Carrier AQUASNAP 30RA010-055 Product Data page 20

Selection procedure (cont)
AquaSnap ® pump selection
Several pump sizes are available for each AquaSnap chiller
size to provide flexibility in matching water system require-
ments. A dual pump option is also available for primary/
standby operation. The Carrier E-Cat Packaged AC Chiller
Builder can be used for pump selection, or selection can be
done manually.
Proper water system design is critical; cooling loads,
water pressure drops and proper water line sizing must be
accounted for in order to ensure proper system operation.
Incorrect or incomplete analysis/design of the water loop
could lead to low water flow, loss of water temperature
control, and excessive cycling of chiller compressors.
The following are the steps for manual selection of water
pumps for the 30RA chillers.
1. Calculate the water flow rate (gpm) and the total
water pressure drop of the system external to the
30RA chiller.
2. Determine the internal pressure drop of the chiller
hydronic package based on the design flow rate (refer
to internal Pressure Drop tables on page 22). Values
given in these charts are based on units with clean
strainers and circuit setter valve wide open.
NOTE: These pressure drops are for water. If glycol is
used, correct by multiplying by the factors below.
3. If an optional storage tank is used, determine the
internal pressure drop by referencing the internal
Pressure Drop tables on page 24.
20
NOTE: Note that these pressure drops are for water. If gly-
col is used, correct by multiplying by the factors below.
% GLYCOL
0 (Pure Water)
10
20
30
40
50
4. Add pressure drops found in Steps 1-3. This is the
total pressure drop and total head required by the
pump.
5. Use the pump envelope charts (page 25) to deter-
mine proper pump sizing. Plot water flow rate
(Step 1) and total head (Step 4), point on the chart.
The region containing the point corresponds to the
correct pump.
NOTE: Although pump bhp increases with glycol concen-
tration, pumps and pump overloads are selected such that
glycol concentrations up to 50% will not trip pump over-
loads if run within the recommended gpm ranges.
Example: Required water flow rate for a 30RA018
chiller is 45 gpm. The pressure drop in feet for the water
system external to the chiller is 50 feet. The system does
not have an accessory storage tank. The single pump is
needed. Select the pump.
Since the flow rate and external head losses (Step 1) are
known, the internal losses in the hydronic package must be
found (Step 2). Using the pressure drop graphs (page 22)
for the 30RA018 units, the internal loss at 45 gpm is
15 feet. Since no accessory storage tank is being used
(Step 3), the pressure drop is 0 feet.
Add all losses together (Step 4). The total pressure rise
needed by the pump is 50 + 15 + 0 = 65 feet. The pump
selection becomes pump C.
ETHYLENE PROPYLENE
GLYCOL GLYCOL
1 1
1.062 1.077
1.114 1.168
1.177 1.271
1.248 1.393
1.316 1.543