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Model 5.600 Fast Aerosol Spectrometer TR-DMPS |
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The primary application for such measurements is in the
exhaust of internal combustion engines.
To measure aerosol size distributions, this instrument system performs three operational functions: charging, size classification, and detection. Particle charging is accomplished by exposing the aerosol sample to intense monochromatic UV light which results in photoelectric ejection of electrons from particle surfaces. The charged aerosol then passes into the classification section of the TR-DMPS, where particles are separated into different size ranges via electrical mobility classification. Finally, particles are collected and detected by measurement of the electrical currents associated with the net charge on the particle. The Model 5.600 uses a bipolar charger to charge the particles. The charged particles enter the 10 DMA columns where they are classified by size. From 10 DMA voltages 21 size channels can be obtained continuously. These voltages can be altered depending on the user specifications. The number of particles is detected by highly sensitive faraday cup electrometers (FCE).The Engine Exhaust Spectrometer (TR-DMPS), Model 5.600, measures sub micrometer particles in the range from 7 to 630nm in electrical mobility diameter. The unique design of this instrument enables it to provide fast particle size distribution measurements. It is intended for measuring engine exhaust particles and even low environmental concentrations. This system is a combination of up to 10 Vienna Type DMA-FCE (Faraday Cup Electrometer) steps. This allows measurements of particle distributions of 3 - 600 nm with a measuring time resolution of 5 Hz. The combination of up to 10 independent and very sensitive fractioning and measuring units allows an accuracy which had not been achieved until now. It is specially designed for measurements in the field of motor testing and fast atmospheric changes. Its resolution and consistency make this this system especially effective at measuring transient driving cycles for automotive emission measurements. Environmental monitoring of fast changing aerosols like in nucleation events or on-road and drive by tests can also be tested. The instrument can operate under different pressure conditions so it is suitable for measurements in front of filters and traps.
In the standard operation mode, the TR-DMPS
reports on 21 channels. The DMA cluster allows the user
to measure with 21 channels from 5 to 630 nm (3
selectable size ranges) with a time resolution of 5 Hz.
Every 200 ms the instrument displays a new size
distribution over all channels. The internal data
acquisition reaches up to 100 Hz.  |
FCE (Faraday Cup Electrometer) The fast resolution can be achieved by the highly sensitive and fast FCE units. Each FCE is separate and has a real response time on aerosol concentration changes within 20 ms and a concentration sensitivity of 0.5 fA for this response time. Our design of the FCEs avoids the use of PTFE (PolyTetraFluoroEthylene) and has an integrated isolator which is far less sensitive to mechanical, pressure, or temperature stress than other existing solutions.
Maintenance
Due to the physical separation of the different size channels and the separated DMAlFCE units, the system is very robust. For maintenance each DMA can be cleaned individually. The electrometers are designed for long term operation without any maintenance. Reference System Standard CPC and SMPS measurement systems are normally calibrated or referenced against DMAI FCE-combinations. A DMAlFCE is the established reference method for validation of any other aerosol measurement system in the nanometer range. Our DMA/FCE system is the basic measurement method assuring highest resolution and reliability. The GRIMM TR-DMPS, built up with 10 DMAlFCE combinations is an absolute measurement system assuring highest size resolution combined with quickest resolution for fast measurements.
A calibration of this system is not needed. Any other
measurement principle will be calibrated and validated
with this unit. Data is collected from all FCEs at a rate of 100 Hz (100 times per second, the total response time of the extremely sensitive unit is 200 ms. This leads with a data reduction algorithm to complete particle size distribution measurements with 5 Hz. Real-time data display is shown 5x per second and can be averaged during data collection. TR-DMPS software is user friendly and full-featured. It includes a complete data inversion algorithm and allows data to be displayed and exported in many different ways to meet a variety of needs. It also has a three dimensional representation of size distribution over time. The software collects data with 5x per second and can display averaged data with 0.5 to 60 seconds averages. Pull-down menus and dialog boxes simplify setup and operation. Tests may be started by a few simple mouse clicks, at a specific time, or by an external trigger.
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(United States)
GSA Contract:
GS-07F-9439S |
(Canada)
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