Q. What is the difference between SUS and Centistokes in viscosity measurement? What type of cross-reference can I use to find the correct viscosity in centistokes from SUS?
A. Kinematic viscosity can be measured via a variety of different methods of which SUS (ASTM D2161) and centistokes (ASTM D445) are two. As a crude “rule of thumb” it is possible to convert approximately any cSt value to an SUS value by multiplying the cSt value by 5 (e.g. 32 cSt = SUS 150). A full cSt to SUS conversion table is given below:
Q. What is the vapor pressure of EMKARATE RL oils?
A. EMKARATE RL lubricants have very low vapor pressures typically <<0.1 mmHg.
Q. What is the boiling point of EMKARATE RL oils?
A. The boiling points of EMKARATE RL oils are extremely high. For all practical purposes the boiling points of EMKARATE RL oils should be considered to be >482°F (250°C) at atmospheric pressure.
Q. What is the aniline point of an EMKARATE RL oil?
A. Aniline points are only applicable to mineral oils. Therefore, EMKARATE RL oils do not have aniline points
Q. Are EMKARATE RL grades biodegradable?
A. Most of the H range of EMKARATE RL products are classed as ready biodegradable as defined by the OECD 301B guidelines (Also known as the Modified Sturm Test)
Storage, Handling, and Disposal
Q. At what temperature will EMKARATE RL oils break down?
A. An oil which has a thermal stability >347°F (175°C) has generally shown to be of sufficient stability to work well in a refrigeration system. The glass sealed tube test, as described by ASHRAE Standard 97, is widely used to assess the thermal stability of refrigeration lubricants. Tubes are charged with lubricant R-134a (or other lubricant if desired) and copper, aluminium and steel strips, and aged at 347°F (175°C) for two weeks. At the end of the test acid number, color and the state of the strips are evaluated. Tests test using this procedure show EMKARATE RL oils give excellent performance.
Q. How do I dispose of Emkarate RL after use?
A. Empty containers retain product residue. Observe all hazard precautions. Do not distribute, make available, or reuse empty container. Remove all product residue from container and puncture or otherwise destroy container before disposal. Disposal should always be carried out in accordance with local, state, and national legislation. For additional handling instructions, consult the Emkarate Material Safety Data Sheet.
Q. Are there any special safety precautions for handling Emkarate RL lubricants?
A. Standard lubricant handling procedures should be followed, namely:
Wear appropriate clothing, e.g. coveralls and wear suitable gloves and eye protection. Nitrile gloves are resistant to most oils, but may not be suitable for all applications. Take care not to get oil inside the gloves. Safety equipment suppliers can advise on the most suitable protection for your task.
Avoid breathing in the oil mists or hot oil vapors. Preferably, avoid producing the mists.
Ensure that the workplace is properly ventilated.
Moisture Related Questions
Q. What is hygroscopicity and what is its connection with lubricants?
A. Hygroscopicity is a term used to describe the affinity for moisture of a lubricant and/or refrigerant. HFC refrigerants and POE oils have a polar molecular structure, which attracts the polar water molecule. The solubility of water in HFCs, such as R-134a is many times greater than in the CFCs they replace. POEs are also hygroscopic and can pick up more moisture from their surroundings and hold it much tighter than the previously used mineral oils. The most hygroscopic refrigeration lubricants in descending order are: PAGs, PVEs, POEs, ABs and mineral oils. The rate at which POEs pick up moisture is dependent on temperature, relative humidity, exposure time, and relative surface area.
Q. How does moisture enter the refrigeration system?
A. Moisture can enter the refrigeration system by a number of routes: - Improper evacuation of the system. - System leaks. - System components. At elevated temperatures water can leach out of elastomeric or plastic system components. - Improper handling of POE lubricants (e.g. excessive exposure to air). - Saturated or incorrect drier.
Q. How is moisture measured in the refrigeration system?
A. The most practical form of system testing is the use of a moisture-indicating sight glass. Typically, this will indicate levels of moisture above 100ppm. This should be used as an indication that either further tests of the refrigerant lubricant mixture or the service change of the filter is required. Karl Fischer titration (ASTM E1064) has become the accepted standard method for laboratory determination of moisture in refrigerants and lubricants. Purpose built equipment is commercially available from several manufacturers.
Q. What should the moisture content be for refrigerant lubricants?
A. Less than 50ppm in the lubricant before addition to the refrigeration system and <100ppm in the system.
Q. POEs are very hygroscopic. Must I throw out any unused lubricant once I have opened the can?
A. Not necessarily. However, since opened POE’s do run the risk of absorbing moisture, it is not a bad idea to sample the material prior to use to verify that the moisture is at an acceptable level.
