Leslie Silverman

A NEW METHOD FOR STUDYING BREATHING, WITH OBSERVATIONS UPON NORMAL AND ABNORMAL SUBJECTS.

The apparatus described in this article is a simple device that will record the changes in the rate of air flow with time during each respiration and without the lag and inertia of other methods. The instrument designed for this purpose consists of a fine platinum wire 200 mm. long and 0.01 mm. (10 microns) in diameter, suspended across the diameter of a 31.6 mm. tube. One end of the wire is attached to a fixed point and the other end to a fine spring. The displacement of the wire when air flows through the instrument is recorded photographically by a moving paper camera. The deflection of the wire is essentially linear with air flow, and the inertia, lag, and frequency of vibration do not interfere with respiratory measurements. Unlike other instruments devised for this purpose, this apparatus does not introduce significant resistance to air flow and, therefore, does not affect normal respiration. The complete measuring apparatus is shown in Figure 1. The inspiratory instrument, with a bell-mouth to prevent turbulent air currents and decrease resistance, is shown at A. The expiratory instrument, with heating bath for preventing condensation in the line, is shown at B. The recording wires of these two instruments are shown schematically in the lower part of the figure. The valves for producing directional air flows through the two instruments are shown at C. A large spirometer with slide valves for shifting from the recording instrument to the spirometer for collection of expired air is also shown in Figure 1. A small half mask with minimal dead space is provided with a Heidbrink pneumatic cushion to ensure an air-tight seal to the subjects fLce. In a recent paper (1), a description was given of the details of construction of this apparatus as adap&kd to measurements of air flow during inspiration. Since that publication, the device has been modified to record both inspiratory and expiratory air flows. The changes made in the original inspiratory instrument to record expiratory air flows are as follows. To eliminate the effect of the turbulence of the expired air, a fine mesh wire screen (150 mesh Monel wire) is located 5 mm. from the recording wire, and to prevent condensation from expired air in the instrument, a heating bath and a straight section of tubing are inserted in the line before the wire

Application of the Pollak-Nolan nucleus counter to the routine testing of air filters☆

Abstract The Pollak-Nolan nucleus counter was employed to measure efficiencies of various filter media with different size particles at various flow rates. Uranine particles were used, and the filter efficiency determined by the nucleus counter was compared with that obtained by aerosol mass analysis. The two methods are in close agreement for highly efficient media. For media of moderate efficiencies, the efficiency given by the nucleus counter (based on particle number) is much higher in general for the air flows considered, than that given by the aerosol mass determination. The differences in efficiencies may be attributed to the heterogeneity of the size of the particles since the nucleus counter responds more effectively to smaller sizes. A number of comparative tests with several comparable filters were made with atmospheric dust using the Pollak-Nolan counter as for the uranine aerosols. These results agreed with the uranine aerosol measurements.

Potassium Pallado Sulfite Method for Carbon Monoxide Detection

Abstract This paper describes an improved method for directly measuring low concentrations of carbon monoxide in air. Carbon monoxide reacts with potassium pallado sulfite impregnated on a chemically inert gel contained in sealed glass tubes. Length of discoloration caused by conversion of yellow sulfite to dark brown palladium or its oxide is an exponential function of CO concentration. Data are presented on the measurement of carbon monoxide in air as well as in oxygen-deficient or oxygen-free atmospheres. Applications are given relative to interfering and non-interfering gases and vapors as well as temperature correction data covering range of −50°F to 120°F and ambient pressure correction.

An Apparatus for Measuring Air Flow During Inspiration

Measurement of the rate of flow of air during inspiration is important in respiratory physiology and for the design of protective respiratory devices. Methods that have been used previously are described and their limitations explained. A new instrument was constructed for such measurements, which offers no appreciable resistance to air flow. This instrument consists of a microscopic platinum wire suspended across the diameter of a 31.6‐mm tube. One end of the wire is attached to a fixed point and the other end to a fine spring. The displacement of the wire when air flows through the instrument is recorded photographically by a moving paper camera. The deflection of the wire is linear with air flow, and its inertia, lag, and frequency of vibration do not interfere with respiratory measurements. A low resistance valve and mask system complete the apparatus.

A Self-Contained Positive Supply Filter Respirator

Abstract A self-contained positive pressure air supply respirator unit is described which can be used with all types of continuous flow supplied air facepieces. Air demand for the wearer is supplied from the exposure environment through an air purification package consisting of a DC motor, air mover, rechargeable battery pack, and air purification element. The air mover is a miniature, positive displacement, Roots type blower delivering 4.0 CFM at a total head of 2″ H2O. The air supply package weighs approximately three pounds and can be conveniently worn on a belt harness. Performance tests under moderate work conditions showed leakages of less than 0.10% for the three-hour life of the unit.

Notes on the design and leak-testing of sampling filter holders.

Abstract Failure to recognize two basic types of air leakage, external and by-pass, with commercial and custom-made sampling filter holders may lead to serious sampling errors. Simple methods for static testing of these devices are discussed for negative and positive pressure operation. Construction details are provided for a filter paper holder which, with conventional sampling media, i.e., membrane filters and all-glass papers, permits essentially leakproof performance.

The Determination of Cotton Textile Dusts in Air

cotton fibers, usually called lint * by laymen. There may be several other contaminants in the textileplant atmosphere which become entrained by the cotton during growth-such as insecticides, fungi fragments, and bacteria. During cleaning, these, too, may be dispersed into the workroom air. The amounts of waste materials (substances other than proper-length cotton fibers) in baled cotton can be considerable. It is well known that the amount of trash in cotton depends principally upon the cot-

Portable Laboratory Scrubber Unit for Perchloric Acid

Abstract A self-contained unit for collecting and disposing of chemical fumes, mists, and gases has been developed and field tested. It is portable and compact and, when assembled, only requires connection to an electrical receptacle and water tap to be completely operational. Although originally designed for use in filter type radiochemical laboratory hoods for safe disposal of perchloric acid fumes arising from acid digestions, it may be used as a substitute for a permanent hood in a variety of locations. Collection arid disposal of the acid at the source of emission is the guiding design principle.

A Field Instrument for Measuring Volume and Instantaneous Flow Rate of Inspired Air

The object of this study was the development of a portable self‐contained instrument which would record the rates of inspiratory air flow through protective canisters under actual field conditions. This instrument was developed so that observations made in the laboratory could be checked under actual field conditions. Measurements of air flow on subjects in tanks or parachute troops or men moving in industrial operations cannot be obtained without a portable instrument.The essential requirements of this instrument are that it obtain records of air flow, air volume, and respiration rate while worn by or held closely to the individual under observation. The apparatus should be rugged and independent of positional effects or a reasonable amount of rough handling. Its operation should be automatic and not require attention by the subject.

AN ADJUSTABLE RESISTANCE WITH LINEAR RESPONSE TO AIR FLOW FOR RESPIRATION EXPERIMENTS.

A. simple easily adjustable linear response resistance apparatus is described. The resistance unit contains a glass filter cloth, the effective area of which is adjusted by a mercury column. The resistance of the unit can be adjusted from 0.1 to 1.0 millimeters of water per liter of air flow per minute. The resistance can be easily increased or decreased during the progress of an experiment. The mercury hazard during inspiration was evaluated and not found significant for experiments of one hour.