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Ministry of DefenceDefence Standard 68-251 Issue 2 Publication Date 7 December 2001 Fuel Soluble Lubricity Improving Additives for Aviation Turbine Fuels NATO Code: S-1747 Joint Service Designation: AL-61 DEF STAN 68-251/2 AMENDMENT RECORD Amd No Date Text Affected Signature and Date REVISION NOTE This Standard has been revised to bring the test methods into line with up-to-date requirements. HISTORICAL RECORD This standard supersedes the following: DERD 2461 dated 1 April 1977 Interim Def Stan 68-251 Issue 1 dated 23 December 1994 DEF STAN 68-251/2 CONTENT Description Page Content 1 Preface 2 Main Text 3 SECTION 1 GENERAL REQUIREMENTS 0 Introduction 3 1 Scope 3 2 Warning 3 3 Related Documents 3 4 Materials 4 5 Product Compliance 4 6 Test Requirements 5 7 Keeping Qualities 7 8 Containers and Marking of Containers 7 Table 1 Test Requirements 5 Fig 1 Schematic Diagram of BOCLE Ball-on-Cylinder 17 Lubricity Evaluator Fig 2 Modification to Arm Support Cylinder 18 Fig 3 Filtering Technique 19 ANNEX A OEM Approval of the Product 8 ANNEX B Procedure for Determining Lubricity Improving 9 Potential ANNEX C Procedure for Determining Solubility in Fuel 21 ANNEX D Procedure for Determining Compatibility with 22 Other Fuel Additives ANNEX E Related Documents 24 1 This standard has been devised for the use of the Ministry of Defence (MOD) and its contractors in the execution of contracts for the MOD. the Directorate of Standardization (DStan) shall be informed so that a remedy may be sought. This standard provides requirements for Fuel Soluble Lubricity Improving Additives for use in Aviation Turbine Fuels. orders etc. Compliance with this Defence Standard shall not in itself relieve any person from any legal obligations imposed upon them. e. If any difficulty arises which prevents application of the Defence Standard. c. f. contracts. Any enquiries regarding this standard in relation to an invitation to tender or a contract in which it is incorporated are to be addressed to the responsible technical or supervising authority named in the invitation to tender or contract. This standard has been produced on behalf of the Standardization Advisory Group (SAG) in collaboration with the UK Aviation Fuels Committee (AFC). liability resulting from negligence) for any loss or damage however caused when the standard is used for any other purpose. b. d. To the extent permitted by law. but without limitation. the MOD hereby excludes all liability whatsoever and howsoever arising (including. and whenever practicable by amendment to those already in existence. 2 .DEF STAN 68-251/2 PREFACE Fuel Soluble Lubricity Improving Additives For Aviation Turbine Fuels Nato Code: S-1747 Joint Service Designation: AL-61 a. This standard has been agreed by the authorities concerned with its use and is intended to be used whenever relevant in all future designs. 2 This Standard and its related Qualified Products List (QPL) 68-251 implement the inspection requirements of NATO STANAG 3390.2 Reference in this standard to any related document means in any invitation to tender or contract the edition and all amendments current at the date of such tender or contract unless a specific edition is indicated. Defence Standards or their use in no way absolves users from complying with statutory and legal requirements relating to Health and Safety at Work. without exemption. 2 WARNING The Ministry of Defence (MOD). like its contractors. Publications are grouped and listed in alphanumeric order. 3 RELATED DOCUMENTS 3. DEF STAN 68-251/2 MAIN TEXT Fuel Soluble Lubricity Improving Additives for Aviation Turbine Fuels NATO Code: S-1747 Joint Service Designation: AL-61 SECTION 1 GENERAL REQUIREMENTS 0 INTRODUCTION Defence Standard 68-251 is the specification for fuel soluble lubricity improving additives for aviation turbine fuels. is subject to both United Kingdom and European laws regarding Health and Safety at Work. 1.1 This Defence Standard specifies the requirements for certain fuel soluble pipeline corrosion inhibiting additives which may be used to improve the lubricity of aviation turbine fuels. 