Q. How is moisture removed from the refrigeration system?
A. Moisture can be removed from refrigeration systems by applying a vacuum. Moisture is harder to remove for higher viscosity lubricants (>ISO 68) and mild heat (>50°C) must be used as it significantly increases the drying rate.
POEs hold moisture more tightly than mineral oil. However, in the case of R-134a, the refrigerant effectively competes with the ester lubricant in partitioning the water; i.e., the water moves from the lubricant to the refrigerant (e.g. approximately 50 to 60% of the moisture in an air-conditioning system remains in the refrigerant and the rest mixes with the compressor oil). R-134a removes moisture from the POE and then transports it to the drier where it is removed.
Q. What procedures are recommended for maintaining low moisture contents in POE lubricants?
A. Good housekeeping practices should eliminate most potential sources of moisture. - Avoid exposing the POE lubricant to air for an extended period of time. - Keep containers of POE lubricants tightly closed except when the oil is actually being dispensed. - Keep the compressor and refrigeration system components closed, except when work is actually being performed on the equipment. Never leave the equipment open during work breaks, overnight, or while doing other work. - Keep POE lubricants in their original containers. - Use the appropriate size container (try to ensure complete use of contents). - Ensure that any vessel or equipment used to transfer the POE is thoroughly dried before used. - The use of a fresh appropriately sized drier, after servicing a refrigeration system, will reduce the impact of any water contamination.
Q. What are the main influences on drier selection?
A. Different OEMs recommend a variety of drier materials based on the selection criteria given below. Several OEMs quote acceptable levels of alumina in mixed drier systems, while others recommend 100% alumina or 100% molecular sieve driers. You need to refer to the OEM’s recommendations when selecting the proper drier. The use of a 100% molecular sieve filter drier is acceptable to all compressor OEMs. ASERCOM, the industry`s global compressor association recommends a minimum 70% molecular sieve and a maximum 30% activated alumina drier. They do not recommend the use of silica gel. The selection of a drier can be affected by a variety of factors:
A 100% molecular sieve drier has no capacity to absorb acids. Alumina driers can.
Molecular sieve driers are better at removing moisture than alumina driers.
Drier capacity should be large enough to remove all the possible moisture in the system.
POE oils are polar molecules and thus can be absorbed by the alumina. Therefore, a filter drier made of this substance can become saturated with oil and is then no longer capable of removing acids from the system.
Alumina may catalyse the hydrolysis of the POE lubricants creating organic acids since both water and lubricant are adsorbed into the pore openings of the alumina. However, provided the filter is not saturated, these acids may remain bound to the drier once they are formed.
Alumina driers may remove the antiwear additives out of certain refrigeration lubricant formulations. This is particular true of POE formulations with high initial TAN values (>0.1mgKOH/g).
The ability to remove water from a refrigeration system is the most important function of a drier. By minimizing the free water in the system, the propensity for acids to form, or hydrolysis to take place is greatly reduced.
Q. What can I use to check the acid level of a refrigeration oil system?
A. The most convenient method of testing the acid level of a refrigeration oil is the acid test kit. Acid value can be used as a simple way of evaluating oil decomposition. As a general rule, the higher the acid value, the greater the oil decomposition. Acid test kits use this as a way of checking the oil. The test is quick and simple but suffers from a few disadvantages. Acids from the breakdown of oil can be absorbed by system components such as dryers. This can result in artificially low acid values. Additives in the oil can also affect the reliability of acid test kits. A more accurate, but less convenient, method of measuring acid value is to send the oil to a certified test laboratory.
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Approval and Choosing the Right Lubricant
Q. Who approves EMKARATE RL oils and for which compressors?
A. Original Equipment Manufacturers (OEMs) such as Emerson, Carrier and Trane approve lubricants. An up-to-date approval list can be found elsewhere on this website. It is important to use OEM approved lubricants as non-compliance usually results in voiding of any warranty. OEM Approvals List >>>
Q. How do I know which EMKARATE RL is approved for use with a specific compressor?
A. Consult the EMKARATE RL Approval List found on the website. OEM Approvals List
Q. Should I use a POE or PAG in my mobile air conditioning system?
A. Both PAGs and POEs can be used successfully. PAGs tend to be used for original fill applications while POEs such as EMKARATE RL 100H are used primarily in the aftermarket. EMKARATE RL 2000 is a high performance POE lubricant designed to extend compressor life and boost system performance.
Q. What viscosity EMKARATE RL should I use?
A. The following chart can be used as a general guide to viscosity selection
Q. Can I use an EMKARATE RL with R-22?
A. Several OEMs have no issues with the use of POEs with R-22, while other OEMs do not recommend it. Generally, POEs can be used with R-22 as long as moisture is tightly controlled. High levels of moisture can lead to copper plating and/or corrosion issues. POEs are also very soluble in R-22 and this can lead to wear and/or foaming issues. To avoid wear it is sometimes necessary to use POEs that are one to two ISO grades higher in viscosity compared to the POEs used with R-134A. OEM advice should always be followed.
