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JACA (Japan Air Cleaning Association)

The Abstracts of the paper carried by the Journal of JACA

vol.56-3(2018/9/30)

Dispersion of suspended particle matter

In this study, the dispersion of suspended particulate matter (SPM) is measured at 6 buildings in detail. In this document, ultra-fine particles (about 10nm -10μm) are measured by using two small size scanning mobility particle sizer (SMPSs) and two laser particle counter (LPCs), and the volume dispersion is calculated. The results are as follows. 1) the distribution of SPM is measured between 10nm and 1,000nm in detail,. 2) the distribution is separated into two shapes and the brunch point is about 1.000nm, it is 1 digit larger than which was said typically, 3) smaller than 1,000nm SPM shaped linier curve and larger than 1,000nm SMP shaped secondary curve in double logarithm graph, 4) about nearby 1,000 nm, the distribution was widely distributed, and 5) about mass concentration the peak number is between 200nm and 300nm.

Calibration system of dust meter for building environments

The owners of the specific buildings shall maintain and manage the suspended particle matter (SPM) concentrations in indoor environments according to the standards for environment and health management of building. The concentration of SMP should be measured using gravimetric methods or dust meter methods calibrated as the standard.
This paper has reported the characteristics of SPM measuring instruments applied in “Law for Environmental Health in Buildings” and the outline of the calibration system for dust meters, such as the methods of conversion to mass concentration and the attention points for light scattering type dust meters.

Measurement of charged state of poly-disperse particles using a differential mobility analyzer in a particle charging part of an electrostatic precipitator

Electrostatic precipitators have less pressure loss than that of air filters of the same performance and can be operated in consideration of the environment because they are generally used again after cleaning. To improve a performance of an electrostatic precipitator, the difference in charging performance when modifying the structure of an ionizer, which is a particle charging part of an electrostatic precipitator, have been compared under the condition of constant size and power consumption. In order to measure charged states of aerosols passing through an ionizer, an electric charge number measurement system has been constructed by combining a DMA and a particle counter with particle size resolution improved by a pulse height analyzer. By this measurement system, a charge number distribution for each particle size that passes through an ionizer can be measured rather than previous measuring methods, it has enabled more detailed investigation. As a result, the aerosols charge amount of the honeycomb type ionizer has been better than that of the wire-to-plate type. In addition, by scanning the sampling port immediately downstream of these ionizers, it has been shown that aerosols having a high charge number immediately after the anode wire influences the charge number distribution.

Attempts to downsize a virtual impactor for PM2.5/10 mass concentration measurements for stack samplings

Regulation by the mass concentration of PM2.5 has been initiated since April 2010 in Japan. However, the current status for PM2.5 emission from stationary sources has insufficiently grasped than that of mobile ones. Our group has already developed and commercialized the two-stage virtual impaction surface impactor (VI) suitable for in-stack particle sampling at a high mass concentration. However, it has frequently happened that the main body of current device was not able to be inserted into a flue duct though a narrower inspection hole (φ75 ID) at overseas plants. In the present study, we have attempted to downsize the conventional device by φ73 OD while keeping or improving the classification performance of conventional one using a CFD software. As a result, the numerical analyses have revealed that it has been a key parameter of design of downsized device that clearance between neighboring nozzles on the classification stages has been kept to be 2 mm or more, and that the diameter of stage basement of the VI was shrunk from φ49 to φ39 to reduce the loss of coarse particles at the 1st stage.

Counting efficiency evaluation of OPC for pharmaceutical industries
~ Standardization of the calibration method using Inkjet Aerosol Generator ~

The particle number concentration of micrometer-sized particles is a good indicator of microbial contaminants in pharmaceutical environments, and the concentration is monitored by using optical particle counters (OPCs). Inkjet aerosol generator (IAG) is a useful tool for evaluating the counting efficiency η of an OPC since IAG can generate monodisperse aerosol particles at precisely controlled rate over micrometer particle diameter range. In this study η of an OPC (RION KC-31) were evaluated using the IAG. Since 0.5 μm and 5.0 μm size-channels are used to monitor airborne particles in pharmaceutical environments the η of these two size channels were evaluated. An isokinetic probe is usually attached to the inlet of an OPC; therefore, the IAG-generated particles were delivered to various points over the inlet plane of isokinetic probe to simulate the sampling of uniformly mixed aerosol from actual monitoring environment. Nearly spherical solid particles (lactose monohydrate, LM) and liquid particles (ionic liquid) were generated. It was experimentally verified that the measured size distribution belongs to the size rage greater than the lower boundary size dch if the mean size of the test particles is 1.5 to 2.0 times larger than dch indicating that the sizes of test particles are suitable for evaluating η. Measured η were nearly 100% when LM particles were used, whereas η dropped to about 50% when ionic liquid particles with 9.4 μm aerodynamic diameter were used.

Laboratory biosafety guideline of Japanese Biological Safety Association

“Laboratory biosafety guidelines” of the Japanese Biological Safety Association has been published on December 11, 2017. This guideline is aimed for the preventive measures against infection of workers handling pathogens and against environmental pollution in biological safety laboratories and facilities.
This guideline shows a concept of safety management for preventing exposure or leakage of the pathogen, and shows synthetically a containment principle, techniques and enforcement methods (rule, engineering, procedure, etc.) to carry out safety management.
The target institutions of this guideline are only experimental facilities, such as research facilities, hospital laboratories and educational facilities. In medical institutions, pharmaceutical institutions, etc., another consideration is necessary depending on each situation.
This paper introduces the basic way of biorisk management and the summary of JBSA “laboratory biosafety guidelines”.

Optimizing HVAC system inlet/outlet layout by using genetic algorithm

Recently, it becomes general to use CFD (Computational Fluid Dynamics) when planning HVAC (Heating, Ventilation and Air-Conditioning system).  However, CFD is generally used to fix the disadvantage.  Therefore basic planning is always carried out by experiment of designer or common belief plans which are excluded by designer is not considered.  So excellent plans have the possibility to be eliminated.  Especially such kind of tendency appears when planning the HVAC system for unique shaped rooms or corridors because experiment or common belief cannot be available.  It is possible to make it superior plan by using CFD.  But the number of combinations of design factor is infinitely.  It is impossible to analyze every combination by using CFD.  We have tried to solve the optimal process to decide the planning of inlet/outlet of HVAC system.  But there is a lot of condition according to its own shape of site or own condition of uses.  Therefore we need to survey the dependence of complex shaped rooms.  In this study, we have aimed to make the method to find the optimal solution of inlet/outlet planning by using genetic algorithm.  The result is as follows, 1) we could make the method to plan the inlet/outlet arrangement by using genetic algorithm, 2) to make the method, genetic algorithm need to its own parameter, and 3) we have succeeded to find the optimal parameter.