INTRODUCTION

MOUDI-II and NanoMOUDI-II cascade impactors are second generation MOUDI impactors and NanoMOUDI impactors. Both series of impactors are precise, high accuracy devices designed for sampling and size-fractionation of airborne particles for gravimetric and/or chemical analysis. The primary difference is the use of internal embedded stepper motors to rotate the impaction plates by the second generation MOUDI-II impactors and the use of external mechanical gear rotation in the original MOUDI cascade impactor, which is offered as an 8 stage or 10 stage cascade impactor.

Both series MOUDI and NanoMOUDI impactors are referred to as Micro-Orifice Uniform Deposit Impactors, since they use micro-orifice nozzles for jet acceleration, and are available with the uniform deposit feature by rotating the impaction plates with respect to the nozzles to spread out the particle deposit uniformly on the collection substrates. The uniform deposit prevents heavy particle build-up under each nozzle to reduce particle bounce and blow-off that may otherwise occur. The micro-orifice nozzles used in these impactors reduce the jet velocity, pressure drop, particle bounce, and evaporative loss.

The original MOUDI series of cascade impactors are noted for their superior aerodynamic design, sharp cut-size characteristics and low inter-stage particle losses. These features, together with their accurate cut-size calibration, have made the MOUDI impactor, the cascade impactor of choice for high quality environmental research. The same characteristics are retained in the MOUDI-II impactors.

PRODUCT HIGHLIGHTS

Model 120-R MOUDI-II is a 10 stage, 30 L/min impactor with internal embedded stepper motors for the rotation of the impaction plates. This impactor is a second generation MOUDI Model 110-Rotating cascade impactor.

Models 122-R & 122-NR NanoMOUDI-II impactors are 13 stage, 30 L/min impactors. The Model 122-R has internal embedded stepper motors for the rotation of the impaction plates, while Model 122-NR is a non-rotating cascade impactor with stationary impaction plates.

Models 125-R & 125-NR NanoMOUDI-II impactors are 13 stage 10 L/min impactors. The Model 125-R has internal embedded stepper motors for impaction plate rotation, while Model 125-NR has stationary, non-rotating impaction plates. Models 120-R, 122-R and 125-R have electronic control for stage rotation, and built-in sensors that continuously monitor the ambient temperature and pressure during sampling. Absolute pressure sensors monitor the pressure in the micro-orifice stages and the stability of flow. Should the micro orifice nozzles of a stage become partially clogged during sampling, change in stage pressure drop will be quickly noted. Built-in electronics oversees the entire instrument operation and records environmental and pressure data generated for post sampling review.

FEATURES

• Sampling flow rate:
  - Models 120-R, 122-R, & 122-NR: 30 L/min
  - Models 125-R & 125-NR: 10 L/min
• Size intervals and stage cut-sizes
  - four equal geometrical increments per decade of particle size
  - Model 120-R: 0.056, 0.1, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10 m
  - Models 122-R & 122-NR: 0.01, 0.018, 0.032, 0.056, 0.1, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10 and 18 m
  - Models 125-R & 125-NR: 0.01, 0.018, 0.032, 0.056, 0.1, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10 m
• Easily removable collection substrates allow for rapid run turn-around times for high productivity
• Models 120-R, 122-R, & 125-R:
  - Volumetric flow control
  - Programmable logic controller (PLC) controls instrument operation including start- and stop times.
  - Temperature and pressures are measured and stored at pre-determined time intervals.
  - Absolute pressures are monitored on the lower stages to provide indication for possible clogging of nozzles as small as 50 m in diameter
• Sharp cut-off characteristics
• Low inter-stage losses
• Up to 6000 micro-orifice nozzles to reduce jet velocity and pressure drop

APPLICATIONS

• Sampling of atmospheric aerosols for research and environmental monitoring
• Work place aerosol analysis
• Diesel emission analysis and monitoring
• Exposure monitoring
• Industrial hygiene studies