Applied Physics
Model 110 MOUDI Cascade Impactor, 56nm - 18um, 30LPM
Model 120 MOUDI-II Impactor, 56nm - 18um, 30 LPM
Model 122 NanoMOUDI Impactor, 10nm-18um, 30 LPM
Model 125 MOUDI Cascade Impactor, 10nm-18um, 10 LPM
Model 130 HFI, High Flow Impactor, 250nm- 2.5um, 100 LPM
Aerosol research and particle sampling

Cascade Impactors, Nano-MOUDI

MOUDI Impactor, Cascade Impactor, NanoMOUDI

Please visit our main site at Applied Physics, which provides information on the Cascade Impactor and Nano-MOUDI. Cascade Impactors come in a variety of performance capabilities, ranging from 10 LPM to 100 LPM flow rates and size ranges from 10nm up to 18 microns. Cascade Impactors are used for indoor and out door particle sampling, such as particle research, smoke stack analysis, and more. The Cascade Impactors are well known as the MOUDI Impactor, NanoMOUDI and MOUDI-II (MOUDI, MOUDI II, NanoMOUDI, NanoMOUDI II, HFI and High Flow Impactor are MSP trademarks), which are second generation cascade impactors. Both the MOUDI-II and the original MOUDI impactor are precision cascade impactors for high accuracy aerosol sampling in order to collect size-fractionated particle samples for chemical and gravimetric analysis. The major difference between the cascade impactors is the use of internal stepper motors in the MOUDI-II to spread out the particle deposit to achieve a nearly uniform deposition on the collection substrate, while in the original MOUDI impactor, such as the M110 Rotating Impactor, external mechanical gear rotation is used to achieve the uniform particle deposition.

Cascade impactors use micro-orifice nozzles to reduce jet velocity, pressure drop, particle bounce, re-entrainment and evaporative loss. Up to 2,000 micro-orifice nozzles as small as 50 microns in diameter are used in the 10 LPM Model 125. In the 30 LPM Model 122 up to 6,000 micro-orifice nozzles of 50 microns diameter are used. The original MOUDI 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 impactor of choice for high quality aerosol and environmental research. The same characteristics are retained in the MOUDI-II impactors. Both the Model 122 and Model 125 MOUDI-II impactors have 13 impactor stages, with the Model 122 operating at 30 LPM sampling flow rate, while the Model 125 at 10 LPM flow rate. They both are available in the rotating version (122-R and 125-R) and in the non-rotating version (122-NR and 125-NR). In addition 10-stage versions of the 30 LPM MOUDI-II are available for sampling to a lower size limit of 56nm, in the rotating (120-R), and non-rotation (120-NR) versions. Model 120-R MOUDI-II is a 10 stage, 30 LPM impactor with internal embedded stepper motors for the rotation of the impaction plates. This impactor is a second generation MOUDI Model 110-R impactor. Models 122-R & 122-NR NanoMOUDI-II impactors are 13 stage, 30 LPM impactors. The Model 122-R has internal embedded stepper motors for the rotation of the impaction plates, while Model 122-NR has stationary 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.

The rotating versions of the MOUDI-II impactors are 2nd generation MOUDI impactors using individual stepper motors embedded in each stage to rotate the collecting substrate for uniform deposition. Power for the stepper motors comes from a single electronic package in the instrument cabinet, with power distributed to the individual motors by miniature flat-ribbon cables. Figure 1 shows a typical rotating stage and Figure 2, a photograph of the stage with the uniform particle having been deposited on the center circular area. Please go to our main link at Applied Physics.

All MOUDI-II impactors have the same aerodynamic design as in the original MOUDI impactors that has led to sharp cut characteristics (see left chart) and low inter-stage wall losses. The available impactor cut-sizes are: 0.010, 0.018, 0.032, 0.056, 0.10, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6, 10 & 18 microns. Because the motors in the MOUDI-II impactors are internal at each stage, each stage can be operated independent of the others and can be added or removed to suit the individual measurement needs. However, removing a high pressure-drop stage from the cascade impactor can cause the absolute pressure and the cut-size characteristics to change for down-stream micro-orifice stages. For this reason, only the upper stages with cut-size ≥0.56 microns should be considered for removal where necessary.

The Models 120-R, 122-R & 125-R are provided with instrument cabinets that also house the electronics for controlling the volumetric flow, monitoring and recording the output of the six pressure transducers for absolute pressure monitoring at the more critical micro-orifice stages. The absolute pressure indicates possible flow instability due to nozzle clogging or leakage in the system. These features insure the high quality samples are collected that would lead to high data quality for the collected particle samples. For applications that do not require stage rotation, Models 122- NR and 125-NR can be ordered with mechanical guages.

The Model 130 Hi-Flow Impactor (HFI) is a precision, 100-LPM cascade impactor for sampling and classifying aerosol particles. It was developed for the Navy (ONR) for airborne sampling on an aircraft, it has a compact, lightweight and low pressure drop design. It also features multiple-nozzle patterns to allow collected particle samples to be subdivided into two or four equal parts for compositional analysis by different techniques. The impactor has been flown successfully in several research missions , such as ACE-Asia, producing valuable, useful data for atmospheric and climate research. The Model 130 provides the same sharp cut-size characteristics as the Model 100 & M110 Micro-Orifice Uniform-Deposit Impactors (MOUDI). However, at 100 LPM, the Model 130 has more than three times the flow rate of the Models 100 and 110. The Hi-Flow Impactor is a five-stage cascade impactor operating at a sampling flow rate of 100 LPM for applications where cascade impactors with traditional 30 LPM flow rate will not suffice to provide sufficient particle samples for analysis. The impactor has five stages with cut-point diameters of 0.25, 0.44, 0.77, 1.4, and 2.5μm. Deposits are collected in four 90 degree quadrants on 75-mm substrates. The substrates can be divided into two or four equal parts for compositional analyses by different techniques. The impactor is made of anodized aluminum to insure dimensional stability of the nozzles with no oxide build-up or corrosion. Multiple nozzles at each stage provide flow conditions that result in predictable and stable cut point, low pressure drop, and sharp-cut size characteristics. Because the Hi-Flow Impactor has a design intended originally for sampling from an aircraft, special attention has been given to reducing the weight and size. This resulted in all five stages plus an after-filter in a cylindrical package, 11 cm diameter by 24 cm high, and weighing only 1.8 kg.

1) Sampling flow rate:
- Models 120R, 122R, & 122NR: 30 LPM
- Models 125R & 125NR: 10 LPM
- Model 130 High Flow Impactor, 100 LPM

2) Size intervals and stage cut-sizes
- four equal geometrical increments per decade of particle size
- Model 110 and 120-R: 0.056, 0.1, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10 microns
- 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 microns
- 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 microns
- Model 130: 0.25, 0.44, 0.77, 1.4 and 2.5 microns

3) Easily removable collection substrates allow for quick turn-around time for productive use of the instrument.

4) Models 120R, 122R, & 125R:
- Volumetric flow control
- Programmable logic controller (PLC) controls instrument operation including start- and stop-times. Temperature and pressures are measured, recorded, 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 microns in diameter

5) Sharp cut-off size characteristics

6) Low inter-stage losses

7) Up to 6000 micro-orifice nozzles to reduce jet velocity, pressure drop, particle bounce and re-entrainment.

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

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