Personal air sampling system

Claim 2

A personal air sampling device which comprises: a housing defining an air passageway having an air intake and an exhaust; an air pump mounted to the housing for pumping air through the air passageway; an air contaminant collection device connected to collect material in the air flowing through the air passageway; air velocity sensor means mounted to the housing and being operable to generate a signal indicative of the velocity of the air passing through the air passageway; converter means coupled to the velocity sensor means for periodically reading the velocity sensor signal and converting it to a digital velocity number indicative of the velocity of the air passing through the air passageway; first calculation means coupled to the converter means for receiving said digital velocity number and calculating an incremental air flow volume number which is indicative of the volume of air flowing through the air passageway during a preset time increment; second calculation means coupled to the first calculation means for adding together each calculated incremental air flow volume number to form a total air volume number; and display means coupled to the second calculation means to receive the total air volume number and provide a visual indication of that number.

Claim 3

The personal air sampling device as recited in claim 1 in which said air velocity sensor is a thermal anemometer.

Claim 4

The personal air sampling device as recited in claim 2 in which said converter means includes an analog to digital converter circuit which converts the thermal anenometer signal to digital form and linearizing means for converting the digitized thermal anemometer signal to a corresponding digital velocity number.

Claim 5

The personal air sampling device as recited in claim 3 in which said linearizing means employs a stored look-up table for converting the digitized thermal anemometer signal to the corresponding digital velocity number.

Claim 6

The personal air sampling device as recited in claim 1 in which said first calculation means includes multiplier means for multiplying the digital velocity number times a digital constant number which represents the effective cross-sectional area of the air passageway.

Claim 7

The personal air sampling device as recited in claim 5 in which said multiplier means also multiplies said digital velocity number by a digital time increment number which represents the time period between each of said periodic readings of the velocity signal by said converter means.

Claim 8

A personal air sampling device which comprises: a housing which defines an air passageway through which sampled air flows; an air contaminant collection device connected to the air passageway to collect material in the sampled air; an air pump mounted to the housing for pumping sample air through the air passageway; a thermal anemometer disposed in the air passageway and operable to generate an analog electrical signal indicative of the velocity of the sample air flowing through the air passageway; an analog to digital converter circuit connected to receive the analog signal generated by the thermal anemometer and convert it to a digital number indicative of sample air velocity; digital processor means coupled to said analog to digital converter circuit and being operable to periodically read the digital air velocity number generated by said analog to digital converter and calculate a total air volume number therefrom which indicates the total sample air flowing through the air passageway during a sample period; and a display coupled to the digital processor means for providing a visual indication of the total air volume number.

Claim 9

A personal air sampling device which comprises: a housing which defines an air passageway through which sampled air flows; an air contaminant collection device connected to the air passageway to collect material in the sampled air; an air pump mounted to the housing for pumping sample air through the air passageway; a thermal anemometer disposed in the air passageway and operable to generate an analog electrical signal indicative of the velocity of the sample air flowing through the air passageway; an analog to digital converter circuit connected to receive the analog signal generated by the thermal anemometer and convert it to a digital number indicative of sample air velocity; digital processor means coupled to said analog to digital converter circuit and being operable to periodically read the digital air velocity number generated by said analog to digital converter and calculate a total air volume number therefrom which indicates the total sample air flowing through the air passageway during a sample period; and a display coupled to the digital processor means for providing a visual indication of the total air volume number.

Claim 10

The personal air sampling device as recited in claim 7 in which the digital processor means is coupled to said air pump by a digital to analog circuit and the processor is operable in response to the digital velocity number from the analog to digital converter circuit to control the speed of the air pumps and to thereby maintain the air velocity in the air passageway at a selected level.

Claim 11

The personal air sampling device as recited in claim 7 in which said digital processor means is a microprocessor system and the calculations are performed in accordance with instructions stored in a memory.

Claim 12

The personal air sampling device as recited in claim 7 in which said digital processor means also calculates a total sample period number and said display is operable to provide a visual indication of the total sample period number.

Claim 13

A personal air sampling device which comprises: a housing defining an air passageway having an air intake and an exhaust; an air pump mounted to the housing for pumping sampled air through the air passageway; a tube connected to the housing to transport sampled air to the air intake of said air passageway; an air contaminant collection device connected to the tube and positioned to collect material in the sampled air transported by the tube; air velocity sensor means mounted to the housing and being operable to generate a signal indicative of the velocity of the air passing through the air passageway; converter means coupled to the velocity sensor means for periodically reading the velocity sensor signal and converting it to a digital velocity number indicative of the velocity of the air passing through the air passageway; first calculation means coupled to the converter means for receiving said digital velocity number and calculating an incremental air flow volume number which is indicative of the volume of air flowing through the air passageway during a preset time increment; second calculation means coupled to the first calculation means for adding together each calculated incremental air flow volume number to form a total air volume number; and display means coupled to the second calculation means to receive the total air volume number and provide a visual indication of that number.

Claim 14

A personal air sampling device which comprises: a housing defining an air passageway having an air intake and an exhaust; an air pump mounted to the housing for pumping sampled air through the air passageway; a tube connected to the housing to transport sampled air to the air intake of said air passageway; an air contaminant collection device connected to the tube and positioned to collect material in the sampled air transported by the tube; air velocity sensor means mounted to the housing and being operable to generate a signal indicative of the velocity of the air passing through the air passageway; converter means coupled to the velocity sensor means for periodically reading the velocity sensor signal and converting it to a digital velocity number indicative of the velocity of the air passing through the air passageway; first calculation means coupled to the converter means for receiving said digital velocity number and calculating an incremental air flow volume number which is indicative of the volume of air flowing through the air passageway during a preset time increment; second calculation means coupled to the first calculation means for adding together each calculated incremental air flow volume number to form a total air volume number; and display means coupled to the second calculation means to receive the total air volume number and provide a visual indication of that number.