10 AGZ 030A through 065A IOM 686
Glycol Solutions
The system glycol capacity, glycol solution flow rate in GPM, and pressure drop through the cooler
may be calculated using the following formulas and table.
1. Capacity -- Find the reduced capacity by multiplying the chiller’s capacity with water by the
capacity correction factor C.
2. Flow -- To determine evaporator gpm (or Delta-T) knowing Delta-T (or gpm) and capacity:
Glycol GPM (from table)=
×
−
×
24 capacity glycol
Delta T
G
( )
For Metric Applications -- To determine evaporator L/s (or Delta-T) knowing Delta-T (or L/s)
and kW:
Glycol L / s (from table)=
× −
×
kW
Delta T
Flow
4.18
3. Pressure drop -- To determine pressure drop through the evaporator, when using glycol, enter the
water pressure drop curve on page 12 at the actual glycol GPM. Multiply the water pressure drop
by PD correction factor from Table 4 or Table 5 to obtain corrected glycol pressure drop.
4. To determine the unit's power consumption when using glycol, multiply the water system kW by
factor kW.
Test coolant with a clean, accurate glycol solution hydrometer (similar to that found in service
stations) to determine the freezing point. Obtain percent glycol from the freezing point table below.
On glycol applications it is normally recommended by the supplier that a minimum of 25% solution by
weight be used for protection against corrosion.
CAUTION
Do not use an automotive grade antifreeze. Industrial grade glycols must be used.
Automotive antifreeze contains inhibitors which will cause plating on the copper tubes within
the chiller evaporator. The type and handling of glycol used must be consistent with local
codes.
Table 4, Ethylene glycol
% Freeze Point
E.G. °F °C Cap. kW GPM PD
10 26 -3 0.991 0.996 1.013 1.070
20 18 -8 0.982 0.992 1.040 1.129
30 7 -14 0.972 0.986 1.074 1.181
40 -7 -22 0.961 0.976 1.121 1.263
50 -28 -33 0.946 0.966 1.178 1.308
Table 5, Propylene glycol
% Freeze Point
P.G. °F °C Cap. kW GPM PD
10 26 -3 0.987 0.992 1.010 1.068
20 19 -7 0.975 0.985 1.028 1.147
30 9 -13 0.962 0.978 1.050 1.248
40 -5 -21 0.946 0.971 1.078 1.366
50 -27 -33 0.929 0.965 1.116 1.481
Note: The procedure
does not specify the
type of glycol. Use
the derate factors
found in Table 4 for
corrections when
using ethylene glycol
and those in Table 5
for propylene glycol.
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