초록 ▼

A method and apparatus for sampling a particle-bearing gas in which a vacuum is applied to the gas to generate a stream of gas, the flow of the stream is maintained constant, and particles are collected from the stream. A constant flow controller responsive to the static pressure of the gas in the s

A method and apparatus for sampling a particle-bearing gas in which a vacuum is applied to the gas to generate a stream of gas, the flow of the stream is maintained constant, and particles are collected from the stream. A constant flow controller responsive to the static pressure of the gas in the stream provides a flow restriction which gradually decreases to compensate for a gradually increasing flow restriction caused by particles collecting on an initially particle-free collection filter located in the stream.

대표청구항 ▼

A method of sampling a relatively static body of particle-bearing ambient gas for the determination of particle concentration, the gas being sampled by a device of the type utilizing a vacuum pump, the method comprising the steps of: generating a stream of flowing gas from the ambient gas to be samp

A method of sampling a relatively static body of particle-bearing ambient gas for the determination of particle concentration, the gas being sampled by a device of the type utilizing a vacuum pump, the method comprising the steps of: generating a stream of flowing gas from the ambient gas to be sampled by operating the vacuum pump; continuously collecting particles in said stream and retaining the collected particles within said stream, such that the rate of flow of said stream and therewith the static pressure in said stream tends to decrease; continuously sensing the static pressure in said stream; and continuously throttling the flow of said stream upstream of the vacuum pump in response to the difference between said sensed pressure and the ambient pressure of the gas while maintaining the speed of the vacuum pump relatively constant, whereby the rate of flow of said stream is maintained relatively constant.