Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
A Standard Specification No 62 Lubricating Oils for Refrigeration Compressors This specification has been revised to detail our preferred oils, and describes the background and detail for the available alternatives, particularly for ammonia and CO2 plant. Guidance on oil brands approved by the compressor manufacturers has been added. The preferred lubricants for various combinations of refrigerant, compressor type and operating conditions are given in the tables. Design staff must note that the oil type should be considered before ordering compressors and then it shall be clearly stated on the order. It is not acceptable to write an oil type on a compressor order unless the compressor manufacturer has previously agreed to it or has expressly agreed to it for that application. Oils of the same basic type and viscosity can usually be mixed but this is best avoided, even if the base stock is the same the additive package will be different between different manufacturers. CPI CP-4628-32 can be used to replace Castrol 2293 and the alkylbenzene CPI oils can be mixed with Esso Zerice S oils. Never top-up a system with a different oil type (base stock) unless agreed with the technical department. It is very important to specify Esso Zerice S type oil for the specified applications listed because Esso sell their mineral oil called Zerice, which is similar to Shell Clavus mineral oil. Zerice S type oil can be recognised because it is a clear, colourless liquid and does not have an oily appearance. For certain retrofit applications e.g. Isceon 49, improved solubility and oil return can be achieved with a single compressor oil change. The polyolester lubricant is soluble in mineral or alkylbenzene remaining in the system. Staff must note the need to keep POE and PAG oils free from moisture, these oils shall be bought in containers that can be used up one a day or so. In addition these oils should not be charged to the compressor until we are ready to charge refrigerant. Design Managers must ensure that the oil supplier and product selected for the system is clearly stated in the notes section of the Diagram of Connections. For application outside the specified temperature ranges or with alternative refrigerants which are not listed please refer to the technical department. October 2002 L:\Standard Specifications\SS062.E.doc Page 1 of 5 A Standard Specification No 62 Ammonia Screw Compressor Applications Mineral Oils We no longer use mineral oils on new ammonia plant due to its generally poorer characteristics including stability, pour point, viscosity index and life. There is evidence that the changing sources of base stock oils has resulted in a deterioration in the characteristics of mineral oils for ammonia refrigeration applications, including the formation of black sludge in the compressor. PAO Oils We have used Castrol 2293 (ISO 32 grade) PAO (polyalfaolefin) with a lot of success. It is a very high quality synthetic oil with good stability, high viscosity index and low pour point. The direct CPI equivalent is CP-4600-32. Castrol 2294 is the ISO 68 grade PAO oil we have used on some Sabroe machines as Sabroe never accepted the lower viscosity oil. A good alternative to the above is CP-4628-32 which is a ISO 32 grade PAO with seal conditioning additive to prevent seal shrinkage. CP-4628-68 is the ISO 68 grade alternative including the seal conditioning additive. We have used alternative oils in the last few years to avoid the problems related to O ring shrinkage which has caused leaks and necessitated expensive repairs due to this known problem (high aniline point of the oil which causes O ring shrinkage) with PAO oil. PAO Alkylbenzene Mix Again this is a high quality synthetic oil and can be considered to have good life expectancy and viscosity characteristics. The pour point tends to be slightly higher than the equivalent pure PAO oils but it has the advantage that the alkylbenzene in the mix counteracts the O ring shrinking effect of the PAO. Some compressor manufacturers have specified a PAO & AB mix for some time. We understand that the Sabroe branded oil currently marketed for use on ammonia applications is this type of oil. It is also one of only a few oils Grasso recommend for use with ammonia. We have had some good success with this oil and have no particular reservations over using it in any ammonia application Hydro-treated Mineral Oils Hydro cracking is a more intensive method of producing mineral oil, we can consider these oils as highly refined mineral oils with improved characteristics. Users changing from mineral oil to hydro-treated mineral oils have reported good results. We have used both Reflo 68A and CP-1009-68 with good results on chill plant. The pour point of these oils is around -40°C so they are best avoided for plant where the evaporating temperature is below -35°C and under no circumstances should they be used in LPR cold store or blast freezer systems. Howden All of the above oils except some of the PAO/AB mixes are approved by Howden. However, Howden compressors have given us most O ring and shaft seal leakage problems. We must ensure that the oil type is agreed with Howden before compressors are ordered as they