Download SS062.E.Lubricating Oil for Ref Compressors

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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
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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
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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
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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
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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
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Originator
DTF
DTF
DTF
AMG
Page 5 of 5
PAO