BS EN 377:1993 download.Lubricants for applications in appliances and associated controls using combustible gases except those designed for use in industrial processes.
Introduction
BS EN 377 specifies the essential physical and chemical characteristics of lubricants to be used in gas and associated controls appliances using combustible gases except those designed for use in industrial processes.
Judgement on the suitability of the use of these lubricants for any given equipment is not the object of the present standard. This has to be verified by functional tests laid down in the appropriate appliance or control standards.
Notwithstanding the limits of operating temperature covered by this standard, it may be necessary to check any specific operating temperature by functional testing and compatibility trials.
The lubricants covered by BS EN 377 are compatible with copper and copper alloys. Compatibility with other metals — e.g. aluminium and aluminium alloys (which might be corroded by alkaline soaps) — has to be confirmed by long term functional tests at the maximum working temperature.
BS EN 377 contains an informative Annex A on the preparation of a standard reference elastomer used for testing the compatibility with elastomers.
1 Scope
BS EN 377 specifies requirements and methods of test for lubricants to be used in gas appliances of all categories including auxiliary equipment mounted or intended to be mounted on such appliances and which may be in contact with combustible gases, except those designed for use in industrial processes.
2 Normative references
BS EN 377 incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to BS EN 377. For undated references the latest edition of the publication referred to applies.
ISO 1817:1985, Rubber, vulcanized— Determination of the effect of liquids.
ISO 2160:1985, Petroleum products — Corrosiveness to copper — Gopper strip test.
ISO 32 19:1977, Plastics — Polymers in the liquid, emulsified or dispersed state — Determination of viscosity with a rotational viscometer working at defined shear rate.
Iso 6743-9:1987, Lubricants, industrial oils and related products (class L) — Classification — Part 9. Family X (Greases).
3 Classification of the lubricants
The manufacturer shall declare the temperature class of the lubricant as given in Table 1.
4 Requirements
4.1 Behaviour at low temperature The flow pressure of the lubricant, determined according to 5.1, shall not exceed 1 500 mbar.
4.2 Behaviour at high temperature The loss in mass of the lubricant, tested according to 5.2, shall not exceed 8% of the initial value.
Table 1 — Temperature classes
Range ofoperating I From temperature °C) to
In addition, the apparent dynamic viscosity of the lubricant shall not be increased by more than 100 % or decreased by more than 50 % compared with the initial value.
4.3 Resistance to gas
The increase in mass of the lubricant in gaseous butane, tested according to 5.3, shall not exceed 10 % of the initial value.
4.4 Compatibility with copper
The appearance of copper test strips tested in accordance with 5.4 shall give a classification 2 or less for all classes in accordance with clause 5 of ISO 2160:1985 when compared with the reference strips.
4.5 Compatibility with elastomers The increase in volume of the standard reference nitrile elastomer, tested in lubricant according to 5.5, shall not exceed 10% of the initial value. The maximum change in hardness is 10 IRHD.
5 Methods of test
5.1 Behaviour at low temperature
5.1.1 Principle
The method consists of determining the relative flow pressure of the lubricant at 0 °C, that is to say, the pressure required for complete expulsion of the lubricant contained in a nozzle.
5.1.2 Apparatus (Figure 1)
The apparatus comprises a tube in the shape of a cross made from glass or metal, with a nozzle and its holder at the end of the lower tube section and a stopper with a hole for the thermometer at the top end of the upper tube section complete with holder. One of the lateral tube sections is connected to an air supply under pressure. the other to a pressure gauge.
These different components are described below.
— Nozzle
The nozzle (Figure 3) is a steel cylinder having a collar and with an orifice in the form of a truncated cone, It is mounted in a nozzle holder (Figure 4) which, in turn, screws onto a brass casing (Figure 2) retained with a suitable glue.
— Thermometer
The thermometer measures the test temperature with an accuracy of± 1 °C. It is inserted into the vertical section of the test apparatus where it is held in position by a rubber stopper through which it passes and which fits into the enlarged section of the tube thus locating the thermometer in the centre of the triangular orifice at the entry to the nozzle in conjunction with the casing.
— Cont rot gauge
This accessory (Figure 5) is used to position the lower part of the thermometer in the casing.
— Pressure gauge up to 1 500 mbar — having readability 5 mbar.
— Test tube with a diameter of around 25 mm and a height of 130 mm to accept the lower part of the equipment with the nozzle. It is closed by a perforated and split rubber stopper.
— Liquid bath with cover, containing a liquid, the temperature of which can be controlled to(0± 1)°C.
The bath cover shall have an opening through which the lower part of the test apparatus (N.B. Inserted into the test tube) can be immersed into the temperature controlled liquid to a depth of at least 65 mm.
— Chronometer, tolerance ± 1 s.
— C’otton lint or absorbent paper
— Glass plate
— Source of compressed air
5.1.3 Method of operation
Clean the base of the apparatus and the nozzle carefully with cotton lint or absorbent paper without using solvents.
The thermometer is mounted as shown in Figure 1 and adjusted by means of the control gauge which is inserted into the apparatus through the nozzle for a length of 21 mm. The lower step of the gauge is positioned level with the exit of the nozzle. The lower end of the thermometer shall touch the upper end of the gauge.
Remove the nozzle.
Fill the nozzle by spreading lubricant on the glass plate as a bubble free layer and placing the nozzle on this bed of lubricant with the large opening underneath, pressing until it contacts the glass plate.The nozzle should then be separated from the glass plate by lateral movement and the operation repeated until lubricant is emitted from the smaller opening. Excess lubricant is removed with a spatula.
Assemble the apparatus with the nozzle arranged as in Figure 1 and insert the lower part into the test tube. Connect one of the laterals to the pressure source and the other to the pressure gauge.
Condition the apparatus at a temperature of (0 ± 1) °C for (2,5 ± 0,5) h in the liquid bath.
Raise the pressure by stages of 25 mbai’ every :30 s. The flow pressure is defined as being the highest level of pressure reached, corresponding to the complete expulsion of the lubricant from the nozzle.
5.2 Behaviour at high temperatures Three weighing devices consisting of two ground glass discs of 60 mni diameter (Figure 6) are cleaned with acetone and weighed. (1 ± 0,05) g of the lubricant is equally distributed on both parts of the devices by circling movements. Then both discs are separated by lateral movement to give a smooth lubrication film. The lubricant samples are weighed to 1 mg and placed for (24 %) h in a normal oven at temperatures as shown in Table 2.
The change in mass with reference to the initial mass of the samples is determined after the devices have cooled down to ambient temperature in a desiccator containing calcium chloride. Use the arithmetic mean value of the three results obtained.
The change of the viscosity is determined on lubricant samples which were stored in the same manner at temperatures shown in Table 3.
The test method is that of cone and plate described in ISO 3219 with the following parameters:
— Temperature (23 ± 0,2) °C;
— Shear rate 250 s.