Gas Detection in Refrigeration Systems

MAKING MODERN LIVING POSSIBLE

Gas detection in refrigeration systems

REFRIGERATION & AIR CONDITIONING DIVISION Application guide

Application guide Gas detection in refrigeration systems

Contents Page Introduction ...... 4 Sensor technology ...... 4 EC - Electrochemical sensor ...... 4 SC - Semiconductor sensor (solid state) ...... 5 CT - Catalytic sensors ...... 6 IR - Infrared ...... 6 Which sensor is suitable to a given refrigerant? ...... 6 Relative cost comparison ...... 7 The need for gas detection ...... 7 Legislation and standards ...... 7 Requirements for gas detection according to EN 378-2000 ...... 8 F-Gas legislation ...... 8 Requirements for gas detection according to prEN 378-2006 ...... 9 USA - Requirements for gas detection according to ASHRAE 15-2004: ...... 9 Installation guideline ...... 10 Location of gas detectors ...... 10 Number of gas detectors ...... 11 in a facility ...... 11 Calibration / test ...... 11 Calibration / test methods ...... 12 Method I - Calibration / test by means of replacing Sensor PCB ...... 12 Method II - Calibration of gas detectors by using a calibration gas ...... 12 Bump test ...... 13 Alarm / sensitivity range ...... 14 gas detectors ...... 14 Danfoss recommendations for alarm levels ...... 14 Occupational Exposure Limits ...... 15 References ...... 15

Annex I - Common refrigeration data ...... 16 Annex II - EN 378:2000 ...... 17 Annex III - prEN 378:2006 ...... 18 Annex IV - ASHRAE 15-2004 ...... 19

Common used abbreviation LFL = Lower flammability level TRK = Technische Richtkonzentrationen MAK = Maximale Arbeitsplatzkonzentrationen OEL = Occupational Exposure L imits TLV = Threshold Limit Value ATEL = Acute-Toxicity Exposure Limit STEL = Short Term Exposure Limit ODL = Oxygen Deprivation Limit PEL = Permissible Exposure Limits OSH = Occupational Safety Limit

ODP = Ozone Depletion Potential GWP = Global Warming Potential

Introduction Gas detection and leak detection are two distinct These locations depend upon the layout of activities that covers the same topic, but the the machinery room and adjacent spaces, on methods are very different. the configuration of the plant and also on the refrigerant in question. Gas detection covers the analysis of air samples to determine whether they contain refrigerant Before selecting the appropiate gas detection gas. Leak detection is a systematic inspection equipment, a number of questions have to be of a refrigeration system to determine whether answered: it is leaking. The terms gas detection and leak Which gases has to be measured and in what detection are not interchangeable, and must not quantities? be mixed. Which sensor principle is the most suitable? Leak detection equipment is normally hand How many sensors are needed?, where and held equipment carried by people, and used for how shall should they be positioned and detection of leaks in refrigeration systems. There calibrated? are several types of leak detectors available, Which alarm limits are appropriate?, how covering from simple techniques like soapy water many are required?, and how is the alarm to sophisticated electrical instruments. information processed?

Gas detection equipment is usually used in This application guide will try to answer these a fixed installation with a number of sensors questions. located in areas where refrigerant might be expected to accumulate in the event of a plant leak.

Sensor technology Danfoss has, depending on the refrigerant and the actual ppm range required, selected the most appropriate sensor for the target refrigerant gas. Danfoss offers the following sensor technologies:

EC - Electrochemical sensor Electrochemical cells are used mainly for toxic An oxidation / reduction reaction generates gases and are suitable for ammonia. an electric current that is proportional to gas concentration. These generally consist of two electrodes immersed in an electrolyte medium.

max. Tolerance range min. “High” gas concentration y it “Low” gas concentration Sensitiv

Time Max operating time before calibration

Fig. 1

They are very accurate (0.02 ppm) and tend to Exposure to large ammonia leaks or constant be used principally for toxic gases which cannot background ammonia will shorten the sensor life be otherwise detected or where high levels of (fig. 2). accuracy are needed (fig. 1). They are subject only to rare cross interference. They were relatively expensive with a limited They may react to sudden large humidity lifetime, however Danfoss now offers specific EC changes but quickly settle. sensors for ammonia in the range of 0-5.000 ppm with a lifetime of approx. 3 years.

DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

EC - Electrochemical sensor (continued) max. Tolerance range min. y

it “Substantial” gas leak

Important! Sensitiv New sensor has to be installed

Time Max operating time before calibration

Fig. 2

SC - Semiconductor sensor The semi-conductor functions by measuring However, they are not selective and are not (solid state) the resistance change (proportional to the suitable for detecting a single gas in a mixture or concentration), as gas is absorbed on to the for use where high concentrations of interfering surface of a semi-conductor, which is normally gases are likely to be present (fig. 3). made from metal oxides. Interference from short term sources (e.g. These can be used for a wide range of gases exhaust gas from a truck) creating false alarms including combustible, toxic and refrigerant can be overcomed by enabling a delay of the gases. alarm.

