The reason we need to be recovering refrigerants from systems prior to repairs or decommissioning is for a number of reasons. Firstly you need to depressurise the system if changing out any faulty valves, compressors or repair leaks. Show Secondly, we do not want to be venting refrigerant to the atmosphere as Click Here for information in regards to the phaseout of certain refrigerants. Reclaim MethodsThere are common methods of recovering refrigerant. these are the vapour, liquid and push pull methods. Vapour Recovery MethodThe vapour method recovers refrigerant from the systems low side (suction port) as a vapour and the recovery unit in turn changes the state of the refrigerant to a liquid before discharging this into the recovery tank. Liquid Recovery MethodThe liquid method recovers the refrigerant in its liquid state and is a much faster way of reclaiming refrigerant. You can connect your gauges or digital manifolds to both high and low sides and slowy meter the refrigerant into your recovery unit. Most modern recovery machines are perfectly ok with recovering liquid. Push-Pull MethodThe push-pull method is a method of recovering refrigerant extremely fast. There are a number of restrictions though and it cannot be used on all systems. The basic idea behind this method is that the recovery or reclaim unit uses vapour from the recovery cylinder and this creates a high-pressure vapour that pushes the liquid refrigerant out of the system and back into the recovery tank. Do not use this method if your system has less the 5kg of refrigerant, has a reversing valve or is a heat pump or if you have an accumulator in between the ports used for the recovery. You have to have a steady flow of liquid refrigerant. All modern machines will come with a diagram of how to connect all these different methods of recovery to your HVAC-R system. See our range of recovery/reclaim units HERE Remember you are required to weigh in and out all refrigerant and keep a log of when and where refrigerant was used. If you don't already have a set of quality digital scales check out our range HERE Recommended Reading - Modern Refrigeration and Air Conditioning Book System Dependent Recovery requires the pressure of a functioning compressor to recover refrigerant. This is also called passive recovery. Recall that in any system, matter will flow from high pressure to low pressure. Since the refrigeration system is pressurized and the compressor increases its pressure, we can use that pressure as our “high” point. If we connect a non-pressurized refrigerant container to the system, the pressure of the container is lower than the pressure inside the system. The refrigerant will naturally flow from high to low, helping us recover our refrigerant. This is how system-dependent recovery works. Passive recovery is limited to appliances with 15 lbs or less of refrigerant. This includes small appliances with 5lbs or less of refrigerant, like household refrigerators. These are appliances which we cover in Type I. 2. Self-Contained Recovery Self Contained Recovery is the use of a recovery device that operates independently of the system you are recovering from. They have their own compressor, pump, or other mechanism to recover refrigerant. This is also called active recovery. When recovering from small appliances, first identify the refrigerant that you are about to recover. Older refrigerators, particularly those built before 1950, may contain non-fluorocarbon refrigerants, which cannot be recovered with current recovery equipment. Active recovery does the job much quicker than passive recovery. Recall that as time to recovery increases, the chances of venting increase. So we want to minimize time spent recovering refrigerants. Active recovery is required for systems containing more than 15 lbs of refrigerant. 3. Recovery LevelsThere are different required levels depending on whether the appliance’s compressor is working. When the compressor in Type I appliances is not working, the EPA Section 608 rules require recovering 80 percent of the charge amount on the appliance nameplate. For appliances with working compressors, the EPA Section 608 rules require either:
For example, with a charge of 5 lbs on the appliance nameplate and a non-functional compressor, you would need to recover 80% of the charge, or 4 lbs of refrigerant. For the same appliance with 5 lbs of refrigerant, we would need to recover 4.5 lbs of refrigerant if the compressor is working. 4. Operating CompressorWith an operating compressor, there should be a big enough pressure difference between the system and your recovery container. The pressure difference makes the refrigerant naturally flow from high to low pressure, into the recovery container. Because there is sufficient pressure, you only need to have one access valve to recover refrigerant. For a system with an operating compressor and a completely restricted capillary tube, we would attach one access valve on the high side of the system. 5. Non-Operating CompressorIf the compressor does not work in the appliance, there may be refrigerant trapped in the compressor oil. Technicians need to take measures to help release trapped refrigerant. This is especially important in passive recovery, since the recovery process relies on the system pressure. It is essential to take measures to help release trapped refrigerant when performing passive recovery and the compressor is not working. Since refrigerant is miscible in refrigerant oil, it can get trapped in the oil, but when we heat it up, the refrigerant vaporizes, separating it from the oil. This is how we can release trapped refrigerant. These measures for releasing trapped refrigerant include:
