Armstrong VSA-92A Instrukcja instalacji i obsługi - Strona 4
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Air and Electrical Connections
B.
If automatic control is not used, the use of a hand
switch to control the fan motor has defi nite ad-
vantages. The fan operates continuously during
the heating season. The motors are oil less in all
positions. Current consumption is low – 6 watts
for all AMEF models.
For FSA, VSA Models (See Figs. 3-4 & 3-5)
A.
Beware of Voltage Drop. If the wire supplying
current to the humidifi er is too small or too long,
there may be a voltage drop that will reduce the
life of your equipment. When the voltage is too
low, the solenoid valve will not open but current
will continue to fl ow and will burn up the coil.
B. 24 Volt Wiring. (VSA Only) Where codes permit
24 volt wiring without conduit, the use of a 120-24
volt transformer relay, as shown in Fig. 3-5 will
lower the installation cost.
Step 7: Install Pneumatic Piping. (AM)
A. Air Supply. Air supply for Armstrong Humidifi ers
should be 15 to 20 psi. This air must be clean and
dry instrument air. Make air connections to fan of
AMAF models.
Sizing and Selection
A survey of your requirements should be taken to deter-
mine the amount of steam needed for humidifi cation, the
number, size and type of units required, and the location of
both humidifi er and humidity controllers.
Sizing and location with natural ventilation.
These are the average industrial humidifi cation applications
with:
Room temperatures – 65° to 80°.
Relative humidities – 35% to 80%.
Natural ventilation – i.e., infi ltration around windows and
doors.
Selection Data Required.
■ Minimum Outdoor Temperature: for most jobs, fi gure
10°F above the lowest recorded temperature for your
locality. The lowest temperatures are seldom
encountered for more than a few hours.
■ Indoor Temperature
■ RH Desired
■ Pressure of Steam Available for Humidifi cation
■ Number of Cubic Feet in Room
■ Air Changes Per Hour: air changes taking place under
average conditions exclusive of air provided for
ventilation or regain of hygroscopic materials.
Rooms, 1 side exposed ................... 1
Rooms, 2 sides exposed ................. 1 ½
Room, 3 or 4 sides exposed ............ 2
Rooms with no windows or
outside doors ............................ ½ - ¾
B. Compressed Air Piping. Plastic tubing or equiva-
lent is used for all air connections.
Step 8: Install Humidity Controller.
Location. The humidistat should be installed anywhere
from 20 ft. to 30 ft. from the humidifi er – at one side of
the air stream from the humidifi er. The hygrostat should
be able to "see" the unit controlled. It must not be hidden
behind piles of goods or in channels of columns where air
movements cannot reach it. It may be necessary to experi-
ment with the location in order to get the best control.
Setting and Adjusting should be done in accordance with
the manufacturer's instructions furnished with the humidi-
stat.
Recommended Option.
A pneumatic or an electric temperature switch is recom-
mended in any system where the steam supply to the
manifold jacket and humidifi er body may be interrupted or
turned off.
Typical Problem:
Design outdoor temperature ............ 0°F
Indoor temperature .......................... 70°F
RH required ..................................... 40%
Air changes per hour ....................... 2
Steam pressure available ................ 5 psi
Room size 400' x 160' with 10' ceiling.
Natural ventilation
Heated by:
Unit heaters – fan on-off control.
Step 1: Steam required for humidifi cation. Our room con-
tains (400' x 160' x 10') or 640,000 cu. Ft.
From the 70°F Table 5-1, read across from 0°F outside
temperature to the 40% RH column where you fi nd the
fi gure .409 lbs. of steam per hour per 1000 cu. ft. of space
for each air change. Then, 640 x .409 x 2 equals 524 lbs. of
steam per hour installed humidifi cation capacity required.
Step 2: Electric or air controlled units. The large fl oor area
calls for multiple humidifi ers. No explosion hazard has
been specifi ed so use of air controlled units is not required.
Electric units are recommended.
Step 3: Number of humidifi ers for job. Divide steam
required by capacity of humidifi ers at steam pressure avail-
able.
Step 4: What size humidifi er to use. For this example, a
large number of smaller capacity units is recommended.
Larger capacity units could cause condensation on the low
ceiling. Also, because of the large fl oor area, the humidi-
stats for fewer units would be widely spaced, which could
result in less accurate control than desirable.
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