It is claimed that they perform better than the Semi-conductors for halocarbons can be used catalytic type in the detection of combustible to detect simultaneously more than one gas or a gases at low concentrations, up to 1.000 ppm. mixture. This is particularly useful in monitoring So they are becoming more popular in this a plant room with a number of different application in refrigeration, given that the refrigerants. hydrocarbon refrigerants should be detected at low levels to avoid potential problems and costs.

These are low-cost, long life, sensitive, stable, resistant to poisoning and can be used to detect a large range of gases including all the CFC, HCFC, HFC refrigerants, ammonia and hydrocarbons.

“Broad” sensitivity spectrum – Semiconductor

y – Catalytic it s

1 2 3 4 5 “Narrow” sensitivity spectrum Gas Gas Gas Gas Gas – Electrochemical Sensitiv Target Ga – Infrared

Gas speciﬁcation Fig. 3

CT - Catalytic sensors Catalytic sensors (sometimes called a bead They can be subject to poisoning in certain or pellistor type) have mainly been used for applications but not generally in refrigeration combustible gases including ammonia and are and are more effective at gas levels of 1.000 ppm the most popular sensors for this application at up to 100% LEL. high detection levels. They are used mainly with combustible gases The sensor functions by burning the gas at and are therefore suited for ammonia and the the surface of the bead and measuring the hydrocarbon refrigerants at high concentrations. resultant resistance change in the bead (which is proportional to concentration). They do sense all combustible gases but they respond at different rates to each and so they can These are relatively low-cost, well established be calibrated for particular gases. and understood, and they have a good life span, up to 5 years. The response time is about 20-30 There are ammonia specific versions. seconds.

IR - Infrared Infrared technology utilises the fact that most However the specificity became a disadvantage gases have a characteristic absorption band in in machinery rooms, as phase out resulted in the infrared region of the spectrum and this mixed gas installations needing a different can be used to detect them. Comparison with a model for each gas, which was a very expensive reference beam allows the concentration to be solution. determined. New models were developed based on broad Infrared sensors when first introduced were infrared wavelength monitoring that could specific to a single gas and therefore not suitable detect a mixture of gases. This, however, reduced for applications involving monitoring more than the specificity and accuracy. one gas. They were very selective and accurate If preferred, refrigerant specific units may be used – reading down to one part per million. Infrared if a possibility of cross interference exists. was typically used where a high level of accuracy and specificity was required. This very precision in performance ensures that they are expensive.

Which sensor is suitable to a given refrigerant? Semi-conducter Electro-chemical Catalytic Infrared Ammonia “low” concentration 4 (< 100 ppm) – – – Ammonia “medium” concentration 4 4 4 (< 1000 ppm) 1) ( ) – ( ) Ammonia “high” concentration 4 4 4 (<10000 ppm) – ( ) Ammonia “very high” concentration 4 4 (> 10000 ppm) – – ( ) Carbon Dioxide 4 CO2 – – – HC 4 4 4 Hydrocarbons ( ) – ( ) HCFC - HFC 4 4 Halocarbons – – ( )

Best solution Suitable - but less attractive Not suitable

Fig. 4

1) Measuring range 0-1000 ppm. Can be adjusted in the whole range.

DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Relative cost comparison Relativ sensor cost sensor Relativ

SC EC CT IR Semi- Electro- Catalytic Infrared conductor chemical Fig. 5

The need for gas detection There are different reasons why gas detection Fluorinated refrigerants all have a certain is needed. It is obvious, that regulation is a very impact on the environment. It is therefore very strong argument, but also important to avoid any leaks from these. Reduced service cost (cost of replacement gas and the service call). CO2 (Carbon Dioxide) is directly involved in the respiration process, and has to be treated Reduced energy consumption cost due to lack accordingly. Approx. 0.04% CO2 is present in the of refrigerant. air. With higher concentration, some adverse Risk for damaging stock products due to a reactions are reported starting with increase in substantial leak. breath rate (~100% at 3% CO2 concentration) and Possible reduced Insurance cost. leading to loss of consciousness and death at CO2 Taxes on non environmentally friendly concentrations above 10%. refrigerants Oxygen - Oxygen deprivation sensors can be Different refrigeration applications requires gas used in some applications, but they are not detection for different reasons. offered by Danfoss, and will not be described further in this guide. Ammonia is classified as a toxic substance with a very unique smell, as such it is “self alarming”. Still Note: Oxygen sensors must never be used in CO gas detectors are very useful to have in a 2 machinery room, as often people are not present installations. to take necessary actions. Further more, ammonia is the only common refrigerant lighter than air.

