Technical equipment required for split air-conditioner installation – review of selected tools

– review of selected tools

There is no doubt that persons performing services related to servicing, operation, supervision or maintenance of equipment charged with refrigerants must hold appropriate skills and authorisations. But skills alone are not enough. Even the most experienced
specialist will not be able to carry out air-conditioner installation work without using appropriate equipment.

Requirements for minimum technical equipment

Rules on installation and service of equipment containing refrigerants are described in detail both in national regulations and in documents applicable in the European Union. A number of guidelines and requirements can also be found in industry standards.

The Regulation of the Minister of Development and Finance of 7 December 2017 (Journal of Laws 2017 item 2417) covers issues related to the minimum technical equipment required to obtain a certificate for entrepreneurs conducting activity consisting in installation, maintenance or servicing, repair or decommissioning of equipment containing fluorinated greenhouse gases.

Cutting pipes

Roller pipe cutters are used for cutting pipes (Fig. 1). With this type of tool attention should be paid to ensuring that the installed blade has a sufficiently sharp edge and no deformation. Using blunt, bent or chipped blades will increase the burr after cutting and may deform the pipe cross-section; therefore if blade wear is found it should be replaced immediately. An interesting solution is cutters with springs ensuring smoother feed pressure control.
Electric cutters are also available on the market (Fig. 2); however, the minimum pipe diameter for which they can be used is usually at least 12 mm, which prevents their use for split air-conditioner installation, where the most common pipe diameters are 3/8” (9.52 mm) and 1/4” (6.35 mm).

Deburring pipes

This extremely important process is often skipped by installers for small-diameter pipes, which may negatively affect further pipe processing, especially combined with incorrect cutting. It should be stressed that deburring aims to remove the sharp edge primarily from the inside of the pipe and will directly affect the quality of the flare connection (connection tightness) and, where further pipe processing such as expanding or bending with bending rods is used, will enable smoother progress of that process (reducing difficulty introducing the working element). For deburring one of two types of deburrer can be used: the so-called pencil deburrer and an internal-external deburrer of cylindrical shape enabling removal of burr from the inner and outer wall of the pipe. During deburring it is very important that the pipe being deburred is pointed downward, which will prevent swarf from entering the pipework and potentially causing mechanical damage to the equipment. In pencil deburrers blades can be replaced, whereas this is not possible in internal-external deburrers.

MINIMUM EQUIPMENT

According to the guidelines of the Regulation of the Minister of Development and Finance of 7 December 2017, an enterprise should have the following minimum equipment:

• electronic portable leak detector with a sensitivity of at least 5 g/year, checked every 12 months;
• foaming fluids for leak detection;
• a set for performing tightness and strength tests, including a cylinder of inert gas and a pressure regulator;
• a refrigerant recovery station;
• pressure hoses with shut-off valves preventing controlled substances or fluorinated greenhouse gases from escaping to the environment during and after recovery or charging;
• a portable vacuum pump capable of achieving a pressure equal to 270 Pa or lower than 270 Pa;
• a set of pressure gauges for measuring pressure in a range appropriate for the controlled substances or fluorinated greenhouse gases used or recovered;
• a pressure cylinder with a two-way valve for each type of controlled substance or fluorinated greenhouse gas currently used or recovered, and a scale with a measuring range adapted to the size of the container being filled, or a cylinder with a replaceable scale;
• a set for hard brazing, gas or electric;
• a set of wrenches including specialist wrenches and instruments used in refrigeration;
• a roller cutter for copper pipes;
• a set of benders for copper pipes;
• a set of flaring tools for longitudinal brazed connections;
• a set for expanding pipes for flare (screwed) connections;
• an instrument for measuring electrical quantities – ammeter, voltmeter and ohmmeter;
• an instrument for measuring temperature from −20ºC to 150ºC, with accuracy of at least 1ºC;
• piercing pliers with a service valve;
• personal protective equipment, including:
  • safety goggles;
  • protective gloves.

Bending pipes

Appropriate tools are recommended for bending pipes. Benders can be classified primarily according to two criteria: bending method and method of transmitting force to the working element. Bender design may be arm-type or crossbow-type. As for drive, manual and electric benders exist. Force transmission to the working element may be mechanical or hydraulic.

Bender size depends on its design (arm or crossbow) and the diameter for which it is suited; having an electric motor increases the mass of the ready-to-work set. Arm benders increase in size as the diameter to be bent increases. An example comparison of bender sizes for 7/8” diameter is shown in Figure 4, and Figure 5 compares electric and manual benders.

Arm benders exist as single tools dedicated to a given diameter, whereas crossbow benders include heads for bending pipes of different diameters. Both types of solution have advantages and disadvantages, and the choice depends on the installer’s preference.

Electric benders are often used as stationary tools on a stand because of their relatively high mass (about 10 kg).

