8Direct Drive Fluid Coolers IOM 1062
General
1. Structure supporting unit must be designed to support both the unit and the fluid.
Table 1 provides weight of fluid per gallon. Provide suitable flashing of the roof, if this
is a roof installation. For ground level mounting, a concrete pad is recommended.
Mounting holes permit the units to be bolted down to withstand wind pressures.
Provide adequate clearance for unobstructed air flow to coils.
2. Level mounting is necessary to ensure proper fluid distribution through the coil as well
as flooded suction for the pump.
Table 1, Fluid Weight Per Gallon at 130
°
°°
°
F
Percent Glycol Pounds per Gallon
Ethylene Glycol
Pounds per Gallon
Propylene Glycol
0 (Water) 8.25 8.22
10 8.33 8.29
20 8.50 8.37
30 8.58 8.42
40 8.80 8.49
50 8.82 8.53
3. Water piping must comply with local codes. Correct pipe sizing will help reduce
pumping power and operating costs.
4. In case of doubt, consult the manufacturer for the dry cooler fluid pressure drop at the
specific conditions on your job.
5. Provide sufficient valves and unions to permit easy access to parts subject to wear and
possible repair or replacement.
6. After fluid piping is completed, all joints should be leak tested.
7. Where city water make-up is required, follow local codes, making certain that
disconnecting provisions are provided.
8. Select wire in accordance with nameplate data and local codes.
Piping Installation
The piping system should provide maximum leak prevention. Weld or sweat joints should
be used where possible. The fact that glycol solutions or other heat transfer fluids will leak
where water will not, must be taken into account.
The glycol system should not employ an automatic fill with a pressure-reducing valve. This
is because a slight leak would lead to dilution of the mixture and possible freeze potential.
Any refill should be controlled so as to maintain the proper glycol-to-water ratio.
Table 2 shows pressure drops for various pipe sizes at flow rates commonly used with a
typical dry cooler. These pipe sizes are not necessarily always correct for the run from the
condenser to the dry cooler. Proper pipe size will depend on available pump head. This can
be determined by subtracting from the total available pump head at design flow, the
condenser pressure drop and the dry cooler pressure drop. Allow some safety factor for last
minute pipe fittings added to the system and for eventual fouling of the system.
a) Glycol piping requires no insulation except when fluid temperature will be below
ambient dewpoint temperatures.
b) Vents are required at all high points in the piping to bleed air when filling the system.
If fluid coolers are at high points, vent valves should be installed at each fluid cooler.
c) It is recommended that gate valves be installed on both sides of the pump to prevent
loss of fluid in the event the pump should require repair or replacement. Shut-off
valves are also recommended at water cooled condensers in case the condensing unit is
to be moved or requires maintenance involving the coolant system.
