BS G 198-5:1997:2005 Edition

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Sleeves and moulded components for aircraft electric cables and equipment wires – Specification for heat shrinkable moulded shapes

Published By	Publication Date	Number of Pages
BSI	2005	66

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Description

This Part of BS G 198 specifies the design, material performance requirements, quality assurance requirements and test procedures for the types of heat-shrinkable moulded shapes shown in Table 1.

In addition to the definitive requirements, this standard also requires the items detailed in clause 3 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be satisfied.

NOTE 1 Guidance for the storage of finished moulded shapes is given in Annex A.

NOTE 2 The latest revision of an aerospace series standard is indicated by a prefix number.

NOTE 3 Moulded shapes that have been shrunk are referred to as recovered.

When specified, moulded shapes used with bonding adhesives shall conform to the compatibility test requirements detailed in Annex D.

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1	BRITISH STANDARD AEROSPACE SERIES BS G 198-5:1997 Sleeves and moulded components for aircraft electric cables and equipment wires – Part 5: Specification for heat shrinkable moulded shapes
2	This British Standard, having been prepared under the direction of the Engineering Sector Board, was published under the authority of the Standards Board and comes into effect on 15 August 1997 Committees responsible for this British Standard The preparation of this British Standard was entrusted to Technical Committee ACE/6, Aerospace avionic, electrical and fibre optic technology, upon which the following bodies were represented: British Airways British Cable Makers’ Confederation British Rubber Manufacturers’ Association Civil Aviation Authority (Airworthiness Division) Federation of the Electronics Industry Ministry of Defence Society of British Aerospace Companies
3	Contents
5	Foreword This Part of BS G 198 has been prepared by Technical Committee ACE/6 and specifies requirements for heat-shrinkable moulded shape materials for aircraft electric cables and insulated equipment wires. BS G 198 is published in the following Parts. It is envisaged that there will be a further Part on heat-shrinkable dual wall sleeves. This Part of BS G 198 specifies requirements for heat-shrinkable moulded shapes in a range of configurations and materials suita… Moulded shapes should be installed in accordance with manufacturer’s or supplier’s instructions and, in particular, it should be… Heat-shrinkable moulded shapes are normally used with a bonding adhesive as detailed in Annex E Table E.1. Some of these adhesiv… It should be noted that the majority of heat guns available for the application of moulded shapes are not suitable for use in po… WARNING NOTE 1. This standard requires the use of substances and/or test procedures that may be injurious to health if adequate … WARNING NOTE 2. It should be clearly understood that the combustion characteristics tests detailed in this standard, i.e. flamma… WARNING NOTE 3. The use of heat-shrinkable materials entails the risk from heat, solvents and gases. Every precaution is to be exercised against the harmful effects by the use of protective gloves and good ventilation etc.
6	This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i to iv, pages 1 to 59 and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.
7	1 Scope This Part of BS G 198 specifies the design, material performance requirements, quality assurance requirements and test procedures for the types of heat-shrinkable moulded shapes shown in Table 1. In addition to the definitive requirements, this standard also requires the items detailed in clause 3 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be satisfied. When specified, moulded shapes used with bonding adhesives shall conform to the compatibility test requirements detailed in Annex D. 2 References 2.1 Normative references This British Standard incorporates, by reference, provisions from specific editions of other publications. These normative refer… 2.2 Informative references This British Standard refers to other publications that provide information or guidance. Editions of these publications current … 3 Information to be supplied by the purchaser The following information to be supplied by the purchaser shall be fully documented. Both the definitive requirements specified … a) the number of this British Standard (i.e. BS G 198-5:1996); b) the total quantity required; c) the colour, if other than black; d) the potting ports, if required (see clause 12); e) the codified identification (see clause 12); f) the packaging requirements; g) compatibility, if required (see Annex D); h) whether the material is to be tested in any further fluids in addition to those given in Table 6 (see 11.13). The description and dimensions of non-standard shapes shall be agreed between the purchaser and the manufacturer or supplier.
8	Table 1 – Types of heat-shrinkable moulded shape materials °C °C °C (4) 4 Materials and characteristics Shapes shall be made from materials which meet the appropriate requirements of clause 11. 5 Colour The colour shall be uniform and evenly dispersed, and recognizable as one of those given in BS 6746C:1993. 6 Finish The moulded shapes, both before and after unrestricted shrinkage, shall be free from bubbles, pinholes, and other defects that may affect performance. 7 Dimensions The dimensions for standard moulded shapes, both before and after unrestricted shrinkage shall be as specified in the appropriate table of Table 7 to Table 27. 8 Shelf life The “use-by” date shall indicate the end of the guaranteed storage time for which clause 7 still applies when stored under the conditions as specified in Annex A.
9	Table 2 – Materials and characteristics 9 Type testing 9.1 Type tests 9.1.1 The manufacturer or supplier shall provide details of the following: a) material composition; b) agreed techniques; and c) evidence to the satisfaction of the approving authority that the material used to manufacture the moulded shapes conforms to the appropriate type tests listed in Table 3, details of which are given in clause 11. All test results shall be recorded and retained for the duration of the approval. The dimensions of the moulded shapes shall be as specified in Table 7 to Table 27. 9.1.2 Unless otherwise specified type tests shall be performed using test sheets as specified in clause 10.4. In the event of a failure of the moulding material to conform to the requirements of any test, the batch of material shall be re… 9.1.3 No changes shall be made to the declared material composition and agreed techniques used in the production of the moulded shapes, without the prior written agreement of the type approving authority.
