Algunos resultados adicionales de análisis funcional

Quality of lube oils (SAE 40) for heavy fuel operation (using HFO)

The specific initial performance produced by modern diesel engines and the use of fuels that reach the quality limits ever more often increase the require-ments on the lube oil and require careful selection of the lube oil.

Lube oils having medium alkalinity have proven to be well-suited for the lubrication of moving components and for lubrication of the cylinder of the turbocharger and for cooling the pistons. Lube oils of medium alkalinity contain additives which ensure, amongst other things, a higher neutralisa-tion reserve than purely alloyed engine oils (HD oils).

There are no international specifications for lube oils having medium alka-linity. It is therefore necessary to carry out a corresponding test run of ade-quate duration in accordance with the instructions provided by the manu-facturer.

You may only use lube oils approved by MAN Diesel. They are listed in Table 5.

Specifications

Base oil The base oil (alloyed lube oil = base oil + additives) must be a narrow dis-tillation section and be refined by modern methods. Paraffins, if they are present, must affect neither the thermal stability nor the oxidation stability negatively.

The base oil must conform to the threshold values given in the table below, especially with regard to resistance to ageing.

Characteristics/Features Unit Testing method Threshold value

Structure - - Preferably based on paraffin

Cold behaviour, still capable of flowing °C ASTM-D2500 -15

Flash point (Cleveland) °C ASTM-D92 > 200

Ash content (Oxide ash) % by weight ASTM-D482 < 0,02

Coking residue (according to Conradson) % by weight ASTM-D189 < 0,50 Ageing tendency after 100 hours heating to 135

°C - MAN Ageing

cabi-net *

-Insoluble n-heptane % by

weight ASTM-D4055

or DIN 51592 < 0,2

Evaporation loss % by

weight - < 2

Drop sample (Filter paper) - MAN Diesel Test There should be no deposits of resin or asphalt-type

prod-ucts of ageing.

Table 1: Lube oils when using heavy fuel as a fuel - target values

* Works-internal process

Medium alkali lube oil The finished oil (base oil with additives) must have the following properties:

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Operating media

Additive The additives must be dissolved in the oil and have a composition which leaves as little ash as possible, even if the engine is operated temporarily using distillate oil.

The ash must be soft: If this condition is not met you must expect increased amounts of deposits in the combustion chamber, particularly on the exhaust valves and on the inlet housing of the turbocharger. Hard additive ash pro-motes pitting on the valve seats and burning away of the valves and increa-ses mechanical wear in the cylinder liners.

Additives must not accelerate filter element blocking, either in the active or consumed condition.

Washability The washability must be at such a level that neither tar nor coke residues from combustion can deposit. The lube oil must not take up any deposits produced by the fuel.

Dispersion capability The dispersion capability must be selected in such a way that common lube oil cleaning systems can remove harmful contaminants from the used oil, that is to say that the oil must have good separation and filter properties.

Diesel properties The properties must comply with the minimum requirements of MIL-L 2104 D or API-CD (without taking into account the neutralisation).

Neutralisation capability The neutralisation capability (ASTM-D2896) must be so high that the acidic products created during combustion are neutralised. The response time of the additives must be matched to the processes in the combustion cham-ber.

Tips for selecting the base number can be taken from Table 3.

Evaporation tendency The evaporation tendency must be as low as possible, otherwise the oil consumption will be negatively affected.

Other conditions The lube oil must not form stable emulsions with water. After one hour a maximum of 40 ml of emissions must have been formed, according to the ASDM-D1410 test.

The foaming behaviour (ASTM-D892) must satisfy the following condition:

Less than 20 ml after 10 minutes.

The lube oil must not contain viscosity index improvers. Fresh oil must not contain any water or any other contaminants.

Lube oil selection

Engine SAE-class

16/24, 21/31, 27/38, 28/32S, 32/40, 32/44, 40/54, 48/60, 58/64,

51/60DF 40

Table 2: Viscosity (SAE-class) of lubricating oils

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Operating media Operation/Operating media General

Approx. BN

(mg KOH/g oil) Engines/Operating conditions

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, 40/54, 48/60 and 58/64 and 51/60DF with entirely HFO operation only at a sulphur content < 1.5 %.

For the engine 51/60 DF with alternating operation (gas/HFO).

40 Under unfavourable operating conditions 230A, 28/32A and 28/32S and with corresponding requirements for oil service life and engine purity.

