𝗪𝗵𝘆 𝘄𝗲 𝘀𝗵𝗼𝘂𝗹𝗱 𝘂𝘀𝗲 𝗶𝘀𝗼𝗸𝗶𝗻𝗲𝘁𝗶𝗰 𝗽𝗿𝗼𝗯𝗲𝘀 𝗳𝗼𝗿 𝘀𝗮𝗺𝗽𝗹𝗶𝗻𝗴❓
For particle monitoring & classification, isokinetic sampling -known as “stainless steel funnel”- should be used in unidirectional airflow conditions to provide correct measurement and maintain flow patterns.
As per the image below, where W represents airflow inside intake unidirectional flow and V represents airflow inside the sampling pattern. In the isokinetic cases (where W=V), all particles flowing toward the intake opening are equally collected. Also, unidirectional airflow patterns can be maintained under the isokinetic probe. If the sample taking velocity is too low (W>V) most of the particles will skip sampling patterns and will cause low particle reading. Excessive air accumulated around the isokinetic probe will cause turbulent air and will break unidirectional conditions. Similar to this, if taking velocity is too high (W<V) heavy particles will not follow their original pattern and can enter the probe due to high suction. This turbulent air will also be observed under the isokinetic probe level which disturbs unidirectional conditions.