21 Aug 2019

Choosing the right particle counter for the application can be confusing with so many options on the market. This mini-guide will help users understand the factors that user should consider when making the choice.

Finding the Right Fit

  • Scenario #1: The user has been tasked with finding a particle monitoring solution for a construction site. The user mainly needs to measure particles generated from cutting wood and similar materials. What kind of instrument does the user need?
  • Scenario #2: The user works in a cleanroom and needs to measure aerosol particles. What type of counter best meets this application?

There are four main factors that will influence the choice of particle counter:

  • The first consideration is the particle size(s) that must be monitored. This is partially determined by the ISO class of the testing/monitoring environment. There are ISO classes that correspond with cleanrooms, workplaces, manufacturing facilities, and more.
  • Another factor is the customer’s needs. Typically a customer will chose one or two particles for the certification test (if the user needs help choosing which particle sizes to monitor please refer to the ISO standard). When purchasing the particle counter user will need to check the specifications to ensure the instrument can measure particles of the appropriate size(s). Make sure the user chooses a particle counter that can measure all the particle sizes that need to be monitored.
  • The third factor is measuring location. Will the instrument be monitoring a specific area at all times? Will the user need to take it with the user to spot-check different areas?
  • The last factor that user’ll want to consider is the flow rate capability of the particle counter. To do that users need to consider one of the formulas from the ISO standard.

Getting Into the Math

This formula will calculate how many liters of air need to be sampled at each location in a cleanroom:

Formula: Vs = (20/Cnm) x 1000

  • Vs = the minimum single sample volume per location, expressed in liters.
  • Cnm = is the class limit (number of particles per cubic meter) for the largest considered particle size specified for the relevant class.
  • 20 = the defined number of particles that could be counted if the particle concentration were at the class limit.