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DEOS-12_UK-MANUAL

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GB9. CablingCheck that

GB9. CablingCheck that cabling will not be subject to wear, corrosion, excessive pressure, vibration, sharp edges or any otheradverse environmental effects. The check shall also take into account the effects of aging or continual vibration fromsources such as compressors or fans.10. Detection of flammable refrigerantsUnder no circumstances shall potential sources of ignition be used in the searching for or detection of refrigerantleaks. A halide torch (or any other detector using a naked flame) shall not be used.11. Leak detection methodsThe following leak detection methods are deemed acceptable for systems containing flammable refrigerants.Electronic leak detectors shall be used to detect flammable refrigerants, but the sensitivity may not be adequate, ormay need re-calibration. (Detection equipment shall be calibrated in a refrigerant-free area.) Ensure that the detectoris not a potential source of ignition and is suitable for the refrigerant used. Leak detection equipment shall be set ata percentage of the LFL of the refrigerant and shall be calibrated to the refrigerant employed and the appropriatepercentage of gas (25 % maximum) is confirmed. Leak detection fluids are suitable for use with most refrigerants butthe use of detergents containing chlorine shall be avoided as the chlorine may react with the refrigerant and corrodethe copper pipe-work. If a leak is suspected, all naked flames shall be removed/ extinguished. If a leakage of refrigerantis found which requires brazing, all of the refrigerant shall be recovered from the system, or isolated (by means of shutoff valves) in a part of the system remote from the leak. Oxygen free nitrogen (OFN) shall then be purged through thesystem both before and during the brazing process.12. Removal and evacuationWhen breaking into the refrigerant circuit to make repairs or for any other purpose conventional procedures shallbe used. However, it is important that best practice is followed since flammability is a consideration. The followingprocedure shall be adhered to:Remove refrigerant;Purge the circuit with inert gas;Evacuate;Purge again with inert gas;Open the circuit by cutting or brazing.The refrigerant charge shall be recovered into the correct recovery cylinders. The system shall be flushed with OFNto render the unit safe. This process may need to be repeated several times. Compressed air or oxygen shall not beused for this task.Flushing shall be achieved by breaking the vacuum in the system with OFN and continuing to fill until the workingpressure is achieved, then venting to atmosphere, and finally pulling down to a vacuum. This process shall be repeateduntil no refrigerant is within the system. When the final OFN charge is used, the system shall be vented down toatmospheric pressure to enable work to take place. This operation is absolutely vital if brazing operations on the pipeworkare to take place.Ensure that the outlet for the vacuum pump is not close to any ignition sources and there is ventilation available.13. Charging proceduresIn addition to conventional charging procedures, the following requirements shall be followed. Ensure that contaminationof different refrigerants does not occur when using charging equipment. Hoses or lines shall be as short as possible tominimise the amount of refrigerant contained in them.Cylinders shall be kept upright.Ensure that the refrigeration system is earthed prior to charging the system with refrigerant. Label the system whencharging is complete (if not already).Extreme care shall be taken not to overfill the refrigeration system.Prior to recharging the system it shall be pressure tested with OFN. The system shall be leak tested on completion ofcharging but prior to commissioning. A follow up leak test shall be carried out prior to leaving the site.14. DecommissioningBefore carrying out this procedure, it is essential that the technician is completely familiar with the equipment and allits detail. It is recommended good practice that all refrigerants are recovered safely. Prior to the task being carried out,an oil and refrigerant sample shall be taken in case analysis is required prior to re-use of reclaimed refrigerant. It isessential that electrical power is available before the task is commenced.a) Become familiar with the equipment and its operation.b) Isolate system electrically.c) Before attempting the procedure ensure that:Mechanical handling equipment is available, if required, for handling refrigerant cylinders; All personal protectiveequipment is available and being used correctly;The recovery process is supervised at all times by a competent person;Recovery equipment and cylinders conform to the appropriate standards.20 /

d) Pump down refrigerant system, if possible.e) If a vacuum is not possible, make a manifold so that refrigerant can be removed from various parts of the system.f) Make sure that cylinder is situated on the scales before recovery takes place.g) Start the recovery machine and operate in accordance with manufacturer’s instructions.h) Do not overfill cylinders. (No more than 80 % volume liquid charge).i) Do not exceed the maximum working pressure of the cylinder, even temporarily.j) When the cylinders have been filled correctly and the process completed, make sure that the cylinders and theequipment are removed from site promptly and all isolation valves on the equipment are closed off.k) Recovered refrigerant shall not be charged into another refrigeration system unless it has been cleaned and checked.15. LabellingEquipment shall be labelled stating that it has been de-commissioned and emptied of refrigerant. The label shall bedated and signed. Ensure that there are labels on the equipment stating the equipment contains flammable refrigerant.16. RecoveryWhen removing refrigerant from a system, either for servicing or decommissioning, it is recommended good practicethat all refrigerants are removed safely.When transferring refrigerant into cylinders, ensure that only appropriate refrigerant recovery cylinders are employed.Ensure that the correct number of cylinders for holding the total system charge is available. All cylinders to be usedare designated for the recovered refrigerant and labelled for that refrigerant (i.e. special cylinders for the recovery ofrefrigerant). Cylinders shall be complete with pressure relief valve and associated shut-off valves in good working order.Empty recovery cylinders are evacuated and, if possible, cooled before recovery occurs. The recovery equipment shallbe in good working order with a set of instructions concerning the equipment that is at hand and shall be suitable forthe recovery of flammable refrigerants. In addition, a set of calibrated weighing scales shall be available and in goodworking order. Hoses shall be complete with leak-free disconnect couplings and in good condition. Before using therecovery machine, check that it is in satisfactory working order, has been properly maintained and that any associatedelectrical components are sealed to prevent ignition in the event of a refrigerant release. Consult manufacturer if indoubt.The recovered refrigerant shall be returned to the refrigerant supplier in the correct recovery cylinder, and the relevantWaste Transfer Note arranged. Do not mix refrigerants in recovery units and especially not in cylinders. If compressorsor compressor oils are to be removed, ensure that they have been evacuated to an acceptable level to make certainthat flammable refrigerant does not remain within the lubricant. The evacuation process shall be carried out priorto returning the compressor to the suppliers. Only electric heating to the compressor body shall be employed toaccelerate this process. When oil is drained from a system, it shall be carried out safely.GB/ 21

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