Mixing type condensation nuclei meter

Claim 2

A condensation nuclei meter for deriving a count of the condensation nuclei particles entrained in a sample atmosphere comprising a condensation chamber, electro-optical means viewing the interior of the condensation chamber for projecting a light beam thereinto and deriving an output electric signal representative of the light modifying effects on the light beam of liquid droplets formed in the condensation chamber, the liquid droplets being formed about condensation nuclei particles as centers of condensation, means for introducing a first filtered gas at a first preSsure and temperature value and at 100 percent relative humidity at the first temperature value into the condensation chamber, means for introducing a second condensation nuclei bearing sample gas to be monitored into the condensation chamber at a second pressure and temperature value different from the first pressure and temperature value and at 100 percent relative humidity at the second temperature, and means for rapidly injecting at least one of said gases into the condensation chamber at a pressure greater than the pressure of the other gas while maintaining the pressure in the condensation chamber substantially unchanged in a manner to assure rapid mixing at the confluence of the two gases whereby supersaturation occurs and condensation takes place about the condensation nuclei particles entrained in the sample gas as centers of condensation due to the temperature differential of the two gases.

Claim 3

A condensation nuclei meter according to claim 1 wherein the means for rapidly injecting at least one of the gases into the condensation chamber comprises means for entrapping a known volume of one of the gases at pressure exceeding the pressure in the condensation chamber and for injecting the entrapped volume of gas into the condensation chamber at a rate sufficient to assure turbulent intermixing of the confluent gases.

Claim 4

A condensation nuclei meter according to claim 2 wherein the means for introducing the first filtered gas includes a filter element and a first humidifier operated at the first temperature value and disposed in a supply path from a first gas source supplying the means for introducing a first filtered gas into the condensation chamber, and the means for introducing the second condensation nucleii bearing sample gas to be monitored includes a second humidifier operated at the second temperature value and disposed in a supply path intermediate a sample gas inlet and the condensation chamber.

Claim 5

A condensation nuclei meter according to claim 3 further including valving means disposed in the supply paths intermediate the condensation chamber and the first gas source and sample gas inlet for controlling introduction of the gases into the condensation chamber in conjunction with the means for rapidly injecting at least one of the gases into the condensation chamber, and valve timing control means for controlling the timing of operation of said valving means.

Claim 6

A condensation nuclei meter according to claim 4 further including temperature regulator means coupled to and controlling the temperature of operation of said first and second humidifiers for closely regulating the temperature difference between said first and second temperature values.

Claim 7

A condensation nuclei meter according to claim 5 wherein the first filtered gas and the second condensation nuclei bearing sample gas are air and the liquid with which they are saturated at 100 percent relative humidity is water whereby water droplets are formed in the condensation chamber during each operating cycle of the meter. condensation

Claim 8

A condensation nuclei meter according to claim 6 wherein the first gas is drawn from a suitable source, filtered, humidified at the first temperature value in the first humidifier and introduced into the condensation chamber, and the second condensation nuclei bearing sample gas is drawn through a sample inlet and second humidifier where it is humidified at the second temperature value and introduced into a known volume collapsible chamber for entrapping a known volume of the humidified sample gas at the second temperature value, said collapsible chamber being connected to said condensation chamber through a suitable valving means, and means for collapsing said collapsible chamber and opening said last mentioned valving means to thereby rapidly inject the entrapped known volume of sample gas at the second temperature value into the condensation chamber where it is turbulently intermixed with first gas to produce water droplets at the confluence of The two gases due to rapid cooling and supersaturation of one of the gases.

Claim 9

A condensation nuclei meter according to claim 7 wherein the known volume collapsible chamber is comprised by a housing interposed between one of said humidifiers and the condensation chamber, a pair of reciprocally and relatively movable, spaced-apart piston members slidably supported within said housing for entrapping a known volume of one of the gases flowing out of the humidifier through a portion of the housing intermediate the spaced-apart piston members, said piston members being movable apart to entrap a known volume of gas and thereafter relatively movable together to squeeze the entrapped volume rapidly out into a passageway interconnected through the last mentioned valving means with the condensation chamber, a source of pressurized air and a vacuum source interconnected with the housing through suitable conduits, control valves for controlling the reciprocal movement of said piston members disposed in the conduits, valve timing control means for controlling the alternate opening and closing of the control valves whereby the reciprocally movable spaced apart members are caused to reciprocate back and forth within the housing, piston arresting means for arresting the movement of one of the pistons while allowing the other to close the space therebetween and rapidly squeeze out the volume of gas trapped between the spaced-apart pistons into the condensation chamber and said vacuum source being coupled to said expansion chamber and to said housing portion for entrapping a sample volume intermediate the spaced-apart, reciprocally movable pistons through suitable conduit and flow regulating means for causing sample gas flow through the meter.

