Many owners of household appliances, when independently diagnosing or ordering spare parts, are faced with the incomprehensible term “locking”. What is this part, why is it needed in the design of the refrigerator, and why is it impossible to have a hermetically sealed connection of the tubes without it? In this article we will analyze in detail the structure of this element, its role in the refrigerant circulation system and the nuances that you need to know before replacing.
Lokring (from English Lockring) is a special connecting ring or clamp that is used to fix and seal the joints of copper tubes in the refrigeration circuit. It is a critical element in ensuring the integrity of the system under pressure. Without reliable locking, normal operation of the compressor and evaporator is impossible, since the refrigerant will simply evaporate into the atmosphere.
It is important to understand that although this element seems simple, its selection and installation require precision. Incorrectly selected lockring can cause freon leakage, which will lead to compressor failure and costly repairs. We will look at how to determine the right size, what tools will be required for the job, and what to pay attention to so that the connection lasts for years.
What is lockring and its role in the refrigeration circuit
A lockring is a metal ring, most often made of steel or brass, which serves as a connecting element in systems that require high tightness. In refrigerators, it is used primarily to connect copper evaporator tubes or capillary tubes to aluminum or steel components. The main task is to create mechanical pressure that presses the flared ends of the tubes against each other, eliminating any gaps.
The principle of operation is based on the deformation of the metal during tightening. When you tighten a nut or compress a connection, the locking cuts into the surface of the tubes, creating a reliable barrier to gas. Tightness of the connection this is achieved not through rubber gaskets, which can dry out, but through the physics of the metal. This makes the system resistant to temperature changes and vibrations that inevitably occur during compressor operation.
The use of lockings is especially common in modern refrigerator models, where manufacturers strive to minimize the number of soldered joints to simplify assembly. However, for a repairman, this means that when replacing an evaporator or filter-drier, he will have to work with precisely these mechanical connections. Copper tubes at the point of contact with the locking, they must be perfectly clean and even, otherwise the tightness will be broken.
⚠️ Attention: Lockring is a one-time item in many cases. Reusing an old, already deformed ring can lead to an immediate leak of freon after starting the system.
The design of the lockring may vary depending on the manufacturer of the refrigerator. In some models Samsung or LG there are composite rings with rubber seals inside, but the classic version is an all-metal part. Understanding exactly what type is in your unit will help you avoid mistakes when ordering spare parts.
Types of lockings and manufacturing materials
On the spare parts market you can find several varieties of these connectors. They differ not only in size, but also in design, as well as the materials from which they are made. Choosing the right type directly affects the durability of the repair.
Steel lockings are highly durable and resistant to corrosion, but require a lot of effort during installation. Brass counterparts are easier to process and are better suited for connections with copper tubing, as they have a similar coefficient of thermal expansion. There are also aluminum optionswhich are used less frequently and require special care when tightening so as not to damage the soft metal.
Composite lockrings deserve special attention. They consist of an outer ring and an inner insert. This design allows you to compensate for small unevenness of the tubes. However, when working with them, it is important to follow the assembly sequence. If the direction of installation of the internal part is reversed, the connection will not be sealed.
The material of manufacture also dictates the choice of lubricant or sealant, if necessary. For steel parts, it is often recommended to use special compounds that prevent “sticking” of the metal. While for non-ferrous metals chemical activity should be minimal so as not to cause electrochemical corrosion at the point of contact.
Size table and compatibility with models
One of the main problems during repairs is the selection of size. Lokrings are available for various tube diameters. Standard tube sizes in refrigeration vary from 6 mm to 16 mm. An error in selection even by a millimeter will make installation impossible or lead to rupture of the connection under pressure.
Below is a table to help you navigate the main standard sizes. Please note that the dimensions may vary slightly between different manufacturers, so it is always better to measure with a caliper.
| Size | Outer diameter of the tube (mm) | Internal diameter of the lockring (mm) | Applicability |
|---|---|---|---|
| LR-6 | 6.0 - 6.35 | 5.8 - 6.1 | Capillary tubes, thin lines |
| LR-8 | 7.9 - 8.0 | 7.7 - 7.8 | Evaporator connections, bends |
| LR-10 | 9.5 - 10.0 | 9.3 - 9.7 | Discharge lines, gas return |
| LR-12 | 12.0 - 12.7 | 11.8 - 12.5 | Main pipelines |
When When ordering spare parts in online stores, only the outer diameter is often indicated. However wall thickness lokringa also matters. A ring that is too thin may burst when tightened, and a ring that is too thick will not allow the nut to close completely. Always check the specification if available.
Compatibility with refrigerator models is often determined not by the brand, but by the type of refrigerant used and the design of the evaporator. For example, in systems with R600a (isobutane) the requirements for tightness are higher due to the explosiveness of the gas, so special attention is paid to the quality of the lockring.
