Alternative RefrigerantsInformation on use of R22

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There is currently no general obligation to convert equipment that is operating with R22 or R22-containing refrigerants to an al-ternative refrigerant. As long as the system has no leaks and does not need to be topped up with additional refrigerant, it may continue to be used without any restrictions.If, however, a decision has been taken to convert to an alternative refrigerant, it must be kept in mind that the compressors will then be subject to greater loads and thus additional wear, which can result in a shorter service life.The following information may be useful if you decide in favour of a conversion. This information is intended for individuals with ap-propriate technical training, knowledge and experience. Individuals who make use of this information do so at their own risk, since the company Bock cannot monitor the application and conditions of use. Bock assumes no liability whatsoever or possible failure or damage.

The information in this publication discusses alternative refrigerants:R422D (MO29)R417A (MO59)R422A (MO79)R438A (MO99)

Replacement refrigerant for R22 in direct evaporation systems for low-temperature refrigeration, normal cooling and air conditioning.

Replacement R22

Disclaimer

This brochure has been produced for you with great care. Never-theless, no responsibility is taken for the correctness, complete-ness and topicality of this information.

The use and application of the content is at the reader's own risk. Subject to change without notice.© Bock Kältemaschinen GmbH 2010

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R422D (MO29) Applications:Versatile R22 replacement in equipment with direct evaporation (air-conditioning systems, chilled water and refrigeration systems for normal and low-temperature operation)

Characteristics:In most systems, performance and efficiency similar to that of R22 -

Lower pressurised gas temperatures compared to R22 may -

extend the service life of the compressor in some systems.

R417A (MO59) Applications:Air-conditioning systems < 15 kWCaution, for water chillers, R422D is recommended

Characteristics:Lower pressurised gas temperatures and compression pressures -

compared to R22 may extend the compressor's service life.Energy savings possible in some systems. -

Alternative refrigerants - Applications and characteristics

R422A (MO79) Applications:Suitable as replacement for: R502, R402, R403, R408 refriger-ant mixtures and as R22 replacement in certain low-temperature refrigeration applications

Characteristics:Better performance as a refrigerant than R22 under a variety of -

operating conditions, with improvements of up to 15% in low-temperature refrigeration applicationsPerformance as a refrigerant comparable to that of R404A and -

R507Field trials have shown that energy efficiency may be better than -

when operating with R22.Lower pressurised gas temperatures compared to R22 may -

extend the compressor's service life.

R438A (MO99) Versatile R22 replacement in equipment with direct evaporation (air-conditioning systems, chilled water and refrigeration systems for normal and low-temperature operation)

Characteristics:In most systems, performance and efficiency similar to that of R22 -

Lower pressurised gas temperatures compared to R22 may -

extend the service life of the compressor in some systems.

Refrigerants

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R417A (MO59) Air conditioning+7°C evaporator, 45°C condenser, 18°C suction gas, 8 K subcooling

Difference to R22

Compression temperature -25 K

Final compression pressure -1.5 bar

Refrigerating capacity -14 %

Energy efficiency +1 %

R422D (MO29) Refrigeration *) -32°C evaporator41°C condenser18°C suction gas6 K subcooling

Normal cooling-7°C evaporator49°C condenser18°C suction gas6 K subcooling

Air conditioning+7°C evaporator49°C condenser18°C suction gas8 K subcooling

Difference to R22

Compression temperature -18 K -36 K -24 K

Final compression pressure +0.7 bar +0.9 bar +0.9 bar

Refrigerating capacity +8 % -5 % -7 %

Energy efficiency +14 % identical -2 %

Data after conversion

The tables show approximate values of the changes in essential data after a conversion. They represent approximate values regard-ing equipment performance.Refrigerating capacity and energy efficiency depend to a large extent on system layout, operating conditions and condition of the equipment.

The data are based on thermodynamic cycle calculations carried out using calorimetric data without heat transfer effects and as-suming identical compressor efficiency.

*) R22 systems with automatic refrigerant injection that inject liquid refrigerant at a certain value in order to lower the final compression temperature.