10	9.1.4 Type approval is valid for 5 years, after which time the manufacturer or supplier shall apply for re-approval of the material. Table 3 – Type tests 9.2 Test conditions 9.2.1 Unless otherwise specified in a particular test, the tests shall be carried out under normal test conditions without control of humidity, at a temperature of (20 ± 5) °C. In the event of a dispute, the tests shall be conducted at (23 ± 2) °C. 9.2.2 A fan assisted air oven shall be used for heating unless otherwise specified in a particular test. 9.3 Conditioning The heat-shrinkable moulded shapes test sheets and measurement gauges if used shall be conditioned for at least 4 h under the conditions specified in 9.2.1 prior to testing. 10 Production routine and quality testing 10.1 Production routine tests Production routine tests shall be applied to test sheets, unless otherwise specified, moulded from every batch of material, and …
11	Table 4 – Production routine tests 10.2 Production quality tests The frequency of application of each production quality test shall be to the satisfaction of the approving authority and will de… Table 5 – Production quality tests 10.3 Batch 10.3.1 Batch of material A batch of material shall consist of that quantity of moulding material, mixed and/or homogeneously blended at any one time. For… 10.3.2 Batch of moulded shapes A batch of moulded shapes is that quantity of the same material type, dimensions and colour produced from one moulding machine, at one time under the same conditions from the same batch of moulding material.
12	10.4 Test sheets Standard test sheets, (2 ± 0.15) mm thick unless otherwise specified, shall be prepared from the same heat-shrinkable material t… 11 Tests and requirements ± 2 °C In the case of dispute an optical method shall be used. Conduct the test in accordance with method A of BS 903-A1:1980.
13	Cut two strips approximately 6.5 mm × 25 mm from a standard test sheet. Place each strip in the bottom of a clean, dry, 13 mm by 300 mm test tube. Suspend the mirrors with the lower edge 150 mm to 180… Prepare a third test tube containing only a suspended mirror as a control. Maintain the lower 50 mm (approximately) of the test tubes at the appropriate following temperatures for (16 ± 0.25) h. ± 2 °C a For information on the availability of suitable mirrors write to the Information Centre, BSI, 389 Chiswick High Road, London W4 4AL.
14	Monitor this temperature using a thermocouple in the vicinity of the glass mirror in one of the test tubes containing a test sample. After cooling, remove the mirrors and examine each one by placing it against a white background in good light. Any removal of co… Conduct the tests for tensile strength and elongation at break in accordance with method 320A of BS 2782-3:1976, except that the test pieces are as described above and the rate of grip separation used is (100 ± 10) mm/min. The values of tensile strength and elongation at break shall be the median value of the results obtained. Breaks at a bench mark or outside the gauge length shall be disregarded and further test pieces shall be tested until five satisfactory breaks are obtained. %
15	Test the conditioned test assembly in air, or oil, conforming to BS 148:1984. If flash-over occurs in air below the required minimum dielectric strength, repeat the test in the oil using a new test sheet. Apply an alternating voltage with a nominal frequency of 50 Hz and a waveform approximately sinusoidal with a peak factor within limits of Æ2 ± 7 % (1.32 to 1.51) between the two electrodes. Apply the test voltage from zero at a uniform rate, such that breakdown or flash-over occurs between 10 s and 20 s. Calculate the dielectric strength by dividing the voltage at which breakdown or flash-over occurs by the thickness of the test sheet. Express the result in kV/mm.
16	Place two standard test sheets in a suitable chamber provided with the means for circulating damp air, and subject them to the damp heat treatment as follows. a) Maintain the chamber for 16 h ± 15 min in such conditions that the temperature near the test sheet is (50 ± 1) °C and the relative humidity is not less than 95 %. b) Turn off the source of heat and allow the closed chamber to cool for at least 5 h with the damp air circulation maintained. c) Turn on the source of the heat so that at the end of 24 h ± 15 min from the beginning of the treatment the chamber conditions specified in a) are restored. d) Repeat the cycle of operations described in a), b) and c). e) Repeat the cycle of operations described in a) and b) except that between 4 h and 5 h after the source of heat has been turne… Within 2 h of removing the test sheets from the chamber, measure the volume resistivity detailed in BS 903-C2 (BS 2782-2:Method 230A) at a test temperature of (20 ± 5) °C. 7·cm (minimum)
17	The test pieces shall be conditioned for a minimum of 4 h with a mandrel of diameter (20 ± 1) mm in a cold chamber maintained at the temperature specified for each type in the following table. While still at the conditioning temperature, wrap each test piece within 10 s through 360° around the mandrel in a close helix. Inspect each test piece whilst it is still on the mandrel. °C ± 2 °C °C ± 2 °C % (min.)
