York Millennium YCAS 0693, Установка, эксплуатация и обслуживание

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YORK INTERNATIONAL
FORM 201.18-NM4
FIG. 5 – PIPEWORK ARRANGEMENT
LD04739
Pipework
Isolating Valve - Normally Open
Isolating Valve - Normally Closed
Flow Regulating Valve
Flow Measurement Device
Strainer
Pressure Tapping
Flanged Connection
Flow Switch
sion of vibrations to the building. Flexible connections
must be used if the unit is mounted on anti-vibration
mounts as some movement of the unit can be expected
in normal operation.
Pipework and fittings immediately next to the cooler
should be readily de-mountable to enable cleaning be-
fore operation, and to facilitate visual inspection of the
exchanger nozzles.
The cooler must be protected by a strainer, prefer-
ably of 30 mesh, fitted as close as possible to the liq-
uid inlet connection, and provided with a means of
local isolation.
The cooler must not be exposed to flushing velocities
or debris released during flushing. It is recommended
that a suitably sized by-pass and valve arrangement is
installed to allow flushing of the pipework system. The
by-pass can be used during maintenance to isolate the
heat exchanger without disrupting flow to other units.
Thermometer and pressure gauge connections should
be provided on the inlet and outlet connections of each
cooler.
Drain and air vent connections should be provided at
all low and high points in the pipework to permit drain-
age of the system and to vent any air in the pipes.
Liquid systems at risk of freezing, due to low ambient
temperatures, should be protected using insulation and
heater tape and/or a suitable glycol solution. The liquid
pump(s) must also be used to ensure liquid is circu-
lated when the ambient temperature approaches freez-
ing point. Insulation should also be installed around the
cooler 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 21°C (37°F) above the freezing tem-
perature of the liquid.
The liquid circulation pump must be controlled by the
unit. This will ensure that when the liquid temperature
falls within 2° or 3°C (3° or 5°F) of freezing the pump
will start.
The cooler is protected by heater mats under the insula-
tion which are supplied from the unit control system
power supply. During risk of freezing the control system
should be left switched on to provide the freeze protec-
tion function unless the liquid systems have been drained.
Any debris left in the water pipework
between the strainer and cooler could
cause serious damage to the tubes in
the cooler and must be avoided. The
installer/user must also ensure that the
WATER TREATMENT
The unit performance given in the Design Guide is based
on a fouling factor of 0.044m2/hr °C/kW (0.00025
ft
2
hr°F/Btu). Dirt, scale, grease and certain types of
water treatment will adversely affect the heat exchanger
surfaces and therefore unit performance. Foreign mat-
ter 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.
Aerated, brackish or salt water is not recommended for
use in the water system(s). YORK recommends that a
water treatment specialist is consulted to determine that
the proposed water composition will not affect the
evaporator materials of carbon steel and copper. The
pH value of the water flowing through the cooler must
be kept between 7 and 8.5.
PIPEWORK ARRANGEMENT
The following is a suggested pipework arrangement for
single unit installations. For multiple unit installations,
each unit should be piped as shown.
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quality of the water in circulation is ad-
equate, without any dissolved gases
which can cause oxidation of steel
parts within the cooler.