Replacement for R22

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R438A (MO99) Refrigeration *) -32°C evaporator41°C condenser18°C suction gas6K subcooling

Normal cooling-7°C evaporator49°C condenser18°C suction gas6K subcooling

Air conditioning+7°C evaporator46°C condenser18°C suction gas8K subcooling

Difference to R22

Compression temperature -12 K -25 K -17 K

Final compression pressure +0.21 bar +0.42 bar +0.34 bar

Refrigerating capacity -5 % -6 % -6 %

Energy efficiency +7 % -2 % -2 %

R422A (MO79) Refrigeration*)

-35°C evaporator, 40°C condenser, 18°C suction gas, 5 K subcooling

Difference to R22

Compression temperature -8 K

Final compression pressure +3.0 bar

Refrigerating capacity +28 %

Energy efficiency +16 %

*) R22 systems with automatic refrigerant injection that inject liquid refrigerant at a certain value in order to lower the final compression temperature.

*) R22 systems with automatic refrigerant injection that inject liquid refrigerant at a certain value in order to lower the final compression temperature.

Refrigerants

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Oil return

Depending on the system design and operating conditions and mainly for more complex systems, oil return problems can occur due to the conversion to alternative refrigerant if the existing oil filling is maintained. For this reason and in order to avoid experi-ments, it is recommended in the course of the refrigerant conversi-on to also convert to a suitable polyolester oil in order to guarantee a reliable oil return. As a further benefit, a conversion to polyole-ster oil also provides a suitable basis to convert to the already well known refrigerants R404A, R507, R407C etc. However, if mineral oil has been used previously, the polyolester oil releases dirt particles and foreign bodies in the system which contaminate the refrigerant circuit and which mainly accumulate in all system filters and in the crankcase of the compressor. Therefore, several oil and filter chan-ges and the use of suction line filters can be required to remove the contamination from the system again. However, this contamination problem does not occur and a corresponding cleaning procedure is not required if alkylbenzene oil has been used previously. A residual portion of the original oil quantity of max. 4-5% should be aimed at for the conversion to polyolester oil.

Using the alternative refrigerants mentioned in this document with mineral or alkylbenzene oil is not recommended on account of poor or lack of mixability. Nevertheless. if it is not attempted to convert to polyolester oil but to retain the existing oil and the oil level drops below the permitted minimum after starting the system, top up with oil until the minimum level is reached. As the oil level can rise again, do not fill to the maximum level. However, if the oil level continues to drop or the oil level is subject to strong fluctuations, this indicates oil return problems. In this case, the addition of polyolester oil can be beneficial to stabilise the oil return. Initially, do not replace more than 10 to 30% of the oil with polyolester oil. The exact quantity depends on the operating con-ditions and the system design. The general rule is to only add the polyolester oil gradually. Start with 10 to 20% of the total amount of oil. Then add small amounts of polyolester oil until the oil level is at the normal level again or remains constant. When adding poly-olester oil, make sure that the oil level directly after filling is below the middle of the sight glass. Also note the amount of oil added in order to avoid overfilling.

General information about conversion

Filter drier

Replace the filter drier when converting. This is a routine operation. There are two types of filter driers that are normally used: those with a solid insert and those with loose desiccant. Replace the filter drier with the same type that was used in the equipment before. The nameplate on the filter drier will indicate the refrigerants with which it can be used. Select a filter drier that is appropriate for use with HCFC refrigerants (many of the models available on the market today are "universal" models suitable for use with almost all fluorinated hydrocarbons).

Elastomer seals, O-rings etc.

R22 and, to some extent, mixtures with R22 react strongly with nu-merous elastomers. This can cause significant swelling and often embrittlement of the elastomers after a certain period of time. The alternative refrigerants listed do not react so strongly with elastom-ers that are normally encountered in refrigeration systems.As a consequence, when replacing R22 (and, to a limited extent, also when replacing R22-containing mixtures),leaks may occur at elastomer seals that come into contact with the refrigerant. This effect is attributable to not only the alternative refrigerants listed, but can also occur when replacing R22 with other HCFC refriger-ants such as R407C and R404A.Leaks do not occur in every converted system and it is actually dif-ficult to predict whether leaks will occur or not. On the other hand, the probability of leaks after a retrofit usually increases with the age of the equipment.It is thus recommended that all seals which are essential for op-eration of the system (e.g. the entire floating ring seal assembly on AM and F Series compressors and those whose replacement requires removal of the entire refrigerant charge, liquid receiver, high-pressure side etc.) are changed in the course of the retro-fit and that additional replacement seals for other components be kept readily available when restarting the system. Conducting thorough leak tests of the equipment before and after the conver-sion will minimise refrigerant loss. All seals should be inspected. This includes manual valves, Schrader valves, solenoid valves, sightglasses, terminal board seals, floating ring seals, oil pump seals, case seals etc.It goes without saying that all seals which were leaking before must also be replaced in the course of the retrofit.

