Quantech QTC4 STYLE A Series, Установка, эксплуатация и обслуживание

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QUANTECH
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SECTION 4 - INSTALLATION
FORM QTC4-NM1
ISSUE DATE: 4/2/2018
Liquid system lines at risk of freezing, due to low am-
bient temperatures should be protected using insula-
tion and heater tape and/or a suitable glycol solution.
The liquid pump(s) may also be used to ensure liquid
is circulated when the ambient temperature approaches
freezing point.
Insulation should also be installed around the evapora-
tor nozzles. Heater tape of 21 Watts per meter under
the insulation is recommended, supplied independently
and controlled by an ambient temperature thermostat
set to switch ON at approximately 2.2°C (4°F), above
the freezing temperature of the chilled liquid.
Evaporator heater mats are installed under the insula-
tion, and are powered from the chiller's control panel.
In sub-freezing conditions, unless the evaporator has
been drained or an appropriate water-to-glycol concen-
tration is maintained, high voltage power to the chill-
er must be kept on to ensure the heater mats assist in
evaporator freeze protection. If there is a potential for
power loss, Quantech recommends that the evaporator
is drained or that water in the chilled water circuit be
replaced with an appropriate water-to-glycol concen-
tration.
Any debris left in the water piping be-
tween the strainer and evaporator could
cause serious damage to the tubes in the
evaporator and must be avoided. Be sure
the piping is clean before connecting it to
the evaporator. Keep evaporator nozzles
and chilled liquid piping capped prior to
installation to assure construction debris
is not allowed to enter.
The installer/user must also ensure that
the quality of the water in circulation is
adequate, without any dissolved gases,
which can cause oxidation of steel or cop-
per parts within the evaporator.
WATER TREATMENT
The unit performance provided in the Design Guide is
based on a fouling factor of 0.018m2/hr °C/kW (0.0001
ft2hr°F/Btu). Dirt, scale, grease and certain types of wa-
ter treatment will adversely affect the heat exchanger
surfaces and therefore the unit performance. Foreign
matter in the water system(s) can increase the heat ex-
changer pressure drop, reducing the flow rate and caus-
ing potential damage to the heat exchanger tubes. Aer-
ated, brackish or salt water is not recommended for use
in the water system(s).
Quantech recommends that a water treatment specialist
should be consulted to determine whether the proposed
water composition will adversely affect the evaporator
materials of carbon steel and copper. The pH value of
the water flowing through the evaporator must be kept
in a range between 7 and 8.5.
PIPEWORK ARRANGEMENT
The following is a suggested piping arrangement for
single unit installations.
FIGURE 7 - PIPEWORK ARRANGEMENT
LD15151
-Isolating Valve - Normally Open
-Isolating Valve - Normally Closed
-Flow Regulating Valve
-Flow Measurement Device
-Strainer
-Pressure Tapping
-Flow Switch
-Flanged Connection
-Pipework
MINIMUM WATER VOLUME
It is good practice to include as much water volume as
possible in a chilled water loop. This increases the ther-
mal mass and “Flywheel” effect within the system (that
is: the more; the better) which in turn promotes stable
water temperature control and increases reliability by
reducing compressor cycling.
For air conditioning applications, a minimum of 3 gal-
lons/ton is required. It is preferred that the gallon/ton
ratio be within the 5 to 8 range. For process applica-
tions, a minimum of 6 gallons/ton ratio is required with
preference towards a range of 7 to 11. Install a tank or
increase pipe sizes to provide sufficient water volume.
LEAVING WATER TEMPERATURE OUT OF
RANGE
The QTC4 chiller line has a maximum leaving water
temperature of 15.6°C (60°F). Where process applica-
tions require a chilled water temperature higher than
what the chiller provides, a simple piping change can
remove the problem. By using a mixture of chiller-
cooled water and returning process water, the chilled