Argo-Hytos SD2EX-B2, Operating Instructions Manual, Page: 19 / 44

Subject to change_SD2EX-B2(B3;B4)_14064_1en_05/2022
Page 19
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› In the event of a power failure to the solenoids or a coil failure, the centering spring will return the valve spool to its base position.
› Based on the results of the risk analysis, the following potential faults have been identified:
› External valve leakage due to seal damage associated with a working fluid leak.
› Loss of valve function, resulting in loss of control of the appliance.
› Mechanical damage to the electrical part of the valve, including the cable
7.5 Extraordinary and emergency situations
Defective valves must be replaced/repaired.
DANGER
Shutdown of electrical power, pressure source and circuit relief
In the event of an emergency, immediately shut off the electrical power supply to the control solenoids and the
pressure source (pump). Relieve all parts of the hydraulic circuit including the hydraulic accumulators by
connecting them to the tank. A malfunctioning valve may cause a dangerous operating situation due to loss of
control. A damaged electrical part can initiate an explosion.
DANGER
Prohibition of handling and repair in explosive atmospheres
A defective valve must not be repaired or dismantled when an explosive atmosphere is present.
There is a risk of initiating an explosion.
CAUTION
Check pressure relief part of the circuit
Always ensure that the circuit is depressurised before intervening in the hydraulic circuit, for example before
removing a valve. Otherwise there is a risk of leakage of working fluid and contamination of persons.
CAUTION
Surface temperature
Before starting disassembly, make sure that the surface of the valve and solenoid coils has cooled to a low
enough temperature to prevent skin burns.
A suitably qualified user is authorised to replace the seals on the valve body base, which are supplied as a kit. They can also replace a malfunctioning
solenoid coil. For valves with a spool position sensor, the user can replace the defective sensor.
7.6 Repairs carried out by specialist
ENVIRONMENTAL PROTECTION
Spilled working fluid must be removed immediately, e.g. with suitable absorbents, contaminated parts of the perimeter cleaned,
contaminated objects in the vicinity cleaned or disposed of. Contaminated objects and residues of leaked working fluid must be
disposed of in accordance with the applicable environmental regulations.
FIRST AID
Electric shock
› Switch off the power supply immediately
› Make sure the casualty is breathing.
› Call emergency medical services
› If the casualty is not breathing, initiate measures to restore basic life functions according to first aid abilities (CPR, artificial
respiration) and equip the workplace (defibrillator) with life-saving equipment.
Contamination by hydraulic working fluid
If contamination of persons occurs, contaminated parts of clothing must be removed immediately and the skin thoroughly washed
with soap or treated with a suitable cream.
If the eyes are contaminated, flush them with clean water and seek medical attention. Seek medical attention also in case of
accidental ingestion of working fluid or skin allergic reaction to splashes of working fluid.
7.6.1 Replacing a defective valve
A defective valve that is not caused by a malfunctioning solenoid coil must be removed and replaced with a new one.
Repairs to a defective valve may only be carried out by the manufacturer.
When replacing the defective valve with a new one, proceed as follows:
› Ensure that no explosive atmosphere is present during the repair period. (see also 7.5).
› Switch off the pressure source (pump) of the hydraulic circuit (see also 7.5).
› Relieve the hydraulic circuit including the accumulators by connecting it to the tank (see also 7.5).
› Ensure that the hydraulic circuit is pressure-free (see also 7.5).
› Switch off the electrical supply to the directional control valve solenoids (see also 7.5).
› Ensure that the surface of the valve and solenoid coils is cooled to a low enough temperature to prevent skin burns (see also 7.5).
› Clean the surface and area around the valve.
› Remove the coil surface ground wire by loosening the M5x10 ground screw.
› Disconnect the electrical supply cable to the coils (see 7.6.3).
› Loosen the coil nut with a wrench (a = 36) and unscrew it.
› Remove the sealing ring and spool from the valve control system.
› Loosen the valve with a wrench (a = 27) and carefully unscrew it.
› Allow the remaining working fluid from the valve to drain into the smaller container provided.
› When installing the new replacement valve, follow the procedure in section 7.2 Product installation