM-Based Instrumentation and Associated Measurement Techniques - Good Cascade Impactor Practices, AIM and EDA for Orally Inhaled Products - page 316

Fig. 10.38 Experimental set-up for the FSI with 500 mL additional dead volume Configuration A
investigated by Pantelides et al . ( From [ 42 ]— used with permission )

6

FSI
FSI + 500mL Config.A

Product 1

5

NGI

4

Product 2

3

Product 3

2

Product 4

1

0

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Time (sec)

Fig. 10.39 Pressure drop-elapsed time profiles at a nominal flow rate of 60 L/min for DPI products
1-4 ( From [ 42 ]— used with permission )

Ph. Eur. induction port [ 41 ]) with all of the DPIs. Pressure ramp rate is related to the
volume of air which is removed from the impactor before peak pressure drop is
attained during the stable flow rate-time portion of the measurement. Importantly,
changing the configuration, shape, and size of the extra dead volume added to the
FSI made a clear difference to the pressure ramp rate, as illustrated with a series of
measurements made with DPI product 1 (Fig. 10.40 ). Thus Configuration B, that