Raw proportional toxic sampler for sampling exhaust

摘要

Components of interest are captured on a resin column from a sample of exhaust gas from an operating vehicle. Makeup air is added to the residual exhaust gas flow exiting the resin column at a junction downstream of the resin column. Makeup air flow rate is determined using a laminar flow element and pressure and temperature gauges associated therewith. The sample and the makeup air are drawn together through a blower and the flow rate through the blower is calculated based on differential pressure across the blower and temperature of the gas drawn through the blower. The controller adjusts a proportional control valve in the makeup air line to regulate the sample flow rate, taken as the blower flow rate minus the makeup air flow rate, at a predetermined proportion of the exhaust gas flow rate.

主权项

1. An apparatus for capturing components of interest from vehicle exhaust gas, comprising:
a device for determining exhaust gas flow rate; a sample tube for capturing a sample of exhaust from an operating vehicle and introducing the captured sample into a sample line; a resin column connected to the sample line for receiving the exhaust gas sample and selectively capturing the components of interest on the resin, with a residual exhaust gas flow exiting the resin column; a makeup air line for adding makeup air to the residual exhaust gas flow at a junction downstream of the resin column; a laminar flow element for receiving a flow of makeup air introduced into the makeup air line and measuring the flow rate of the makeup air; a proportional control valve for controlling the makeup air flow rate; a blower for drawing the sample through the sample line, the makeup air through the makeup air line and the combined sample and makeup air through a blower inlet line; associated with the blower, pressure sensors in the blower inlet line and downstream of the blower and a temperature sensor; and a controller for calculating the makeup air flow rate and blower flow rate through the blower, based on signals from the temperature and pressure sensors associated with the blower, and controlling the proportional control valve to indirectly regulate the sample flow rate, taken as the blower flow rate minus the makeup air flow rate, as a set percentage of the exhaust gas flow rate.