A system that dispenses a dry fog comprising a water-based liquid into ambient air in an enclosed volume over a long period, said system comprising:
- a) a reservoir that is able to contain the water-based liquid;
- b) a dispenser comprising:
- i) an enclosed dispensing chamber that is able to contain the water-based liquid, and is separate from the reservoir,
- wherein the dispensing chamber comprises a top and a bottom;
- ii) an electrically powered ultrasonic wave generator positioned at the bottom of the dispensing chamber:
- wherein the ultrasonic wave generator comprises a piezoelectric crystal and an ultrasonic membrane each capable of vibrating at ultrasonic frequencies;
- iii) an input orifice positioned at the top of the dispensing chamber, wherein the water-based liquid can enter the dispensing chamber;
- iv) an inner chamber comprising:
- an inner chamber exterior further comprising a top a bottom, and an enclosure surface;
- at least one slit in the enclosure surface positioned proximate to the bottom of the enclosure surface wherein liquid may enter the inner chamber;
- a vent hole positioned at the top of the inner chamber to allow air to exit the inner chamber;
- at least one liquid level sensor;
- v) an electrically powered fan positioned at the top of the dispensing chamber capable of blowing air into the dispensing chamber;
- vi) an output orifice positioned at the top of the dispensing chamber, said orifice comprising two ends, wherein one end resides inside the dispensing chamber and the other end resides outside the dispensing chamber;
- vii) a mesh, sieve, or filter positioned at the end of the orifice that is inside the dispensing chamber, which is able to pass particles of the water-based liquid sized less than or equal to the maximum size required for the dry fog, and causes droplets of the water-based liquid sized greater than that maximum size to remain inside the dispensing chamber;
- c) an electrically powered electronic controller comprising an electrical connection to the at least one liquid level sensor;
- d) a water pump electrically connected to the controller and physically connected to the reservoir and the input orifice;
- wherein:
- the ultrasonic membrane is always submerged under the water-based liquid;
- the ultrasonic membrane is positioned between the piezoelectric crystal and the water-based liquid;
- the at least one liquid level sensor is positioned to sense a minimum liquid level desired to keep the ultrasonic membrane submerged;
- the at least one liquid level sensor sends a signal to the controller when the liquid level is at the minimum level;
- when the controller receives the signal from the at least one liquid level sensor, the controller causes the pump to engage and to propel the water-based liquid from the reservoir into the dispenser chamber via the input orifice.