Brief about R717 (Ammonia)
Ammonia has been used in industrial applications since the 1930s and is generally acknowledged as being the most efficient refrigerant.
It has a low boiling point (-33 deg.) and low freezing point (-77.7 deg.) and is favored because it is a highly energy efficient refrigerant which also has minimal environmental impact, having zero ODP (Ozone Depletion Potential) and zero GWP (Global Warming Potential).
EFFECT OF MOISTURE CONTAMINATION OF AMMONIA REFRIGERANT
The effects of the moisture contamination of ammonia refrigerant are many. The pressure-temperature relationship is impaired. Chemical changes occur to the compressor oil Organic acids and sludges are formed. Pump operation, piping pressure drop, and evaporator performance are adversely affected.
DETECTION OF MOISTURE CONTAMINATION
Detection of the effects of moisture contamination of a system may take years before the problem is recognized. During this time room temperatures may have been compromised, more compressors operated, suction pressure lowered, and much additional electrical energy consumed and wasted. The presence of moisture in the ammonia can be determined by a method similar to that used for testing samples of ammonia shipped by manufacturers or large distributors.
APPARATUS
The apparatus required for obtaining the sample and making the test consists of:
- Ammonia evaporation test tube.
- Rubber gloves
- Face shield
TEST PROCEDURE
The test procedure is as follows:
- Place evaporation tube in the water bath with fume hood.
- Maintain temperature of the water from 80° to 90° F. Do not increase temperature of the water to speed up evaporation otherwise test results will be incorrect. Care should also be taken to prevent water in bath from entering the test tube.
- After the ammonia has evaporated, remove test tube from water.
- If the residue which remains is greater than the 0.5 ml which can be read in the bottom of the test tube, it should be transferred to a container graduated so that 0.5 ml can be read or estimated.
- Record the volume of the residue to the nearest 0.5 ml. If oil is present on top of the residue, do not include that amount in the quantity of the residue.
SAFETY PRECAUTIONS
Safe working conditions and prudent concern for detail are absolutely necessary to avoid injury. In preparation for the taking of samples, locate a portable fan so that the working area will be well ventilated and free of ammonia fumes as the sample is being drawn. Personnel should protect themselves from direct contact with liquid ammonia when taking samples and performing the tests. Protective hats, glasses, gloves and clothing should be worn. A source of water should be nearby.
OTHER PRECAUTIONS
In the event of a rapid influx of water into the ammonia contained in a heat exchanger, two abnormal conditions occur. The ammonia water solution becomes heated because of the reaction heat generated when the water and ammonia mix. When this happens thermal-hydraulic shock occurs. It is important to stop water flow in and out of the heat exchanger and to stop the ammonia flow in the suction line from the heat exchanger. Since the operation of such improvised equipment involves use of some unusual procedures which can involve pressure buildup, we stress that it be done by knowledgeable operating personnel.
EFFECT OF MOISTURE ON SCREW ELEMENT OF YOUR COMPRESSOR.
Presence of moisture in ammonia reduces the life span of the screw element by preventing proper lubrication of the element as a result the screw element gets heated and friction start taking place between the male and female screw hence the compressor becomes bad.
If you notice reduction in efficiency of your refrigeration equipment there may be need to test for moisture content and remove if found in your refrigerant.
