Compressor Service

Secop teams up with VULKAN Lokring – manufacturer of solder-free tube connections for the refrigeration and air-conditioning industry to deliver a educational film "Compressor Service for R600a, R290 – Step by Step". Servicing and repair for R600a and R290 systems is possible for skilled and well trained service technicians.

Very careful handling is required due to the flammability of the gas, which is a potential danger during work on the refrigeration system. Good ventilation of the room is necessary and the discharge of the vacuum pump must be lead to open air. The equipment of the service technician must meet the requirements of R600a and R290 in terms of evacuation quality and refrigerant charge accuracy.

Summary of topics:

Compressor Service for Isobutane and Propane – Step by Step

Refrigerants R600a (isobutane) and R290 (propane) are possible replacements for other refrigerants which have a heavy impact on the environment and are used, in small hermetic systems, such as factory-made household and commercial refrigerators and freezers. These refrigerants have zero ozone depletion potential (ODP) and a negligible global warming potential (GWP).

Converting a R22, R12, R502, or R134a system to R600a or R290 is not recommended by Secop, since these systems are not approved for flammable refrigerant use, so electrical safety is not proven in accordance with the relevant standards.

  • Assemble the compressor

Servicing and Repair

Hydrocarbons (HC) progressively replace synthetic refrigerants due to their environmental sustainability and efficiency from the market, although their flammability requires additional safety measures. For example, brazing is only allowed in combination with the use of nitrogen as a protective gas. Therefore the connections between two tubes are established with pressure fitted connections.

Hydrocarbons are the environmentally friendly alternative to CFCs, HCFCs and HFCs. They save the ozone layer and have a much lower Global Warming Potential (GWP) of 3 in comparison to the GWP-value of R404A which is at 3900.

As a pioneer of environmentally friendly refrigeration, Secop promotes the conversion of refrigerants actively and already used environmentally friendly hydrocarbons (HC) such as R290 (propane) and R600a (isobutane) as refrigerants since the 1990s. They play a key role in the reduction of harmful greenhouse gases. A normal supermarket, for example, emits 5-10 % of its used refrigerant into the atmosphere due to leakages. HCs as a replacement are able to reduce the greenhouse gas emissions by many tons per year.

The biggest challenge in the handling of a system with R600a or R290 is the flammability of the used gases. In most States there are laws, regulations and standards in place to avoid explosions and increase e safety level when it comes to hydrocarbons.

  • Assemble the compressor

Secop’s Educational Film Supports You in Servicing Appliances with Refrigerants R600a and R290

Secop compressors for flammable refrigerants are provided with a special warning-sign. The maximal filling capacity is 150 g per system, which equates to approximately 8 g/m³ in a 20 m³ kitchen and thereby around 25 % of the lower flammability limit. These precautions minimize the risk of an ignition in case of a leakage. Under favorable conditions however, the overstepping of these numbers is officially allowed.

All manufacturers of HC-systems have to follow these safety regulations. The customer service, as well as the repair of R600a and R290 applications, should only be accomplished by highly trained and experienced personnel. This implies also knowledge about tools, transportation of compressors and refrigerants as well as laws, regulations, and standards.

National safety regulations demand leakage simulations and strictly require the isolation of electrical components close to the flow of refrigerants.

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Braze Free Compressor Replacement

The disposal of R290 and R600a does not include the filling of a recycling cartridge. Due to the low GWP, the flammable refrigerants are directed away from the workplace into the open through a tube. During the process, external ignition sources must be avoided.

Furthermore, those refrigeration systems must be opened with a pipe cutter. The brazing on HC cooling circuits is only allowed if the existing refrigerant has been disposed according to regulations and if the high and low-pressure circuits are subsequently flushed separately with nitrogen. Even if the compressor is not to be replaced, the brazing is only allowed under flowing nitrogen as a protective gas. On all other occasions, the brazing close to flammable refrigerants is strictly forbidden.

During the work at a system, the connections have to be established with pressure fitted connections. With a braze free connection, this can be established for aluminum, copper or steel pipes. The connection consists of two rings and a connection piece to receive the two pipes, which is to be connected. Because of the conical internal contour of the rings and the special external contour of the connection piece, the radius of the connection piece will be reduced to the diameter of the pipes to generate a hermetic metal to metal compound.

  • A LOKRING® connection can also be used to create a hermetic connection between two different materials, e.g. aluminum and copper, source: VULKAN Lokring

Required Tools and Materials

Prior to assembly, the pipe ends have to be cleaned thoroughly with fine steel wool or abrasive sheets in a rotating motion. Thereby scratches will be avoided along the pipes, which could lead to reduced sealing.

To ensure a sealed connection, the pipe ends are treated with LOKPREP®. This evens out any irregularities at the pipe’s surface and quickly hardens. After the insertion of the pipe end into the connection pieces, the pipes should be rotated by 360°, to guarantee the even spread of the sealant. Afterwards, the two rings are compressed to the stop in the middle with a special pair of pliers for manual assembly.

  • Cross-section of a LOKRING®-connection, source: VULKAN Lokring

Depending on the material and the environmental temperature, the LOKPREP® hardens in three to four minutes, so that all necessary connections can be established alongside the replacement of the compressor and filter dryer as well as the filling process. Due to maximal precision in the manufacturing process, the connection can be established with minimal effort. It guarantees an absolutely clean, inseparable and purely mechanical pipe connection with high durability regarding the hermetical seal.
An electronic scale is recommended to control the refrigerant charge with the required accuracy.

  • With the pliers for manual assembly, a hermetic connection will be established due to pressure, source: VULKAN Lokring

Using LOKRING® Tube Connectors on Secop BD Nano Compressors

To ensure that no heat is generated at the connection point, braze-free LOKRING® tube connectors by the company VULKAN can be used.(see figure 1).

These have been used for OEM applications as well as for applications in the field for more than 40 years. LOKRING® tube connections can be made, using simple hand assembly tools (see figure 2) or battery powered tools (see figure 3).

The TÜV approved LOKRING® connectors fulfill the requirements of ISO 14903 and ensure an absolutely clean and permanent mechanicaltube connection with long-term hermetic gas-tightness.

For details, please visit Illustrations by kind permission of VULKAN Lokring Rohrverbindungen GmbH & Co. KG

Secop Product Bulletin

  • Fig.1 LOKRING® connectors type 00 on a BD Nano