Questions:
Answers:
1: What is the difference between a regular smoke generator, a security smoke machine and a fogger?
Technically they are essentially equivalent. Each machine produces a thermal aerosol. The prime distinction is in how the machines are calibrated. The security unit is kept at operating temperature at all times so that it is ready to instantly release a large burst of obscuring smoke. It generates a sufficient amount of smoke to fill the target area. The other two machines require a few short minutes to reach operating temperature.
They can operate for as long as the fluid supply provides for. The smoke generator produces 'dry' smoke. The fogger can be set to produce somewhat ‘wetter’ fog (larger droplets), if required to ensure optimal impingement on the target. Corona fluid should be used in the two smoke machines. The operator of a fogger decides on the feedstock for his unit in due observance of all label warnings and instructions and all applicable regulations.
Corona does not provide any specialty fluids for foggers. That is why the warranty on the fogger is restricted to those parts that are not directly in contact with chemicals.
2: What is the relevant measure for comparing the smoke output of alternative generators?
Output of smoke of a defined quality over a given time period! Volumetric output by itself is an incomplete and therefore misleading comparative measure.
One relevant measure is the effect on visibility – which is what Corona uses in its machine specifications since it suits the majority of customers. However, this measure is not fully pertinent if the prime use of the generator is laser measurements or the dispersion of special-purpose chemicals.
When comparing the performance of alternative generators it is important to realize that smoke composition – specifically the size of the smoke particles - makes a vast difference. For instance, a 0.3 micron particle will remain airborne 8 times longer than a 1 micron particle and 31 times longer than a 2 micron particle.
The number of droplets for a given amount of fluid and their combined surface area grow exponentially with a reduction in droplet size. To reduce visibility to one meter requires only 12% of the fluid if the smoke is comprised of particles that are 0.3 micron rather than 3 micron in diameter. After 1 hour a 0.3 micron particle drops 1.5 centimeters while a 3 micron particle descends almost a meter. As a result, it requires 15 times as much fluid for 3 micron particle smoke compared to 0.3 micron smoke to maintain 1 meter visibility for one hour.
Or to put it in smoke output terms: a generator that produces 3 micron size particles needs to produce 15 times the output of a machine that delivers 0.3 micron size particles to maintain a given ‘smoke effect’.
3: What is the difference between an "obscuring" aerosol and real smoke?
True smoke is created by a burning process and is composed of solid and liquid particles that are often toxic. Artificial smoke represents benign liquid particles that are suspended in air or an inert harmless gas.
4: How does a smoke generator work?
A mixture of a fluid and a propellant gas is passed through a heat exchanger. The liquid becomes a vapor, which condenses in the cooler atmosphere to become a visible "smoke". Corona’s heat exchanger is made of steel allowing lifelong operation and uniform heating throughout the block. The removable (serviceable) spiral probe in the core of the block provides for an optimal pathway for efficient heat transfer.
5: How do I compare smoke generators for their performance?
Performance of smoke generators should be measured in terms of the time it takes to achieve a desired reduction in visibility and by how much smoke fluid is required to maintain it. A simple reference to the output capacity of the generator is irrelevant since this fails to take into account the density of the smoke. The smaller the droplets the denser the "smoke". Large droplets need more ready replacement to maintain obscurity. The more fluid is released, the greater the chance of visible deposition and the higher the operating cost.
A typical Corona generator (Spirit) reduces visibility in a 1,000 cu. ft. room to five feet within 4 seconds, using 235 mg. of fluid.
6: Why do suspended liquid particles look like smoke?
Light is reflected and deflected – scattered – by the suspended liquid particles in the artificial smoke. Corona smoke particles match the optimal size for scattering regular light (0.3 micron).
7: How is the liquid deposition of artificial smoke avoided?
Quality thermal aerosol should contain liquid particles that remain small even after they bond together while bouncing around in the air so that gravitational force does not cause them to form visible deposition. Corona’s machines create particles that remain sufficiently small not to drop by gravity. Because of the extended hanging time, less liquid is required to maintain a given visibility.
