SELECTED TECHNICAL PAPERS STP1573 Editor: John Sherman Fire Resistant Fluids ASTM Stock #STP1573 ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19438-2959 Printed in the U.S.A Library of Congress Cataloging-in-Publication Data Fire resistant fluids / editor, John Sherman pages cm “ASTM Stock #STP1573.” Includes bibliographical references and index ISBN 978-0-8031-7591-4 (alk paper) Fire testing Hydraulic fluids Testing Fire resistant materials I Sherman, John II American Society for Testing and Materials TH9446.H9F575 2014 628.9’22 dc23 2014033297 Copyright © 2014 ASTM INTERNATIONAL, West Conshohocken, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use, or the internal, personal, or educational classroom use of specific clients, is granted by ASTM International provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http://www.copyright.com/ The Society is not responsible, as a body, for the statements and opinions expressed in this publication ASTM International does not endorse any products represented in this publication Peer Review Policy Each paper published in this volume was evaluated by two peer reviewers and at least one editor The authors addressed all of the reviewers’ comments to the satisfaction of both the technical editor(s) and the ASTM International Committee on Publications The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of the peer reviewers In keeping with long-standing publication practices, ASTM International maintains the anonymity of the peer reviewers The ASTM International Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM International Citation of Papers When citing papers from this publication, the appropriate citation includes the paper authors, “paper title”, STP title, STP number, book editor(s), page range, Paper doi, ASTM International, West Conshohocken, PA, year listed in the footnote of the paper A citation is provided on page one of each paper Printed in Bay Shore, NY September, 2014 Foreword This Compilation of Selected Technical Papers, STP1573 on Fire Resistant Fluids, contains nine papers presented at a symposium with the same name held in Montreal, Quebec, Canada, on June 24, 2013 and JAI102180, published June, 2009, Volume 6, Issue and determined to be pertinent to the topic The symposium was sponsored by the ASTM International Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and Subcommittee D02.N0.06 on Fire Resistant Fluids The Symposium Co-Chairpersons and STP Editors are John Sherman, BASF Corporation, Canton, MI, USA and Betsy Butke, Lubrizol Corporation, Wickliffe, OH, USA Contents Overview Use of Thickened High Water Hydraulic Fluid in Flat Rolled Steel Production J Sherman, J Maloy, E Martino, P Cusatis, and P Fasano Fire Resistant Fuel for Military Compression Ignition Engines S R Westbrook, B R Wright, S D Marty, and J Schmitigal vii 24 Ion Exchange and Mechanical Purification of Fire-Resistant Phosphate Ester Fluids Used in Steam-Turbine Control Systems W D Phillips, J W G Staniewski, and S Suryanarayan 38 Phosphate Ester-based Fluid Specific Resistance: Effects of Outside Contamination and Improvement Using Novel Media M G Hobbs and P T Dufresne Jr 75 Thirty-Seven Years of Fleet Operating and Maintenance Experience Using Phosphate Ester Fluids for Bearing Lubrication in Gas-Turbine/Turbo-Compressor Applications P T Dufresne 93 Property and Performance Evaluation of Water Glycol Hydraulic Fluids P Cusatis, J Sherman, P Fasano, and R Bishop 109 Anhydrous Fire-Resistant Hydraulic Fluids Using Polyalkylene Glycols M R Greaves and A Larson 126 Polyalkylene Glycol Hydraulic Fluids, 20 Years of Fire Resistance K P Kovanda and M Latunski 143 Performance Comparison of Non-Aqueous Fire-Resistant Hydraulic Fluids S Rea and D Barker 155 Assessing and Classifying the Fire-Resistance of Industrial Hydraulic Fluids: The Way Ahead? W D Phillips 181 Overview Fire-resistant fluids are an integral component to the safe operation of key processes for many industries where fire is a major hazard Industries using fire-resistant fluids today include steel manufacturing, aluminum die-casting, automobile manufacturing, food processing and electrical and nuclear power utilities The requirements for fire-resistant fluids are not static but dynamic as industries using these fluids in turn move to more efficient and greater performing equipment These improvements in equipment and systems come at a cost which may increase the risk for fire For example, higher operating temperatures or pressures can directly change the range of conditions under which fire can occur for that system, and so too the conditions under which fire-resistant fluids must perform in that system The proceedings of the Symposium on Fire Resistant Fluids were held at the Fairmont Q.E Montreal Hotel in Montreal, Quebec, Canada on June 24th, 2013 The topics of the papers were related to fire-resistant hydraulic and compressor fluids and liquid fuels Specific chemistries discussed in one