Abstract: Air sampling apparatus usable with airflow measuring equipment includes probe apparatus for inserting into airflows remote from a meter and the probe apparatus includes wands having ports for communicating with an airflow and boundary layer separation slots to control the separation of boundary layer airflow between the ports, and includes a manifold grid having a plurality of ports for sensing air pressure over a relatively large area.

Abstract: Apparatus measures airflow when used with a hood to control the flow of air through the hood. The apparatus measures air velocity when used with a pitot tube, a probe, or a grid. Differential pressure is measured, and absolute pressure is also measured. A temperature probe and a humidity probe are used to obtain temperature and humidity measurements, and the measurements are used to correct airflow and air velocity measurements for the effects of temperature, humidity, and absolute pressure. Back pressure is compensated for when the hood apparatus is used for airflow measurements by utilizing a pair of movable flaps that are mechanically inserted into and removed from the airflow. A differential pressure circuit includes a voltage controlled oscillator which is linearized over a specific operating range, and the specific operating range depends on the differential pressure being measured.

Abstract: Manifold apparatus for air sensing equipment includes a pair of separate but parallel tubular manifolds, and apertures communicating with the interior of the manifolds are disposed in a predetermined pattern for sensing and averaging the airflow. An apertured plate may be placed over the manifolds to provide a predetermined apparent increase in the flow to the manifold which enables very low flow rates to be measured.