Cambridge Refrigeration Technology

Transcription

1 Cambridge Refrigeration Technology Guide to Sample Taking and Flame Testing Refrigeration Units and Bottles for Chlorine Contamination 8 th May 2013 Cambridge Refrigeration Technology Limited Registered Office 140 Newmarket Road Cambridge, England Registration No Newmarket Road Cambridge, CB5 8HE Tel: +44 (0) Fax: +44 (0) crt@crtech.co.uk Web:

2 8 th May 2013 Guide to Sample Taking and Flame Testing Refrigeration Units and Bottles for Chlorine Contamination Flame Halide Detector This method describes how to check refrigerant gas for the presence of chlorinated compounds using the described Flame Halide Detector. At present no other field method has been found that will satisfactorily find mixtures of gases containing chlorinated products. This test will detect if there are chlorine contaminants in the refrigerant, sensitivity 300ppm (parts per million). R-134a is fluorinated and does not change the colour of the flame. A green flame indicates the presence of chlorine. For example, R-22 will show a green flame. Halide detectors were commonly used by service engineers for more than twenty years but became largely obsolete when chlorine-free refrigerants, like R-134a, were introduced. To familiarise yourselves with this, try a test using a bottle of R-22. This link shows what you should expect: 1

3 Any refrigerant bottles or systems marked R-134a that show a green flame should be quarantined and NOT USED. Principle of Halide Torch Leak Detection The use of a halide leak detector is the most positive method of detecting refrigerants containing chlorine; sensitivity is about 300ppm. Such a detector consists essentially of a torch burner, a copper reactor plate, and a rubber exploring hose. Refrigerant gas suspected of containing chlorine is drawn through the hose into the torch burner of the detector. Here the air passes over the copper reactor plate, which is heated to incandescence. If there is a minute trace of a chlorine-containing refrigerant present, the colour of the torch flame changes from blue (neutral) to green as the chlorine-containing refrigerant contacts the reactor plate. The shade of green depends upon the amount of halogen refrigerant; a pale green colour shows a small concentration and a darker green colour, a heavier concentration. It is recommended that a sample of gas from any bottles or systems that fail the test be sent to a laboratory for analysis. Taking Samples Bottles and systems should not be directly tested. To minimise the risks associated with flammable gases and to comply with F-gas regulations, minimising release of F-gas, there are two methods: Method 1) Using a set of service gauges, including coupling ball valves, quick connector, a capillary and a sample bag. Method 2) Using a quick connector, a coupling ball valve and a sample bag. These methods are detailed below. 2

4 Method 1: Using Service Gauges Confirm the reefer is switched off and the power supply is disconnected. Leak check the extraction device. Confirm the extraction device is clean and free from contamination. Place the extraction device as shown into a vacuum. Identify an access/sample port on the reefer unit. Insure the access port is clean. Connect the device to the unit and take a sample of gas while insuring the device moves from a vacuum into a positive pressure. Close all valves and disconnect the device from the unit. Connect the capillary tube to the extraction device. Proceed to the field Halide Flame Test Station (detailed below). If positive, fill bag and send to laboratory After a positive test, check for gauge/hose contamination before reusing. This method has the disadvantage in that there is the possibility of cross contamination. Once this equipment has come into contact with some chlorinated refrigerants, it has been found to be difficult to clean and in some cases it has not been possible to reuse some of the components. 3

5 Method 2: Using Sample bag Confirm the reefer is switched off and the power supply is disconnected. Leak check the extraction device. Confirm the extraction device is clean and free from contamination. Place the extraction device as shown into a vacuum. Identify an access/sample port on the reefer unit. Insure the access port is clean. Connect the device to the unit and take a sample of gas while ensuring the device moves from a vacuum into a positive pressure observable by inflation of the bag. Close all valves and disconnect the device from the unit. Proceed to the field Halide Flame Test Station (detailed below). If positive, send bag to laboratory use new sample bag for next test. Check valve and pipe for contamination. The tube (a) needs to be disposed of once a contaminated sample has been found. The quick connector (b) and ball valve (c) also need to be flushed with nitrogen or air. One it is found that a sample bag contains contaminated gas, it should labelled, packed and shipped for testing in a laboratory as quickly as possible. 4