3. 3 . Material provided to this specification shall possess satisfactory performance and properties when used in appropriate vehicles and/or gas turbine or engines operated by the Crown.1 The publications shown in Annex E are referred to in the text of this standard. or for which the Civil Aviation Authority is the certificating agency. 1 SCOPE 1. which is under the Technical Authority of the Defence Fuels Group and replaced DERD 2461 on 23 December 1994. All Defence Standards either directly or indirectly invoke the use of processes and procedures that could be injurious to health if adequate precautions are not taken. and place of manufacture of the product shall not be changed without the written approval of the Technical Authority. The products that satisfy the requirements of this specification are listed in QPL 68-251. 5.DEF STAN 68-251/2 SECTION 1 GENERAL REQUIREMENTS 3. 4.2 above. the Technical Authority reserves the right to require additional evidence that the product is compliant. Responsibility for the correct application of standards rests with users. particularly when forming part of an invitation to tender or contract. the source of component supply. 4. Requests for such information can be made to the DStan Helpdesk.4 Once submitted. How to contact the helpdesk is shown on the outside rear cover of this Defence Standard. in confidence.5 In addition to testing the finished product in accordance with Table 1.2 The Ministry of Defence and/or its appointed agent(s) reserves the right to require that the material and any components used are subject to toxicological and physiological tests to ascertain their suitability for use. formulation details. 4 . users shall be fully aware of the issue and amendment status of all related documents. MATERIALS 4. and place of manufacture of the product to the Technical Authority. 5. The procedure for a new product to be added to QPL 68-251 can be obtained from the Technical Authority. 5 PRODUCT COMPLIANCE 5. the whole consignment may be rejected. 5.3 In consideration of 3.3 The manufacturer shall submit any supporting evidence (if available) for the product’s use in similar applications. the manufacturer shall demonstrate that the product meets the requirements of Table 1. source of component supply.1 Before any product can be considered as complying with this Standard.4 DStan can advise regarding where related documents are obtained from. 5.1 The materials must be essentially hydrocarbon in nature and must not contain phosphorus.6 If any sample taken from the consignment is found not to comply with the requirements of this Standard.2 The manufacturer shall submit. Testing of the base stock and components at any stage of the manufacturing process may be required by the Technical Authority. 5. the formulation. 3. sediments and other impurities 2 Density at 15 °C kg/m3 Report IP 365/ASTM D4052 3 Flash Point °C Report IP 34/ASTM D93 4 Viscosity. Table 1 Test Requirements Test Property Units Limits Method 1 Appearance Clear. bright and free Visual Examination from undissolved water.78 Annex B Potential. Alternative technically equivalent methods may be used with the agreement of the responsible Technical Authority. Wear scar diameter at MEC 11 Micro Separometer Rating Min 70 ASTM D3948 (MSEP) (See NOTE 5) 5 .05 IP 4/ASTM D482 (See NOTE 3) 8 Pour Point °C Max Minus 18 IP 15/ASTM D97 9 Minimum Effective mg/1 Report ASTM D5001 Concentration (See NOTE 4) (MEC) for lubricity 10 Lubricity Improving mm Max 0. which covers the use of precision data.3 The IP 367 (ISO 4259) procedure.2 Methods quoted in the table are referee methods and shall be used in cases of dispute. DEF STAN 68-251/2 SECTION 1 GENERAL REQUIREMENTS 6. Kinematic mm2/s Report IP 17/ASTM D445 at 40 °C 5 Acid Number mg Report IP 177/ASTM D664 KOH/g (See NOTE 1) 6 pH Report (see NOTE 2) 7 Ash Content % m/m Max 0. TEST REQUIREMENTS 6. may be used for the interpretation of test results in cases of dispute between purchaser and supplier.1 Properties of the product shall not exceed the maximum nor be less than the minimum values set out in Table 1. 