Honeywell AUTOMATIC CONTROL User Manual

ENGINEERING MANUAL OF AUTOMATIC CONTROL
VALVE SELECTION AND SIZING
446
Where:
W1 = Humidity ratio entering humidifier, pounds
of moisture per pound of dry air.
W2 = Humidity ratio leaving humidifier, pounds of
moisture per pound of dry air.
=The specific volume of air at standard
conditions of temperature and atmospheric
pressure.
= Cubic feet per minute (cfm) of air from the
fan.
=A conversion factor.
Simplifying:
5. When Equivalent Direct Radiation (EDR) is known:
Q=EDR (Total) x 0.24
Where:
EDR (Total) = Radiators are sized according to Equivalent
Direct Radiation (EDR). If controlling
several pieces of radiation equipment with
one valve, add the EDR values for all pieces
to obtain the total EDR for the formula.
0.24 = A scaling constant, lb steam/unit EDR. See
Table 4.
QUANTITY OF STEAM
To find the quantity of steam (Q) in pounds per hour use one
of the following formulas:
1. When Btu/hr (heat output) is known:
Where:
gpm = Gallons per minute of water flow through
converter.
TDw = Temperature difference of water entering
and leaving the converter.
0.49 = A scaling constant. This value is derived as
follows:
Simplifying the equation:
Where:
Btu/hr = Heat output.
1000 Btu/lb = A scaling constant representing the
approximate heat of vaporization of steam.
2. For sizing steam coil valves:
Where:
cfm = Cubic feet per minute (ft
3
/min) of air from
the fan.
TDa = Temperature difference of air entering and
leaving the coil.
1.08 = A scaling constant. See NOTE.
1000 Btu/lb = A scaling constant representing the
approximate heat of vaporization of steam.
NOTE: The scaling constant 1.08 is derived as
follows:
Where:
Simplifying the equation:
The specific volume of air at standard
conditions of temperature and atmospheric
pressure.
To find the scaling constant for air conditions other
than standard, divide 14.40 Btu by specific volume of
air at those conditions.
3. For sizing steam to hot water converter valves:
Q=gpm x TDw x 0.49
4. When sizing steam jet humidifier valves:
60 min
hr
ft
3
min
13.35 ft
3
lb air
Q =
Btu/hr
1000 Btu/lb stea
m
0.49 =
8.33 lb water
1
g
al
x
60 min
1 hr
x
1 lb steam
1000 Btu
x
1 Btu
lb water ˚
F
0.49 =
0.49 min lb stea
m
g
al hr ˚F
Q =
()
W
1
– W
2
lb moisture
lb air
x
1
13.35 ft
3
lb air
x
ft
3
min
x
60 mi
n
hr
Q = 4.49
()
W
1
– W
2
lb moistur
e
hr
Q =
CFM x TD
a
x 1.0
1000 Btu/lb steam
1 lb air
13.35 ft
3
=
1.08 =
0.24 BTU
lb air ˚F
x
60 min
1 hr
x
1 lb air
13.35 ft
3
1.08 =
14.40 Btu mi
n
˚F hr 13.35 f
3

Honeywell AUTOMATIC CONTROL Specifications

General

Brand	Honeywell
Model	AUTOMATIC CONTROL
Category	Controller
Language	English