Zanotti un0 060, Workshop Manual

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55
3.4 Filter Drier and Sight
Glass
Cooling Circuit
Check Valve Replacement
(a)
Disconnect unit from electrical supplies (Battery and Main).
(b)
Open unit door and right or refrigeration side cover and fold down electrical Box.
(c)
Recover Refrigerant 3.2.2 Section.
(d)
Disconnect check-valve from copper tubes with soldering
flame.
CAUTION
!
Cover with a wet rag all parts which are not to
be replaced and copper tubes near welding area.
(e)
Clean pipe ends with a special brush and blow with dry
nitrogen.
CAUTION
!
Never blow with normal air, it contains too much
humidity.
(f)
Check Non-return valve operativity blowing with nitrogen.
(g)
Place new valve in position.
CAUTION
!
Check that valve orientation is in accordance with
refrigerant flow
CAUTION
!
Pay attention to valve flux direction.
(h)
Braze new valve
(l)
Vacuum unit.
(m)
Respect a waiting time and check for leaks 3.2.5 Section.
(n)
Charge refrigerant 3.2.4 Section.
3.4 Filter Drier and Sight Glass
Humidity affects cooling system with ice
obstruction, corrosion, and POE oil degradation
(hydrolysis) cause of its hygroscopic properties.
Filter drier is installed inside cooling circuit to
avoid or mitigate moisture bed effects
absorbing water passing trough, and to purify
refrigerant from solid particulate, as a normal
filter while liquid sight glass shows refrigerant
humidity state.