Herrmidifier Load Calculator User Manual

Page 6

L o a d C a l c u l a t i o n G u i d e

w w w. h e r r m i d i f i e r- h v a c . c o m

When moisture evaporates from the surface of the skin it

causes a degree of evaporative cooling. During the winter,

when heated air is dry, this evaporation occurs more readily,

causing a higher degree of evaporative cooling and a feel-

ing of chilliness. Raising the temperature will help alleviate

the feeling of chilliness, but will actually aggravate the other

problems of dry, parched throat and eyes, because the air

at this higher temperature can now hold still more moisture

(refer to Table 1 -A), which causes the R. H. to drop and the

pull for moisture from body to air becomes even greater.

More comfort can readily be obtained by raising the level of

relative humidity. Often, by raising the R.H. the temperature

can then be lowered while maintaining the same comfort

level. The following Table 1 -B illustrates various comfort

levels possible. As you can see from the chart, raising

the R.H. could result in your being able to lower the tem-

perature, thereby saving energy. In this age of expensive

energy, this could be a big boost for any industry, office or

home. In addition the annoying parched throat, sore eyes

and dry nose may be eliminated. Generally, R.H. levels of

35% to 50% are considered to be in the comfort range.

Table 1-B

Comfort Levels vs. Temperature/Humidity

Factory

Office

°F

% RH

°F

% RH

Humidity And Dust

Dust is not only a cleaning and maintenance nuisance but

a common vehicle for microorganisms. It is well known

that the R.H. of the air will significantly affect the amount of

dust in the air. A higher level of R.H. (50%) will cause the

particles to settle out of the air.

Also, dry air will pull moisture from the fibers of carpets and

rugs causing them to become brittle, break off and float in

the air. By raising the level of R.H. in the air this problem

can be significantly reduced. For example, in one study a

carpet cleaned weekly, under low levels of relative humid-

ity, produced 3 to 4 bags of broken fibers or “fuzz.” After the

R.H. in the office was raised to 50% the weekly cleaning

produced only a half bag of “fuzz.” Needless to say, the

carpet life was probably extended, as well as a reduction of

dust from the fibers of the carpet achieved.

Humidity And Its Effect On Bacteria And Virus Life

Several studies on various bacterial strains and viruses

have shown that at R.H. levels close to 50% these micro-

organisms fail to survive for long periods of time. Possible

explanations of this are that at low levels of R.H. these mi-

croorganisms can enter a “dormant” state and simply float

around in the air until such time as they contact a moist

surface where they can become “active” again. At high lev-

els of R.H. there is enough moisture in the air that these mi-

croorganisms may be able to thrive “actively.” In the middle

levels of R.H., near 50%, there is enough moisture in the

air that these microorganisms cannot remain “dormant,” but

not enough that they can thrive “actively” either.

“Dry Air” And Static Electricity

Dry air permits the buildup of static electricity charges

on machinery, materials and people. These electrostatic

charges may cause production problems because of the

electrostatic attraction built up between materials, unpleas-

ant shocks to personnel, and in some cases, explosion

hazards.

Static electricity charges are built up by movement of

machinery and materials, such as in a printing press or

a spinning machine, by people walking across carpeted

floors, etc. These charges are constantly being generated

and their buildup and discharge are affected by the level

of R.H. Relative humidity levels above 45% will serve to

eliminate electrostatic charge buildup and discharge. What

happens when R.H. is higher is that an invisible moisture

film will form on the surface of materials and equipment.

This film contains impurities, from the air, which allow it to

be a conductor. As electrostatic charges are generated, this

film conducts the charges to ground before they can build

up sufficiently high to cause a spark to jump.

Control of static electricity is important in many industries.

Printing plants need to eliminate the static electricity caused

problems of erratic feeding, sticking sheets, tacky ink and

misregistration of color. Textile mills can ill afford to have

huge electrostatic charges build up on spindles and cards.

Data Processing is especially sensitive to static electricity

as it can cause malfunction by improper feeding of cards

and paper, brittle tape and electrostatic discharges. Ex-

plosive production areas must be humidified. To chance a

static discharge in an explosive atmosphere is extremely

dangerous.