6. 6. 10 g – 0. NOTE 2 Use 0.11 g of sample in 125 ml of IP 177 / ASTM D664 titration solvent. or other evidence of incompatibility 14 OEM Approval Annex A NOTE 1 Use a sample size of 1 g. The heating of the residue shall be at (875 ± 25)°C. cloudiness. The concentration of the inhibitor in the blend shall be not less than 23 mg/1. Read the constant pH as defined in note 10 of IP 177 or note 15 of ASTM D664. NOTE 4 The inhibitor shall be tested in accordance with ASTM D5001 using Isopar M as the solvent and a 1 kg load on the ball. The MEC is the amount of inhibitor that gives a wear scar diameter of 0. NOTE 5 The test shall be carried out on a blend of the inhibitor in the reference fluid base as described in ASTM D3948. or other evidence of incompatibility 13 Compatibility There shall be no Annex D precipitation. cloudiness. NOTE 3 The electric muffle furnace shall be capable of maintaining a temperature of (875 ± 25) oC.65 mm or less. 6 . The heating of the crucible prior to ashing shall be at (850 ± 50) °C.DEF STAN 68-251/2 SECTION 1 GENERAL REQUIREMENTS Table 1 Test Requirements Test Property Units Limits Method 12 Solubility There shall no Annex C precipitation. A sample size of 25 g shall be used. clean and dry containers.3 It shall be the responsibility of the contractor to comply with any legal requirements for the marking of containers. CONTAINERS AND MARKING OF CONTAINERS 8. The product identification shall be specified in the contract or order. Markings shall be in accordance with the requirements of Def Stan 05-52 (Part 1). suitable for the product and in accordance with the requirements of the contract or order. 8. when suitably stored in its original sealed containers.1 The product shall be supplied in sound. 8. 7 . shall retain the properties described in this Standard for a period. or not less than 12 months in temperate climates and not less than 6 months in tropical climates. DEF STAN 68-251/2 SECTION 1 GENERAL REQUIREMENTS 7 KEEPING QUALITIES The product.2 Coatings and paint finishes shall comply with the requirements of the contract or order. 8. from the date of filling. Any additional tests required and the methods employed to gain such approval will be at the discretion of the relevant OEM.1 The product defined by this specification shall be certified by the appropriate OEMs as approved for use in certain aircraft systems. All products shall meet the requirements of Table A of this specification. Defence Fuels Group Defence Petroleum Centre West Moors Wimborne Dorset BH21 6QS 8 .DEF STAN 68-251/2 ANNEX A OEM APPROVAL OF THE PRODUCT A. Details of the OEMs responsible and the relevant aircraft systems may be obtained from the address below. For qualification purposes and until precision criteria are established. B.1 WARNING – Compressed gas under high pressure. A fixed steel ball in a vertically mounted chuck is forced against an axially mounted steel ring with an applied load. Farnborough.1 Ball-on Cylinder Lubricity Evaluator (BOCLE) as stated in ASTM D5001 and shown in Figure 1.1. except that the load descent distance is to be reduced to 1 mm by fitting a suitable spacer into the support cylinder as shown in Figure 2.2 WARNING – Flammable vapours can cause flash fires.4 APPARATUS B.2 The method assesses the ability of the candidate additive to inhibit scuffing wear on steel rubbing surfaces.2 Constant Temperature Bath Circulator. It utilises the same testing equipment and overall methodology with some modifications. this procedure will be carried out at the manufacturer’s own expense at QinetiQ Ltd. B.3 Microscope capable of 100X magnification with a glass slide micrometer having a scale ruled in 0. The ring remains wet with the fluid and continuously transports it to the