18	% (max.) WARNING. Care should be exercised during this test as toxic fumes may be given off during combustion. It is recommended that the…
19	Totally immerse the test pieces in the relevant fluida for (24 ± 1) h at the temperature specified in Table 6. The volume of the fluid shall be not less than 20 times that of the test pieces. Remove the test pieces from the fluid, lightly … If the test pieces are found to be acceptable on visual examination, then test them for tensile strength and elongation at break in accordance with the method given in 11.6. Calculate the tensile strength based on the original cross-sectional areas, and the elongation based on the gauge lengths marked on the test pieces after immersion. WARNING. Some test fluids may have a flashpoint close to or below the temperature of test. Appropriate precautions should be tak… The tensile strength and elongation at break shall be not less than the following. MPa % a The purchaser may require materials to be tested in further fluids in addition to those listed in Table 6, in which case the additional fluids should be discussed with the manufacturer or supplier. See clause 3
20	Suspend the test pieces vertically in an oven at the relevant temperature specified below for a period of 4 h ± 10 min. After bending through 360° the test pieces shall show no signs of cracking. Any change of colour shall be ignored. Leave the test pieces in the conditions specified in 9.2.1 for a period of 1 h ± 30 min and then wrap in a close helix, through 360° around a mandrel of diameter (20 ± 1) mm. While the test pieces are still on the mandrel, examine them using normal reading vision.
21	Each test piece shall be mounted in a tensile strength machine in axial alignment in the direction of pull. The range of the tensile strength machine shall be such that the maximum load is between 15 % and 85 % of the maximum scale reading. Measure the extension by means of an extensometer or by jaw separation to an accuracy of 2 %. The length of the test piece between the jaws or reference lines depending on the method of measurement chosen, shall be not less than 100 mm. The strain rate shall be (0.1 ± 0.03) mm per mm·min, e.g. for a distance between the jaws of 120 mm, the speed of the moving jaw shall be (0.1 × 120) mm = 12 mm per min. If an initial tensile force F is needed to straighten the test piece this force shall not exceed 3 % of the final value. Record the force F. MPa Increase the force until the extension between the jaws or reference lines reaches 2 %. Record the force F1 required to produce this extension. Calculate the secant modulus from the determination of the tensile stress necessary to produce in the test piece an extension of 2 % of the length between jaws or between reference lines as follows: 2 % secant modulus =
22	The end point for the ultimate elongation shall be 50 % absolute value. The colour to be tested shall be black. There shall be no detectable halogen gases. Shrink each moulded shape under the conditions specified in 11.2. °C
23	Observe and report the number of the wool standard whose first detectable fading corresponds to that of the test piece. Table 6 – List of test fluids °Ca BS 903-A16:1987 test liquid B BS 903-A16:1987 test fluid 103 BS 903-A16:1987 test liquid 101 a Or 20 000 h temperature of the material if lower (see Table 1). b NATO H515 may be used as an alternative. c NOTE For information on the availability of the fluids given in this table, write to the Information Centre, BSI, 389 Chiswick High Road, London W4 4AL. d If a cleaning fluid is required then the test fluid shall be as agreed between the manufacturer/supplier and the purchaser (see clause 3). 12 Marking and packaging Each package of moulded shape/shapes shall be marked with the following information. a) the number and date of this British Standard, (i.e. BS G 198-5:1996); b) the material type code (see Table 1 and Table 2); c) the moulded shape style (see Table 7 to Table 27); d) the size code (see Table 7 to Table 27);
24	e) the adhesive type code, if relevant (see Annex E Table E.1); f) the manufacturer’s or supplier’s name or identification mark; g) the batch number; h) the use by date; i) the quantity.
25	Figure 1 – Style A (lipped straight bottle with short body) Table 7 – Dimensions of style A ± 10 % ± 20 % ± 20 % ± 30 % g
26	Figure 2 – Style B (lipped straight bottle with medium body) Table 8 – Dimensions of style B ± 10 % ± 10 % ± 20 % ± 20 % ± 30 % g
27	Figure 3 – Style C (lipped straight bottle with long body) Table 9 – Dimensions of style C ± 10 % ± 10 % ± 10 % ± 20 % ± 20 % ± 30 % g
28	Figure 4 – Style D (non-lipped straight bottle) Table 10 – Dimensions of style D ± 10 % ± 20 % g
29	Figure 5 – Style E (lipped straight bottle with long tail) Table 11 – Dimensions of style E ± 10 % ± 20 % ± 20 % ± 30 % g
30	Figure 6 – Style F (lipped right angle boot) Table 12 – Dimensions of style F ± 20 % ± 10 % ± 20 % ± 20 % ± 30 % g
31	Figure 7 – Style G (non-lipped right angle boot) Table 13 – Dimensions of style G ± 10 % ± 10 % ± 20 % g
32	Figure 8 – Style H (lipped right angle boot with long tail)
33	Table 14 – Dimensions of style H ± 10 % ± 10 % ± 20 % ± 20 % ± 30 % g
34	Figure 9 – Style I (lipped right angle boot with longer tail) Table 15 – Dimensions of style I ± 10 % ± 20 % ± 20 % ± 30 % g
35	Figure 10 – Style J (lipped straight bottle with longer tail) Table 16 – Dimensions of style J ± 10 % ± 20 % ± 20 % ± 30 % g
36	Figure 11 – Style K (non-lipped straight long tail boot) Table 17 – Dimensions of style K ± 10 % ± 20 % g
37	Figure 12 – Style L [transitions (“T” junction)] Table 18 – Dimensions of style L ± 15 % ± 10 % ± 30 % ± 30 % ± 30 % g