Hydrocarbons are classified as flammable. It is therefore very important to verify that the concentration around the refrigeration system does not exceed the flammability limit.

Legislation and standards The requirements for gas detection are different Note! in many countries worldwide. An overview of the The requirement for gas detection is not most common rules and regulation can be found identically in EN 378-2000 and prEN 378- below. 2006. Requirements for gas detection Europe: equipment in Europe are covered by The present safety standard for refrigeration national legislation in the different systems in Europe is EN 378-2000. During the last countries, and can therefore differ from few years this standard has been undergoing a the requirements specified in EN 378. very extensive update. Requirements for gas detection according to This work has been completed (prEN 378-2006), EN 378:2000 and prEN 378:2006 are limited but the standard has not been finally approved to machinery rooms. It has to be noted that yet. machinery rooms according to these standards, are restricted arears. The specified alarm levels do It is recommended to read this version of the not reflect long term effects (personal safety). standard, because this version is much more stringent, and with different requirements.

Requirements for gas detection Start according to EN 378-2000 EN 378-3:2000

Y Ammonia Clause 6.2.5.1 N

No N Charge > Charge > N No requirements 10 kg “practical” requirements limit

Y Y Gas detection Clause 7.5 Gas detection required required high/low level Fig. 6

Gas detection is required by EN 378:2000 for in the special machinery room can never reach all installations where the concentration in the the practical limit then there is no need for fixed machinery room may exceed the practical limit gas detection. However, if the concentration can for that space. reach the practical limit, even for A1 refrigerants, then fixed detection must he installed. In the case of flammable and toxic refrigerants this means virtually all commercial and industrial The practical limits for various refrigerants are systems, but in the case of A1 refrigerants it is given in Annex II and III, which are extracted from possible to have small systems, which do not EN 378-2000 part 1 and prEN 378-2006. In these require gas detection. However, in the majority tables the practical limit of ammonia is based of larger plants it is likely that the practical limit upon its toxicity, and the practical limits of the will be exceeded in the event of a major leak, and hydrocarbons are based upon their flammability therefore gas detection is required. and are set at 20% of their lower flammable limit. The practical limits for all the A1 refrigerants are Guidance can be found in EN 378:2000 part 3 set at their Acute Toxicity Exposure Limit (ATEL). paragraph 7.2, which states that “the refrigerant concentration in each special machinery room If the total refrigerant charge in a room, divided shall be monitored at one or more points”. by the net room volume, is greater than the This covers all refrigerant groups including “practical limit” (see annex II and III), then it is A1. However, in paragraph 7.4.1 the standard reasonable to conclude that fixed gas detection states “If a refrigerating system… is equipped system should be installed. with refrigerant detectors….” raising the question of whether detection is required or not. EN 378-2000 only requires fixed gas detection to be installed in machinery rooms. It can he concluded that, if it can be shown by calculation that the concentration of refrigerant

F-Gas legislation The F-Gas Regulation (EC) No 842/2006. The A periodical leakage check by certified personnel objective of the Regulation is to contain, prevent is required, with the following frequency, and thereby reduce emissions of fluorinated depending on the quantity used: greenhouse gases covered by the Kyoto Protocol. 3 kg or more: at least once every 12 The F-gas directive is mandatory in all EU and months – except for hermetically sealed EFTA member States. systems containing less than 6 kg; The Regulation covers the use of HFCs, PFCs and 30 kg or more: at least once every 6 months SF6 (GWP > 150) in all their applications, except (12 months with an appropriate leakage Mobile Air Conditioning, covered by the Directive detection system); and Domestic Refrigerators. 300 kg or more: at least once every 3 months (6 months with an appropriate The Regulation entered into force on 4 July 2006 leakage detection system – which is anyway and a number of the measures will apply from 4 mandatory). July 2007. Leakage detection systems shall be checked at least once every 12 months. Leakage checking requirements, which will be the basis for operators to use “all measures which are technically feasible and do not entail disproportionate cost” to prevent leakage repair any detected leakage.

DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Requirements for gas detection prEN 378:2006 is an update of EN378:2000. The according to prEN 378-2006 standard has not been finally approved yet, but it contains important information regarding gas detection.