ball/ring interface. Use with extreme caution in the presence of combustible materials. The size of the wear scar generated on the ball is a measure of the scuffing inhibiting property of the additive.1.01 mm divisions.1. The ring is rotated at a fixed speed while being partly immersed in the fluid.3 WARNING B.4.3.2.3.1 SCOPE B. B. B. Cody Technology Park.2 OUTLINE OF METHOD B. GU14 0LX.3 This test method is based on the standard ASTM D5001 Test Method for Measurement of Lubricity of Aviation Turbine Fuels by the Ball-on-Cylinder Lubricity Evaluator (BOCLE). Hants. Fuels and Lubricants Centre. DEF STAN 68-251/2 ANNEX B PROCEDURE FOR DETERMINING LUBRICITY IMPROVING POTENTIAL B. capable of maintaining the fluid sample at (25 ± 1) °C when circulating heat transfer fluid through the base of the reservoir.4.1 A fluid sample containing the Candidate additive is placed in a reservoir in which the air atmosphere is maintained at 60 % RH (relative humidity) at 25 °C. Ively Road. B.1 This method describes a procedure used to determine the lubricity enhancing characteristics of candidate fuel soluble lubricity improving additives as a qualification test to QPL 68-251.4. Building 415. B. 9 . B. B. 7.4. B. Vessel B 500 ml stainless steel dedicated to a mixture of equal parts by volume of propan-2-ol and petroleum spirit (or 2.DEF STAN 68-251/2 B.4-trimethylpentane).3 One 500 ml flask with stopper for clay treatment B.4.6 Vacuum pump.4.5 REAGENTS AND MATERIALS B. B.66 mm. Vessel D 500 ml stainless steel dedicated to petroleum spirit for secondary stage cleaning.6 Vessels for the cleaning procedure: Vessel A 500 ml stainless steel dedicated to initial ball and ring cleaning. The HRC shall be 64 to 66 (HV 800 to 860). Vessel E 500 ml stainless steel dedicated to acetone.7. B. B. Ra.2 Chrome alloy steel test ball made from AISI steel No E-52100 with a diameter of 12. B.5 Desiccator containing a suitable drying agent.4 Clamp for holding filter holder and flask together.4. be made on each ring at points around the outside diameter and an average taken to confirm compliance with these requirements.7.4. B.4 Ultrasonic bath of adequate capacity B.1 Glass filter holder of 300 ml capacity with glass support B. in the axial direction.5 Whatman No 2 paper filters.7 mm (0.4.4.5.4. B.4.4. 10 .5. It is recommended that eight surface measurements.7 Clay Treatment B. 0.1 Test ring (NOTE 1) of SAE 8720 steel having a Rockwell hardness ‘C’ scale (HRC) number of 58 to 62 (Hardness Vickers number HV655 to HV750) and surface texture.7.56 mm to 0.2 One 500 ml glass flask suitable for filter holder.7.2.5 in) grade 5 to ten extra polish finish. Vessel C 500 ml stainless steel dedicated to petroleum spirit for primary stage cleaning.7. Experience has shown that an average ball wear scar diameter of (0. B.7 Reference Fluids B.5 Wiping tissue. B. lint-free. B.3 and with 10 mg/1 of an approved anti-oxidant (NOTE 3) added after treatment.1 ppm hydrocarbons and less than 50 ppm water. part No SKF RB12.3 Compressed air containing less than 0.7. part No F-25601: Falex International Ltd PO Box 349 Ascot Berkshire SL5 9SR B.5.5.08) mm is produced. disposable. Petroleum spirit boiling range 60 °C to 80 °C. 2. disposable. Analar grade. cotton.4 Gloves.5. Isopar M (NOTE 2) clay treated according to the procedure under section B. B. lint-free. DEF STAN 68-251/2 NOTE 1: UK suppliers of test rings and balls are: Rings and balls: MED-LAB Limited Copeland Street Derby DE1 2PU Balls.8 ± 0. clean.7/310996A: BSL Unit 5 The Rutherford Centre Rutherford Road Basingstoke RG24 8PD Rings.6 Propan-2-ol. 11 .2.1 Fluid 1 – A low lubricity reference fluid. The fluid shall be tested according to section B.5. hydrocarbon-free.5. light duty.4-trimethylpentane and acetone.8.5.5.7. NOTE 3: Approved anti-oxidants are listed in Def Stan 91-91. NOTE 2: Manufactured by EXXON Chemicals and supplied by: Multisol Limited.5.7.5. Broad Lane (off Goose Green Way).5.1.8.1. B. B.1. B. B. WA16 6DX.3 and with 20 mg/1 of linoleic acid (NOTE 4) added after treatment.1.3.7.1 The balls and rings shall be stripped of any protective coating by manually rubbing them with rags or paper towels saturated with 2.1.3 Repeat C.DEF STAN 68-251/2 Fluid 2 – A high lubricity reference fluid. The Old Brickyard.8 Test Fluid. B.6.6.6. B.1.7.1 Cleaning of balls and rings as received. Experience has shown that an average ball wear scar diameter of (0. 