General chemical and physical properties of R717
Natural halogen-free substance without any ozone depletion potential (PDP=0) and without green-house effect (GWP=0).
- High toxicity:
- Occupational exposure limit value: 20 ppm (formerly "Maximum workplace concentration" - MAK value).
- Intense odour, therefore good perceptibility even at harmless concentration (from approx. 5 ppm).
- Odour nuisance occurs at a concentration of approx. 250 ppm or more.
- In case of suddenly occurring high concentration: irritation of the mucous membranes, panic reaction, coughing, cramps, or even paralysis and suffocation.
- Explosive between approx. 15 .. 30 vol. % in air (150.000 .. 302.00 ppm)
- Due to the high ignition energy and ignition temperature (auto-ignition temperature 651°C), the risk of explosion is classified as low. Special measures for explosion protection are not required!
- Ammonia vapour is lighter than air
- and therefore moves upward. In the case of emissions, natural or mechanical ventilation is relatively easy to ensure. The contaminated air must therefore be extracted below the ceiling and supply air must be introduced at floor level.
The design and the protection of the system corresponds to the national regulations and standards for refrigerants of group B2L (EN378-1). In Germany, the following regulations apply: Accident prevention regulations BGR500, chap. 2.35, formerly VBG 20, safety standard EN378, Industrial Safety Regulation (BetrSichV), Technical Regulations for Safety in the Workplace (TRBS), "Technical Regulations for Pressure Vessels" (TRB), "Technical Regulations for Pipelines" (TRR), AD codes of practice.
The resulting consequences include: - Evidence of the staff’s special expertise in installation, commissioning, operation and service is required.
- Special requirements for the planning and design of the system.
- Separate machinery rooms for refrigerant charges of more than 50 kg (e.g. with monitored venting system -> gas warning system)
- Welded joints of refrigerant-carrying pipes (from DN 25) must be checked by specialists or technical experts.
- Access to system only by authorized persons having received an appropriate training.
- Limitations in areas open to the public (use of systems with secondary (brine) circuit.
- All important guidelines are summarised in the report on the AiF research project 9404B "Safety of ammonia refrigeration projects".
- R717 has a corrosive effect on copper materials
- and non-ferrous metals and is incompatible with a number of plastics
Resulting measures:
- Refrigerant lines, heat exchangers, fittings must be made of steel or stainless steel. Welded connections on larger pipes (from DN 25) are subject to examination by experts.
- Use resistant plastic materials or elastomers.
- Use of compressors with open drive (Compressors).
NOTICE
Ammonia (R717) is strongly hygroscopic!
Work carefully and avoid penetration of water and/or air humidity into the system!
Work carefully and avoid penetration of water and/or air humidity into the system!
Ammonia (R717) is strongly hygroscopic!
Work carefully and avoid penetration of water and/or air humidity into the system!
A high water content in ammonia systems modifies the evaporation temperature and reduces system efficiency, especially for low temperature applications!
Moreover, water can only be removed with great effort using so-called system cleaners or by renewing the refrigerant charge!
- When draining R717 into water, use a check valve.
- System parts to be opened must be flushed with dry nitrogen first.
- Avoid the formation of condensate! Let cold components warm up.
- Evacuate the system carefully before (re-)commissioning.
- Due to the special conditions in compact air conditioning systems, high demands are placed on the dryness (use R717 with a water content of max. 400 ppm)!
R717 has a high electric conductivity − resulting design criteria:
- Observe special requirements for electrical components inside the refrigeration circuit (e.g. canned motor pumps).
R717 is nearly insoluble in conventional lubricants − resulting selection criteria or measures (Oils and their influence on system design):
- The use of flooded evaporators combined with high efficiency oil separators and oil return from the systems (automatic or, in case of regular maintenance, manual).
- For compact systems with "dry" or semi-flooded evaporators, the use of flowable oils is necessary, possibly in combination with special oil separators and oil return devices.