Carrier Aquasnap 30RB 080R - Page 43

12.2.5 - Brine option
this option enables brine to be produced down to -8 °C. The unit
is equipped with suction pipe insulation and a fan frequency
converter.
The operating range depends on the suction pressure, which itself
depends on the following factors:
- the brine type,
- the brine concentration,
- the ow rate,
- the brine temperature,
- the condensing pressure (ambient temperature).
Example: for operation with 30% ethylene glycol and a brine
temperature of -8 °C (with -3 °C at the inlet), the maximum
operating ambient temperature will be approximately 35 °C.
Refer to the section relating to the operating ranges
12.2.5.1 - Frost protection
The evaporator low pressure and frost protection depends on the
amount of antifreeze added to the water circuit. The operating
principle for the evaporator (LWT - SST) and the frost protection
are based on this amount.
It is therefore essential to check the amount of antifreeze in the
water loop at the rst start-up (circulate for 30 minutes to ensure
the mixture is distributed uniformly before taking the sample).
Refer to the manufacturer’s data to dene the frost protection,
based on the concentration rate measured.
The frost protection temperature must be used in the unit software
parameters.
This value will allow the denition of the following limits:
1. Evaporator frost protection
2. Low pressure protection
It is recommended that the commissioning of a brine system is
done by Carrier.
For information: The protection values given by our supplier, based
on the antifreeze solutions used in the Carrier Montluel laboratory,
are as follows: (these values can change for di󰀨erent suppliers).
% by weight,
glycol
Freeze point, °C
ethylene glycol
Freeze point, °C
propylene glycol
10 -3.8 -2.6
15 -6.1 -4.3
20 -8.8 -6.6
25 -11.8 -9.6
30 -15.2 -13
35 -19.1 -16.7
40 -23.6 -20.7
45 -29 -25.3
Based on the table below, if the ethylene glycol concentration by
weight in the water loop is 35%, the value of -19.1 °C must be
used in the software.
It is essential to check the amount of glycol at least once a year,
and adjust the frost protection value in the software based on the
proportion measured. This procedure must be performed each
time water or antifreeze solution is added.
The curve below shows the minimum frost protection activation
temperature that must be observed, based on the leaving water
temperature.
Minimum frost protection activation temperature
Evaporator leaving water temperature, °C
Minimum frost protection temperature, °C
NOTES:
• For frost protection of the unit at low air temperatures,
the brine percentage must be assessed.
• The maximum glycol rate for units with hydraulic kit
(options 116) is 45%.
• The temperature of - 8 °C brine can only be obtained
with ethylene glycol at 30%.
• The maximum recommended temperature di󰀨erence is
5 K.
IMPORTANT: For glycol concentrations below 20%, a
corrosion inhibitor suitable for the application must be used
to avoid corrosion which can be caused by the brine.
The presence of glycol reduces the life of the pump ttings.
It is recommended to change the ttings or the pump:
- every 40,000 hours for applications with water,
- every 15 000 hours for applications with glycol
concentrations above 30%.
To facilitate maintenance operations, it is recommended to
install shut-o valves upstream and downstream of the unit.
12 - OPTIONS
43