System design
DANGER
Danger to life in case of refrigerant leakage!
Ammonia (R717) is toxic and, when present in high concentration, causes burns to the skin, mucous membranes and eyes and leads to paralysis and suffocation!
In liquid form, it can cause frostbite on contact with the skin!
When working on the system: Wear personal protective equipment!
Equip the machinery room and the hazardous area according to EN378-3, 5.17!
- From a refrigerant charge of 50 kg, install a gas warning system!
- From a refrigerant charge of 500 kg, take additional measures to detect possible ammonia contamination in all connected water or liquid circuits!
Since ammonia (R717) is lighter than air, the contaminated air must be extracted below the ceiling and supply air is introduced at floor level.
DANGERRisk of bursting of components and pipes due to excess liquid pressure.
Vessel and pipes may burst, small components may shoot out. The pressure wave may be lethal.
Leave sufficient gas volume above the liquids.
- Make sure not to exceed maximum admissible pressures!
- Avoid overcharging the system with refrigerant under all circumstances!
- Protect system areas where liquid refrigerant can be trapped during operation against excessive pressure! For this, overflow devices or pressure relief valves can be used.
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)!
Due to the special properties of R717, observe the following points when designing the system:
Installation
The system must be installed according to all applicable regulations and standards!
- Refrigeration systems with a charge of >300 kg must be installed in a special machinery room.
- Leaking refrigerant must be safely discharged to the outside without danger to the environment.
- The tightness of the refrigeration system must be monitored by a gas warning system (charge > 50 kg).
- All components and parts used must be compatible with R717.
- Access to and working in the machinery room is permitted for qualified and authorised staff only.
- Personnel protective equipment must be made available to all employees working on the R717 refrigeration system.
Pipe layout
Observe the following points for the design and pipe layout of systems with flooded evaporators:
- Due to the use of R717-insoluble oils, there is no oil return with the suction gas. A highly efficient oil separation is required!
- When using an automatic oil return from the system, the oil quality on the suction side must be controlled at regular intervals. On the low pressure side, there will be a high concentration of dirt particles and water!
- The suction gas line connected to the R717 suction accumulator or evaporator is a "dry suction gas line". No oil is returned with the suction gas!
- Thanks to the flooded operation, there is (almost) no overheat on the suction side. Due to control fluctuations, condensate formation in the suction gas line cannot be excluded. In order to avoid a wet operation of the compressors, the suction gas line must be installed with a slight upward inclination in flow direction. This will ensure that the condensate can flow back against the gas flow.
Technical documents for further information:
- AT-300: Schematic wiring diagrams for BITZER products
- AT-320: Connections and shut-off valves for BITZER compressors
- KT-420: BITZER reciprocating compressors with external frequency inverters
- ST-420: Bitzer screw compressors with external frequency inverters