or more of the papers included phosphate ester, polyol ester, polylalkylene glycol, water glycol, and thickened and un-thickened high water fluids The editors wish to express their thanks and appreciation to the authors and attendees of the symposium and to all the reviewers of these papers We also owe a debt of gratitude to the ASTM staff who were an essential part of both the successful symposium proceedings and the publication of this volume John Sherman Betsy Butke vii FIRE RESISTANT FLUIDS STP 1573, 2014 / available online at www.astm.org / doi: 10.1520/STP157320130179 John Sherman,1 Jonathon Maloy,3 Emidio Martino,3 Patrice Cusatis,2 and Paul Fasano2 Use of Thickened High Water Hydraulic Fluid in Flat Rolled Steel Production Reference Sherman, John, Maloy, Jonathon, Martino, Emidio, Cusatis, Patrice, and Fasano, Paul, “Use of Thickened High Water Hydraulic Fluid in Flat Rolled Steel Production,” Fire Resistant Fluids, STP 1573, John Sherman, Ed., pp 1–23, doi:10.1520/STP157320130179, ASTM International, West Conshohocken, PA 2014.4 ABSTRACT Thickened HFA-E hydraulic fluid is in the class of most fire-resistant hydraulic fluid as tested according to ISO 15029-2 A thickened HFA-E hydraulic fluid demonstrated improved lubricity, load carrying capabilities, corrosion protection, and bacterial resistance in comparison to the standard HFA-E (95/5) high water hydraulic fluid while in operation in the roughing and finishing mill hydraulic systems at the ArcelorMittal Dofasco steel production complex The improvements in hydraulic fluid properties and hydraulic system operation resulted in increased system reliability, decreased maintenance costs, and extended equipment life for the roughing and finishing mill hydraulic systems Keywords fire-resistance, polyalkylene glycol, high water hydraulic fluids, HFA-E hydraulic fluids, FM approvals Manuscript received November 30, 2013; accepted for publication May 30, 2014; published online July 18, 2014 BASF Corporation, Fuel and Lubricant Solutions, 1609 Biddle Avenue, Wyandotte, Michigan 48192 BASF Corporation, Fuel and Lubricant Solutions, 500 White Plains Road, Tarrytown, New York, 10591 ArcelorMittal Dofasco, 1330 Burlington Street East, Hamilton, ON, L8N 3J5, Canada ASTM Symposium on Fire Resistant Fluids on June 24, 2013 in Montreal, Quebec, Canada C 2014 by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959 Copyright V PHILLIPS, DOI 10.1520/STP157320140090 (1) the ease of ignition or ignitability of the fluid; (2) the behavior of the fluid on ignition (i.e., does it propagate flame or is it selfextinguishing) As a consequence, the test methods that are available for assessing combustion behavior fall into such categories as follows: • ease of ignition/ignitability; • heat release or flame propagation; • smoke and other products of combustion, or both; and • an intrinsic physical property (e.g., heat of combustion) However, many tests claim to measure more than one parameter and therefore this classification is unsatisfactory An alternative scheme might be to categorize them according to the physical form of the fluid or the mode of ignition: • bulk fluid ignition; • ignition of a pool or thin film; • ignition of a droplet, intermittent stream, spray, or jet; • ignition when absorbed on a substrate; • ignition by an open flame; • ignition by a hot surface; or • ignition by a spark In practice, combinations of the above approaches have been used but the main emphasis has been on selecting tests which simulate the potential application hazards Where this is done the test conditions should simulate or reflect that hazard as closely as possible As stated in BS 6336 [7]: “If more than one hazard is present then different tests may be required for each hazard In practice, simplifications may be necessary to reduce the time and cost involved but the conditions finally adopted should relate as nearly as possible to the actual environment in which the hazard is thought to arise If a test is designed to assess different products for a specific use it is essential that the method be capable of being applied to all possible materials, and on an equal basis (author’s emphasis).” When selecting tests to represent a specific hazard, preference should be given to the following: • Standard tests, i.e., those issued by a national or international standards organization • Tests which have precision data In the absence of precision data a reference or calibration fluid(s) which are made from pure components may be used • Tests which discriminate between fluids, i.e., are able to rank fluids in order of fire resistance A pass/fail test is of limited use as there is no indication of how good (or bad) the fluids are relative to one another (or to any reference fluid) However, even when all these restrictions are applied it should be acknowledged that, as with any laboratory test, it is only possible to assess fluid behavior under very specific conditions Although these are