Carrier AQUASNAP 30RBM Series Installation, Operation And Maintenance Instructions page 58

Refrigerant charge for the low-temperature brine solution option
30RBM and RBP
Circuit A, unit with option 6B
(1)
Circuit B, unit with option 6B
(1)
(1) Options: 6B Low-temperature brine solution.
Frost protection
The low-pressure and frost protection of the evaporator
depend on the antifreeze level in the water loop.
The evaporator pinch (LWT – SST) and the antifreeze
protection depend on this level.
It is therefore essential, when first activating the unit, to check
the antifreeze level in the loop (circulate for 30 minutes to
ensure good mixing homogeneity before sampling).
Refer to the manufacturer data to define the antifreeze
protection, dependent on the measured concentration level.
The minimum frost protection temperature must be entered
in the unit controller's parameters.
This value will be used to define the following limits:
1. Evaporator antifreeze protection.
2. Low-pressure protection.
For information, for the different antifreezes used in our
laboratory, the protection values given by our supplier are as
follows (these values may change depending on the suppliers):
It is therefore recommended that a low or very low temperature
installation be commissioned by the manufacturer.
Glycol concentration required
Ethylene and Propylene glycol freezing curve
50
45
40
35
30
25
20
15
10
5
0
-26 -24 -22 -20 -18
Minimum frost protection temperature (°C)
Ethylene glycol (%)
Ethylène glycol (%)
Propylene glycol (%)
Propylène glycol (%)
58
-16 -14 -12 -10 -8 -6 -4
160 180 200
kg 8,40 10,90 10,90
tCO e 17,5 22,8 22,8
2
kg 12,25 12,60 12,05
tCO e 25,6 26,3 25,2
2
Minimum frost protection temperature to be observed
based on the leaving water temperature.
Minimum frost protection temperature based on the
leaving water temperature (example)
0
-5
-10
-15
-20
-25
-16 -14
For example, based on the above curves, if the ethylene glycol
mass concentration measured in the loop is 30%, the frost
protection temperature value of -14.8°C must be entered in the
software. This corresponds to a minimum leaving water
temperature of -6.7°C. The control point must be added as a
result.
IMPORTANT:
• It is vital to perform a (minimum) annual inspection of
the glycol level and adjust the software's frost protection
based on the measured level.
• This procedure must be systematic when topping up with
water or antifreeze solution.
• Observe the minimum frost protection temperature based
on the leaving water temperature.
NOTE:
• In the case of frost protection of the unit by low air
temperature, the percentage brine must be evaluated
accordingly.
• The maximum glycol level in the case of units equipped
with a hydraulic module is 45%.
• The maximum recommended temperature differential is
5K.
• In order to facilitate maintenance operations, it is
-2 0 recommended to install isolation valves upstream and
downstream of the unit
220 260 300
12,60 12,55 14,15
26,3 26,2 29,5
12,70 12,55 20,20
26,5 26,2 42,2
-12 -10 -8 -6 -4 -2
Water outlet temperature (°C)
330 360 400
14,90 20,30 20,60
31,1 42,4 43,0
19,70 19,90 21,70
41,1 41,6 45,3
0 2 4 6