48A Kings Street.3.5. B. shake the mixture in a flask with stopper for 1 minute.2 Using 250 g of clay (NOTE 5) per litre of Isopar M.4 Add 10 ppm of an approved anti-oxidant (NOTE 3) to the filtrant and mix thoroughly.5.6.1.3. Yate Mills. B.6.1.5.04) mm is produced.4-trimethylpentane.7.6. B.6 PREPARATION B. B.5.7.1 Cleaning of Equipment and Test Components.2.3 Filter using the technique shown in figure 3.8.2 Immerse partially cleaned balls and rings in Vessel A containing petroleum spirit and clean ultrasonically for 10 minutes. Knutsford.6.4 Rinse balls and rings with fresh petroleum spirit. NOTE 5: Clay is White Bentonite (Mineral colloid BP) and is available from Fordomin Ltd. The fluid shall be treated according to Section B. 12 .1 The test fluid for qualification testing of an additive shall be 25 mg/1 additive in Isopar M. New Road.3 Clay Treatment Procedure.50 ± 0. Gillingham. SP8 4JL. B. Cheshire.1. NOTE 4: Linoleic Acid is available from Aldrich Chemical Company Ltd.1.2 with fresh petroleum spirit. Dorset. Yate.1 Set up the filtering equipment as shown in figure 3. Isopar M clay treated according to the procedure B.5. B. B.1. Bristol BS17 5LA.7.3. 2. Note 6: Vessels used for this cleaning procedure should be dedicated to the procedure as stated in Section B.6.7.6.7.1.7. B.6.5 Rinse the components in acetone in Vessel E and blow dry.4.6. Ring Mandrel Assembly Wrenches and Tweezers. Change the solvent after every test.2.2.8 Rinse the balls and rings with fresh acetone in vessel E and blow dry. B.3 Immerse the components in fresh propan-2-ol mix in Vessel B and clean ultrasonically for ten minutes.2 Cleaning of Components Between Runs (NOTE 6). B. B. B.7. B.6.2. B. B.9 Dry and store in a desiccator. Discard balls that exhibit pits.2.1.4 Rinse the components in fresh petroleum spirit in Vessel D and blow dry.2. Change the solvent after every five tests.4 The test period is 2 minutes.6.2.1. The conditioning gas is air at (60 ± 0.1.6. B.2.6 Handle all clean rings and balls with clean forceps or disposable gloves.2 The assembly and operating procedure in section 10 of ASTM D5001 applies with the following changes: B. Ball Chuck. B.7.7 ASSEMBLY AND OPERATING PROCEDURE B.1 Visually inspect test balls before each test. rings and machine parts – Reservoir and cover.6.1 The operating air pressure is 180 kPa. B.1.1. B.2.1. Ball Lock Ring.2) % Relative Humidity (RH).1.5 The applied load is 2 kg (1 kg mass on arm).2. B.6. B.1.7.6. DEF STAN 68-251/2 B.1. Change solvent every test.4-trimethylpentane) and clean ultrasonically for 10 minutes. corrosion or surface abnormalities.2 Rinse the components with fresh petroleum spirit in Vessel C.6.6. 13 .3 The conditioning period is 15 minutes. B.5 Immerse balls and rings in Vessel B containing fresh propan-2-ol mix (equal parts by volume of propan-2-ol and petroleum spirit or 2.2.7 Rinse the balls and rings with fresh petroleum spirit in vessel D and blow dry.7.1 Cleaning of balls. Transfer used solvent to Vessel C.2. but waste from Vessel D can be used. B. 7. B. This should be 10 s with a load of 1 kg (500 g on arm) at 180 kPa.DEF STAN 68-251/2 B.1 A summary of test conditions is included in Table B.1 Reference Fluids.54 mm B.7.7.7.04 mm for Reference Fluid 2.2 The cleaned components are assembled and fitted to the BOCLE.3.8.8.7.4 The loading arm drop time is checked. B.7.72 mm to 0.7. B.6 After the 15 minutes the load is applied via the loading switch.46 mm to 0. B.3.3.3.5 The motor and the 5 minutes conditioning period are started. B.7 After 2 minutes the load is released. but not from the blue retaining