8: How do water and oil based artificial smoke differ?
Water-based thermal aerosol disperses more quickly and disappears under high temperatures. In order to maintain a certain level of visibility less oil based fluid is required. Corona offers both types of smoke fluids. Typically oil based "smoke" is more appropriate in controlled industrial and scientific settings.
9: Is it possible to color artificial smoke?
The quality of artificial smoke suffers from foreign elements in the constituent fluid. An aerosol reflects incoming natural light - which is white. The greater its scattering performance, the more readily the "smoke" will take on the appearance of incoming light of another color.
10: How does artificial smoke affect health?
Any health concerns need to be assessed on the basis of the exposure to the amount and the composition of the constituent fluid. It is wise to wear a respirator in the case of frequent or extended exposure to an aerosol, while such protection is mandatory for certain special fluid applications. Used in accordance with recommended practice, Corona’s regular "smoke" should not impose any health hazards.
11: How does artificial smoke effect computers and delicate objects?
Fluid deposition depends on a number of factors including the quality of the generator, its calibration, the type of fluid, and the operating conditions. Corona machines are designed and manufactured under the highest Quality Assurance criteria (ISO 9001). If used with the right fluids they should reliably generate consistent and high quality "smoke". Due to the uniquely small size of the particles that make up Corona’s smoke, computers and other sensitive equipment are not harmed.
12: How do I get rid of the artificial smoke?
Eventually all aerosol particles will evaporate or deposit. The rate at which this occurs depends on the initial size of the particles. The smaller the particles the greater their longevity. Induced air supply and turbulence will accelerate the break-down of the "smoke". Corona recommends venting of the premises immediately after the "smoke" is no longer required. This practice can be accelerated with the aid of fans.
13: Can I use any type of smoke fluid?
Smoke fluids should not be tampered with. They represent balanced recipes for which the machines are carefully calibrated. Amending the formulas may result in harmful and ineffective "smoke" and may damage the generators. For safe and reliable performance, Corona machines are purposefully designed and calibrated for use with designated fluids only.
14: Can I be burned by artificial smoke?
While the heat exchanger may reach a temperature in excess of 800 degrees Fahrenheit, the aerosol cools almost instantaneously upon exiting the generator. Touching the nozzle of a generator should be avoided. It is perfectly safe to hold a hand in the smoke plume, a foot or so beyond the nozzle of a Corona generator. The outside casing of the generator remains cool at all times. For extra safety, each Corona generator is equipped with a thermal cut-out switch to avoid overheating.
15: Can the Corona machines produce smoke in a pressurized environment?
Absolutely. The unit can be located inside the area in question - assuming it is a non-explosive environment - and should operate as usual, producing regular type smoke. Obviously, care has to be taken when introducing a CO2 canister into the pressurized environment. If the machine is to be located outside the pressurized area, smoke can be produced inside a holding chamber first using nitrogen as the "carrier" (to avoid any flammability danger).
Under additional nitrogen pressure the smoke can subsequently be driven out of the holding chamber into the target area. The additional pressure should exceed by one atmosphere (140 psi), the pressure in the target area. Depending on the extent of pressurization the particle size of the smoke might be reduced slightly.
16: Can artificial smoke be pressurized?
Pressure encourages aerosol particles to bond into larger droplets. Depending on their initial size, pressurized particles will turn into liquid. Corona's generators produce particles that are sufficiently small to allow them to be directed through a fan, to extend their reach or accelerate their dispersion without undue deterioration in fog quality.
17: How do I judge artificial smoke quality?
The quality of artificial smoke is primarily a function of the diameter of its aerosol particles. The smaller the particles, the brighter the smoke’s appearance, the longer its ‘hang time’, the more multidirectional its distribution, the greater its versatility for ducted applications, and the deeper its penetration into tiny cracks. The particles of Corona "smoke" measure between 0.2 and 0.3 microns in diameter – the smallest particles produced by any standard generator in the industry (A micron is one thousandth of a millimeter).
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