38	Figure 13 – Style M [transitions (30°/45° junction)] Table 19 – Dimensions of style M ± 15 % ± 10 % ± 30 % ± 30 % ± 30 % g
39	Figure 14 – Style N [transitions (“Y” junction 45° low profile)] Table 20 – Dimensions of style N ± 30 % g
40	Figure 15 – Style O (straight, high ratio lipped boot) Table 21 – Dimensions of style O ± 10 % ± 10 % ± 20 % ± 20 % g
41	Figure 16 – Style P [transitions (“Y” junction)] Table 22 – Dimensions of style P ± 15 % ± 15 % ± 30 % ± 30 % g
42	Figure 17 – Style R [transitions (three branched outlets)] Table 23 – Dimensions of style R ± 15 % ± 15 % ± 30 % ± 30 % g
43	Figure 18 – Style S [transitions (four branched outlets)] Table 24 – Dimensions of style S ± 10 % ± 30 % ± 30 % g
44	Figure 19 – Style T (D sub-miniature boot straight) Table 25 – Dimensions of style T ± 5 % ± 5 % ± 10 % ± 20 % ± 20 % g
45	Figure 20 – Style U (D sub-miniature boot right angle) (longitudinal) Table 26 – Dimensions of style U ± 5 % ± 5 % ± 10 % ± 20 % ± 20 % g
46	Figure 21 – Style V [D sub-miniature boot right angle (across width)] Table 27 – Dimensions of style V ± 5 % ± 5 % ± 10 % ± 20 % g
47	The following recommendations are intended to assist in the prevention of moulded shape deterioration caused by conditions existing in the storage area. a) For shelf life conditions see BS 3F 68:1977. b) Shapes should not be stored in direct sunlight. c) Shapes should not be stored within 2 m of a direct ultra violet (fluorescent) light source. d) Shapes delivered in packages should remain packaged until required. e) Material used for packaging should preferably be opaque. f) Packages which are opened for removal of part of their contents should be adequately resealed. g) Unpackaged shapes should be stored in dust-excluding containers. h) Periodically, according to conditions and local quality control agreements, containers should be emptied and cleaned if they contain unpackaged shapes. i) Artificial conditions, such as high ambient temperatures, dry humidities and chemical vapours, should be avoided. B.1 Definitions For the purposes of this test method the definitions given in BS 6401:1983 apply, together with the following. smoke index The numerical summation of the rates of change in the specific optical density of the smoke produced from the start of the test to light transmittance values of 70 %, 40 %, 10 % and the minimum light transmittance value as applicable. B.2 Principle A test sheet is exposed to specified thermal conditions of pyrolysis and combustion in a continuous procedure. The change in opt… B.3 Apparatus B.3.1 General The apparatus shall conform to that specified in BS 6401:1983 modified as specified in B.3.1 to B.3.4. B.3.2 Mixing fan, a small mixing fan centrally near the top of the chamber to ensure complete dispersion of the smoke homogeneou… B.3.3 Auxiliary heating chamber, with an auxiliary heater to reduce the time required to heat the chamber walls to (33 ± 4) °C. … B.3.4 Burner B.3.4.1 Use a multi-jet burner constructed as shown in Figure B.1 with premixed air/propane gas fuel. Centre the burner in front…
48	B.3.4.2 Provide an ignition system such that the burner can be ignited remotely without opening the chamber, for example a plati… B.4 Test pieces Cut a test piece from a test sheet large enough to completely cover the face area of the test piece holder. B.5 Conditioning Prior to mounting the test piece in the test piece holder, condition the test piece at (23 ± 2) °C and (50 ± 5) % relative humidity for at least 24 h. B.6 Mounting of test pieces B.6.1 To prevent excessive buckling and distortion of the test piece during test, use a wire mesh, manufactured from 1.5 mm diameter stainless steel wire with a spacing of 12.5 mm and a square mesh configuration to support the test pieces. B.6.2 Place the test piece holder, face down, onto a flat surface and insert the wire mesh. Position the test piece in the holde… B.7 Safety During the following test there is a danger that flammable and/or toxic fumes will be evolved from the test piece, and adequate precautions should be taken to avoid possible exposure of the operators to the evolved fumes. B.8 Procedure B.8.1 Set up the test chamber and carry out all necessary checks and calibration in conformance with BS 6401:1983, and in accordance with the manufacturer’s instructions. B.8.2 Turn on the propane and air supplies to the burner and ignite it. With a blank test piece holder in position in front of t… B.8.3 Clean the optical windows of the chamber and switch on the auxiliary heating system. Allow the apparatus to stabilize with the vents open, until the chamber wall temperature is within the range (33 ± 4) °C. Close the inlet vent. B.8.4 Stabilize the output of the furnace at 2.5 W/cm2 and close the exhaust vent. Set the zero and 100 % levels of the amplifier and the recorder. Start the recorder at a minimum speed of 10 mm/min. B.8.5 Place the test piece holder containing the material under test in its position in front of the furnace and mark this point on the recorder as the start of the test. Simultaneously start the timing device. B.8.6 After an interval of 300s from the start of the test, turn on the gas supplies and ignite the burner, immediately adjusting the gas flow rates to those previously noted in B.8.2. B.8.7 Expose the material simultaneously to the output from the furnace and the burner for a further 15 min ± 5 s. Record the pe… B.8.8 At the end of this operation, and without opening the chamber, turn off the gases to the burner and move the test piece ho… B.8.9 Throughout the test period, adjust the ranging of the photo-detector amplifier system to maintain the level of the readings recorded for the percentage light transmission at a minimum of 10 % of the full scale value.