Q. Are there EMKARATE RL lubricants for low temperature applications?
A. EMKARATE RL ‘H’ series possess excellent lubricating performance and good oil return to temperatures as low as -166°F(-110°C). The ‘H’ series has been formulated to avoid the use of components with poor low temperature flow properties. EMKARATE RL 22H and 32H are particularly suitable for cryogenic applications.
Q. When retrofitting a CFC system to an HFC, why must the mineral oil be reduced to a concentration of below 3-5%?
A. HFC refrigerants are more polar than the CFCs they replace and therefore require the use of polar synthetic lubricants such as EMKARATE RL. Mineral oil is less polar, therefore has poor solubility with HFC refrigerants. Residual lubricant left after a retrofit can result in mineral oil being deposited on heat exchanger surfaces, reducing heat transfer, therefore markedly reducing system performance. It is important to minimize the level of residual mineral oil in the system. Optimum system performance will only be achieved when the mineral oil content is below 3-5%.
Q. Are there any lubricants approved by the military?
A. Yes. Consult the OEM approval list which can be found on the website. OEM Approvals List
Q. What elastomers are compatible with EMKARATE Refrigeration Lubricants.
A. The table below gives a general guide to elastomer compatibility with EMKARATE RL/HFC systems. Specific elastomer compounds within a class may give different results. Consult with the compressor OEM for specific recommendations.
Q. When should I change the refrigeration oil in the compressor?
A. As recommended by the OEM.
Q. What refrigerants are Emkarate RL oils compatible with?
A. All CFCs, HCFCs, HFCs, carbon dioxide and hydrocarbons (e.g. R-290, R600a) refrigerants.
Q. Why must I use POE oils with the newer HFC refrigerants like R-404A, R-507, etc?
A. HFCs refrigerants are very polar. For a lubricant to be miscible with such refrigerants it also must be polar. This is why HFCs have very poor miscibility with mineral oil, marginal miscibility with alkyl benzenes and excellent miscibility with POEs.
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Q. What does the term hydrolysis mean?
A. Hydrolysis is the reverse of the esterification process. During hydrolysis water reacts with an ester to form partial esters, the original organic acid and alcohol.
The degree of hydrolysis is driven by the amount of water present. The water may come from absorbed moisture. A high moisture level will lead to a higher degree of hydrolysis. The speed at which hydrolysis occurs is dependent on the temperature of the system and the acid value (acids can act as a catalyst). Certain additives, high initial acid values and impurities inside the system can also catalyse this reaction. For hydrolysis to occur, a sufficient amount of water must exist in the refrigeration system at an elevated temperature. Even at relatively high moisture contents the rate of hydrolysis is insignificant at low ambient temperatures. When the water content of the system is low, hydrolysis does not occur.
Q. Is hydrolysis of ester lubricants a common occurrence?
A. No. The concern over hydrolysis has arisen as a result of hydrolytic stability tests which have been conducted at very high water levels (>2000ppm) and highly elevated temperatures; orders of magnitude greater than expected or seen in the oil under normal operating conditions. While there is a theoretical potential for hydrolysis in refrigeration systems, this is severely restricted by the lack of available water. The industry standard recommendation is that the level of water after assembly should be maintained below 50ppm in the lubricant and preferably below 100ppm in the system. In addition, the water removal rates with suitable capacity driers are extremely rapid even for wet systems.
Q. What causes copper plating?
A. Copper plating has been associated with:
The presence of air.
The use of certain chlorine and sulfur containing process chemicals.
High levels of acid.
High levels of moisture.
Certain types of chlorine and sulfur containing lubricant additives.
Copper plating on steel and iron parts has been a problem in air-conditioning and refrigeration systems for many years, first in the CFC/HCFC-Mineral oil systems and now in the HFC/POE systems. Copper plating may reduce clearances between moving parts resulting in failed bearings, valves, oil pumps and other moving parts. Under certain circumstances copper can also deposit onto insulating films leading to a reduction in their electrical insulating properties.
Q. How is copper plating prevented?
A. The most likely causes of copper plating are high moisture content and contamination from chlorinated chemicals. Tight control of moisture and careful control of process chemicals is vital. Tight control of water is especially important in R-22 systems where copper plating can be problematic. In certain circumstances, copper-deactivating agents can help to reduce the effects of copper plating. However, extreme care is required. At elevated temperatures, these additives can result in deposits leading to capillary tube restrictions. Poorly formulated lubricants should be avoided and only OEM approved lubricants should be used.