ring. Wipe clean with wiping tissue and measure scar diameter under the microscope (see section B.7.6 The arm drop time is set to 10 s with 1 kg applied load (500 g on arm) and 1 mm drop distance.1 Carry out three tests on each new batch of the reference fluids in accordance with Section B.3.7. Reject the Reference Fluid batch if: (a) the wear scar diameters for the repeat tests again differ by more than the 0.8. Repeat the three tests if the wear scar diameters differ by more than 0.3.04 mm for reference Fluid 2.9 Remove the test ball from locking nut.3 (50 ± 1) ml of test fluid is placed in the bath.3. The load switch and timer are turned off and the motor stopped. Reference Fluid 1 – 0.1. (b) the average wear scar diameter for the three results does not fail within the following values. B. B.08 mm for Reference Fluid 1 or by more than 0. B.7 using a ring previously calibrated by reference fluid testing.2. B.8 The apparatus is stripped and the components closed.11).2 Rings 14 .7.08 mm for reference Fluid 1 or by 0. B.3 Procedure.3.8 CALIBRATION AND STANDARDIZATION B. B.7.3. B.88 mm Reference Fluid 2 – 0. mm B.46 mm to 0.3.88 mm.3 Levelling of Load Arm. The ring is acceptable if the ball wear scar diameter is within 0. Reject ring if: (a) The two values for wear scar diameter differ by more than 0. that is.1 Position the test ball under the microscope such that the scar is centred within the field of view.54 mm.4 in ASTM D5001.8. The ring is acceptable if the wear scar diameter is within 0.08 mm from each other.10.10 REPORT B.2 Test each new ring with Reference Fluid 2.1 Test each new ring with Reference Fluid 1. B.54 mm.2.72 mm to 0. WSD = Wear Scar Diameter. carry out a repeat test.8.1 Report the test conditions and results on the data sheet as shown in Figure 4. carry out a repeat test.88 mm.8. Record the readings on the Data sheet as shown in Figure 4.9.2 Calculate the wear scar diameter as follows: WSD = (M+N)/2 where. mm N = Minor Axis. B. For adjustment instructions see section B.46 mm to 0.01 mm.9 MEASUREMENT OF THE WEAR SCAR B. Note condition of wear area if different from reference test.1 The level of the load arm shall be inspected before every test. (b) Both the values for wear scar diameter are not within 0.08 mm from each other. debris colour. Reject ring if: (a) The two values for wear scar diameter differ by more than 0. B. 15 .8. B. If not. If not.9.9. Measure the major and minor axes to the nearest 0. mm M = Major Axis.2. unusual particles or wear pattern and particles in the reservoir etc. (b) Both the values for wear scar diameter are not within 0. B. DEF STAN 68-251/2 B.72 mm to 0. 8 l/min of conditioned air flowing over the fluid.2 % RH (at 25 °C) Conditioning Time 15 minutes Ring Rotational Speed 240 r/min ± 1 r/min Applied Load 2 kg (1 kg weight) Arm Drop Time 10 s using 1 kg weight (0.5 kg on arm) Test Duration 2 minutes Fluid Pretreatment: 0.DEF STAN 68-251/2 B.5 l/min of conditioned air flowing through and 3.3 1/min flowing over the fluid for 15 minutes Fluid Test Condition: 3. However.0 ml Fluid Temperature 25 °C ± 1 °C Conditioned Air 60 % ± 0. Section 14 may be used as a guide. 16 . TABLE B Operating Conditions PROPERTY LIMITS Fluid Volume 50 ml ± 1. experience has shown that the precision criteria in ASTM D5001. repeatability and reproducibility of the method has yet to be established.11.1 The precision.11 PRECISION B. DEF STAN 68-251/2 Figure 1: Schematic Diagram of BOCLE: Ball-on-cylinder Lubricity Evaluator 17 . DEF STAN 68-251/2 Figure 2: Modification to Arm Support Cylinder 18 . DEF STAN 68-251/2 Figure 3: Filtering Technique 19 . °C start __________________ Base Temperature. mm _______________ Observations: ________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 20 .DEF STAN 68-251/2 Scuffing Test Date: _______________________ Sample: Ring No. kg __________________ Fuel volume used. mm _______________ Major axis. _____________________ Track No. ml __________________ Scar Type: Elliptical Circular Other Minor