Daikin McQuay AGZ-D Operating And Maintenance Manual page 5

Glycol Solutions
The use of a glycol/water mixture in the evaporator to prevent freezing reduces system capacity and
efficiency, as well as increase pressure drop. The system capacity, required glycol solution flow rate,
and pressure drop with glycol may be calculated using Table 1.
1. Capacity – Multiply the capacity based on water by the Capacity correction factor from Table 2
through Table 5.
2. Flow – Multiply the water evaporator flow by the Flow correction factor from Table 2 through
Table 5 to determine the increased evaporator flow due to glycol.
If the flow is unknown, it can be calculated from the following equation
3. Pressure drop -- Multiply the water pressure drop from page 10 by Pressure Drop correction
factor from Table 2 through Table 5. High concentrations of propylene glycol at low temperatures
can cause unacceptably high pressure drops.
4. Power -- Multiply the water system power by Power correction factor from Table 2 - Table 5.
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 tables below. It is
recommended that a minimum of 25% solution by weight be used for protection against corrosion or
that additional compatible inhibitors be added.
Concentrations above 35 % do not provide any additional burst protection and should be carefully
considered before using.
Table 1, Flow/Tons/Delta-T Relationship
Glycol Flow (gpm)
Glycol Flow (l/s)
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
Table 2, Ethylene Glycol Factors for Models AGZ 025D to 130D
Freeze Point
% E.G.
o
F
10 26
20 18
30 7
-7
40
50 -28
Table 3, Propylene Glycol Factors for Models AGZ 025D to 130D
Freeze Point
% P.G.
o
F
10 26
19
20
30 9
40 -5
50 -27
OMM 1087

24 Tons Capacity
Delta
kW Capacity
 
. 4 18 Delta
WARNING
!
and handling of glycol used must be consistent with local codes
Capacity Power
o
C
-3.3 0.998 0.998
-7.8 0.993 0.997
-13.9 0.987 0.995
-21.7 0.980 0.992
-33.3 0.973 0.991
Capacity Power
o
C
-3.3 0.995 0.997
-7.2 0.987 0.995
-12.8 0.978 0.992
-20.6 0.964 0.987
-32.8 0.952 0.983
AGZ 025D through 190D
( glycol )

Flow Correction
T

Flow Correction Factor
T
Flow PD
1.036 1.097
1.060 1.226
1.092 1.369
1.132 1.557
1.182 1.791
Flow PD
1.016 1.100
1.032 1.211
1.057 1.380
1.092 1.703
1.140 2.251
Factor
5