Refrigerant gas leak detection, location, & repair: this article describes refrigerant gas leak detector tools and the methods used to find refrigerant gas leaks such as Freon leaks and other halogen gas leaks. We also discuss where refrigerant leaks most often occur.
We explain the effects of refrigerant leaks on air conditioners and heat pumps, refrigerators, freezers, etc. including both the effects of lost refrigerant and the effects of refrigerant piping leaks that admit moisture and dirt contamination into the system. We also explain how a refrigeration gauge set should be connected to HVAC equipment to avoid contamination damage.
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Guide to Refrigerant Leak Detection & Types & Tips for Using the TIF 5000 automatic halogen gas leak detector
As we explain in our articles on lost cooling capacity or air conditioning systems or heat pumps that are not working, a refrigerant leak in your air conditioner or heat pump means that eventually it will just not produce cool air (during air conditioning) nor warm air (during heating if it's also a heat pump).
Carson Dunlop Associates' sketch (left) illustrates some of the common areas where vibration or other stresses or damage are often the cause of leaks in refrigerant piping at a home air conditioner or heat pump.
Before assuming that you need to add refrigerant, see the diagnostic steps at LOST COOLING CAPACITY.
Refrigerant leak detection methods
Using a sensitive instrument such as the TIF 5000 is a useful way to quickly find refrigerant gas leaks on air conditioning and heat pump systems.
Alternative leak locating methods are also useful, such as a thorough visual inspection for stains or discoloration at HVAC refrigerant piping, evaporator or cooling coils, condensing coils, and fittings. In addition, some HVAC technicians include a leak-detecting oil in the refrigerant charge in order to (possibly) provide visual evidence of where leaks are occurring in the system.
Some common causes of air conditioner or heat pump refrigerant leaks include:
Refrigerant leaks occur at a number of locations on cooling equipment, including
Practical tips for checking for refrigerant gas leaks
What most refrigerant gas leak testing instrument instructions fail to point out is a practical procedure for actually examining air conditioning or refrigeration systems for refrigerant gas leaks.
Effects of refrigerant leaks or loss of charge show up in different ways depending on where the refrigerant leak is occurring.
Leaks on the high side of a refrigeration system show up as loss of refrigerant and will be discovered.
Leaks on the low side of a refrigeration system are harder to discover until enough air leaks into the refrigerant piping system. At that point the compressor head pressure goes way up until a safety device shuts down the compressor motor or a service tech discovers a problem. A leak on the low side is ugly because now the whole system has become contaminated with air, moisture, and dirt.
Effects of Refrigerant Leaks: Dirt & Moisture on Thermostatic Expansion Valves or Capillary Tube Refrigerant Metering Devices
Moisture freezes in the refrigerant metering device, further interfering with proper cooling system operation, and dirt can also jam up a TEV or clog a capillary tube. When moisture is freezing up a thermostatic expansion valve the system will stop working (and thus begin to warm up) until the ice melts. The system may run normally for some time - until water droplets pass through the system and again reach the TEV and cause it to freeze again.
Unlike moisture, dirt in the refrigeration system is more likely to cause the Thermostatic Expansion Valve to clog and just stop working permanently, as it can also do a capillary tube metering system.
You might diagnose a moisture-in-expansion valve or cap tube problem by adding heat to the device to see if it will thaw and begin operating.
See THERMOSTATIC EXPANSION VALVES for details about these devices.
Moisture in the refrigerant piping system also mixes with the refrigerant to form an acid which can short out compressor motor windings by dissolving the lacquer on the wire windings. Refrigerant combined with moisture becomes a black stinky liquid.
Effects of Air in the refrigeration system; how we diagnose the presence of air inside the air conditioner or heat pump
The pressure of air is additive to the pressure of the refrigerant in any refrigeration system. And of course the amount of air pressure that is added to the system depends on the temperatures of the refrigerant gas, compressor, coils, etc. Put simply, air inside the refrigerant handling system (piping, controls, compressor, coils) raises the pressure on both the HIGH and LOW sides of the system even if the air is not also adding moisture. The result is that the air conditioner or heat pump operates at a lower efficiency.
For example, at 70 degF and using R12 refrigerant, we would expect the static or idle (compressor not running) pressure of the refrigerant in the system to be at 70 psi.
How We Know Air has Contaminated the Refrigerant System
If you know that your refrigerant is R12 and that the pressure should be 70 psi when the A/C or heat pump has not run in some time, and ambient temperature is also 70F.
So provided there are no blockages or clogs in the system refrigerant piping, coils, compressor, controls,
Then IF you see a gauge pressurehigher than 70 psi that suggests you have air in the system. You may in fact see high head pressure and high back pressure if there is significant air contamination in the refrigerant.