Start prEN 378-3:2006

Y Ammonia Clause 8.1 N Clause 8.1

No N Charge > Charge > Y requirements 100% ATEL/ODL “practical” limit Y N

N Gas detection Charge > Charge > Y Gas detection required 50 kg 25 kg required

Y N Clause 8.1 Gas detection No Clause 8.7 required high/low level requirements Fig. 7

USA Requirements for gas detection acc. to ASHRAE Requirements for gas detection 15-2004 state requirements for rooms with according to ASHRAE 15-2004: refrigerating equipment including machinery rooms. The “Low Level” alarm values are less or equal to TLV-TWA levels. (see also “Occupational Exposure Limits”, page 14)

Start

Y (Clause 7.2.a) Charge < 3 kg No requirements

Y (Clause 8.11.2.1) Machinery Gas detection room required

N (Clause 7.2, table 1 *) Charge > No requirements limit

Y Additional (Clause 7.2.2) Gas detection requirements required Fig. 8

* Note: The charge limit, stated in ASHRAE 15-2004, can also, for selected refrigerants, be found in Annex IV (Practical limit)

Installation guideline There are two approaches, perimeter protection For gases lighter than air, sensors should be or point detection. With perimeter detection mounted high up on the walls, ceiling or near you place sensors all around the perimeter of the exhaust, but convenient for maintenance. space in question to make sure you monitor the If equal density, mount at face level. whole space. In some countries it can be mandatory to have an With point detection you locate a sensor at a UPS (Uninterruptible Power Supply) connected particular position where you are concerned to the Gas detectors, to ensure safely operation about a leak e.g. at the compressor. during a power failure. For gases heavier than air, sensors should be located close to the ground/lowest point.

Relativ density (air refrigerant @ 25°C / 1 bar [–]) 4

0 a 2 C A A R2 R717 R744 R507 R290 R600 R134a R600 R1270 R407 R404

Fig. 9 R410

Location of gas detectors Gas detectors must be powered as specified in the instruction manual and located within the specified cable length from the central control unit / monitor.

In general: Do not mount to a structure that is subject to Do not mount where it will be exposed to vibration and shock, such as piping and piping direct solar heating. supports. Do not install in areas where condensation Do not locate near excessive heat or in wet or may form. damp locations.

The two methods of locating sensors: Point Detection, where sensors are located as near as possible to the most likely sources of leakage. Perimeter Detection, where sensors completely surround the hazardous area.

The most appropriate method is selected Important! depending on the size and nature of the site. Do not place immediately in front of a coil due to temp and humidity fluctuations. These can Detectors shall be located high / low occur especially during defrost or loading of a according to the density of the actual cold store. refrigerant. Make sure that pits, stairwells and trenches are If mechanical ventilation exists in a machinery monitored since they may fill with stagnant room, air will move towards the fan. In pockets of gas. Monitoring such areas is problematic locations a smoke tube can generally required by standards. indicate air movements in a space and assist in the location of sensors. In a cold store, sensors should if possible be placed on the wall in the return airflow below head height.

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Location of gas detectors The arrangement of the equipment in the room (continued) can also have an impact on the most effective place to sample. As general guideline: If there is one compressor / chiller in the room Place the sensor in the location(s) most likely sample at the perimeter of the unit. For two to develop a gas leak including mechanical chillers, sample between them, with three or joints, seals, and where there are regular more chillers, sample between and on each changes in the system’s temperature and side. Ensure that the area being sampled pressure or excessive vibration such as is sufficiently monitored. Don’t skimp on compressors and evaporator control valves. sensors.

Locations requiring most protection in a Accessibility to enable calibration and service in machinery or plant room would be around gas the future must be considered. You should not boilers, compressors, pressurised storage tanks, mount to a structure that is subject to vibration gas cylinders or storage rooms or pipelines. and shock, such as piping and piping supports. Avoid areas of excessive heat, wet, damp or Most vulnerable are valves, gauges, flanges, where condensation may form. T-joints, filling or draining connections etc. Sensors should be positioned a little way back Consideration should also be given to areas from any high-pressure parts to allow gas clouds where it is anticipated that leaks may occur for to form. Otherwise any leakage of gas is likely example in the vicinity of valves, pipe flanges, to pass by in a high-speed jet and will not be compressors etc, and also the possibility of detected by the sensor. pockets of gas collecting in the event of a leak.

Number of gas detectors The requirements for the number of gas detectors in a facility in a facility are not specifically stated in standards. As general guideline: A detector can normally cover an area of system or down wind of such equipment about 50-100 m2 depending on the actual in the direction of continuously operating condition of the space to be covered. In ventilation extractors. spaces with several obstructions, and lack Where there are deep beams and lighter of ventilation the coverage is approx. 50 m2, than air refrigerants it is recommended that provided it is mounted near ceiling level or the detectors are mounted between pairs near floor level depending on the refrigerant of beams and also on the underside of the density. In non-obstructed spaces with good beams. mechanical ventilation, the coverage can be increased up to approx. 100 m2. If there is a continuous airflow in the Machinery rooms: It is recommended that room a sensor/sensing point should be detectors are sited above or at both sides of located downstream from the last compressors or other non-static parts of the potential leak source.

