Quantity Of Water - Honeywell AUTOMATIC CONTROL Engineering Manual

VALVE SELECTION AND SIZING
1.6
40%
50% BY MASS
1.4
30%
1.2
20%
10%
1.0
WATER
0.8
0 40
TEMPERATURE, °F
REPRINTED BY PERMISSION FROM ASHRAE HANDBOOK—
1996 HVAC SYSTEMS AND EQUIPMENT
Fig. 14. Pressure Drop Correction for
Ethylene Glycol Solutions.
1.6
50% BY MASS
30%
40%
1.4
20%
1.2
10%
1.0
WATER
0.8
0 40
TEMPERATURE, °F
REPRINTED BY PERMISSION FROM ASHRAE HANDBOOK—
1996 HVAC SYSTEMS AND EQUIPMENT
Fig. 15. Pressure Drop Correction for
Propylene Glycol Solutions.

QUANTITY OF WATER

To find the quantity of water (Q) in gallons per minute use
one of the following formulas:
1. When Btu/hr is known:
Btu/hr
Q =
K x TD w
Where:
Btu/hr = Heat output.
K = Value from Table 3; based on temperature of
water entering the coil. The value is in
pounds per gallon x 60 minutes per hour.
TD w = Temperature difference of water entering
and leaving the coil.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
ETHYLENE
GLYCOL
SOLUTION
80 120 160
M12226
PROPYLENE
GLYCOL
SOLUTION
80 120 160
M12227
Table 3. Water Flow Formula Table.
Water
Temp F K
40 502
60 500
80 498
100 496
120 495
150 490
180 487
2. For hot water coil valves:
cfm x 1.08 x TD a
Q =
K x TD w
Where:
cfm = Airflow through the coil.
1.08 = A scaling constant. See Note.
TDa = Temperature difference of air entering and
leaving the coil.
K = Value from Table 3; based on temperature of
water entering the coil (pounds per gallon x
60 minutes per hour).
TDw = Temperature difference of water entering
and leaving the coil.
NOTE: The scaling constant 1.08 is derived as
follo ws:
0.24 BTU
1.08 =
lb air ˚F
Where:
The specific volume of air at standard
1 lb air
=
conditions of temperature and atmospheric
13.35 ft 3
pressure.
Simplifying the equation:
14.40 Btu min
1.08 =
˚F hr 13.35 f 3
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 fan system chilled water coil valves:
cfm x Btu/lb
Q =
113 x TD w
Where:
cfm = Airflow through the coil.
Btu/lb = Heat per pound of dry air removed. Includes
both sensible and latent heat.
113 = A scaling constant.
TDw = Temperature difference of water entering
and leaving the coil.
442
Water
Temp F K
200 484
225 483
250 479
275 478
300 473
350 470
400 465
60 min 1 lb air
x x
13.35 ft 3
1 hr