Instructions for replacing the lockring with your own hands
Replacing the lockring is a procedure that requires care and the presence of a special tool. If you decide to do this job yourself, you will need a flaring kit, a pipe cutter, wrenches, and possibly a torch if you need to remove old solder near the joint.
The first step is to completely defrost the refrigerator and ensure access to the joint. Lockrings are often located in hard-to-reach places, behind the back panel or in a foamed space. Be careful not to damage adjacent tubes.
☑️ Checklist for preparing to replace the lockring
The installation process begins with cutting the tube. The cut must be strictly perpendicular. Use only a special pipe cutter; hacksaws for metal leave burrs that break the seal. After trimming the edges of the tube, it is necessary to clean and calibrate.
Next, a nut (if the design is collapsible) and the locking itself are put on the tube. The tube is inserted into the mating part until it stops. When tightening, it is important not to overdo it. Excessive force may cause it to burst or become deformed, and the locking itself may crack. Tighten the nut until characteristic resistance appears, then make another half turn. copper tube will burst or become deformed, and the locking itself will crack. Tighten the nut until a characteristic resistance appears, then make another half turn.
⚠️ Attention: Do not use “Moment” type sealant or epoxy resin to fix the lockring! These materials are not designed to work with freon and can destroy the rubber seals inside the connection.
After assembly, be sure to check the connection for leaks. To do this, the system is vacuumed and filled with nitrogen or dry air under pressure, treating the joints with a soap solution. The appearance of bubbles will indicate a defect in the work. Only after a successful check can the refrigerator be refilled with refrigerant.
Typical installation errors and their consequences
Even experienced craftsmen sometimes make mistakes when working with locking systems. The most common of them is an attempt to reuse the old lockring. The metal has already gone through the process of deformation and lost its elastic properties. Installing such an element is a guarantee of repeated leakage in a short time.
The second mistake is insufficient cleaning of the tubes. Oxides, dirt or oil residues on the surface of the copper will prevent the lockring from creating a tight connection. At the site of contamination, a microscopic channel will remain through which gas will escape. Use fine sandpaper or a special brush for cleaning.
The third problem is the distortion of the tubes. If the tubes approach the joint at an angle and are under tension, the locking will tend to break. Vibration from the compressor will quickly loosen such a connection. The tubes should approach the joint freely, without tension. If necessary, use pipe benderto change the trajectory of the line.
What happens if the lockring is chosen incorrectly?
If the diameter of the lockring is too large, it simply will not be able to compress the tube, and the gas will come out immediately. If it’s too small, you either won’t be able to put it on, or you’ll crush the tube during installation, cutting off the flow of refrigerant.
Ignoring these rules leads to the fact that the refrigerator stops freezing, the compressor works non-stop, trying to gain temperature, and eventually burns out. Repair in this case will cost much more than the correct installation of one small part.
Where to buy high-quality lockrings and analogues
Searching for original spare parts can be difficult, since manufacturers rarely sell lockrings separately from assemblies. However, there are universal repair kits on the market. You should look for them in specialized stores of spare parts for refrigeration equipment, and not in ordinary hardware departments.
When purchasing, pay attention to the packaging. High-quality lockrings are often supplied in individual bags indicating the size and material. Cheap analogues without markings can be made of silumin, which breaks at the slightest stress.
If the original could not be found, you can consider analogues. The main thing is to comply with the size and material. High quality brass locking is often better than low quality steel. There are also adapters that allow you to connect copper and aluminum without soldering, using lockring technology, which simplifies the repair of older models.
You should not skimp on this part. The cost of locking is not comparable with the risk of losing the entire volume of refrigerant or compressor failure. A reliable connection is the key to the long service of your refrigerator after repair.
Frequently asked questions (FAQ)
Is it possible to replace the locking with conventional soldering?
Theoretically, it is possible if you remove the connection and solder the tubes directly. However, this requires completely draining the freon, evacuation and refilling, which is almost impossible to do at home. Lockring allows you to carry out repairs without complex equipment for working with refrigerants.
Why does lockring leak after installation?
There may be several reasons: insufficient tightening, misalignment of the tubes, the use of an old or defective ring, the presence of dirt at the connection point, or a crack in the tube itself that occurred during installation. It is necessary to remake the connection by replacing the lockring with a new one.
Do you need to lubricate the lockring before installation?
In most cases, metal lockrings do not require lubrication. However, some manufacturers recommend lightly lubricating the threads or interior with refrigeration compressor oil to ease installation and prevent corrosion. Read the instructions for the specific part.
What tool is needed to work with lockings?
You will need: a pipe cutter for copper, a rimmer (for chamfering), a calibrator, a set of wrenches (open-end or box-end), as well as a torque wrench to control the tightening force if the work is done professionally.