axis. r/min __________________ Applied load. °C __________________ Base Temperature. mm _______________ WSD. ______________ Ambient temperature. °C end __________________ Base Temperature controlled (Y/N) __________________ Precondition reservoir time __________________ Start test time __________________ Air Humidity __________________ Ring Speed. _______________ Ball No. cloudiness or other evidence of insolubility. for precipitation.1 SCOPE C. DEF STAN 68-251/2 ANNEX C PROCEDURE FOR DETERMINING SOLUBILITY IN FUEL C. C. and shall contain no other additives.2.1 This method describes the procedure used to determine the solubility of the additive in fuel.2 The mixture shall be inspected visually.1. AVTUR F-35 conforming to Def Stan 91-91 C. immediately after mixing and after 24 hours.2.1 The additive shall be mixed with aviation turbine fuels as detailed below. at a concentration of 23 mg/1. The aviation turbine fuel shall contain the maximum allowable concentration of the specified fuel system icing inhibitor.2 PROCEDURE C. 21 . The presence of static dissipator additive is permitted. the samples shall be visually inspected for precipitation. At the end of a 24 hour period. The use of an epoxy- coated container is suggested. D.1 This method describes the procedure used to determine the compatibility of the lubricity improving additive with other additives in fuel.2. NOTE: Some loss in fuel conductivity may occur over time when bare glass bottles or bare metal cans are used with fuels which contain static dissipater additives. fuel conductivity is temperature sensitive.3 The solution containing the additive under test shall then be mixed in equal proportions with each of the solutions containing the other approved additives.2 OTHER LUBRICITY IMPROVING ADDITIVES D. 22 .2.1 AVTUR F-35 (Def Stan 91-91) filtered through clay as described in appendix X. cloudiness.DEF STAN 68-251/2 ANNEX D PROCEDURE FOR DETERMINING COMPATIBILITY WITH OTHER FUEL ADDITIVES D. and the maximum allowable concentration of the specified fuel system icing inhibitor. in each case containing 23 mg/1 of the approved additive.1. no significant change in temperature should be allowed during the test. cloudiness. No other lubricity improving additive shall be present in this solution. no more than a ± 40 per cent change in the electrical conductivity of the fuel shall have occurred as a result of the test inhibitor.3.2. or other evidence of incompatibility. The post-test visual inspection of the sample shall reveal no precipitation. D.2 After a 24 hour period. Also. the corrosion inhibitor additive under test shall be added and mixed. D. The solution shall also contain the maximum allowable concentration of the specified fuel system icing inhibitor. or other evidence of incompatibility.1 of ASTM D3948 shall be blended with each static dissipater additive listed in Def Stan 91-91 to provide test fuels which have a conductivity of 400 pico siemens per meter (pS/m) ± 100 pS/m. D. The fuel electrical conductivity shall be measured using either IP 274 or ASTM D4308 test methods.1 The additive under test shall be added to AVTUR F-35 (Def Stan 91-91) or AVCAT F-44 (Def Stan 91-86) to obtain a concentration of 23 mg/1. D.2 Solutions shall also be made up for each of the other approved lubricity improving additives. At the end of another 24 hour period. to ensure equilibrium fuel conductivity has been established.3.1 SCOPE D.3 STATIC DISSIPATER ADDITIVE D. At the end of a 24 hour period.4. or other evidence of incompatibility. cloudiness.4 THERMAL STABILITY IMPROVER ADDITIVE D.1 of ASTM D3948 shall be blended with each approved thermal stability improver additive at the specified concentration. The corrosion inhibitor additive under test shall be added to obtain a concentration of 23 mg/1 and mixed.1 AVTUR F-35 (Def Stan 91-91) filtered through clay as described in appendix X. 23 . DEF STAN 68-251/2 D. the samples shall be visually inspected for precipitation. (Part 1) Lubricants and Associated