Calibration / test Calibration / test of gas detectors is an extremely From a technically and safety point of view, the important issue. Different factors have to be sensors offered by Danfoss have to be taken into consideration. Generally three issues calibrated / tested according to the stated are of particular importance: intervals in the table (fig. 10). Requirements of national legislation. IMPORTANT! Gas detectors like electrochemical sensors If national legislation requires calibration / test are consuming products, which have to be with intervals less than stated in table fig. 10, renewed periodically, depending on actual these intervals have to be followed. type and refrigeration concentration. Generally lifetime of the sensors. Note: EN 378 requires testing on an annual basis.

Estimated life time Min. recomended Recomended test interval** calibration interval [year] [year] [year] SC Semi-conductor >5 2 1 EC Electrochemical 2-3* 2 1 CT Catalytic ~5 2 1 IR Infrared >5 2 1 * The sensor has to be renewed if it has been exposed to high ammonia concentrations ** Should be a “bump” test Fig. 10

Calibration / test methods Two different methods are available for performing calibration / test procedures. By replacing the Sensor PCB (Print Circuit Board) By using a Calibration Gas In addition to these methods, a “bump” test can be used.

Method I This method requires that the supplier offers After the main PCB of the gas detector has been Calibration / test by means of factory calibrated PCB sensor boards with tested with the GD tester, the new calibrated replacing Sensor PCB calibration certificate and traceability codes. Sensor PCB can be installed. Additionally an electrically simulation is required to verify the output signals and alarm settings. Danfoss recommends that the calibration / test procedure is done by means of replacing the This method can by compared with the method Sensor PCB, because: used for safety valves. The manufacturer This method ensures that the customer produces, tests and certifies the product, which basically has a new Gas Detector after can then be mounted in the system. replacing the Sensor PCB, because the sensor is the component whose lifetime is reduced Danfoss offers the above mentioned solution. over time. The PCB sensor board, which is the essential This method, when offered by Danfoss, is very measuring element of the gas detector, is price competitive, compared to the calibra- produced, calibrated, tested and certified by tion / test carried out on site Danfoss.

Test and calibration of GD Main Board by the use of GD tester

Certificate

XXXXXXXXXXXXXXXXXXXXX Certificate: XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX Gas / calibration levels etc. XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX Traceability

Exchange of Electrical Gas sensor Fig. 11 PCB sensor board + test of alarm � tested

Method II The calibration of gas detectors by means of Some calibration gas cylinders are treated as Calibration of gas detectors by calibration gas is relatively complicated, time dangerous substances, and therefore specific using a calibration gas consuming and expensive. The method requires requirements have to be fulfilled to ship them. special test equipment and competence in calibration. Calibration equipment (calibration kit) consists at least of: Valve / flow regulator Gas cylinder with the correct calibration gas for each refrigerant and concentration (ppm) Calibration instruction for the specific sensortype (EC,SC,CT or IR sensor).

Calibration “on site” with gas requires special competence

Gas calibration Test procedure Gas sensor tested Fig. 12 + �

12 DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Bump test A bump test can not supersede any tests involving calibration; it is only a function test. (signal or no signal)

Bump test of gas sensors (this test is a function test - it is not a calibration) SC EC CT IR Semi- Electro- Catalytic Infrared Method Refrigerant conductor chemical Ampoules Ammonia 4 Ampoules or (Lighter gas) HCFC, HCF 4 4 Lighter gas HC - Hydro Carbon 4 4

Ampoules or (Breath on sensor) CO2 4 Fig. 13

The different types of refrigerants can be Danfoss can upon request calibrate for all most grouped in different families. In the HFC group common used refrigerants. Please contact your many different types of refrigerants exist. A local Danfoss sales office. specific Gas detector calibrated for a specific gas may also be used with a good result on other refrigerant within the same group, but in this case the sensitivity is slightly different (see fig. 14).

Sensitivity of sensors with gases different than calibration gas Calibration gas Actual Refrigerant Relative Sensitivity Ammonia R717 R717 100%

Carbon Dioxide (CO2) R744 R744 100% Halocarbon HCFC R22 R22 100% R404A 100% Halocarbon HFC R404A R507 95% R290 100% R600 104% Hydrocarbon HC R290 R600a 101% R1270 94%

Example:

Relative sensitivity (95%) (100%) 0 - 950 ppm 0 - 1000 ppm

Fig. 14 Calibration gas Actual gas

Alarm / sensitivity range All commonly used gas detectors have a A main alarm should rarely (and preferably never) gas detectors proportional output signal (4-20 mA, 0-10 V, or be necessary! 0-5 V), and some pre-set alarm settings. When selecting the actual measuring range Alarms can be chosen to warn against gas and sensor type, several factors have to be concentrations less than levels acceptable for considered: personal safety on short term or long term. Alarm levels can also be chosen to specific levels In general, alarm levels should be as low as due to flammability / exclusivity risk. practically possible, depending on the actual refrigerant, and the purpose of the alarm. The following recommendations are based on There are often requests for more alarm levels, the present experience with suitable limits, but experience shows that two alarm limits are taking into account the above mentioned sufficient for gas detection. conditions, but also requirements in EN 378:2000, prEN378:2006 and ASRAE 15:2004. The pre-alarm provokes a reaction, either automatically and/or in the form of alarm The GD gas detector offers two pre-set instructions; if not, the main alarm may alarms and a proportional output signal. With be triggered. This entails a whole series of this configuration, is it possible to fulfil all consequences, including switching off requirements for alarm levels needed, within the machines. specific operation range of the sensor.

Danfoss recommendations DANFOSS recommendations for alarm levels: National Comply: EN 378 / prEN 378 for alarm levels EN 378:2000 & prEN 378:2006 requirements LEVEL LEVEL LEVEL I II III Personal safety (pre-alarm) (main-alarm) (occupational) (TWA-values) Sensor type Sensor type Sensor type [ppm] [ppm] [ppm]

Machinery rooms EC 500 CT 10000

Ammonia R717 Machinery rooms EC 25 EC 150

Safety valves - – SC 1000 vent line

Carbon Dioxide R744 (CO2) IR 5000 IR 10000 Halocarbon R22 SC 5001) SC 1000 HCFC Halocarbon R134a, R404A, SC 5001) SC 1000 HFC R407C,R410A, R507 Hydrocarbon R290, R600, R600a, Concentration CT 800 CT 2500 HC R1270 ≤ 20% of LFL 1) 50% of TWA-value Note: All proposed levels are ≤ the max. values in EN 378:2000 & prEN 378:2006 Fig. 15

DANFOSS recommendations for alarm levels: Comply: ASRAE 15:2004 ASRAE 15:2004 LEVEL LEVEL I II Personal safety (pre-alarm) (occupational) (TWA-values) Sensor type Sensor type [ppm] [ppm]

Machinery rooms EC 25 EC 500 Ammonia R717 Safety valves - – SC 1000 vent line

Carbon Dioxide R744 (CO2) IR 5000 IR 10000 Halocarbon R22 SC 5001) SC 1000 HCFC Halocarbon R134a, R404A, SC 5001) SC 1000 HFC R407C,R410A, R507 Hydrocarbon R290, R600, R600a, Concentration CT 800 CT 2500 HC R1270 ≤ 25% of LFL 1) 50% of TWA-value Note: All proposed levels are ≤ the max. values in ASRAE 15:2004 Fig. 16

14 DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Occupational Exposure The Occupational Exposure Limits are different Further information can be found on the Limits in EU/USA and worldwide. Below, a short following homepage: description from selected countries is shown. http://agency.osha.eu.int/good_practice/risks/ It is strongly recommended that you check the dangerous_substances/oel/members.stm/ relevant national legislation. document_view?

Europe Germany Italy In Germany, there are two kinds of OELs for air in The Italian exposure limits are identical with the the workplace: TLVs established by the ACGIH (USA) TRKs (Technische Richtkonzentrationen), which are technical guidance concentrations, and France MAKs (Maximale Arbeitsplatzkonzentrationen), In France, the Occupational (Air) Exposure Limits which give the maximum concentration of a (OELs) are called “Valeurs limites d’exposition chemical substance in the workplace. professionnelle aux agents chimiques en France” (VL). The Netherlands In the Netherlands, there are two types of OELs: Denmark Legally binding OELs, and In the Danish OSH system, the “Grænseværdier administrative OELs. for stoffer og materialer” (limit values for substances and materials), are administrative They both have a different basis and a different instructions that are enforced under the Working status. Occupational Exposure Limits (OELs) Environment Act. The Ministry of Labour sets are called MAC-values (Maximaal Aanvaarde up the regulation on these limit values and the Concentraties). “Arbejdstilsynet” (Labour Inspectorate) publishes the OEL list and supervises their execution.