Make sure we are only warming up the system with a heating blanket and not an open flame. Recall from Core that this can cause an explosion since refrigerant cylinders are pressurized and refrigerants may be highly flammable. If we tap the compressor to release trapped refrigerant, make sure we are using a rubber mallet. We need to make sure that we are not damaging the appliance. If we use a metal mallet, this may damage the appliance and release refrigerant, damage equipment, or worse. When performing passive recovery and the compressor is not working, we need to access the system from both the high and low side to recover as much refrigerant as possible. Because we are performing passive recovery, the recovery process depends on the compressor. With a non-operating compressor, we need to access both high and low sides to try to get to the 80% required level of recovery. Technicians need to take measures like this to make sure that we can recover the required level of 80% of the nameplate charge when the compressor doesn’t work. 6. ConclusionIn this module, we discussed the requirements for recovering refrigerants in Type I appliances. For appliances with non-functional compressors we need to recover 80% of the nameplate charge. This is required for both passive and active recovery. And for active recovery on appliances with working compressors, we need to recover either 90% of the nameplate charge or to a 4 inch vacuum. Question #1: System dependent recovery
Scroll down for the answer... All of these are correct These are all true. Question #2: System dependent recovery captures refrigerant in a pressurized container to keep it fresh. Scroll down for the answer... False! This is false. With system dependent recovery, we use a non-pressurized container to capture the refrigerant. Question #3: A recovery machine is required for all systems. Passive recovery is a thing of the past. Scroll down for the answer... False! Active recovery using a recovery device is necessary for all appliances with 15 lbs or more of refrigerant. Recovery machines are not required for appliances with less than 15 lbs of refrigerant. Question #4: For both active recovery and passive recovery, we must recover 80% of the appliance charge if the compressor is not working. Scroll down for the answer... True! This is true. The method of recovery is irrelevant if the compressor is not working. We need to recover 80% of the appliance charge if the compressor is not working. Question #5: When performing active recovery and the compressor is working, we must recover to what levels?
Scroll down for the answer... Either (a) or (b) If the compressor is working and we are performing active recovery, we must either:
Question #6: Let’s say we have a system with an operating compressor and the capillary tube is completely restricted. How many access valves do we need to recover refrigerant on a system that is sealed?
Scroll down for the answer... One We only need one access valve. Question #7: If the compressor is not working and we are performing passive recovery, we need to take steps to do what?
Scroll down for the answer... Release trapped refrigerant from the compressor oil. If the compressor is not working, there is likely refrigerant trapped in the compressor oil. If we do not recover it, the refrigerant will vent, which is a violation of the Venting Prohibition if the refrigerant is an ODS (or a non-exempt substitute). That is why we need to take measures to release the trapped refrigerant so we can recover it. Question #8: What should we do to help recover refrigerant when we have a compressor that is not working? (Select all that apply)
Scroll down for the answer... Tapping the compressor with a rubber mallet so we don’t damage it Heat with a heating blanket To help with recovery when the compressor is not working, we can tap the compressor with a rubber mallet to avoid damage and heat up refrigerant with a heating blanket. Question #9: When the compressor is not working and we are performing passive recovery, we need to access the system from both the high and low side. Scroll down for the answer... True! Recall that with passive recovery, the recovery process depends on the pressure of the compressor. If the compressor is not working during passive recovery, we need to access both the high and low sides of the system to recover as much refrigerant as possible. |
What type of refrigerant does not need to be recovered?
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