49	Figure B.1 – Schematic details of burner for smoke index test
50	Figure B.2 – Schematic front view of smoke index test piece holder B.8.10 At the end of the test, ensure that the inside of the chamber, the auxiliary apparatus and the supporting framework are clean. B.8.11 Repeat the test on two further test pieces. B.9 Calculation of results B.9.1 General The progressive build up of deposits on the optical windows during the test run artificially depresses the recorded transmittanc… B.9.2 Correction of transmittance values B.9.2.1 Using the plot obtained from the recorder, identify the following values: a) Tc the clear beam transmittance at the end of the test run; b) Tmin the minimum transmittance obtained during the test run. B.9.2.2 Convert Tc and Tmin to the equivalent specific optical densities Dsc and Dsmax The conversion of percentage transmittance to specific optical density Ds, for the chamber is given by:
51	B.9.2.3 If Dsc is 3 % or less of Dsmax no further correction to the recorded plot need be made. B.9.2.4 Subtract Dsc from Dsmax to obtain the corrected maximum specific density Dsmaxc. Convert Dsmaxc to percentage transmittance and plot this value on the recorded chart as the corrected minimum transmittance Tminc, at the same time interval. B.9.2.5 If Dsc is more than 3 % of Dsmax and where Tminc is less than 70 %, produce a new plot from the recorder trace as follows. Convert the percentage transmittance to specific optical density as in B.9.2.2 and correct these values using the formula given as follows: B.9.2.6 For example, to obtain the corrected specific optical density at 70 % transmittance (where Ds = 20): Similarly, corrected values for specific optical density at 40 % transmittance (where DST40) and 10 % transmittance (DST10) may be calculated. B.9.2.7 Convert the corrected values for specific optical density obtained in B.9.2.6 back to percentage transmission. Construct… Read from the graph the corrected times (in minutes) from the start of the test to reach 70 %, 40 % and 10 % transmittance. B.9.3 Calculation of the smoke index B.9.3.1 Where the corrected minimum transmittance value is not less than 70 %, calculate the smoke index from the original plot as follows: B.9.3.2 Where the corrected minimum transmittance value is less than 70 % calculate the smoke index from the corrected curve as follows:
52	B.10 Test report Include the following details in the test report: a) the mean value of the smoke index for the repeat tests (a minimum of three) to the first decimal place; b) a description of the burning behaviour (see B.8.7); c) the thickness of the test sheet; d) include the following statement: C.1 General As far as is practicable, all surfaces and all items of equipment within the test chamber shall be constructed from, or coated w… C.2 Test chamber A test chamber comprising: a) an airtight enclosure of at least 0.7 m3 lined with an opaque plastics material and having a hinged or sliding door fitted with a transparent plastic window; b) a forced air extraction system which can be closed at the exit from the chamber when required during the test; c) a mixing fan installed horizontally and centrally at roof level within the chamber. The fan shall have a minimum diameter of 200 mm and shall consist of six axially mounted blades rotating at between 1 200 r.p.m. and 1 500 r.p.m.; d) a means for switching the fan on and off from outside the chamber. C.3 Burner A bunsen type burner with the following features: a) able to operate on natural gas (methane) having a gross calorific value of approximately 30 MJ/m3; b) an air supply external to the chamber; c) a modified collar to prevent oxygen depletion and the consequential extinguishing of the flame or reduction of the flame temperature; d) capable of producing a flame approximately 100 mm in height and having a temperature of (1 150 ± 50) °C at its hottest point; e) a means for igniting and extinguishing the burner from outside the chamber.