USA The Occupational Safety Systems in the United OSHA States vary from state to state. Here, information The Occupational Safety and Health is given on major providers of the Occupational Administration (OSHA) of the U.S. Department Exposure Limits in the USA - ACGIH, OSHA, and of Labour (USDOL) publishes (PEL) - Permissible NIOSH. Exposure Limits (PELs) are regulatory limits on the amount or concentration of a substance in ACGIH the air, and they are enforceable. The American Conference of Governmental OSHA uses in a similar way as the ACGIH the Industrial Hygienists (ACGIH) following types of OELs: TWAs, Action Levels, (TLV-TWA) - Threshold Limit Value - Time- Ceiling Limits, STELs, Excursion Limits and in Weighted Average, the time-weighted average some cases BEIs. concentration for a conventional 8-hour workday and a 40-hour workweek, to which it is believed NIOSH that nearly all workers may be repeatedly The National Institute for Occupational exposed, day after day, without adverse effect. Safety and Health (NIOSH) has the statutory (TLV-STEL) - Threshold Limit Value-Short - Term responsibility for recommending exposure Exposure Limit, the concentration to which levels that are protective to workers. NIOSH has it is believed that workers can be exposed identified Recommended Exposure Levels (RELs) continuously for a short period of time without for around 700 hazardous substances. These suffering from it. limits have no legal force. (REL) = Recommended Exposure Levels. ACGIH-TLVs do not have a legal force in the USA, they are only recommendations.

References EN 378:2000 Refrigerating systems and IoR – Guidance Note 13, Refrigeration heat pumps – Safety and environmental Detection requirements. http://agency.osha.eu.int/good_practice/risks/ prEN 378:2006 Refrigerating systems and dangerous_substances/oel/members.stm/ heat pumps – Safety and environmental document_view? requirements(draft). Danfoss Literature: GD sensor- Literature No. ASRAE 15:2004 Safety Standard for RD7HA. Refrigeration Systems. F-Gas Regulation (EC) No 842/2006 IoR – Safety code for Refrigeration systems Utilising Carbon Dioxide (2003).

Annex I 100 ] 0 1 3 3 3 3 [– 1700 1 3 00 3 260 1520 1900 3 800 GWP Portential Global Warming Warming Global ] – – 0 0 0 0 0 0 0 0 0 0 [ ODP ODP 0.055 Portential Portential Ozone Pepletion Pepletion Ozone ] – [ 0.6 1.5 3 .1 3 .6 3 .5 3 .1 2.6 3 .5 1.6 2.1 2.1 1.5 @ 25°C / 1 bar Relativ density Relativ density ] 3 0.704 1.808 3 .587 4.258 4.057 3 .582 3 .007 4.108 1.8 3 2 2.440 2.440 1.745 [kg/m @ 25°C / 1 bar Vapour density Vapour B2 A1 A1 A1 A1 A1 A1 A2 A 3 A 3 A 3 A 3 Safety group Safety 3 CH 2 3 2 ) 3 3 3 CH CH 2 2 2 FCF CH CH CH=CH 3 2 2 3 3 3

Formula NH CO CHCIF CH – – – – CH CH 2-CH(CH CH

flammability Name Ammonia Dioxide Carbon Chlorodifluoromethane 1,1,1,2-tetraflouroroethane Increased R125/14 3 a/1 4a (44/52/4) R 3 2/125/1 4a (2 /25/52) R 3 2/125 (50/50) R125/14 3 a (50/50) Propane Butane Iso-butane Propylene B1 B2 B 3 Refrigerant R717 R744 R22 R1 3 4a R404A R407C R410A R507 R290 R600 R600a R1270 toxicity Increased

A1 A2 A 3 Safety groups

flammability Increased Increased Refrigerant Refrigerant type – – HCFC HFC HFC HFC HFC HFC HC HC HC HC Common refrigeration data refrigeration Common

16 DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Annex II ------25 800 800 TWA TWA 5000 1000 1000 [ppm] effect) (NIOSH) week without week (40 hours work (40 hours work

MAX MAX (prEN [ppm] 30000 3 78:2006) Main-alarm refrigeration refrigeration concentration concentration

500 MAX MAX level level 4200 3000 3500 5000 [ppm] 55000 84000 59000 87000 120000 145000 120000 Pre-alarm (20% LFL or refrigeration refrigeration Practical limit; Practical concentration concentration R717-500ppm) ------4148 2951 3 525 4928 [ppm] 29545 LFL (20%) Flammabillity Flammabillity ] 3 ------LFL 0.104 0.0 3 8 0.0 3 6 0.04 3 0.04 3 [kg/m Flammabillity Flammabillity - - - - 497 [ppm] 55 3 10 8 3 6 5 5871 3 86544 118 3 14 146 3 25 119279 Practical Limit Practical ] 3 0.1 0. 3 0.25 0.48 0. 3 1 0.44 0.49 0.008 0.008 0.008 0.008 [kg/m 0.000 3 5 Practical Limit Practical L2 L1 L1 L1 L1 L1 L1 L2 L 3 L 3 L 3 L 3 L group B2 A1 A1 A1 A1 A1 A1 A2 A 3 A 3 A 3 A 3 Safety group Safety B1 = L2 B2 = L2 B 3 = L toxicity L groups Increased

