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% Ethylene
Freeze protection
20%
-10°C
30%
-16°C
40%
-25°C
50%
-39°C
Freeze protection of ethylene glycol solutions
Glycol systems require specific inhibitors compatible with the materials of construction they come into
contact with. These inhibitors generally come pre-mixed with the glycol additive for the cooling circuit.
If the system must be operated with water, the following conditions must be met simultaneously:
1. Maintain a minimum flow through the unit at all times. (see table below)
2. Maintain a minimum heat load, so that the temperature of the water leaving the coil(s) will not fall below 10°C
based on -14°C ambient temperature and 20 m/s wind velocity.
3. In order to prevent coil freezing, the 3-way valve must be positioned to let the full flow circulating through the
prime surface coil.
If the process load is extremely light or shut off, it may be necessary to apply an auxiliary heat load during freezing
conditions. Consult your local BAC Balticare representative for advice, if these conditions cannot be met.
Draining of the coil(s) is not recommended as a normal method of freeze protection unless the coil(s) are
constructed from stainless steel or are of the cleanable type. For standard hot dip galvanized coils draining is
ONLY acceptable as an emergency method of freeze protection, since draining will lead to internal corrosion of the
coil. For this purpose an automatic drain valve and air vent needs to be installed to drain the coil(s) if flow stops or
the fluid temperature drops below 10°C when the ambient temperature is below freezing.
Ensure that all coils and/or coil sections (split coils/multi-circuiting) can drain individually.
Model
Minimum flow (l/s)
HFL 36X - 48X
4,1
HFL 72X – 96X
7,9
HFL 108X – 144X
12
HFL 150X – 192X
15,8
HFL 180X – 240X
19,9
HFL 216X – 288X
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Minimum requirements for water flow
Draining of the coil is not recommended as a normal method of freeze protection. Frequent draining promotes
oxidation inside the coil tubes. Full draining of the heat exchanger coil is not guaranteed because of rising coil
circuiting on the finned discharge coil (optional) and the risk for coil freeze-up remains. The local BAC Balticare
representative should be consulted for guidelines on the installation of an emergency coil drain system.
W W W . B A L T I M O R E A I R C O I L . E U
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