supposed to be representative of service, such is the variety of operating conditions and possible fluid release mechanisms in use 185 186 STP 1573 On Fire Resistant Fluids that an accurate prediction of the mode of fluid escape (and hence an accurate simulation) is usually impossible to accomplish But perhaps this is not essential In most cases only a comparison of performance under the same conditions, either between different fluids or with a reference fluid, is sought It should also be remembered that fluids can behave differently in different tests and that, as stated in BS 6336 [7], in order to obtain a complete picture of fire resistance behavior, performance in several different tests is usually required This is essential when, as is frequently the case, several different hazards may exist for the same application One assumption made in fire-resistance testing is that no change in performance under test (or in use) can take place Unfortunately there are conditions when this can occur as follows: – If water is lost when testing water-based products – If polymeric materials shear down in use resulting in a reduction in viscosity – If the material degrades thermally or oxidatively in use to form significant amounts of flammable degradation products – Contamination of the operating fluid with mineral oil or another more combustible material Test selection is therefore a complex procedure This is not helped by the large number of tests which purport to measure some aspect of fluid fire-resistance In a relatively recent count there were over 50 [8]! This probably reflects the difficulty of translating the wide variation in conditions under which combustion can take place into a simple and precise test method Table identifies the most widely used tests for assessing hydraulic fluid fire resistance and which can be used to assess a range of different fluid types Not all are capable of ranking fluids in their current form TABLE Standard fire tests for industrial hydraulic fluids Physical Form of Fluid Ignition Mode Bulk Ignition (Pool and Thin Film) Droplet, Stream, Spray, or Jet Adsorbed on Substrate “Spray” tests: ASTM D5306-92 Flash and Fire Open flame Points: Wick Tests: (piloted ASTM D92 ISO 15029-1/2 ISO 14935 ignition) ISO 2592 Factory Mutual 6930 Std IEC 1197 Manifold ignition: ISO 20823 Autoignition: Hot surface Spark Note: NA ¼ none available ASTM D2155/E 659-78 NA NA NA PHILLIPS, DOI 10.1520/STP157320140090 There are, of course, other types of standard fire test (e.g., oxygen index, cone calorimetry, etc.) which, for various reasons, are not specified for hydraulic fluids Further information on these procedures and their limitations can be found in Refs and It will be seen in the table that there are no current tests for assessing fireresistance in the presence of a spark This may reflect the low probability of such a form of ignition and also the difficulty in selecting test conditions which could be regarded as “representative.” Current practice in evaluating and comparing fire resistance therefore focuses on the procedures given in Table Of these the spray tests, autoignition, manifold ignition, and the ISO wick test are the most widely used Although not a hazard related test, use is sometimes made of net heat of combustion measurements in assessing fluid fire-resistance, for example, in the Factory Mutual Corp spray ignition test More detailed comments on this test are given later under the assessment of the Factory Mutual procedure The Performance of Different Fluid Types in Standard Fire Resistance Tests The data given in Table are based on fluids that are commercially available and are a mixture of information available in product data sheets and the results of tests that have been carried out by independent laboratories Obviously it is impossible to provide data on all the different fluids that are commercially available but it is believed that the figures quoted are representative of their respective types Further information on fluid performance is available in Refs 6, 8, and 10 No data are presented on fluid types HFAE/HFAS as these fluids normally contain such a high water content that they are very difficult or impossible to ignite and, in any case, most of the standard tests cannot be used to evaluate these fluids As can be seen from the table: • Flash and fire point values not correlate with other test data • With the exception of HFDR fluids, most fluids display similar autoignition temperature values including the water-glycol fluid • A much wider spread of results is seen with the manifold ignition test [11] • Autoignition [12] and manifold ignition test data for mineral oil and HFDU fluids are fairly similar • The ISO 15029–2 [13] spray test discriminates well between the fluids, whereas the Factory Mutual test [14] shows less discrimination and in some cases its results conflict with the ISO rating This is mainly because of the incorporation of a “critical heat flux” measurement (see below) • All the HFDU fluids propagated flame in the Wick test [15] Use of Current Test Methodology to Assess Fluid Fire Resistance There are two main specifications for industrial fire-resistant fluids, each with a different approach to assessing fire resistance The first is ISO Standard 12922 [16] 187 188 Fluid Typea Fire-Resistance Test Flash point ( C) Min Oil HFBb HFCb HFCE HFDRb HFDUb (polyol esters) HFDUb (veg oils) HFDUb (PAG) 230–250 NRc NRc NRc 240–270 260–320 >290 270 260–285 NRc NRc NRc 335–370 335–378 >345 310 380–400 385 425 No 545– > 625 400–435 390 395 - ASTM D92 Fire point ( C) – ASTM D92 Autoignition ( C) – ASTM D2155 Manifold ignition ( C) data 370–395 >650 >650 >650 700–750 440–480 420–465 400–420 H F B-C E D-E G-H H F Not classified Not tested Approved No data Approved – ISO 20823 Spray ignition-ignitability class – ISO/DIS 15029-2 Spray ignition-spray flamm factor Approved/ Approved/ Approved/ specification specification specification testedd Testedd testedd – FM 6930 std Wick flame persistence (secs) Continuous Pass Pass No data Pass burning – ISO 14935 a The data are typical for fluids of ISO VG 46 and 68 viscosity grades; HFA, HFB, etc., are the ISO definitions of different types of hydraulic fluids and taken from ISO standard 6743–4 [4] c NR¼Not relevant d “Specification tested” means that the fluid failed to meet the FM Approved Fluid limits b Continuous burning STP 1573 On Fire Resistant Fluids TABLE Typical fire-resistance performance for the different fluid types PHILLIPS, DOI 10.1520/STP157320140090 which covers all grades of fluid used in general industrial applications and the second is Factory Mutual Standard “Flammability Classification of Industrial Fluids, Class Number 6930” [14] ISO 12922, Lubricants, industrial oils and related products (class L)—Family H (hydraulic systems)—Specifications for categories HFAE, HFAS, HFB, HFC, HFDR, and HFDU; this standard uses three separate ISO fire-resistance tests: – ISO 15029: Spray test (This standard is currently in three parts but two of the methods–Parts and 3–are likely to be of limited interest in the future and most attention will focus on Part 2, the Stabilized Flame Heat Release Method [13]; – ISO 20823: Manifold ignition test; and – ISO 14935: Wick flame persistence method Each of these methods is capable of evaluating a wide range of fireresistant fluids though it is unnecessary to evaluate the fire-resistance of products with a very high water content (>80 %) ISO 15029–2 and ISO 20823 are capable of ranking the different fluids while ISO 14935 is currently a pass/fail procedure The first two procedures primarily assess ignitability while 14935 (and also 20823) evaluate flame propagation The advantage of using three tests means that we have confirmation of the performance under ignitability and propagating conditions and an attempt to modify the performance of the fluid by the use of additives (e.g., adding droplet modifiers to reduce ignitability in a spray) may be identified as they not significantly improve hot surface ignition performance ISO/DIS 15029-2 was developed in order to harmonize EU test requirements for fire-resistant fluids and to be able to evaluate all the different types of fluid [10] It is an “ease of flame stabilization” test and measures exhaust gas temperatures of the burning fluid This test is based on the concept that the more easily a fluid combusts, the greater the amount of heat is released The exhaust temperature of the burning test fluid is compared with the temperature without the test fluid but with the igniter operating From these measurements an ignitability factor (IF) is obtained However, to rank fluids (and to take into consideration the potential repeatability of the test) the range of IF values is broken down into “Classes,” from A to H, with A being the least flammable and H the most flammable Figure shows a schematic of the test equipment while the results of testing some commercially available fluids are shown in Fig [17] Full details of the method are, of course, to be found in the ISO Standard while the background to its development can be found in Reference 18 Advantages: • The test can be adapted to measure heat release rates or oxygen depletion but, for simplicity, temperature measurements are preferred It can also measure other combustion parameters such as smoke production • Although no formal precision data are yet available (see below) a series of calibration (or reference) fluids based on mixtures of distilled water and pure ethylene glycol are used to ensure the consistency of the test conditions Some 189 190 STP 1573 On Fire Resistant Fluids FIG The ISO/DIS 15029-2 Spray Flammability Test apparatus • attempts are made to control the ambient environment in terms of temperature and humidity as these have been shown to be highly influential in determining the test result [19], however further restrictions may be required This test is able to evaluate and compare