sometimes change the O ring and shaft seal specification dependant on the oil type, in addition they don’t always pay attention when we write the oil type on our compressor order! October 2002 L:\Standard Specifications\SS062.E.doc Page 2 of 5 A Standard Specification No 62 Grasso Unfortunately Grasso no longer accept the use of oils on ammonia plant screw compressors other than Reflo 68A, Mobil SHC 326 and CPI CP-4628-68. Special acceptance for particular oils in particular applications can be sought before ordering the compressor but use of Grasso machines with pure PAO, if accepted at all, will require special (HNBR) O rings with additional cost and extended delivery. Sabroe Sabroe no longer offer their compressor warranty on new screw compressors on ammonia applications with oils other than their own unless specifically agreed at time of order. CO2 Applications This section has been included for general guidance, particularly for sales staff. All oils selections for CO2 applications will be referred to the technical department, to ensure best use of recent experience, until further notice. Compressor manufactures including Grasso and Howden have good experience of using PAO oil in CO2 applications, the latter for many years in process gas compression applications. PAO oil is not miscible with CO2 and will float on top of the refrigerant so the oil separation system needs special consideration (to ensure very high efficiency) as does the means of separating oil carried over from the compressor pack. Our preferred oil is CPIs CP-4628-68 as it is a PAO but it will also resist O ring shrinkage. Grasso have approved this oil for use with their screw compressors on CO2. Use of CP-4628-68 also means that we can put the same oil in the CO2 compressors and ammonia compressors on a cascade plant. It would obviously be an advantage to use a miscible oil with CO2 and we have some experience with POE which satisfies this requirement, but our tests were not conclusive. Unfortunately there is little industry experience of this refrigerant and oil combination so we will not use it in the near future except in a development application. October 2002 L:\Standard Specifications\SS062.E.doc Page 3 of 5 A Standard Specification No 62 Refrigerant Compressor Type Evaporating Pressure (°C) Oil Supplier Oil Brand / Product Oil Type / Viscosity R22 R403a (Isceon 69S) R403b (Isceon 69L) R413A (Isceon 49) Open reciprocating(1) >+10°C (and all Grasso recips regardless of evap pressure) CPI CP-4700-100E* Alkyl-benzene/100 Esso Zerice S100 Alkyl-benzene/100 CPI CP-4700-68E* Alkyl-benzene/68 Esso Zerice S68 Alkyl-benzene/68 CPI CP-4700-46E* Alkyl-benzene/46 Esso Zerice S46 Alkyl-benzene/46 CPI CP-4700-100E* Alkyl-benzene/100 Esso Zerice S100 Alkyl-benzene/100 Castrol SW 68* Polyolester / 68 Mobil EAL 68 Polyolester / 68 Castrol SW32 Polyolester / 32 Bitzer BSE32 Polyolester / 32 Mobil Artic 22 cc Polyolester / 32 ICI Emkarate RL32CF Polyolester / 32 R134a <+10°C (not Grasso recips) Semi-hermetic recips(1) All conditions Screws(1) All conditions Recips inc Grasso not DWM Copeland or Bitzer >-30°C Bitzer recips >-30°C DWM Copeland recips R404A R407a R407b R507 All screws All conditions Recips inc Grasso not DWM Copeland or Bitzer >-40°C <0°C Castrol >-15°C <+15°C Castrol All Castrol SW32 Polyolester / 32 Bitzer BSE32 Polyolester / 32 Mobil Artic 22 cc Polyolester / 22 ICI Emkarate RL 32CF Polyolester / 32 Bitzer BSE 170 Polyolester / 170 Bitzer recips DWM Copeland (1) (2) >-30°C All Bitzer screws All Other screws All conditions Consult Technical Department Mobil Mobil SW 68* Polyolester / 68 (2) EAL 68 Polyolester / 68 SW 100* Polyolester / 100 EAL 100 (2) Polyolester / 100 Consult Technical Department Consult technical department for new plant or check approval of oil brand/product with compressor manufacturer Not Grasso compressors October 2002 L:\Standard Specifications\SS062.E.doc Page 4 of 5 A Standard Specification No 62 Refrigerant R717 Compressor Type Reciprocating Evaporating Pressure (°C) > -30°C Oil Supplier Oil Brand / Product Oil Type / Viscosity CPI CP-1009-68* Hydro-treated mineral / 68 Petro Canada Reflo 68A Hydro-treated mineral / 68 Esso Zerice 68 Mineral / 68 Consult Technical Department <-30°C Howden Screws All except below LPR <-30°C Grasso Screws All except below LPR <-30°C Bitzer All except below LPR <-30°C R744 Other Screws All All Compressors All conditions CPI CP-4628-68* PAO with seal conditioning additive / 68 Castrol 2294 PAO / 68 Mobil SHC224 PAO / 32 CPI CP-4628-32* PAO with seal conditioning additive / 32 Castrol 2293 PAO / 32 Mobil SHC224 PAO / 32 CPI CP-4628-68* PAO with seal conditioning additive / 68 Mobil SHC 326 PAO / AB mix / 68 Petro Canada Reflo 68A Hydrotreated Mineral 68 CPI CP-4628-68* PAO with seal conditioning additive / 68 Mobil SHC 326 PAO / AB mix / 68 CPI CP-4628-68* PAO with seal conditioning additive / 68 Castrol 2294 PAO / 68 Mobil SHC224 PAO / 32 CPI CP-4628-32* PAO with seal conditioning additive / 32 Castrol 2293 PAO / 32 Mobil SHC224 PAO / 32 Consult Technical Department Consult Technical Department *Preferred choice Date 17-03-93 07-04-93 29-11-95 20-01-03 Issue 2 3 4 E October 2002 L:\Standard Specifications\SS062.E.doc Originator DTF DTF DTF AMG Page 5 of 5 PAO