General information

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Other

A refrigerant conversion requires a check for overheating in any case and, if necessary, correction of the overheating setting. It is possible that the valve insert may need to be adjusted or that the valve may need to be replaced entirely. A refrigerant conversion usually also involves changing the pres-sure and current settings. Accordingly, the sizing and suitability of wiring, contactors, motor overload protection switches, fuses, other electrical components, heat exchangers, pressure switches, pressure regulators, solenoid valves, frequency converters etc. and their settings must be checked.

Systems with a capillary tube

Replacement of these expansion elements is time-consuming and complicated. Usually, replacement is not necessary as part of the conversion. The temperature in the evaporator may be slightly lower than when operating with the original refriger-ant. In a system with a capillary tube, the amount of refriger-ant must be selected to ensure that the evaporator temperature reaches the required value and enough superheating is pro-vided. If superheating drops to a minimal level (usually 6 to 8 K) no more refrigerant may be added, even if the evaporator tem-perature is lower than desired. Additional refrigerant could result in slightly higher condensation temperatures. Increasing the fill level by more than 5 to 10 % of the recommended R22 filling capacity rarely leads to improved performance.

Maintenance

Systems with the above-mentioned alternative refrigerants are easy to service and maintain. When performing maintenance, re-frigerant can be topped up without having to remove the entire previous charge beforehand. The system will then continue to op-erate normally. The reasons for leakage of the refrigerant should be found and corrected as quickly as possible.

Note: When performing maintenance on A/C systems where the fill level is a critical parameter, the entire charge should be removed. This procedure is also recommended for systems with HCFC-22.

General information

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Conversion guidelines

1. Determining the performance (refrigerating ca-pacity) with the existing refrigerant.Record the performance data while the system is still operating with the old refrigerant. Check the fill level and operating condi-tions. Temperature and pressure readings from various locations in the system (evaporator, condenser, compressor suction and dis-charge lines, superheating, subcooling etc.) under normal operating conditions are useful for optimising the system after conversion to the replacement refrigerant.

2. Capturing the refrigerant in an recovery cylinder.Recover the refrigerant from the system and capture it in a cylinder. For this purpose, use an extraction/recovery machine that can gen-erate a vacuum of 50 to 65 kPa absolute. If the recommended fill level for the system is not known, weigh the refrigerant recovered. This figure can be used to calculate the initial new amount to be filled (see Step 5). Evacuate the system to ensure complete removal of any refrigerant that may be dissolved in the compressor oil. Use dry nitrogen to break the vacuum.

3. Replacing the filter drier and critical elastomer seals.Filter driers are usually replaced in the course of regular mainte-nance. Ensure that the filter drier and replacement refrigerant are compatible.While the system is still empty, inspect and replace all elastomer seals that will shortly be reaching their maximum service life. Even though there have been no leaks, a change in the amount of swell-ing upon converting to a new refrigerant (e.g. from an R22-contain-ing refrigerant mixture to an HCFC refrigerant) as well as the work on the equipment can, when restarting the system, result in leaks at seals that have experienced minor damage previously. Although the alternative refrigerant is compatible with conventional seals, the original seal may shrink after the conversion (which may be the case with other HCFC refrigerants as well) and allow refrigerant to escape.Critical components that may experience leaks include the seals in Schrader valves, the receiver, solenoid and ball valves as well as flange gaskets. In addition, all external seals that come into con-tact with refrigerant should be inspected carefully, since they rep-resent potential sources of leaks after the conversion. Experience has shown that the probability of leaks increases with the age of the equipment. It is thus recommended that all critical seals in the system be replaced (i.e. those whose replacement requires removal of the entire refrigerant charge, e.g. in the receiver or condenser).