Products. Def Stan 91-91 Turbine Fuel. IP 34 Determination of Flash Point – Pensky – Martens Closed Cup Method. IP 15 (ISO 3016) Petroleum Products – Determination of Pour Point. ASTM D93 Standard Test Methods for Flash-Point by Pensky- Martens Closed Cup Tester. IP 365 (ISO 12185) Crude Petroleum and Petroleum Products – Determination of Density – Oscillating U-Tube Method. Def Stan 91-86 Turbine Fuel. Aviation Kerosene Type Jet A1. Aviation: High Flash Type. IP 367 (ISO 4259) Petroleum Products – Determination and Application of Precision Data in Relation to Methods of Test. IP 71 (ISO 3104) Petroleum Products – Determination of Kinematic Viscosity and Calculation of Dynamic Viscosity. QPL 68-251 QPL of Materials to Defence Standard 68-251 Fuel Soluble Pipeline Corrosion Inhibitors/Lubricity Improving Additives for Aviation Turbine Fuels. Def Stan 05-52 (Part 1) Markings for the Identification of Fuels. IP 274 (ISO 6297) Petroleum Products – Aviation and Distillate Fuels – Determination of Electrical Conductivity. ASTM D482 Standard Test Method for Ash from Petroleum Products. Containers holding 210 litres or less. IP 4 (ISO 6245) Petroleum Products – Determination of Ash. Carbon Manganese Alloy and Stainless Steels.DEF STAN 68-251/2 ANNEX E RELATED DOCUMENTS Designation Title BS 970: Part 1 General Inspection and Testing Procedure and Specific Requirements for Carbon. ASTM D445 Standard Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (the Calculation of Dynamic Viscosity). Containing Fuel System Icing Inhibitor. ASTM D2624 Standard Test Methods for Electrical Conductivity Of Aviation and Distillate Fuels. ASTM D97 Standard Test Method for Pour Point of Petroleum Products. STANAG 390 Inspection Standards for Fuel Soluble Corrosion Inhibitors/Lubricity Improvers. IP 177 Determination of Weak and Strong Acid Number – Potentiometric Titration Method. 24 . ASTM D664 Standard Test Method for Acid Number of Petroleum Products by Potentiometric Titration. 25 . ASTM D4052 Standard Test Method for Density and Relative Density of Liquids by Digital Density Meter. ASTM D4308 Standard Test Method for electrical Conductivity of Liquid Hydrocarbons by Precision Meter. ASTM D5001 Standard Test Method for Measurement of Lubricity Of Aviation Turbine Fuels by the Ball-On-Cylinder Lubricity Evaluator (BOCLE). DEF STAN 68-251/2 ASTM D3948 Standard Test Method for Determining Water Separation Characteristics of Aviation Turbine Fuels by Portable Separometer. . Inside Rear Cover . when making use of a Defence Standard encounters an inaccuracy or ambiguity is requested to notify the Directorate of Standardization (DStan) without delay in order that the matter may be investigated and appropriate action taken. Information on all Defence Standards is contained in Def Stan 00-00 Standards for Defence Part 3 . . Contract Requirements When Defence Standards are incorporated into contracts users are responsible for their correct application and for complying with contractual and statutory requirements. It is important that users of Defence Standards should ascertain that they are in possession of the latest issue or amendment. Index of Standards for Defence Procurement Section 4 ‘Index of Defence Standards and Defence Specifications’ published annually and supplemented regularly by Standards in Defence News (SID News). © Crown Copyright 2001 Copying Only as Agreed with DStan Defence Standards are Published by and Obtainable from: Defence Procurement Agency An Executive Agency of The Ministry of Defence Directorate of Standardization Kentigern House 65 Brown Street GLASGOW G2 8EX DStan Helpdesk Tel 0141 224 2531/2 Fax 0141 224 2503 Internet e-mail [email protected]. Revision of Defence Standards Defence Standards are revised as necessary by up issue or amendment.uk File Reference The DStan file reference relating to work on this standard is D/DStan/68/251. Any person who. Compliance with a Defence Standard does not in itself confer immunity from legal obligations.