Safety groups & Safety groups

A1 = L1 A2 = L2 A 3 = L

flammability Increased Increased Name Ammonia Dioxide Carbon Chlorodifluoromethane 1,1,1,2-tetraflouroroethane R125/14 3 a/1 4a (44/52/4) R 3 2/125/1 4a (2 /25/52) R 3 2/125 (50/50) R125/14 3 a (50/50) Propane Butane Iso-butane Propylene B1 B2 B 3 R717 R744 R22 R1 3 4a R404A Refrigerant R407C R410A R507 R290 R600 R600a R1270 toxicity Increased

A1 A2 A 3 Safety groups

flammability Increased Increased Refrigerant Refrigerant type - - HCFC HFC HFC HFC HFC HFC HC HC HC HC EN 378:2000

Annex III ------25 800 800 TWA TWA 5000 1000 1000 [ppm] effect) (NIOSH) week without week (40 hours work (40 hours work MAX MAX (prEN [ppm] 3 0000 3 78:2006) Main-alarm Main-alarm refrigeration refrigeration concentration concentration ? 500 MAX MAX 4200 3 000 3 500 5000 [ppm] 19500 42000 29400 59200 4 33 00 7 3 200 (20% LFL or refrigeration refrigeration Practical limit; limit; Practical concentration concentration R717-500ppm) Pre-alarm level Pre-alarm level ------4148 3 525 3 525 4585 [ppm] 29545 LFL (20%) Flammabillity Flammabillity ] 3 ------LFL 0.104 0.0 3 8 0.04 3 0.04 3 0.040 [kg/m Flammabillity Flammabillity - 249 2865 (50%) [ppm] 19 3 58 41818 29 3 57 59157 4 3 272 7 3 16 2456 3 3 89 4 12295 ATEL /ODL ATEL - 0. 3 0.07 0.25 0.48 0. 3 1 0.44 0.09 0.19 0.06 0.01 0.000 3 5 [kg/m 3 ] ATEL /ODL ATEL ] 3 0. 3 0.07 0.25 0.48 0. 3 1 0.44 0.49 0.008 0.008 0.0086 0.0086 [kg/m 0.000 3 5 Practical Limit Practical B2 A1 A1 A1 A1 A1 A1 A2 A 3 A 3 A 3 A 3 Safety group Safety Carbon Dioxide Dioxide Carbon Name Ammonia Chlorodifluoromethane 1,1,1,2-tetraflouroroethane R125/14 3 a/1 4a (44/52/4) R 3 2/125/1 4a (2 /25/52) R 3 2/125 (50/50) R125/14 3 a (50/50) Propane Butane Iso-butane Propylene B1 B2 B 3 toxicity Refrigerant R717 R744 R22 R1 3 4a R404A R407C R410A R507A R290 R600 R600a R1270 Increased

A1 A2 A 3 Safety groups

flammability Increased Increased - Refrigerant Refrigerant type - HCFC HFC HFC HFC HFC HFC HC HC HC HC prEN 378:2006

18 DKRCI.PA.000.B2.02 / 520H1724 © Danfoss A/S (RA Marketing/MWA), 08 - 2007 Application guide Gas detection in refrigeration systems

Annex IV – – – – – – 25 800 800 TWA TWA 5000 1000 1000 [ppm] effect) (NIOSH) week without week (40 hours work (40 hours work – – – – 500 4400 3 400 3 400 3 400 [ppm] 50000 42000 60000 Practical Limit Practical ] 3 – – – – 8 91 8.2 8.2 5.9 150 250 0. 3 5 [g/m Practical Limit Practical L2 L1 L1 L1 L1 L1 L1 L2 L 3 L 3 L 3 L 3 L group B2 A1 A1 A1 A1 A1 A1 A2 A 3 A 3 A 3 A 3 Safety group Safety Name Ammonia Dioxide Carbon Chlorodifluoromethane 1,1,1,2-tetraflouroroethane R125/14 3 a/1 4a (44/52/4) R 3 2/125/1 4a (2 /25/52) R 3 2/125 (50/50) R125/14 3 a (50/50) Propane Butane Iso-butane Propylene Refrigerant R717 R744 R22 R1 3 4a R404A R407C R410A R507 R290 R600 R600a R1270 Refrigerant Refrigerant type - - HCFC HFC HFC HFC HFC HFC HC HC HC HC ASHRAE 15-2004

Danfoss Refrigeration & Air Conditioning is We focus on our core business of making a worldwide manufacturer with a leading quality products, components and systems position in industrial, commercial and that enhance performance and reduce supermarket refrigeration as well as air total life cycle costs – the key to major conditioning and climate solutions. savings.

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DKRCI.PA.000.B2.02 / 520H1724 Produced by Danfoss RA Marketing, MWA. 07-2007