Aktobis AG WDH-520EB Schnellstart-Handbuch - Seite 4

Blättern Sie online oder laden Sie pdf Schnellstart-Handbuch für Luftentfeuchter Aktobis AG WDH-520EB herunter. Aktobis AG WDH-520EB 12 Seiten.

Seite drucken
9. Repairs to hermetically sealed components
During repairs to hermetically sealed components, all power to the appliance must be disconnected before removing sealed
covers etc. If it is essential that power is supplied to the appliance during maintenance, a permanent leak detection system must
be in place to warn of a potentially dangerous situation.
Particular attention must be paid to the following point to ensure that when working on electrical components, the housing is not
modified in such a way that the degree of protection is impaired. This includes damage to cables, an excessive number of
connections, terminals that do not meet the original specification, damage to seals, improper fitting of sealing screws, etc.
Ensure that the appliance is securely mounted.
Ensure that seals or sealing material are not so worn that they no longer serve their purpose to prevent the ingress of flammable
atmospheres. Replacement parts must be in accordance with the manufacturer's specifications.
NOTE: The use of silicone sealants may hinder the effectiveness of some leak detectors. Intrinsically safe components do not
need to be sealed before working on them.
10. Repair of intrinsically safe components
Do not apply a permanent inductive load or capacitance load to the circuit without ensuring that it does not exceed the allowable
voltage and current for the equipment being used. Intrinsically safe components are the only types that can be worked on while
connected to the mains in the presence of a flammable atmosphere. The test equipment must have the correct ratings. Replace
components only with parts specified by the manufacturer. Other parts may cause the refrigerant to ignite in the atmosphere due
to a leak.
11. Wiring
Check that the wiring is not subject to wear, corrosion, excessive pressure, shocks, sharp edges or other harmful environmental
effects. The test must also take into account the effects of ageing or continuous vibration from sources such as compressors or
fans.
12. Detection of flammable refrigerants
Under no circumstances should potential ignition sources be used when searching for or detecting refrigerant leaks. A halogen
search lamp (or any other search device that uses naked flames) must not be used.
13. Leak detection methods
The following leak detection methods are considered acceptable for systems containing flammable refrigerants.
Electronic leak detectors must be used to detect flammable refrigerants, but their sensitivity may not be sufficient or they may
need to be recalibrated. (Detection equipment must be calibrated in a refrigerant-free area.) Ensure that the leak detector is not
a potential ignition source and that it is suitable for the refrigerant used. Leak detection equipment must be set to a percentage
of the lower explosion limit and must be calibrated to the refrigerant used and the adequate percentage of the gas (25%
maximum) must be confirmed.
Leak detection fluids are suitable for use with most refrigerants, but the use of cleaning agents containing chlorine must be
avoided as chlorine can react with the refrigerant and degrade the copper piping.
If a leak is suspected, remove/extinguish all naked flames.
If a refrigerant leak is detected that requires brazing, all refrigerant must be recovered from the refrigeration system or isolated
(by shutting off valves) in a part of the system remote from the leak. Oxygen-free nitrogen must then be purged through the
system before and during the brazing process.
14. Removal and draining
When intervening in the refrigerant circuit to carry out repairs - or for any other reason - conventional methods must be used.
However, it is important that best practice is always followed, as flammability must be taken into account. The following
procedure should be followed:
- Remove the refrigerant
- Purge the circuit with inert gas
- Deflate the circuit
- Purge again with inert gas
- Open the circuit by cutting or brazing
The refrigerant charge must be prepared in the correct preparation cylinders. The system must be "purged" with oxygen-free
nitrogen to keep the appliance safe. This process may need to be repeated several times. Compressed air or oxygen must not
be used for this purpose.
Purging can be achieved by intervening in the vacuum in the system with oxygen-free nitrogen and continuing to fill until the
working pressure is reached and then releasing to atmosphere and finally drawing into a vacuum. This process must be
repeated until there is no more refrigerant in the system. When the last filling with oxygen-free nitrogen takes place, the system
must be vented to atmospheric pressure. This is absolutely necessary if soldering work has to be carried out on the pipework.
Make sure that the outlet for the vacuum pump is not near any ignition sources and that ventilation is available.
Aktobis AG, Borsigstr. 20, D-63110 Rodgau / Germany
www.AKTOBIS.de