Laser Show Systems - Support Equipment
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.
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
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
F/X International and LaserFX.com - All rights reserved.