Structural Concepts Fusion MD User Manual page 16

Preventive Maintenance
Maintenance and Service Notes
WARNING! TURN OFF CASE BEFORE PERFORMING PREVENTATIVE MAINTENANCE
Repairs to sealed components
• During repairs to sealed components, all electrical supplies shall be disconnected from the equipment being worked
upon prior to any removal of sealed covers, etc. If it is absolutely necessary to have an electrical supply to equipment
during servicing, then a permanent opening form of leak detection shall be located at the most critical point to warn of a
potentially hazardous situation.
• Particular attention shall be paid to the following to ensure that by working on electrical components, the casing is not
altered in such a way that the level of protection is affected. This shall include damage to cables, excessive number and
connections, terminals not made to original specification, damage to seals, incorrect fitting of glands, etc.
• Ensure that the apparatus is mounted securely.
• Ensure that seals or sealing materials have not degraded to the point that they no longer serve the purpose of preventing
the ingress of flammable atmospheres. Replacement parts shall be in accordance with the manufacturer's specifications.
Repair to intrinsically safe components
• Do not apply any permanent inductive or capacitance loads to the circuit without ensuring that this will not exceed the
permissible voltage and current permitted for the equipment in use.
• Intrinsically safe components are the only types that can be worked on while live in the presence of a flammable
atmosphere. The test apparatus shall be at the correct rating.
• Replace components only with parts specified by the manufacturer. Other parts can result in the ignition of refrigerant in
the atmosphere from a leak.
• NOTE The use of silicon sealant can inhibit the effectiveness of some types of leak detection equipment. Intrinsically safe
components do not have to be isolated prior to working on them.
Cabling
• Check that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges, or any other adverse
environmental effects. The check shall also take into account the effects of aging or continual vibration from sources such
as compressors or fans.
Detection of flammable refrigerants
• Under no circumstances shall potential sources of ignition be used in the searching for or detection of refrigerant leaks. A
halide torch (or any other detector using a naked flame) shall not be used.
• The following lead detection methods are deemed acceptable for all refrigerant systems.
• Electronic leak detectors may be used to detect refrigerant leaks but, in the case of FLAMMABLE REFRIGERANTS the sensitivity
might not be adequate, or might need recalibration. (Detection equipment shall be calibrated in a refrigerant-free
area.) Ensure that the detector is not a potential source of ignition and is suitable for the refrigerant used. Leak detection
equipment shall be set at a percentage of the LFL of the refrigerant and shall be calibrated to the refrigerant employed,
and the appropriate percentage of gas (25% maximum) is confirmed.
• Leak detection fluids are also suitable for use with most refrigerants but the use of detergents containing chlorine shall be
avoided as the chlorine can react with the refrigerant and corrode the copper pipe-work.
• NOTE examples of leak detection fluids are
-Bubble method.
-Fluorescent method agents.
• If a leak is suspected, all naked flames shall be removed/extinguished.
• If a leakage of refrigerant is found which requires brazing, all of the refrigerant shall be recovered from the system, or
isolated (by means of shut off valves) in a part of the system remote from the leak. Removal of refrigerant shall be
according to the removal and evacuation procedures below.
Fusion® MD User Manual 16