Man L23/30DF, Project Manual

Page: 148 / 392

The ash must be soft. If this prerequisite is not met, it is likely the rate of dep-
osition in the combustion chamber will be higher, particularly at the outlet
valves and at the turbocharger inlet housing. Hard additive ash promotes pit-
ting of the valve seats, and causes valve burn-out, it also increases mechani-
cal wear of the cylinder liners.
Additives must not increase the rate, at which the filter elements in the active
or used condition are blocked.
The washing ability must be high enough to prevent the accumulation of tar
and coke residue as a result of fuel combustion. The lubricating oil must not
absorb the deposits produced by the fuel.
The selected dispersibility must be such that commercially-available lubricat-
ing oil cleaning systems can remove harmful contaminants from the oil used,
i.e. the oil must possess good filtering properties and separability.
The neutralisation capability (ASTM D2896) must be high enough to neutral-
ise the acidic products produced during combustion. The reaction time of
the additive must be harmonised with the process in the combustion cham-
ber.
For tips on selecting the base number, refer to the table entitled
Base num-
ber to be used for various operating conditions .
The evaporation tendency must be as low as possible as otherwise the oil
consumption will be adversely affected.
The lubricating oil must not contain viscosity index improver. Fresh oil must
not contain water or other contaminants.
Lubricating oil selection
Engine SAE class
16/24, 21/31, 27/38, 28/32S, 32/40, 32/44, 35/44DF, 40/54,
45/60, 48/60, 58/64, 51/60DF
40
Table 2: Viscosity (SAE class) of lubricating oils
Lubricating oils with medium alkalinity and a range of neutralization capabili-
ties (BN) are available on the market. At the present level of knowledge, an
interrelation between the expected operating conditions and the BN number
can be established. However, the operating results are still the overriding fac-
tor in determining which BN number provides the most efficient engine oper-
ation.
Table
Base number to be used for various operating conditions indicates the
relationship between the anticipated operating conditions and the BN num-
ber.
Approx. BN
of fresh oil
(mg KOH/g oil)
Engines/Operating conditions
20 Marine diesel oil (MDO) of a lower quality and high sulphur content or heavy fuel oil with a sulphur
content of less than 0.5 %.
30 generally 23/30H and 28/32H. 23/30A, 28/32A and 28/32S under normal operating conditions.
For engines 16/24, 21/31, 27/38, 32/40, 32/44CR, 32/44K, 40/54, 48/60 as well as 58/64 and
51/60DF for exclusively HFO operation only with a sulphur content < 1.5 %.
Washing ability
Dispersion capability
Neutralisation capability
Evaporation tendency
Additional requirements
Neutralisation properties
(BN)
Specification of lubricating oil (SAE 40) for heavy fuel operation (HFO)
D010.000.023-11-0001
General
2017-07-11 - de
010.000.023-11
MAN Diesel & Turbo
2 (5) D010.000.023-11-0001 EN