53	C.4 Test piece support An annulus, cut from 2 mm to 4 mm thick non-combustible material, of (100 ± 1) mm outside diameter and (75 ± 1) mm internal diam… C.5 Timing device A timing device capable of measuring periods of up to 5 min with an accuracy of ± 1 s. C.6 Gas sampling and analytical equipment C.6.1 Gas sampling equipment To minimize losses of the products of combustion through adsorption or condensation prior to measurement, all sampling lines sha… C.6.2 Analytical equipment The equipment used for the analysis of the gases from the combustion of the test sample shall be such as to allow rapid detectio… C.7 Test pieces Cut the test piece from a test sheet to a size and shape such that during the test it is entirely engulfed in the flame. The mas… C.8 Conditioning After preparation, condition the test piece at (23 ± 2) °C and (50 ± 5) % relative humidity for at least 24 h. C.9 Safety During the following procedure, there is a danger that flammable and/or toxic fumes will be evolved from the test piece, and operators should take adequate precautions to avoid exposure to the evolved fumes. C.10 Procedure C.10.1 Analysis In order to eliminate the unnecessary analysis for gases that are not produced during the combustion of the material under test,… C.10.2 Determination of background correction factor C.10.2.1 Position the burner in the centre of the test chamber floor. Close the chamber and all inlet and outlet vents to the ch… C.10.2.2 Prepare the chamber for the analysis of carbon monoxide, carbon dioxide and oxides of nitrogen and close all sampling p… C.10.2.3 Close the chamber and all inlet and outlet vents. Ignite the burner and simultaneously start the timing device. Maintai… C.10.2.4 Forcibly extract all fumes from the chamber with it open to the free passage of air for a period of 3 min. Repeat the procedure in C.10.2.2 and C.10.2.3, but maintain the burning time for 2 min ± 1 s and 3 min ± 1 s in separate determinations. C.10.2.5 Plot curves of the concentration of carbon monoxide, carbon dioxide and oxides of nitrogen against the time of burning …
54	C.10.3 Determination of evolved gases C.10.3.1 Forcibly extract all fumes from the chamber with it open to the free passage of air for a period of at least 3 min. C.10.3.2 Weigh a test piece to the nearest milligram and place it on the support in the centre of the chamber at a height above … C.10.3.3 Prepare the chamber for the analysis of the evolved gases. Close all sampling ports other than those required for the analysis. Where the method of analysis is to be by use of colorimetric tubes place these within the chamber. C.10.3.4 Close the chamber and all inlet and outlet vents. Ignite the burner and simultaneously start the timing device. Maintai… Where the presence of halogen acids is suspected, determine the concentration of these first, in order to reduce losses through adsorption or condensation. C.10.3.5 After the analysis is complete, forcibly extract the remaining fumes from the chamber for at least 3 min with the chamber open to the free passage of air. C.10.3.6 Examine the residue of the test piece for signs of incomplete combustion. If any part of the test piece remains, or appears to be incompletely burnt, repeat the test using a new test piece. C.10.3.7 Repeat the test using further test pieces until the analyses of three complete combustions have been obtained. C.11 Calculation of combustion products index C.11.1 Calculate the concentration of each of the gases produced when 100 g of material is fully burnt and the products of combustion are diffused in air in a volume of 1 m3, C0 in g/m3 from the following equation: In the cases of carbon monoxide, carbon dioxide and the oxides of nitrogen the values of C0 shall be corrected by subtracting th… C.11.2 Using the mean values of C calculated from the three tests for each gas, calculate the combustion products index as follows: C0,1, C0,2, C0,3 ……. C0,n represent the calculated concentration of each gas produced from 100 g of material. Cf,1, Cf,2, Cf,3 ……. Cf,n are the concentration factors (see C.13 for each gas in p.p.m.) C.12 Combustion products The analysis of the products of combustion of the test piece shall include the quantitative determination of the following gases. This may be determined by classical chemical techniques or colorimetric change (see C.10.3.3). a) acrylonitrile (CH2CHCN); b) ammonia (NH3);
55	c) carbon dioxide (CO2); d) carbon monoxide (CO); e) formaldehyde (HCHO); f) hydrogen bromide (HBr); g) hydrogen chloride (HCl); h) hydrogen cyanide (HCN); i) hydrogen fluoride (HF); j) hydrogen sulfide (H2S); k) nitrogen oxides (NO + NO2); l) phenol (C6H5OH); m) phosgene (COCl2); n) sulfur dioxide (SO2). C.13 Concentration factors of combustion products For the purposes of this method the following values of concentration factors, Cf, are used to calculate the combustion products index: a) acrylonitrile 400; b) ammonia 750; c) carbon dioxide 100 000; d) carbon monoxide 4 000; e) formaldehyde 500; f) hydrogen bromide 150; g) hydrogen chloride 500; h) hydrogen cyanide 150; i) hydrogen fluoride 100; j) hydrogen sulfide 750; k) nitrogen oxides 250; l) phenol 250; m) phosgene 25; n) sulfur dioxide 400. C.14 Test report Include the following details in the test report: a) a full description of the material tested, e.g. the type of the test piece; b) the combustion products index; c) a reference to this method of test; d) a list of the gases detected during the test; e) include the following statement: D.1 Principle This test is designed to evaluate the compatibility of heat shrink sleeving materials and heat shrink moulded shape materials wi…
56	D.2 Rolling drum peel to aluminium (test method) Three test assemblies shall be prepared for each sleeving or moulded shape material as follows. The apparatus shall be as shown in Figure D.1. The underlying substrate shall be a tube of aluminium with an outside diameter (9… A narrow strip of paper or adhesive tape shall be positioned longitudinally above or below the adhesive to facilitate subsequent… Pre-coated sleeving and shapes shall be shrank onto the prepared aluminium surface. For uncoated items the prepared aluminium su… The portion of heat-shrinkable shapes used for this procedure should be parallel, similar to a length of sleeving. The heat shri… After shrinking (and curing, if required by the manufacturer’s/supplier’s instructions), the test pieces shall be allowed to coo… Measure the width of the test piece. Insert a rolling drum into the aluminium tube. Clamp the flap of material in the grip of the tensile test machine. Separate the grip and the rolling drum support at a rate of (50 ± 5) mm/min. Record the peel force in newtons over the entire peeling operation. Calculate the average peel force in accordance with BS 903-A47:1982. Record the method of calculation, the median peak force and the range of peak values in the test report. Calculate the peel strength using the following formula: The peel strength shall be the mean of the three peel strengths obtained. The peel strength shall be not less than 60 N/25 mm.