One of the most popular pipe-bending methods for split air-conditioner installation is the use of flexible inserts (Fig. 6). Their undoubted advantages are low mass and simplicity of use. When using inserts several very important rules should be remembered, such as bending the pipe in stages: after making one bend the insert should be withdrawn, because after making, for example, two bends of about 90° each, extracting the insert will be very difficult. Additionally, after prolonged use a reduction of insert cross-section can be observed, which during bending may reduce the pipe cross-section. Introducing rods into pipes that have not been deburred results in very rapid damage to flexible inserts.

Flaring pipes

Making flares accompanies every split air-conditioner installation. A correctly made flare directly affects the tightness of the entire installation. Of course, the nut must be fitted before making the flare.

Pear-type flaring tool, or eccentric flaring tool

One of the most commonly used flaring tool designs is the so-called eccentric (“dziadkowa”) flaring tool. In this design the flare is made by three cones set in rotary motion with feed adjustable by a clutch. When the clutch is not depressed, axial feed is locked and only rotary motion of the said cones is performed to smooth the flare surface. Depressing the clutch enables movement toward the pipe and return. This type of flaring tool has no automatic stop, so the quality of the flare made and above all its size depends on the operator’s skill. Basic advantages of the device are its small size and the ability to precisely expand the pipe end.

Bar-type flaring tool

The bar-type flaring tool is a very popular design, and its undoubted advantage is simplicity of use. Tools of this type have a stop that prevents the tube being inserted too far. It should be remembered, however, that despite the simplicity of the device it is very important to immobilise the pipe when locking the bar, because it may be moved during locking. Bar flaring tools are often equipped with a screwdriver connection that enables speeding up the flaring process. In this type of design usually one eccentric cone forms the flare, and an automatic clutch prevents over-expanding the pipe.

Battery-powered flaring tool

Another method of preparing flares that is used increasingly often is battery-powered flaring tools. For this type of tool several types of mounting for securing the pipe in the working element can be found; examples of these solutions are shown in Figures 9 and 10. The tools are equipped with pipe positioning stops ensuring correct placement, and the flaring process is fully automatic.

Turret flaring tool

Another type of device for making flares is the so-called turret flaring tool, characterised by compact construction, while integrated drum dies allow quick diameter change.

Bits for a screwdriver, so-called spin tools

Spin tool sets contain flaring bits in several sizes typical of pipework used in air conditioning. To make a flare it is enough to connect the appropriate spin size to a drill. In this type of pipe processing no additional clamps or holders are required, and the high temperature generated by friction facilitates making the flare.

Tightening flare connections – torque wrenches

Pipework properly prepared and fitted with nuts is first tightened manually so that the flange seats on the cone without stress, and then with a torque wrench and a second counter wrench the flange is drawn up. Tightening of a flare connection should be performed with a torque wrench set to the torque appropriate for the size of the connection being made. Information on the required torque can always be found in the air-conditioner installation manual and in tables supplied by torque wrench manufacturers. For ¼” pipe the recommended tightening torque is 14÷18 Nm, and for 3/8” diameter the torque is usually 33÷42 Nm. Manufacturers offer various head designs for torque wrenches. It should be remembered that torque wrenches allow force application in one direction only.

The direction in which force should be applied is marked with an arrow on the wrench handle; otherwise the torque wrench does not perform its function. To ensure correct long-term operation of the wrench, after finished work the screw enabling torque selection should be loosened.

Tightness test

The tightness test is a very important element of air-conditioner installation. Before performing a tightness test, information on the test pressure for the equipment being installed should always be checked. The main (pressure) tightness test is performed using an inert gas.

Service hoses

Connecting lines must be in proper technical condition. Therefore they should not have mechanical damage. The outer surface of the lines must carry legible information on compatibility with the gas with which they will be used. Furthermore, the pressure at which they will operate must not be higher than the maximum working pressure for which the hoses were approved. Valves and union nuts must be fitted with seals. Most hoses and accessories have a 1/4” SAE thread, whereas valves on the air conditioner have a 5/16” SAE thread.

Manifold gauge set

When characterising pressure gauges, two commonly used types can be indicated with regard to how pressure values are read: analogue and electronic gauges. When selecting the above measuring device, attention should be paid to the accuracy class of the gauge, which indicates the magnitude of measurement error relative to the actual pressure value.

An advantage of analogue gauge sets is that batteries are not required to power them. Furthermore, the device can easily be replaced in case of mechanical damage or excessive pressure.

An advantage of electronic gauges is elimination of parallax error, which may be made with analogue gauges when reading the pressure indication carelessly. Additionally they have a much wider range of refrigerants with which they can work (information on saturation temperature of vapour and liquid at the measured pressure for a specific refrigerant). Another significant advantage of a large proportion of electronic gauges is the ability to connect them to a device recording the entire course of the tightness test.