Detailed conversion guidelines In addition, appropriate replacement seals should be kept read-ily available in case leaks occur during the conversion. Schrader valves can normally be replaced with the aid of special tools (even when under pressure) and are thus not considered critical. To pre-vent refrigerant loss, conduct thorough leaks tests before and after the conversion.

4. Evacuate the system and check for leaks (as you would normally in the course of performing main-tenance).In order to remove any remaining air or other gases as well as moisture from the system, draw a vacuum (0.1 kPa absolute). Dis-connect the vacuum pump from the system and observe the read-ings. If the vacuum cannot be maintained in the system, there is probably a leak. Pressurise the system with nitrogen (make sure not to exceed the maximum system pressure) and look for the leak. Do not use refrigerant/air mixtures to locate the leak, as such mix-tures may be combustible when pressurised. After the leak test, extract the remaining nitrogen with the aid of a vacuum pump.

5. Charging.Remove the refrigerant from the charging cylinder only in the liquid state. If the charging cylinder is not equipped with a dip tube, turn it over so that the valve is at the bottom.Use a manifold or flow control valve to allow the refrigerant to ex-pand into the system.

Caution: Do not fill any liquid refrigerant into the compressor. This causes irreparable damage!

Normally, the new charge is smaller than the original R22 charge. In some cases, however, a larger charge may be needed. The opti-mal charge depends on the design of the system and the operating conditions. The initial charge is about 85 % of the standard R22 charge. The total charge is about 95 %.These values apply only to systems where no changes to mechani-cal components affecting the capacity of the system were made during the conversion.

Note: In systems with receivers, fill with refrigerant until the level in the receiver has reached the normal value.

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Conversion guidelines

6. Starting the system and adjusting the refrigerant charge. (systems without a receiver)Start up the system and wait until the readings have stabilised. If the charge is insufficient (noticeable as superheating at the com-pressor discharge or subcooling at the condenser discharge), add refrigerant in small amounts until the operating conditions have reached the desired values. Make sure that here, too, you are add-ing only liquid refrigerant from the charging cylinder. In a system with a capillary tube, the amount of refrigerant added must be se-lected to ensure that the evaporator temperature reaches the re-quired value and enough superheating is provided. If superheating drops to a minimal level (usually 6 to 8 K) no more refrigerant may be added, even if the evaporator temperature is lower than desired. Additional refrigerant could result in slightly higher condensation temperatures. Increasing the fill level by more than 5 to 10 % of the recommended R22 filling capacity rarely leads to improved per-formance.Use appropriate pressure-temperature tables to compare the pres-sures and temperatures and to calculate the optimal values for su-perheating and subcooling for the refrigerant you are using. The charge in the system can be checked via the sightglasses in the liquid line. To establish the correct charge, it is necessary to meas-ure operating parameters such as suction and discharge pressures, the temperature in the suction gas line, the current draw of the compressor's motor, the superheating etc. Filling the system until the sightglass has no bubbles can result in overfilling.Correct adjustment of superheating is indispensable for reliable op-eration of equipment running with an alternative refrigerant. Experi-ence indicates that the superheat (at the compressor inlet) should be the same as with the original refrigerant.Caution: Liquid refrigerant that reaches the compressor during operation can cause oil level problems in the compressor and rapid compressor failure.

7. Monitoring the oil levels.While restarting the system, careful monitoring of the compressor oil level (or the oil return to the compressor) is essential to ensure that enough oil is being returned to the compressor (see oil return on page 6).

8. Attaching the refrigerant sticker.The sticker documents the refrigerant used in the system and the oil type(s). Conversion of the refrigerant or replacement of other components (e.g. the refrigeration oil) must also be recorded in the system's documentation.

IMPORTANT: Conduct thorough leak tests. As noted in Step 3, leaks may occur during or after the conver-sion. Experience has shown that leaks may not appear until after the system has been charged with the new refrigerant. Check locations with elastomer seals in particular.

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Notes

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Notes

BOCK Kältemaschinen GmbHBenzstrasse 7D-72636 FrickenhausenTelephone: +49 7022 9454-0Telefax: +49 7022 9454-137mail@bock.dewww.bock.de

Art. No. 96151-05.2010-GbSubject to change without notice