Generally 16/24, 21/31, 27/38, 32/40, 32/44CR, 40/54, 48/60 and 58/64 and 51/60DF with purely heavy fuel operation as long as the sulphur content is above 1.5 %.

50 The oils 32/40, 32/44CR, 40/54, 48/60 and 58/64 are inadequate at a BN number of 40 with regard to oil service life or engine purity (high fuel sulphur content, very low lube oil consump-tion).

Table 3: Determination of the base number for the operating conditions Operation with low-sulphur

fuels In order to maintain emission regulations, these days we use fuels with var-ious different sulphur contents. In environmentally-sensitive areas (SECA) a fuel with low sulphur content must be used. Outside the SECA zones you may use a fuel with a higher sulphur content. In this case the BN number of the lube oil must be selected to comply with the requirements for operation with sulphur-rich fuels. Only in the case of exclusive operation with low-sulphur fuel can you use lube oil having a lower BN number.

The final criterion for the decision concerning which additive component is permitted is, however, the practical result of the most economical engine operation.

Cylinder lube oil On engines with a separate cylinder lubrication the pistons and cylinder lin-ers are supplied with lube oil by a separate lube oil pump. The volume of lube oil is set in the factory in accordance with the fuel to be used and the operating conditions that are to be expected.

A lube oil as specified above is to be used for the cylinder and circulation lubrication.

Speed governor On mechanical-hydraulic governors with separate oil sump you should pref-erably use 5W-40 multigrade oil. If this oil is not available when filling you can, under exceptional circumstances, use a 15W-40 oil. In doing so it does not matter if multi-coloured oils based on synthetic or mineral oil are used.

(Designation for armed forces in Germany: O-236)

The oil quality specified by the manufacturer must be used for the remaining plant components on the engine.

Experience shows that, for engine L27/38, the operating temperature of the Woodward governor OG10MAS and the corresponding setting unit for UG723+ can reach more than 93 °C. In cases such as these we would rec-ommend a synthetic oil such as Castrol Alphasyn HG150. Engines delivered after March 2005 are already filled with this oil.

Lube oil additives The inclusion of additives in the lube oil or the mixing of different brands (oils from different manufacturers) of lube oils is not permitted since the performance of the carefully matched additives, that are made to measure for the base oil, can be affected. In this case the lube oil manufacturer (lube oil supplier) also no longer can guarantee the lube oil properties.

Selection of lube oil/Guaran-tee

The majority of mineral oil companies have close and continuous contact with engine manufacturers and can therefore state which oil from its own product line is approved by the engine manufacturer for the application.

Independently of this information, the lube oil manufacturer always provides

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a guarantee for the quality and properties of their products. In the event of any questions we would be pleased to provide further information.

Oil in use There are no prescribed oil change intervals for MAN Diesel medium range engines. The oil properties must be checked at regular intervals. As long as the oil properties are within the defined threshold values (see threshold val-ues table) the oil can continue be used. An oil sample must be analysed every one to three months (see maintenance schedule). The quality of the oil can only be maintained if the oil is cleaned using suitable equipment (e.g.

a separator).

Threshold value Process

Viscosity at 40 °C 110 - 220 mm²/s ISO 3104 or ASTM D445

Base number (BN) BN at at least 50 % fresh oil ISO 3771

Flash point (PM) Minimum 185 °C ISO 2719

Water content Maximum 0.2 % (maximum 0.5 % for

short periods) ISO 3733 or ASTM D1744

n-Heptane insoluble max. 1.5 % DIN 51592 or IP 316

Metal content depends on the engine type and operating conditions

Table 4: Threshold value

Tests

We carry out examination of lube oils for our customers in our laboratories.

We require a representative sample of about 0.5 l.

Manufacturer Base Number (mgKOH/g)

20 30 40 50

AGIP — — Cladium 300 Cladium 400 — —

BP Energol IC-HFX 204 Energol IC-HFX 304 Energol IC-HFX 404 Energol IC-HFX 504

CASTROL TLX Plus 204 TLX Plus 304 TLX Plus 404 TLX Plus 504

CEPSA — — Troncoil 3040 Plus Troncoil 4040 Plus Troncoil 5040 Plus

CHEVRON

(Texaco, Caltex) Taro 20DP40 Taro 20DP40 Taro 40XL40 Taro 50XL40

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Operating media Operation/Operating media General

MAN Diesel SE accepts no responsibility for the use of these oils.

6680 3.3.6-01 EN 5 (5)