Method and apparatus for evaporating multi-component liquids

Apparatus for evaporating a multi-component liquid solution, said apparatus comprising:

• a liquid reservoir containing a multi-component liquid;
• a liquid delivery system;
• and
• an atomizer;
• said liquid delivery system being arranged to convey liquid from said reservoir to said atomizer;
• said atomizer being constructed to form a mist or cloud of small liquid droplets having diameters within a predetermined range and to eject said droplets into the atmosphere to predetermined heights above an adjacent surface toward which they fall;
• said multi-component liquid comprising a plurality of components having respective vapor pressures, the component having the lowest vapor pressure being related to those droplets having the larger diameter such that
• 1.2×1012×Dp4/[H×Pv]≦1
• where Dp is the diameter, in centimeters, of the droplet having the largest diameter, H is the height in centimeters, to which said larger diameter droplets are ejected and Pv is the vapor pressure, in millimeters of Hg, of those components having the lowest vapor pressure.

A method of evaluating a liquid for suitability for atomization by means of a vibrating plate atomizer and by evaporation of droplets produced from said atomizer, said method comprising the steps of:

• forming a pendant drop of said liquid;
• allowing said pendant drop to evaporate while sensing its rate of decrease in size;
• and
• producing a signal which represents suitability for atomization when said sensing indicates that said rate of decrease in size is greater than a predetermined rate.

A method of ascertaining whether a multi-component liquid fragrance or a multi-component liquid insecticide, when atomized into droplets having a particle size of up to 50 microns and ejected into the atmosphere to a height of at least 8 centimeters above a surface, and where no more than 10% of the total volume of the droplets is larger than 15 microns, will be suitable for complete evaporation before falling back onto the surface, said method comprising the steps of:

• forming a pendant drop of said liquid, the size of said pendant drop being about 6 microliters;
• allowing said pendant drop to evaporate while sensing its size;
• when the pendant drop has become reduced in size by about 70% of its original volume, calculating its rate of evaporation and its surface tension;
• and
• providing an indication of suitability for complete evaporation when the evaporation rate of said pendant drop is at least 1.0×10−8 cubic meters per square meter per second and the surface tension of said droplet is no more than 35 dynes per centimeter.

Apparatus for evaluating a liquid for suitability for atomization by means of a vibrating plate atomizer and by evaporation of droplets produced from said atomizer, said apparatus comprising:

• means for forming a pendant drop of said liquid and suspending said drop while liquid evaporates therefrom;
• a sensor constructed and arranged to sense a rate of decrease in size of the pendant drop during evaporation of liquids therefrom;
• and
• an indication producing device connected to said sensor and to produce a signal which represents suitability for atomization when said sensor indicates that said rate of decrease in size is greater than a predetermined rate.

Apparatus for ascertaining whether a multi-component liquid fragrance or a multi-component liquid insecticide, when atomized into droplets having a particle size of up to 50 microns and ejected into the atmosphere to a height of at least 8 centimeters above a surface, will be suitable for complete evaporation before falling back onto the surface, said apparatus comprising:

• a drop forming means which forms a pendant drop of said liquid about 6 microliter in size and allows said droplet to evaporate;
• a sensor constructed and arranged to sense a rate of decrease in size of the pendant drop during evaporation of liquids therefrom;
• and
• an indication producing device connected to said sensor and to produce a signal which represents suitability for atomization when said sensor indicates that said rate of decrease in size of the pendant drop is greater than a predetermined rate;
• said sensor and said indication means being arranged such that when the pendant drop has become reduced in size by about 70% of its original volume, its rate of evaporation and its surface tension are sensed and an indication of suitability for complete evaporation is provided when the evaporation rate of said pendant drop is at least 1.0 x I 0-8 cubic meters per square meter per second and the surface tension of said pendant drop is no more than 35 dynes per centimeter.

A method of evaporating a multi-component liquid solution, said method comprising the steps of:

• operating a vibrating plate atomizer to form a mist or cloud of small liquid droplets of the solution;
• ejecting said mist or cloud of small droplets into the atmosphere;
• and
• allowing said droplets to fall back toward an adjacent surface;
• said liquid solution having evaporation characteristics such that the size of a pendant drop of the liquid decreases at a predetermined rate which corresponds to evaporation of said liquid droplets prior to falling on an adjacent surface after having been ejected into the atmosphere by said atomizer, said evaporation being such that the unevaporated liquid in said droplets is insufficient to have an adverse effect on said surface.