most of the different types of fireresistant fluid However, fluids containing >80 % water will not normally combust under these test conditions FIG Results of the ISO/DIS 15029-2 Spray Test on a range of fire-resistant hydraulic fluids PHILLIPS, DOI 10.1520/STP157320140090 Disadvantages and concerns: • The test “does not give a total measure of the heat output as it does not measure radiative heat but uses convective heat as a means of providing a relative indication of the degree of completeness of combustion” [18] • The current procedure uses volume flow rates and therefore does not take into consideration the significant difference in density between fluids Without such compensation the comparison between products is not strictly valid • This is a relatively expensive test to carry out requiring relatively large volumes of fluid, and presently there are only four test rigs known to be in existence Currently no precision test data (repeatability or reproducibility) are available but following the publication of the standard test method (expected in 2009) a limited round robin test program is to be initiated ISO 20823 is a method that previously appeared in Aeronautical Material Standard 3150 C and measures the ignitability of fluid when in contact with a hot surface; in this case the hot surface is in the form of a manifold or tube Advantages: • This is a relatively low cost test that is able to compare most fluid types which ignite up to a temperature of about 800 C It requires only small amounts of test fluid • The test also examines the propensity to propagate flame after the fluid has moved away from the ignition source Disadvantages and concerns: • Currently there is no precision data but the use of reference fluids is being examined together with the possibility of comparative testing on the existing test rigs • Since residence time is a key variable with hot surface tests, the ignition temperatures would not be expected to be identical with tests carried out on a flat surface but the ranking of fluids would be expected to be unchanged ISO 14935 examines the flammability of a fluid when soaked onto an adsorbent “wick.” A propane flame is applied to the top edge of a piece of ceramic board for varying times and the time it takes for any resulting flame to self-extinguish is measured Advantages: • This is an easy, low-cost test which requires only small amounts of fluid • It is capable of testing and comparing most fluids except those with a very high water content Disadvantages and concerns: • The test is of the pass/fail type and therefore does not lend itself to the production of precision data • It does not currently measure the relative tendency of the flame to propagate although it could be adapted to so The Factory Mutual Standard 6930 (January 2002)-Flammability Classification of Industrial Fluids is a method that was developed to replace a previous spray test that measured the persistence of burning but was a pass/fail procedure and susceptible to spray droplet size A new method was therefore required to rank all the 191 192 STP 1573 On Fire Resistant Fluids different fluid types and, if possible, to eliminate the effect of polymeric thickeners on spray flammability [20] It was eventually decided to use a heat release test utilizing some of the components from the previous spray ignition test but the new test involved a vertical burn so that the products of combustion could be more easily measured [20] Figure [14] shows a schematic of the test equipment Instead of relying on measurements of exhaust gas temperatures as in the ISO 15029-2 method, the FM procedure measures the generation rates of CO and CO2 and calculates the chemical heat release rate from these In the early stages of the test development, it was found that volatile (and flammable) solvents such as methanol, ethanol, and heptane gave low heat release values In order to avoid such FIG The Factory Mutual heat release measurement apparatus PHILLIPS, DOI 10.1520/STP157320140090 products being confused with fire-resistant hydraulic fluids, the concept of “critical heat flux for ignition” was introduced [21] An expression for a dimensionless spray flammability parameter (SFP) was derived by combining the total chemical heat release data with the critical heat flux in the following equation: (1) SFPnormalized ¼ 11:02 106 Qch =qf qcr mf where: Qch ¼ chemical heat release rate (kW), qf ¼ density of the fluid (kg/m3), and qcr ¼ critical heat flux for ignition (kW/m2) and (2) qcr ¼ a r T where: a ¼ fluid surface resistivity (assume to be unity), r ¼ Stefan-Boltzmann constant (5.67 1011 kW/m2 K4), T ¼ fire point temperature ( K), and mf ¼ fluid mass flow rate during the heat release rate measurement (g/s) Advantages: • Both the spray and fire point tests use relatively small amounts of fluid • The spray test can be used to assess smoke production and also flame length Disadvantages and concerns: • The test is not a national or international