Particle Counter

28373

ATI (Air Techniques Inc) TDA-2E

This Air Techniques Inc model TDA-2E particulate detection unit is a completely self-contained near forward light scattering linear analog aerosol photometer. The basic function of a photometer is to sample air or gas and react to any particulate being drawn through the sampling train. The photometer consists of distinct sections, each working with the others to provide the desired result. Sampling: an integral GAST continuous duty, oil-less type vacuum pump capable of providing a 1 cfm of flow is the source of sample flow for the instrument. HOW IT WORKS: When air or gas is drawn through the scattering chamber by the vacuum pump, any particulate matter in the sample flow will pass through the focal point of the cone. This scatters light into the normally dark area of the cone. The phototube is activated by the scattered light and sends a signal to the amplifier. The amplifier augments the signal linearly and sends it to the front panel indicator meter, the remote scanning probe and the 0-1 VOLT DC recorder jack. The main use of the instrument is for detection of particulate matter in air or gas, registering the concentrations encountered on the various readout scales. Detectable particle sizes range from below 0.1 micron to approximately 100 microns. Experience has shown that particulates of various shapes and sizes give an exponential reaction when passed through the apparatus - theoretically, 100 one micron particles or 10 ten micron particles will give the same reaction. Therefore, since the instrument will read concentrations of particulate matter (regardless of size, shape or color) many applications are possible providing a 100% base line of aerosol is established with the unit. It is then possible to take samples of an atmosphere and read the concentrations in relation to the base. The most common use of the instrument is the measurement of leaks in high efficiency filter systems. In establishing the integrity of a filter bank it is necessary to use a challenge agent such as aerosolized polyalphaolefin (PAO) or DOP as a test aerosol. The challenge agent is used because there is not enough particulate in the ambient air to provide a valid test. The test aerosol should be introduced into the upstream side of the filter or filters as far from the filters as is practical to insure adequate mixing. 10 duct diameters are considered ideal. A sample of the aerosol-air mixture should be taken from the upstream side, close to the filters. This sample is used to set the 100% base line since it is the concentration of the challenge aerosol. The apparatus is adjusted as described in the Operating Section of the manual to set the 100% reading and then the straylight is adjusted. The straylight adjustment is necessary to compensate for any signal caused by dark current or reflection of internal surfaces of the scattering chamber. After these simple adjustments have been made the equipment is ready for checking leaks on the downstream side of the filters. The filter test is performed with the use of the scanning probe. The filter and the perimeter of the filter pack should be scanned by passing the probe in slightly overlapping strokes so the entire area of the filter is sampled. The end of the probe should be held one inch from the filter surface. Separate passes should be made around the entire periphery of the filter, along the bond between the filter pack and the frame, and around the seal of the filter. Readings on the meter will indicate percent of penetration, and 0.01%, 0.1%, 1.0%, or 10% scales may be used as required. To avoid switching ranges, the log scale may be used on log units. The scanning probe is supplied with 3 types of nozzles which can be screwed into the end of the flexible probe. The round black nozzle is 1 inch (25 mm) in diameter which complies with National Sanitation Foundation Standard #49. The round Red nozzle is an Isokinetic nozzle which complies with many standards. The rectangular Blue Isokinetic nozzle is used for faster scanning techniques and is also acceptable by many standards.

Used

110 Volts, 50/60 Hz,

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