For AHEAR TEM collection, what is the acceptable flow rate range?

• A. 0.5-5 lpm
• B. 1-10 lpm
• C. 5-15 lpm
• D. 10-20 lpm

Answer: (B)

For TEM collection, the flow rate needs to provide enough air volume to capture a representative sample without overloading the grid or disturbing deposited particles. The AHEAR TEM protocol specifies a pump flow in the range of about 1 to 10 liters per minute. This range strikes a balance: it’s high enough to gather a meaningful sample for analysis, but low enough to keep particle loading on the TEM grid manageable and to prevent distortion or loss of particles during collection. Flow rates below 1 LPM may yield too few particles for reliable analysis, while rates above 10 LPM can overload the grid or cause sampling artifacts. So, 1–10 LPM is the appropriate range.