And if the air conditioner/heat pump or other refrigeration system is contaminated by any of the problem materials we've discussed: air, moisture, dirt and debris, you will need to evacuate and vacuum the system to remove these contaminants.
Suggestions for Using the TIF5000 to detect refrigerant leaks
The TIF 5000 automatic halogen leak detector is used for air conditioning and cooling system refrigerant leak detection. The TIF 5000 replaces and combines functions previously provided by the TIF HLD440 halogen leak detector, with an added circuit which TIF refers to as "automatic ambient control".
This feature "adjusts and corrects for the atmospheric ambient refrigerant in the vicinity of the tip." [TIF 5000 product literature].
As you'll notice in our photograph of our instrument, its external appearance is similar to the TIF 8800 except that the 8800 detects a wide range of combustible gases while the TIF 5000 is designed to focus on the halogen gases - air conditioning refrigerants such as the now discontinued R12 and R22.
The instrument weighs about 28 ounces and is 8" x 3" x 1.8" in size, not counting the length of the flexible sensor tip.
What gases does the TIF 5000 leak detector detect?
The TIF 5000 halogen leak detector is used principally on air conditioning and refrigeration equipment, heat pumps, and possibly dehumidifiers.
This leak detector also detects the following halogen gases or halogen gas mixtures:
Step by Step Guide to Using the TIF 5000 Leak Detector on Refrigeration and Air Conditioning Equipment
Instructions for use of the TIF5000 to check for refrigerant gas leaks couldn't be much simpler, and they are printed on a label affixed to the device:
But as with other gas leak detection devices of this type, if you're using the TIF 5000 refrigerant gas leak detector in an area which may already be contaminated with a high level of gas leakage, special (but simple) steps are needed to permit the leak detector to find the point of refrigerant gas leakage:
This procedure is the opposite of what we do with the TIF8800 when testing for combustible gases (and the hazards are different since halogen gases do not present an explosion hazard).
Critical Maintenance Tips for Refrigerant Gas Leak Detectors
The sensing tip on the TIF 5000 and some of the electronics of the instrument therefore are of course different.
Because debris contamination will interfere with proper operation of the TIF5000 halogen leak detector (refrigerant gas leak detector) the sensor is supplied with filter paper pre-cut into a cross shape which is inserted around the sensing tip under its protective spring cover. When the paper is soiled it is simply replaced.
The glass vial shown in our photo contains a substance used to confirm that the sensing tip will respond to a halogen gas (refrigerant gas) leak as it should.
Here are some tips from TIF for maintenance of the TIF 5000 Halogen Leak Detector
To change the sensing tip: turn of the TIF 5000 leak detector before changing the sensing tip. Turn the tip counter-clockwise to remove it, and attach the new tip by turning it clockwise when screwing it in place.
Screw the new tip finger tight. Do not contaminate the new tip with oil or grease such as hand cleaner or refrigerant oil, and do not get your sweat on the tip. To protect the tip from contamination by dust and grease during use, use the filter paper we show in the photo above. Use a new filter paper when installing a new sensor tip.
Spare sensor tips: A spare leak detector sensing tip can be stored in the battery compartment.
Batteries: Use two fresh "C" alkaline batteries to power the TIF 5000. Batteries are installed by removing a battery cover on the back of the instrument. If the batteries are fresh you should see the red LED turn on when the power switch is turned on.
If the LeD does not light, change the batteries.
If the LeD lights but the unit does not operate (won't respond to refrigerant or test gases) change the sensing tip. If that doesn't work you'll need to return the instrument to TIF for repairs.
Operating temperature range: the TIF 5000 is rated to operate between 30 deg. F. and 100 deg. F. This warmer temperature function can be important when sniffing around a hot compressor motor.
Other specialized gas detection methods include use of solid state circuitry, CMS chips, and special instruments which may be designed to give a quick alarm or a reading in PPM for specific gases.
Other gas and air monitoring equipment use pumps which collect and insert a specific volume of air into a vacuum container for later analysis. We've found that for typical field use, the colorimetric gas detector tube method is extremely convenient and very accurate, and it presents minimal requirements for instrument calibration.
In related documents we give references and explanation regarding toxicity of several of the most common indoor gases, based on literature search and obtained from the U.S. government and expert sources. This text may assist readers in understanding these topics. However it should by no means be considered exhaustive.
Continue reading at REFRIGERANT LEAK REPAIR
or see LOST COOLING CAPACITY or select a topic from the More Reading links shown below.
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