28
impurities maybe the cause of the wear or corrosion
by puncture.
•
Filter the heat exchange fluid check and carry out
internal inspections as described in EN 378.
•
In case of re-testing please refer to the maximum
operating pressure given on the unit nameplate.
• The reports of periodical checks by the user or operator
must be included in the supervision and maintenance file.
Repair
Any repair or modification, including the replacement of
moving parts:
•
must follow local regulations and be made by qualified
operators and in accordance with qualified procedures,
including changing the heat exchanger tubes.
•
must be made in accordance with the instructions of the
original manufacturer. Repair and modification that
necessitate permanent assembly (soldering, welding,
expanding etc.) must be made using the correct
procedures and by qualified operators.
•
An indication of any modification or repair must be
shown in the monitoring and maintenance file.
Recycling
The unit is wholly or partly recyclable. After use it contains
refrigerant vapours and oil residue. It is coated by paint.
Operating life
The evaporator and oil separator are designed for:
•
prolonged storage of 15 years under nitrogen charge
with a temperature difference of 20 K per day.
•
452000 cycles (start-ups) with a maximum difference
of 6 K between two neighbouring points in the vessel,
based on 6 start-ups per hour over 15 years at a usage
rate of 57%.
Corrosion allowances:
Gas side: 0 mm
Heat exchange fluid side: 1 mm for tubular plates in lightly
alloyed steels, 0 mm for stainless steel plates or plates with
copper-nickel or stainless steel protection.
11.2.1 - Evaporator
30XW chillers use a flooded multi-tube evaporator. The
water circulates in the tubes and the refrigerant is on the
outside in the shell. One vessel is used to serve both
refrigerant circuits. There is a centre tube sheet which
separates the two refrigerant circuits. The tubes are 3/4”
diameter copper with an enhanced surface inside and out.
There is just one water circuit with two water passes (one
pass with option 100C, please refer to chapter 6.5).
The evaporator shell has a polyurethane foam thermal
insulation and a water drain and purge.
It has been tested and stamped in accordance with the
applicable pressure codes. The maximum standard relative
operating pressure is 2100 kPa for the refrigerant-side and
1000 kPa for the water-side. These pressures can be different
depending on the code applied. The water connection of
the heat exchanger is a Victaulic connection.
The products that may be added for thermal insulation of
the containers during the water piping connection procedure
must be chemically neutral in relation to the materials and
coatings to which they are applied. This is also the case for
the products originally supplied by Carrier.
11 - MAJOR SYSTEM COMPONENTS AND OPERATION
DATA
11.1 - Direct-drive twin-screw compressor with
variable capacity slide valve
•
30XW units use 06T geared twin-screw compressors
equipped with a variable capacity slide valve for
control between 35% and 100% of full load. For
compressor that are able to monitor down to 15%, the
stages between 15% and 30% may be continuous or
discontinuous.
•
The 06T compressor models used are:
06TT-266, 06TT-301, 06TT-356, 06TU-483, 06TU-554,
06TV-680, 06TV-753, 06TV-819
11.1.1 - Oil filter
The 06T screw compressor has an independent oil filter.
11.1.2 - Refrigerant
The 30XW is a liquid chiller operating only with refrigerant
R-134a.
11.1.3 - Lubricant
The 06T screw compressor is approved for use with the
following lubricant: CARRIER MATERIAL SPEC PP
47-32.
11.1.4 - Oil supply solenoid valve
An oil supply solenoid valve is installed on the oil return
line as standard to isolate the compressor from oil flow
when the compressor is not operating. The oil solenoid
valve is field replaceable.
11.1.5 - Capacity control system
The 06T screw compressor has an unloading system that is
standard on all compressors. This unloading system consists
of slide valve that permits changing the length of the screw
used for the refrigerant compression. This valve is controlled
by the action of a piston controlled by two solenoid valves
on the oil return line.
11.1.6 - Suction valve (option 92)
An isolating valve can be added to ease maintenane on
compressor. This valve can be moved only without
pressure differential upstream and downstream of this
valve.
11.2 - Pressure vessels
General
Monitoring during operation, re-qualification, re-testing
and re-testing dispensation:
•
Follow the regulations on monitoring pressurised
equipment.
•
It is normally required that the user or operator sets
up and maintains a monitoring and maintenance file.
•
If no regulations exist or to complement regulations,
follow the control programmes of EN 378.
•
If they exist follow local professional recommendations.
•
Regularly inspect the condition of the coating (paint)
to detect blistering resulting from corrosion. To do this,
check a non-insulated section of the container or the
rust formation at the insulation joints.
•
Regularly check for possible presence of impurities
(e.g. silica grains) in the heat exchange fluids. These
