The right tool for the job, and using it correctly: Compiled by Benjamin Brits

The right tool for the job, and using it correctly

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Compiled by Benjamin Brits

Tools will always be required by refrigeration technicians, no matter if hand, electronic or testing work needs to be performed to care for a client’s investment.

Although the primary use of any tool is to perform work on a system, too often hear of harrowing stories of misfortune such as people getting injured or losing their lives in work accidents as a result of simple errors.

As an HVACR technician, there are obvious risks because of pressurised systems and tool operation, as well as refrigerant gases, extremely cold or hot components, and oils and electrical hazards that need to be considered.

Speaking to various suppliers recently, it is evident that the incorrect use of tools in a technician’s possession can also lead to not only costly damage to a client’s property, but damage to tools and even damage to self. An example is the use of undersized equipment in a pressurised system resulting in tool failure, and in extremes, gauges bursting causing injury to the technician.

It is therefore highly important to use the correct tools correctly, and so in this article, product professionals advise on the most common tools used by refrigeration technicians and the some of the ways failure or system damage arises when these tools are used incorrectly.

Product professionals, being in the refrigeration and AC sales environment for many years, are often posed the question of what the ‘essential tools’ are that a technician requires to perform the commissioning of new installations, or fault-finding on existing units or installations.

Looking at the basics, there are the essential tools that are required to fulfill most, if not all, general tasks, some suppliers specialise in particular tools, while others sell a value ranges or sets of tools. Tools are considered to exist to “make any technician’s job simpler and more enjoyable”.

Refrigeration gauge/manifold set

This is by far the most invaluable tool that a technician has at his disposal, as this gives the tech the ability to ascertain the running conditions of the system he is working on as most manifolds have both the HP and LP gauges and will also give a clear indication on the current system operation conditions.

Gauges come in varying pressure-ratings and usually indicate the pressure in Bar, PSI and kPa, and accordingly with the gas it is supposed to measure. Options these days are great, as there are mechanical and electronic units that can be utilised, and although you get sets that can read almost all the gases that are used in our industry, you still need to ensure you use the right tool, for the right application.

Here are some general safe handling rules for your gauge sets. Use the right manifold for the right gas, suppliers see many failures due to ‘overpressure’ damage to the internals of the gauge which is caused by using a gauge that is not rated for the pressure it is used for.

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It is essential to be aware of how much refrigerant a service cylinder can recover, as different refrigerants have different properties

An easy example, using a R22 set, to try and read R410a, the pressure of the R410a system is about double the operating pressure of the R22, thus, the gauge is then subjected to “overpressure” which damages the bourdon tube inside the gauge, essentially reducing the gauge to scrap, as these internals cannot be repaired.

Never use a manifold set, while nitrogen is being used on the system, many injuries occur, when nitrogen is used on systems without regulators and then just ‘pops’ the manifold, as a result.

Incidents have occurred where the manifold ‘sight glass’ blew out, due to the nitrogen pressure, and was embedded in the eyes of the technician. This is a serious injury result and can cause blindness. All technicians are advised to avoid this action.

The tong tester

This is a crucial tool, as this allows you to measure the running load amperes while the compressor operates, and in turn, using this information and cross referencing this with the manufacturer’s indicated load amperes on the same operating conditions.

You can quickly ascertain the current operating conditions of the system. By checking the amperes, you can identify if the system has a gas charge issue, over or undercharge, and whether your system has a blockage or refrigerant flow issues, superheat setting on the TXV perhaps.

Generally, most technicians know how to safely use a tong tester, however, failures are common, due to the following issues:

Vacuum pumps

For a system to operate as efficient as possible, you need a system with no moisture or air, thus a ‘dry’ system, and no other contaminants to be present when the system is commissioned.

As a rule, your system/pump must be able to reach 500 microns on vacuum, and keep that level, until it is time to commission, this also gives you a clear and immediate indication of any possible leaks on the system. Leaks usually occur where there is a ‘connection’, being either welded or flare, and if your system does not keep the vacuum, there is a leak somewhere.

As with all tools, ensuring that the right tool is used for the right application is critical. The size of the pump, usually indicated in CFM, or m³/h flow rates, should match the system that you are intending to vacuum (not using a 2.5cfm), and then trying to vacuum a VRV rooftop unit used on a building as has been seen, and thus, overloading the unit and causing the electrical motor of the pump to burn out.

Ensuring your vacuum pump oil level is always sufficient and replacing the oil when it starts to show any signs of cloudiness or particles in the oil, is crucial to the life span of the pump, and should ensure many years of reliable service from your vacuum pump, just look after your tools, it is as simple as that.

Evacuating a refrigeration or air conditioning (AC) system is also of utmost importance to safeguard a long lifespan of the compressor(s). Millions of compressors are destroyed every year due to an inadequate evacuation process, leaving residues of moisture in the system, which leads to irreparable damages and consequently a costly replacement of compressors.

“A tool that has become a requirement by law in most countries, especially of you are doing refrigeration/AC work is the refrigerant recovery unit.”

A proper evacuation process avoids this, but requires a lot of time, and time is money as they say – however, there are ways to evacuate more efficiently, by simply increasing the flow rate. Removing the Schrader valve increases the diameter tremendously, thus allowing the refrigerant during recovery and evacuation to flow faster.

The removal or even exchange of Schrader valves at systems under pressure can easily be achieved with valve core tools that are available for various pipe sizes. A further improvement of the evacuation speed can be achieved with a hose of a larger diameter; this allows a quicker evacuation and filling process, and new pumps today have been especially designed for deep vacuum applications.

Deep vacuum requires a strong vacuum pump (here, torque and tightness by high accuracy are more important than horsepower), which enables he HVAC/R technician to pull a constant vacuum down to 15 micron.

Generally, all wear-and-tear parts of vacuum pumps can be replaced, thereby turning this tool into a lifetime investment.

Refrigerant recovery

A tool that has become a requirement by law in most countries, especially of you are doing refrigeration/AC work is the refrigerant recovery unit. This unit is similar to the vacuum pump and being able to perform most of the same functions of the vacuum pump, it is still different.

It not only vacuums the refrigerant, but it also condenses the refrigerant, and pumps it into a recovery cylinder.

The recovery units are used to evacuate and recover the refrigerant into a service cylinder, and not venting the refrigerant into the atmosphere, as this has a direct impact on greenhouse gasses and global warming, and is illegal, in most environmentally conscious countries.

These are refrigerant cylinders that usually have connections for both liquid and vapour, and can be used repeatedly, after the recovered refrigerant has been properly disposed of or recycled. These are not disposo cans, which are meant for one time use only. Disposo cans should never be used to recover refrigerant!

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Due to the inherent danger of using a ‘disposable’ can, it is not meant for refilling or recovery at all, and possible injury and refrigerant burns, if it should fail or explode, due to
overfilling are likely.

It is crucial to be aware of how much refrigerant a service cylinder can recover too, with regards to the refrigerant in question, as densities and weight of refrigerants all differ, and overfilling is a risk. Caution must always be practised when working with any refrigerant, as the burns caused by them heal very slowly, and are extremely painful.

Always employ a drier when recovering, a separate drier for each different refrigerant you recover, it is also better to have a unit with an oil separator, as this will ensure you do not fill your service cylinders with nasty old oil when recovering! Thus, if these simple guidelines are adhered to, your tool’s condition and your own safety, will never be a concern.

Article Contributors:

Aubrey Champion, product & technical sales manager, refrigeration & air-conditioning, MACS Cool (Pty) Ltd.

Benno Brinlinger, marketing & sales manager of REFCO Manufacturing Ltd, Switzerland.