Adapters with reduction

Performing a tightness test without adapters enabling connection of the previously described elements to the equipment is impossible. On split air conditioners (on the outdoor unit) there is a valve with a 5/16” SAE thread, whereas most hoses and gauge sets have a 1/4” SAE thread. Using an element providing transition to the required diameter is possible thanks to a service adapter or reducing valve of appropriate diameters. The reduction function may be performed by a low-loss charging valve, which in addition to providing transition to the required diameter can allow connection to the equipment in a way that ensures a minimal level of refrigerant emission (when connecting to equipment during service) or air entering the completed installation (after vacuuming the system).

Vacuum pumps

During split air-conditioner installation a practice can often be observed of treating evacuation of the system simultaneously as a tightness test. The reason for this is that the installer does not have a gas cylinder (usually nitrogen) at the installation site and wishes to minimise air-conditioner installation time (evacuation of the system is required after the pressure tightness test).

Installation of split air conditioners, given typical pipework lengths, does not require a high-capacity vacuum pump. Using a pump of about 50÷60 l/min capacity (which will have low mass and dimensions) will allow efficient evacuation of the system. Using a higher-capacity unit will allow faster and more effective evacuation. An advantage of selected units is battery power, allowing work without mains supply.

It should be stressed that not all vacuum pumps are suitable for use with flammable refrigerants (A2L and A3). It should be remembered that evacuating a system in which a flammable refrigerant was used should be performed with a vacuum pump that ensures safe operation with refrigerant residues. Additionally, for example with hydrocarbons, pump manufacturers recommend diluting refrigerant residues using an inert gas (e.g. nitrogen). Of course, a vacuum pump used in accordance with minimum technical equipment requirements should allow a pressure of at least 270 Pa to be achieved.

Only after evacuation can the valves on the outdoor unit be opened and refrigerant from the outdoor unit thereby introduced into the installation we have made.

Scale

Using a scale when introducing refrigerant into the system or recovering it from the installation allows precise determination of the amount of refrigerant collected in the cylinder. Most scales intended for refrigeration use are equipped with an electronic display enabling ongoing monitoring of refrigerant mass in the cylinder. Maximum scale load (usually in the range from 50 kg to 100 kg) enables commonly used refrigerant cylinders to be used on them. For some refrigeration scales that can work with a dedicated solenoid valve, automated charging based on set parameter values, e.g. refrigerant mass, is possible.

Means/devices for locating leaks

Using preparations (foaming agents or soap solution) to locate leaks in the system involves applying the substance to a given installation element, e.g. by spraying with an appropriate detection fluid. A potential location of a leak will then be indicated by bubbles appearing on the element surface. This method allows leak location practically anywhere in the system (even in hard-to-reach crevices). Using fluorescent detection fluids or dyes introduced directly into the system may only be done when the equipment manufacturer provides for this possibility (and subsequent flushing of the system may also be required). Leak detection in an air-conditioning system may also be performed using an electronic portable leak location instrument. A detailed characterisation of portable electronic refrigerant leak detectors was given in issue 3/2023 of the journal Chłodnictwo&Klimatyzacja.

Tools for preparing electrical connections

Tools helpful when making electrical connections of air conditioners include, among others, cable cutters, insulation strippers, ferrule and connector crimping pliers. Example designs of tools used are shown in Figs. 17–19. It should be remembered that for tools used in live work it is important that they are properly insulated (have approvals) and thereby protect the installer against electric shock.

Conclusions and summary

Correct installation is essential to ensure correct and trouble-free operation of the air-conditioning system for a long time. For this purpose a range of specialist tools is required, as well as their appropriate use during the work (selected elements of technical equipment are presented in the article). Failure to exercise due care during installation may result in a number of undesirable phenomena, from reduced cooling capacity of the air conditioner, through emergency shutdown, to refrigerant leakage from the equipment to the environment. It should also be remembered that continuous competence development by the installer and obtaining appropriate authorisations enabling installation of refrigeration equipment are extremely important.

References

Regulation of the Minister of Development and Finance of 7 December 2017 on minimum technical equipment, procedures and a system for documenting activities when conducting activity consisting in installation, maintenance or servicing, repair or decommissioning of equipment containing fluorinated greenhouse gases (Journal of Laws 2017 item 2417) Website COCH home page, accessed 13.07.2023 COCH training materials.

Authors:
MSc Eng. Łukasz JURASZ - Central Refrigeration Centre “COCH” in Kraków
Eng. Miłosz GRATKOWSKI - Central Refrigeration Centre “COCH” in Kraków

Article from the journal Chłodnictwo&Klimatyzacja No. 5/2023 www.chlodnictwoiklimatyzacja.pl