57	Figure D.1 – Schematic arrangement for peel testing
58	Table E.1 – Bonding adhesives °C Flexible Fluid resistant Flexible Fluid resistant More flexible than Z Fluid resistant Low operating temperature Flexible Flexible Fluid resistant High operating temperature Fluid resistant The purchaser shall specify the materials and adhesive required for compatibility. Table E.2 – Guide to adhesive compatibility WARNING NOTE. Users are advised to seek guidance from the manufacturer or supplier where adhesives are required to bond to cable jackets and/or connector backshells.
59	F.1 Introduction This annex gives general procedures to be followed when using adhesives with heat-shrinkable moulded shapes and sleevings. Reference should be made to the manufacturer’s/supplier’s procedures for further details. WARNING NOTE 1. The use of heat-shrinkable materials entails risk to people from heat, solvents and gases. Every precaution is to be exercised against harmful effects by the use of protective gloves and good ventilation etc. WARNING NOTE 2. Crimped joints can be relaxed by the application of heat. It is essential that care should be taken to ensure the joints are not overheated beyond their operating temperature. F.2 Compatibility The combination of sleeving, cable jackets and connector/adaptors may be unique. Annex E details the recommended combinations of… F.3 Associated equipment F.3.1 Heat source, e.g. infra-red or hot air. F.3.2 Emery paper, of 100 to 400 grade. F.3.3 Degreasing solvent. F.3.4 Paper tissues. F.4 Selection of materials F.4.1 Sleevings and moulded shapes should be selected from approved products (refer to manufacturers or suppliers for Certificate of Approval) ensuring that these products are compatible by referring to Annex E. F.4.2 The selection of heat-shrinkable products, wherever possible, should be such that when installed the recovered product is close to its designed fully recovered dimensions to ensure that the designed wall thickness is achieved. F.5 Preparation of surfaces All possible contact surfaces of the heat-shrinkable products and the substrates to which it is to be shrunk onto, should be thoroughly degreased. The adhesive contact areas of the heat-shrinkable products and cable jackets shall be thoroughly abraded. WARNING NOTE. Users are advised to seek guidance from the manufacturers or suppliers where adhesives are required to bond to cable jackets and connectors/adaptors. F.6 Procedure for epoxy adhesives (types U and Z) F.6.1 The adhesives should be prepared according to the manufacturer’s or supplier’s instructions. F.6.2 Prepare the surfaces in accordance with clause F.5. F.6.3 Apply the adhesive to one heat-shrinkable product or substrate surface, ensuring an even thin coating is applied to the whole of the prepared surface. F.6.4 Refer to Figure F.1 and Figure F.2 for recovery technique. Position the heat-shrinkable product over the substrate and app… F.6.5 Remove excessive adhesive using a dry tissue taking care not to bend the substrate. Allow the joint to cure according to the manufacturer’s/suppliers’s instructions. Normally the following times and temperatures are used:
60	F.7 Procedures for hot melts (types W1 and W2) F.7.1 These hot melts are normally supplied pre-coated on the moulded shapes, but can be supplied as separate tapes to be applied by the user. F.7.2 These hot melts are available in two operating temperature ranges, (- 40 to + 70) °C and (- 55 to + 105) °C. The user shall select the appropriate adhesive for the anticipated environment of the finished joint. F.7.3 Except for the adhesive pre-coated moulded shapes, prepare the surfaces in accordance with F.5. F.7.4 For hot melt tapes, one layer of the tape is wound around the prepared contact area and the moulded shape slid over the tape. F.7.5 Apply the heat source as detailed in F.6.4 and after the product is fully shrunk continue to apply heat until the hot melt can be seen to flow from the ends. WARNING NOTE. Attention is drawn to the heat sink effect with large assemblies when using hot melt adhesives. The underlying sub… F.8 Other adhesives For the application of all other adhesives listed in Annex E, refer to the manufacturer or supplier.