6 Both of the methods have been used successfully: Method 1 has the advantage of using readily available components but the disadvantage of cross contamination. Method 2 requires a sample bag but has the advantage of virtually eliminating cross contamination and faciitates further laboratory testing. Halide Flame Test Station To minimise the risks associated with the product of degradation fumes, fabricate a fume cupboard with an extractor fan. The enclosure should have a dark background to facilitate flame colour. Vessels and depots could use existing air extraction devices such as welding or exhaust extractors. In some cases, provided the exhaust flue is upright and sufficiently long, the fan can be omitted. After each test, where contaminated gas is detected, it is essential the equipment is cleaned and checked for decontamination, confirmed by the presence of a blue flame. 5

7 Method 1 Bubble the gas through some water to ensure the flow rate is minimal. Use bottled water to avoid the possibility of chlorinated tap water. Just a few bubbles will suffice, as the test is very sensitive. Place the explore tube of the flame halide torch above the water. After a positive test, replace the water. Method 2 Connect sample bag to T-connector and explorer tube. Open bag valve and allow the explorer tube to draw out gas from the bag. If the bag is squeezed, this should be very lightly to avoid saturating the torch. The picture shows a blue flame and therefore this gas is not contaminated. Note: a standard blowtorch cannot be used, as the copper reaction plate is required. 6

8 Good: Blue flame = R-134a Contaminated: Green flame = presence of chlorine Note also that the test will not be effective unless the copper reactor plate is up to temperature. Light the torch and heat copper reactor plate for 2 to 3 minutes, the flame should initially be blue. The centre of the flame tip should be adjusted so that it is in the middle of the flame shield window. 7

9 List of Decomposition Products Small quantities of the following chemicals may be produced as a result of the flame test. The following data could be used in any necessary risk assessment: Chemical Formulae TLV ppm Comments Hydrofluoric acid HF 5 Degradation acid from fluorinated chemicals Hydrochloric acid HCL 3 Degradation acid from chlorinated chemicals Phosgene COCl Toxic gas degradation from chlorinated chemicals Carbonyl fluoride COF 2 2 Toxic gas degradation from fluorinated chemicals Carbon monoxide CO 25 Product of incomplete combustion The threshold limit value (TLV) of a chemical substance is a level to which it is believed a worker can be exposed day after day for a working lifetime without adverse health effects. Strictly speaking, TLV is a reserved term of the American Conference of Governmental Industrial Hygienists (ACGIH). However, it is sometimes loosely used to refer to other similar concepts used in occupational health and toxicology. TLV s, along with biological exposure indices (BEI s), are published annually by the ACGIH. 8

10 Reporting All tests should be documented: with the tester, the test results and container number clearly identified. Flame Test Example 9

11 GC Test Example 10

12 F-Gas Regulation (Europe) Re: Deliberate release of F-Gas for Testing Purposes For technical or research uses that are not specifically detailed in the EC, F-gas Regulation, it the opinion of f gas-support opinion that anyone using the equipment you describe needs to be aware of their obligations in relation to recovery under Article 4.3 of the EC F gas Regulation. Article 4.3 states: "The fluorinated greenhouse gases contained in other products and equipment, including mobile equipment unless it is serving military operations, shall, to the extent that it is technically feasible and does not entail disproportionate cost, be recovered by appropriately qualified personnel, to ensure their recycling, reclamation or destruction." So it is considered that appropriate recovery of F-gases does apply where possible, if it is not possible to recover the R-134a during this process, we suggest that you document your rationale regarding technical or economic barriers that prevent proper recovery of the gas. There are no formal personnel qualifications specified for this type of activity, however "in -house" training that covers the necessity to do all possible to contain emissions and recover the gas/fluid where possible may be appropriate. So it would be a requirement to ensure that your engineers are aware to minimise any emissions and it would be good practice to use qualified personnel to do this work. In the method described above the release is minimised by regulating the flow by bubbling through water. Document prepared by: Cambridge Refrigeration Technology This document is provided as a guideline only and should be used in conjunction with all other local legal requirements and safety procedures that apply in your country.