14
3.6 - HYDRAULIC SYSTEM FEATURES AND
CONNECTIONS
The installer is responsible for selecting and installing the sys-
tem components, that must be done in a workmanlike manner
and in accordance with current legislation.
The designer is responsible for sizing the system, in all its
parts.
When realising the hydraulic system, use only ferrous materi-
als, preferably seamless carbon steel pipes of excellent quality.
Do not use copper and its alloys as their contact with the dia-
thermic oil favours its oxidation.
The pipes must be clean inside, free of rust
or paint, otherwise you must pickle the cir-
cuit before filling with oil.
The joints must be welded or flanged (use
flanges or collar): DO NOT make threaded
joints.
Threaded joints are only permitted for very
small diameters (max ½”) of secondary pipes
(vent pipes, connecting to tools, etc.)
The flanges in the heaters and components are in class PN16.
The generator, once positioned in the boiler room, must be con-
nected to the following points:
- Diathermic oil flow (
T1
)
- Diathermic oil return (
T2
)
- Load/Unload (
T3
)
The pipe dimensions are indicated in paragraph 2.5 - DIMEN-
SIONS.
The generator connections must not be stressed by the weight
of the system pipes: these must be supported and arranged so
as not to create dangerous strains.
In dimensioning the main circuit pipe, the circulation speed of
the oil must be about 1.5 - 2 m/s (the connections of our heat-
ers are sized in this regard).
The circuit must be compensated by thermal expansions.
The steel pipes extend by 1.2 mm/m every 100 K of thermal
gradient: this means that from the room temperature (20°C) to
a work temperature of 270°C, ten metres of pipes stretch by 30
mm. If not compensated, the expansions cause tremendous
efforts on the system components.
The way to compensate the expansions depends on the sys-
tem itself:
- if it is compact, without long straight sections and full of
bends, it could be considered auto-compensated;
- if it is extended and with long straight sections, insert axial
expansion compensators, providing the necessary guides
and fixed points.
The circuit must be fitted with vents and drains of pipes to
speed up system loading and emptying.
Vents and drains must be conveyed to the storage tank.
Provide the system with an inlet for the withdrawal
of diathermic oil to be analysed.
The diathermic oil must be withdrawn cold (max
40°C) with system off or in operation after cooling
the oil with the use of a sampling device (on the
market).
Do not take the oil from the vents or drains.
After realising the system, perform an hydraulic sealing test of
the welds.
The sealing test is carried out with compressed air: after ex-
cluding the expansion vessel and the storage tank, pressurise
the circuit and with soapy water wet all welds to highlight any
leaks.
Do not introduce water in the circuit to perform the sealing test.
The circuit must be insulated AFTER THE HOT START of the
system
For the insulation use high density (min 100 kg/m3) mineral
wool with minimum thickness of 60 mm.
After the insulation, all flanged joints and expansion compensa-
tors must remain visible.
ATTENTION:
- do not insulate the expansion pipe;
- do not provide flanged joints and com-
pensators on the electrical components
(motors, electric panels, etc.): in case of
dripping or oil leak they may cause a fire.
T1
T2
T3
