Leader in Misting & Temperature Control Systems

Dust is typically formed by pulverization or the mechanical disintegration of solid
matter into particles of smaller size by processes such as grinding, crushing, and
drilling. Particle sizes of dust range from a lower limit of about 1 micron up to 100
microns and larger. Dust particles are usually irregular in shape and will not
flocculate or settle under the influence of gravity. Common examples incluse fly-
ash, rock dust, and ordinary flour. Dust collection is concerned with the removal
of these particles for the purpose of:

1) Air-pollution reduction
2) Equipment-maintenance reduction
3) Safety or health hazard elimination
4) Product-quality improvement
5) Recovery of a valuable product

It is well known that increasing the relative humidity of air will significantly reduce
the amount of dust in the air. The “MISTER” system controls low humidity levels in
the air, thereby reducing this problem.


Smoke implies a certain degree of optical density and is typically derived from the
burning of organic materials such as wood, coal, and tobacco. Smoke particles
are very fine, ranging in size from less than 0.01 m to 1 m. They are usually
spherical in shape if of liquid or tarry composition and irregular in shape if of solid
composition. Owing to their very small particle size, smokes can remain in
suspension for long periods of time and exhibit lively Brownian motion.

Convection flow causes reburn.


A) Hygroscopic Materials

Hygroscopic materials are defined as those which are able to take on or give up
moisture, thereby changing their regain. They are particularly sensitive to
humidity changes in their environment. When these materials finally reach a
balance, where they are stable and no longer take on or give off moisture, they
are said to have reached their equilibrium moisture content (EMC).

When a hygroscopic material is stabilized at its EMC for a particular temperature
and relative humidity, there is little effect on the material. The problems begin
when the relative humidity begins to drop and the air pulls moisture from the
material, upsetting its EMC. When the material loses moisture it will shrink, warp,
crack, and become thirsty for solvents. This causes problems not only with the
material, but also with the machinery, finishing processes, coatings, etc. Weight
and texture are also significantly effected.

When the EMC is upset to the point of damaging a product and rendering it
unsalable, economic loss results. This includes the loss of any and all energy
required to manufacture that product, and the additional energy input and labour
expense if the product is reworked.

B) Wood

Wood is a hygroscopic material, able to take on or give up moisture to the
surrounding air. As wood takes on moisture it swells, as it gives up moisture it
shrinks. The amount of moisture in the wood, expressed as a percentage of it’s
dry weight, is referred to as its regain. Regain will vary with temperature, relative
humidity, and type of material.
                                             .....(continued top right)

As wood loses moisture it shrinks, however, the tangential shrinkage is much
greater than radial shrinkage. This causes dimensional changes and
instability in the wood and it will pull apart along the grain, causing cracks. If
the wood is strong enough not to crack, it will warp as the uneven shrinkage
occurs. This is why it is important to condition wood to the proper regain for
best workability and then stabilize it at the corresponding EMC by maintaining
proper humidity control.

Optimum conditions for wood constitute a regain between 5% - 9%, depending
on the wood and its use. This corresponds to the EMC with 35% - 45%
relative humidity air at 75 F.        

C) Dry Kilns

The “MISTER” system is ideal for use in lumber dry kilns. It can be used with
lumber of any species and thickness and can be installed in both conventional
and dehumidification dry kilns.

The “MISTER” system provides solutions to many problems experienced
during conditioning and equalization. First, it eliminates the tendency of the
dry bulb temperature to rise uncontrollably. This rise in temperature
decreases the relative humidity in the kiln, reduces the effectiveness of the
conditioning process, and lengthens the time required for
equalization/conditioning. This temperature rise is due largely to an enthalpy
decrease when high-temperature, high-pressure steam is released into the
kiln interior. A smaller heating effect results from the temperature change
undergone by the steam as it leaves the spray line. It is estimated that the
combined effect of these two factors result in a release of 1,270 BTU each for
pound of water vapor absorbed into the lumber. If a cool water spray were to
be used in place of live steam, approximately 1,112 BTU/lb of spray would be
used in raising the temperature of the water droplets to the kiln interior
temperature. This would largely offset the 1,270 BTU/lb released when the
vapor entered the wood surfaces, thereby significantly reducing the heat

Another advantage of using the “MISTER” high pressure system with
conventional kilns is the steam savings. Take the case of a mill with several
kilns which are heated by a waste wood boiler. When the mill was constructed,
the boiler was oversized to allow for future kilns. As these were added, the
excess heat capacity of the boiler decreased to the point that the output of the
boiler would not support additional kilns. By replacing the steam spray
systems in all kiln attached to the boiler with the “MISTER” system, enough
energy can be saved to permit the construction of additional kilns without an
expensive boiler upgrade.

All of MEC’s misting systems come with
a 1 year warranty on the pumping unit
and 5 years on the stainless steel nozzle
line, however,  proper maintenance of
your misting system is necessary to
ensure optimum performance and
MEC SYSTEMS INC. warranty based on regular maintenance
Copyright © 2017 MEC Systems Inc.