MSP Corporation

- Model M1610 - PM Sampler and Mass Monitor (PSMM)

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The Model 1600 PM Sampler and Mass Monitor (PSMM) is a modern instrument designed for PM sampling and mass monitoring. Samples are collected on 47-mm-diameter filters while mass monitoring is accomplished with a quartz crystal microbalance (QCM). In its standard configuration the instrument includes two filter samplers and one QCM mass monitor. The filter samplers are used for PM10 and PM2.5 particle sampling, and the QCM is typically used for mass monitoring in the PM2.5 size range.

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A PM sampler and mass monitor with dual PM sampling and mass monitoring capabilities. Designed to meet the modern demand for accurate PM measurement, the system provides user-friendly features, such as computer control and graphical user interface for instrument setup, data recording, and analysis.

Figure 1 shows the mass sensing QCM. The thin circular quartz plate is coated with gold to form electrodes on both sides. Particles are deposited electrostatically in the circular area on one side for mass sensing. Upon excitation by an electrical signal, the AT cut quartz crystal will vibrate in the transverse direction parallel to its surface. The deposited particle mass will cause the resonant frequency of the crystal to decrease. The shift in frequency is proportional to the deposited particle mass on the crystal, thus providing a signal output for mass monitoring. The QCM is placed in a monitoring chamber maintained at 40 oC to minimize the effect of moisture on the measured particle mass.

Sampling and Inertial Separation
Aerosol from the ambient atmosphere enters the system through the weather-proof inlet shown in Figure 2. Particles larger than 10 μm in aerodynamic equivalent diameter are removed by inertial impaction. The inlet is of a conventional US EPA louvered design, operating at a sampling flow rate of 16.7 liters per minute.

Half of the total flow entering the inlet then flows through the filter sampler shown in Figure 3 for PM10 particle sampling. The sampling flow rate is 8.33 LPM. The collected particles can be subjected to gravimetric and/or chemical analysis. The filter sampler accepts standard 47-mm-diameter filters. Quartz-fiber filters are generally used. Other filters compatible with the gravimetric and/or chemical analysis techniques can also be used.

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Figure 4 shows a virtual impactor particle separator for removing particles larger than 2.5 μm for sampling and mass monitoring in the PM2.5 size range. Aerosol is sampled into the inlet nozzle to accelerate the flow to a high velocity. Particles larger than 2.5 μm in aerodynamic equivalent diameter are impacted into the receiving tube and carried by the minor flow to the outlet to be discarded. The PM2.5 particles are deflected sideways and carried by the major flow to the outlet for the PM2.5 sampling and mass monitoring. The virtual impactor is designed to operate at a total-to-minor flow ratio of 20 to 1.

This PM2.5 stream then enters a filter sampler similar to that shown in Figure 3. A small amount of flow is also sampled into the charging and deposition chamber for PM2.5 mass monitoring by the QCM.

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Mass Monitoring
Figure 5 shows the chambers used for charging the particles and depositing them on the QCM for PM10 or PM2.5 mass monitoring. The PM10 or PM2.5 aerosol enters the upper chamber where a high-voltage corona discharge creates positive corona ions to charge the particles. The charged particles then enter the lower chamber for them to deposit on the QCM for mass monitoring. The flow rate through each chamber is 0.5 liters per minute.

To prevent water vapor in air from condensing on the QCM both the upper and lower chambers of Figure 5 are maintained at an elevated temperature. A typical chamber temperature is 40 degree C.

Mounting Options
Figure 6 shows three standard mounting options for the PSMM System. Other options can be provided by special request.

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Figure 7 is a simplified schematic diagram of the PSMM™ system in its standard configuration. Ambient air is sampled into the system through the PM10 inlet to remove particles larger than 10 μm in aerodynamic equivalent diameter. Half of the total flow then passes through a filter sampler for PM10 particle sampling. The remaining half then flows through the virtual impactor to remove particles larger than 2.5 μm in diameter for sampling and mass monitoring in the PM2.5 size range.

Airflow in the PM10 sample stream is maintained at its set-point value by a small variable-speed pump through feedback control. Air flow in the PM2.5 stream is first manually balanced and then controlled to the desired set-point value by automatic control.

An optional system with two filter samplers and two mass monitors is also available, one for PM10, and the other for PM2.5 measurement. In addition, customized systems for PM10 and PM1.0 particles can also be provided for research related to particulate air pollution and its health effect on humans.

Subject to change without notice

Physical and Electrical

  • Electrical: 100-240 VAC, 50/60 Hz, 250W
  • Dimensions: 1.2 m x 0.5 m x 0.5 m (HxWxD)
  • Weight: 20 kg without mounting pedestal

Other

  • Sample flow: 16.7 L/min
  • Mass range: 0 to 1000 μg/m3
  • Mass precision: < 1μg/m3
  • Mass uncertainty: <2%
  • Mass averaging: 10 – 600 sec (real time)
  • Data output: Ethernet and USB
  • Internal storage: 2 GB
  • Temperature: -40 to +40C (sampled air)
  • Temperature: 0C to 40C (instrument enclosure)
  • Humidity: 0 to 100% RH (sampled air)
  • Humidity: 10 to 90% RH (instrument enclosure; non-condensing)

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