Claim 10

A condensation nuclei meter according to claim 8 wherein the condensation chamber and one of the humidifiers comprises a unitary structure containing a pool of water through which one of the gases is bubbled for humidification, said humidifier portion being separated from the expansion chamber portion by light baffles for preventing specular reflection due to, wave action and the like from interfering with the electro-optic read-out of water droplet formation in the expansion chamber.

Claim 11

A condensation nuclei meter according to claim 9 further including by-pass conduit means interposed between the sample gas inlet and the vacuum source on-off control valve means and flow regulating control valve means interposed in the by-pass conduit for controlling and regulating flow therethrough, and additional on-off control valve means disposed in the supply path to and from the condensation chamber from one of the gas supply sources and the vacuum source during periods of rapid injection into the condensation chamber.

Claim 12

A condensation nuclei meter according to claim 6 further including conduit means for supplying the condensation nuclei bearing gas sample drawn through a sample inlet during non-measurement periods to the first humidifier where it is humidified at the first temperature value, pumping means for pumping gas supplied through the first humidifier to a higher pressure, filter means supplied by said pump means to form the first filtered gas, and conduit means supplying the first filtered gas to the second humidifier where it is humidified at the second temperature value and introduced into the condensation chamber and continuously drawn off and exhausted, means for storing a volume of the filtered first gas prior to being humidified at the second temperature value in a plenum under pressure, and conduit means coacting with the valving means during measurement periods to connect the pressured plenum through the first humidifier to the condensation chamber rapidly whereby the condensation nuclei bearing sample gas contained in the first humidifier at the first temperature value suddenly is injected into the condensation chamber where it is turbulently intermixed with the filtered first gas at the second temperature value to produce supersaturatIon of one of the gases and formation of water droplets about the entrained condensation nuclei particles as centers of condensation.

Claim 13

A condensation nuclei meter according to claim 11 further including flow regulating means interposed in the conduit means for regulating the flow rate from the first humidifier to the pump means and the flow rate from the pump means to the second humidifier.

Claim 14

A condensation nuclei meter according to claim 12 further including means for introducing make up fresh-air into the flow path intermediate the outlet from the first humidifier and the inlet to the pump means, and means for regulating the flow rate of such make-up fresh air.

Claim 17

A method of measuring condensation nuclei particles according to claim 14 wherein at least one of the gases introduced into the condensation chamber is entrapped in a known volume at a pressure exceeding the pressure in the condensation chamber and the entrapped volume of gas injected into the condensation chamber at a rate sufficient to assure turbulent intermixing of the confluent gases.

Claim 18

A method of measuring condensation nuclei particles according to claim 15 wherein the first filtered gas is drawn from a suitable source, filtered, humidified at the first temperature value and introduced into the condensation chamber, and the second condensation nuclei bearing sample gas is drawn through a sample inlet humidified at the second temperature value, entrapped in a known volume and then injected rapidly into the condensation chamber by collapse of the known volume where it is turbulently intermixed with first gas to produce water droplets at the confluence of the two gases due to rapid cooling and supersaturation of one of the gases. A method of measuring condensation nuclei particles according to claim 15 wherein during non-measurement intervals a condensation nuclei bearing gas is humidified at the first temperature, pumped and flow regulated, filtered and the resulting filtered gas supplied under pressure to a storage plenum and at a second regulated flow rate humidified at the second temperature and supplied to the condensation chamber and during measurement intervals while maintaining the pumped, filtered and regulated flow of gas humidified at the second temperature through the condensation chamber, rapidly switching the pressured volume of humidiFied filtered gas at the first temperature to rapidly isolate and inject a known volume of nuclei particle bearing sample gas humidified at the first temperature into the condensation chamber where it is turbulently intermixed with the filtered gas at the second temperature value to produce supersaturation of one of the gases and formation of water droplets about the entrained condensation nuclei particles as centers of condensation.