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Smoke Machines Vs. Hazers 

     There are a variety of smoke machines and hazers available on the market.  What are the advantages and disadvantages of the two types?  Which is best for laser shows?  This article attempts to provide answers based on both theory and field experience.
Smoke machines and hazers are important to laserist as light is invisible to the eye.  What the eye sees is the reflection of light from surfaces.  In order to create spectacular laser beam effects, we need particulate matter in the air in order to reflect or scatter the light towards the viewer's eyes.

Definitions

We should start by defining our terms.  Smoke machines are defined as machines that operate using water based smoke fluids.  Common examples are the Rosco, Gem, American DJ, Lightwave, AquaFog and other similar types.  These are very common, popular and usually low priced.
Hazers, also sometimes called crackers, use oil based fluids and some form of compressed gas to force it through a fine nozzle or nozzles thus 'cracking' the fluid into very small particles. Common examples are the MDG machines, DF50, Compass and other similar types.  These types of machines are less common and tend to be more costly.

Smoke Machines

Typical smoke machine - Photo courtesy of Rosco

Smoke machines generally operate by pumping the water based smoke fluid, usually with an electrical pump, into a heated evaporation chamber.  Here the fluid is evaporated and ejected from the nozzle at the front of the machine.  What comes out is a thick cloud of white 'smoke' which consists mostly of water vapour and some carbonized particles from the smoke fluid.  Typical particle size in the smoke are 150 microns or more.
Since the output contains lots of water vapour, this adds to the humidity in the room which can cause increased condensation on cold plates and inside the head of water cooled laser systems.

Hazers

A specialized  hazer design for very find haze - Photo courtesy of MDG

Hazers operate by using a compressed gas, commonly CO2 or compressed air, to force the oil based fluid through a very fine nozzle (or nozzles).  This breaks the fluid down into very fine particles.  In some systems, those particles are then sent through a heated evaporation chamber, while in others, a fan is used to blow the particles directly into the air. What comes out is usually a very find haze or a cloud of white 'smoke' which typically has particle sizes in the 5-10 micron range.
The output rarely contains water vapour so hazers do not add to the humidity in the venue.

Particle Size

Particle size is an important consideration as we shall see.  Most smoke machines using water based fluids pump out vast clouds of smoke that look impressive. The size of the particles in this smoke are usually over 50 microns and often even larger.  These particles 'clump' in the air forming heavier clumps that soon fall to the ground. This is why you have to have to use frequent blasts of smoke from water based machines to keep up the haze levels - not enough small particles are produced. The cloud of dense smoke often blocks the laser beams absorbing power and cutting down on the effect the audience sees until the smoke disperses.
Hazers produce particles in the under 10 micron range, typically around 5 microns. These particles also clump but produce smaller clumps.  Since the particles are smaller to start with, it takes much longer for the larger clumps to reach critical mass and fall to the floor.  The smaller particle sizes make a fine haze - perfect for laser shows. The fine haze spreads evenly making the laser beams highly visible without absorbing all of the laser power.

Hang Time

An important consideration for laserists is 'hang time' or how long the particles stay suspended in the air.  As mentioned above, larger particle fall to the ground rapidly necessitating frequent bursts of smoke from water based machines to replenish them.  Hazers produce very fine particles that hang in the air four or five times longer then those typically produced by water based machines. A 30 second burst of smoke from an MDG machine will remain suspended in the air far longer than a 30 second burst of smoke from the typical water based smoke machine.

Dispersal

The smoke or haze from a hazer disperses rapidly and evenly through the room producing a fine almost invisible haze, while water based smoke tends to produce a large clouds that dissipates rapidly . You can blow the smoke from a hazer directly into an air-conditioner intake; the particles are so fine that most of the haze will be be redistributed by the air system. If you do this with water based machines, most of the particles will be trapped in the filters and very little is re-circulated.

Fire Alarms

Most water based smoke machines also emit significant amounts of carbon particles from burning that takes place in the evaporation chamber. The carbon particles can trigger smoke detectors and fire alarms causing havoc at shows and ill-will from clients.
A clean and well maintained hazer emits almost undetectable levels of carbon. Laserists have successfully used MDG machines at venues equipped with smoke detectors and had plenty of haze for the show with no false fire alarms.

Due to the fine, well dispersed haze produced by hazers, and the long hang time of the haze, they have a clear advantage over water based machines with their thick clouds of smoke and shorter hang time.  However, because hazes often cost considerably more, some opt for the lower cost smoke machines which may not be such a good option when we examine cost of ownership.

Cost Of Ownership

Finally we should take into consideration the cost of ownership of the two different types of machines,  This will be a major factor in making a buying decision.  Let us take as an example the following conditions; 25 shows per year (that is one every other week on average) in a large space such as a small arena or large hall, each show requiring and average of 8 hours of smoke machine operation.
The typical water based smoke machine goes through about one liter of fluid for every 4 hours of operating in a large space. Based on the parameters above, that would require 2 liters of smoke fluid per show times 25 shows = 50 liters of smoke fluid.  At an average cost of $12.00/liter that comes to $ 600.00 in fluid plus an initial cost of $600.00 to acquire a quality water based machine. [note that this does not take into account maintenance costs on the water based machine which tend to be higher than hazers due to corrosion from the fluid.]
Taking the MDG Max 3000 as an example, the machine goes through about .4 of a liter of fluid in an 8 hour show, times 25 shows = 10 liters of fluid.  At an average cost of $10.00/liter = that comes to $100.00 for fluid.  The acquisition cost of a MAX 300 is about $1,800.00.
With a little math, we discover that while the initial cost of acquisition of the MDG machine is high, the lower operating costs mean that within two years [given the parameters in the first paragraph] the cost of ownership of the MDG machine has fallen to around $150.00 per year for fluid and supplies while the water based machine is still costing $600.00/ year in fluid for inferior results.  The cost of ownership of the MDG machine falls faster with more shows due to it's economical use of fluid.

Safety Notes

Most smoke machines and some hazers produce output that is at a high temperature compared to ambient. In the case of water based machines, the output contains significant quantities of hot water vapour [steam] which can cause burns, just as hot oil vapour from some hazers can cause burns.  Make sure that the machine is placed at least 2 meters from any point where the audience can access the output to allow enough time for the output to spread and cool.  Dispersing the output with a fan is also a good idea.
Almost all smoke machines and hazers also eject some some unused fluid, particularly during heavy use and as the machine ages.  Another good reason to keep the machines separated from the audience so as to prevent slips and falls from the fluid residue.

Summary

A hazer type of smoke machine is the clear choice for laserists.  It produces a finer haze which disperses easily without blocking the beams, and has a longer hang time so less haze fluid is required for a better result.  The finer haze also makes the laser beams appear brighter to the eye than with water based machine smoke.  A well maintained hazer is also far less likely to set off fire alarms than your typical water based smoke machine.  While the acquisition cost of a quality hazer is higher than the typical water based machine, the long term cost of ownership is lower.
The most popular hazers in the laser show industry have been the MDG MAX3000 and Atmospheres machines.  They were originally designed for industrial applications such as firefighter training and are exceptionally rugged and reliable with consistent results and low, long-term cost of ownership.

DISCLAIMER: Some of the information in the Backstage area is provided by the persons or companies named on the relevant page(s). Laser F/X does NOT endorse or recommend any products/services and is NOT responsible for the technical accuracy of the information provided.  We provide this information as a service to laserists using the Backstage area. 

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