61	Figure F.1 – Sequence of operations for installation of a heat-shrinkable straight boot
62	Figure F.2 – Sequence of operations for installation of a heat-shrinkable right angled boot
64	List of references BSI publications BRITISH STANDARDS INSTITUTION, London BS 148:1984, Specification for unused mineral insulating oils for transformers and switchgear. BS 903, Physical testing of rubber. BS 903-A1:1980, Determination of density. BS 903-A2:1995, Method for determination of tensile stress-strain properties. BS 903-A16:1987, Determination of the effect of liquids. BS 903-A19:1986, Heat resistance and accelerated ageing tests. BS 903-A47:1982, Analysis of multi-peak traces obtained in determinations of tear strength and adhesion. BS 903-C2:1982, Determination of volume resistivity. BS 903-C4:1983, Determination of electric strength. BS 1595, Propan-2-ol (isopropyl alcohol) for industrial use. BS 1595-1:1986, Specification for propan-2-ol (isopropyl alcohol). BS 2011, Environmental testing. BS 2011-2.1, Tests. BS 2011-2.1J:1989, Test J and guidance. Mould growth. BS 2782, Methods of testing plastics. BS 2782-1, Thermal properties. BS 2782-1:Method 140A:1992, Determination of the burning behaviour of horizontal and vertical specimens in contact with a small flame ignition source. BS 2782-1:Method 141:1986, Determination of flammability by oxygen index. BS 2782-1:Methods 143A and 143B:1989, Determination of flammability temperature of materials. BS 2782-2, Electrical properties. BS 2782-2:Methods 220 and 221, Determination of electric strength: rapidly applied voltage method. Determination of electric strength: step-by-step method. BS 2782-2:Method 230A, Determination of volume resistivity. BS 2782-3, Mechanical properties. BS 2782-3:Methods 320A to 320F:1976, Tensile strength, elongation and elastic modulus. BS 2782-4, Chemical properties. BS 2782-4:Methods 430A to 430D:1983, Method 430A. Determination of water absorption at 23 °C – Method 430B. Determination of wat… BS 2782-5, Optical and colour properties, weathering. BS 2782-5:Method 540B:1982, Methods of exposure to laboratory light sources, (xenon arc lamp, enclosed carbon arc lamp, open-flame carbon arc lamp, fluorescent tube lamps). BS 5350, Methods of test for adhesives. BS 5350-A1:1976(1991), Group A: Adherend preparation. BS 5691, Guide for the determination of thermal endurance properties of electrical insulating materials. BS 6401:1983, Method for measurement, in the laboratory, of the specific optical density of smoke generated by materials. BS 6580:1992, Specification for corrosion inhibiting, engine coolant concentrate (“antifreeze”). BS 6746C:1993, Colour chart for insulation and sheath of electric cables. BS 3G 100, Specification for general requirements for equipment for use on aircraft. BS 3G 100-2, All equipment.
65	BS 3G 100-2.3, Environmental conditions. BS 3G 100-2.3.12:1991, Fluid contamination. BSI publications BRITISH STANDARDS INSTITUTION, London BS 5345, Code of practice for selection, installation and maintenance of electrical apparatus for use in potentially explosive atmospheres (other than mining applications or explosive processing and manufacture). BS 5345-2:1983, Classification of hazardous areas. BS 3F 68:1977, Specification for controlled storage of vulcanized rubber for use in aerospace applications. Other references [1] Defence Standard 81-41/3-2. Packaging of defence materiel. Available from Ministry of Defence, Directorate of Standardization.
66	BS G 198-5:1997 BSI 389 Chiswick High Road London W4 4AL BSI – British Standards Institution BSI is the independent national body responsible for preparing British Standards. It presents the UK view on standards in Europe and at the international level. It is incorporated by Royal Charter. Revisions British Standards are updated by amendment or revision. Users of British Standards should make sure that they possess the latest amendments or editions. It is the constant aim of BSI to improve the quality of our products and services. We would be grateful if anyone finding an ina… BSI offers members an individual updating service called PLUS which ensures that subscribers automatically receive the latest editions of standards. Buying standards Orders for all BSI, international and foreign standards publications should be addressed to Customer Services. Tel: 020 8996 9001. Fax: 020 8996 7001. In response to orders for international standards, it is BSI policy to supply the BSI implementation of those that have been published as British Standards, unless otherwise requested. Information on standards BSI provides a wide range of information on national, European and international standards through its Library and its Technical… Subscribing members of BSI are kept up to date with standards developments and receive substantial discounts on the purchase pri… Copyright Copyright subsists in all BSI publications. BSI also holds the copyright, in the UK, of the publications of the international st… This does not preclude the free use, in the course of implementing the standard, of necessary details such as symbols, and size,… If permission is granted, the terms may include royalty payments or a licensing agreement. Details and advice can be obtained from the Copyright Manager. Tel: 020 8996 7070.

Additional information

Status	Confirmed
Pages	66
Publication Date	2005-11-16
ISBN	0 580 26858 6
Standard Number	BS G 198-5:1997
Title	Sleeves and moulded components for aircraft electric cables and equipment wires – Specification for heat shrinkable moulded shapes
Descriptors	Quality assurance, Dimensions, Elongation at fracture, Thermal testing, Density, Designations, Temperature, Colour-fastness tests, Life (durability), Classification systems, Heat-shrinkable materials, Dielectric-strength tests, Shape, Tensile testing, Dimensional tolerances, Testing conditions, Moulded materials, Dimensional changes, Flexibility, Performance, Fluids, Storage, Flammability, Specimen preparation, Combustion index, Heat ageing tests, Microbiological-resistance tests, Marking, Grades (quality), Colour, Low-temperature testing, Endurance testing, Water-absorption tests, Chemical-resistance tests, Test specimens, Thermal-shock tests, Aircraft components, Type testing, Corrosion tests, Preferred sizes, Mouldings (shaped section)
Publisher	BSI
Committee	ACE/6
Amends	BS G 198-5:1997
ICS Codes	49.060 - Aerospace electric equipment and systems

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