standard (but is known internationally) • The test is expensive and requires sophisticated equipment • As a result of problems in the testing of water-based fluids, the above procedure is no longer applicable to fluids of type HFA/B/C and a different test protocol for these fluids is currently under development Therefore there can be no comparison between water-containing and non-aqueous fluids Fluids with 60 % water (w/w) are regarded as possessing excellent fire resistance and testing of these products is therefore not required [21] • The ability to rank fluids is limited to two broad categories by SFP limits; these are “FM approved” and “FM approvals specification tested.” Approved fluids require no additional fire protection over that specified for construction or occupancy of a building while “specification tested” products may require additional fire protection due to the hazard posed by the fluid • Currently there is only one test facility and therefore full precision data (repeatability and reproducibility) cannot be established No repeatability data appear to have been published • The test only investigates the ignitability behavior of the fluid It does not take into consideration the behavior of the combusting fluid once it is removed from the ignition source, i.e., its propagating tendency 193 194 STP 1573 On Fire Resistant Fluids • • • • • • • • No attempt has been made to control ambient test conditions (e.g., air temperature and humidity), which have been shown elsewhere to have a significant effect on test results The calculation of chemical heat release rate assumes that the heat released by the production of CO/CO2 is solely responsible for the heat released and that no other reactions are involved While this assumption might be valid for products containing C, H, and O, it is not safe to assume this applies to products containing, for example, phosphorus On combustion, phosphorus compounds will also produce phosphorus oxides which will react quickly with any water present to produce phosphorus acids, therefore the combustion reaction mechanism is significantly more complicated than the sole production of oxides of carbon All these other reactions will influence the net heat released “The use of CO /CO2 generation as a way of calculating heat release rates is regarded as substantially less accurate than measurement of O2 consumption as ‘fuels’ not have a universal constant for this correlation” [22] As was mentioned above, the concept of critical heat flux to ignition was introduced in order to compensate for the volatility of some fluids After examining several alternative tests it was eventually decided to use fire point (open cup) and combine both heat release rate and critical heat flux into one mathematical expression called the Spray Flammability Parameter The justification for combining the two terms is not clear as volatile liquids could have easily been identified and eliminated by limits on separate tests but, as a result, the SFP value is significantly influenced by the fire point result as its value (in the equation above) is present to the fourth power The method states thata1 % error in the measurement of fire point results in a critical heat flux error of >2 % Since the repeatability value for open cup fire point is 8 C, for a fluid with a fire point of 350–400 C (typical for non-aqueous fluids) the error in critical heat flux determination could therefore be >4 % This would be in addition to any errors in the measurement of the mass of CO/CO2 The results of fire point tests (a piloted ignition test) not necessarily correlate with those of other fire tests For example, trioctyl phosphate has a fire point of 170 C but a manifold ignition temperature of 465 C (cf polyol ester values of about 350 C and 450 C, respectively) The FM procedure suggests that net heat of combustion measurements by ASTM D240, can be used in the absence of chemical heat release rate data This is of concern for the following reasons: ASTM D240-02, “Standard Test Method for Heat of Combustion of Liquid Hydrocarbon Fuels by Bomb Calorimetry”, is currently only valid for products containing C, H, O, S, and N [23] It is not valid for products containing other elements, e.g., phosphorus and therefore cannot be used to compare the complete spectrum of fire-resistant fluids ASTM D240 assumes the products of combustion are carbon dioxide, nitrogen oxides, sulfur dioxide, and water If, say, a phosphate ester is combusted, phosphorus oxides would be expected to be produced and these oxides react rapidly with any water present to produce phosphorus acids (Water is present in the test fluid as an impurity; is generated as an oxidation product from the PHILLIPS, DOI 10.1520/STP157320140090 TABLE Fire test behavior on different fire-resistant fluid types (ISO VG 46 Fluids) (see Ref 24) Fire Resistance Test Results Fluid Spray Ignition Test-Ignitability Factor (ISO/DIS15029-2) Manifold Ignition Test C (ISO 20823) Wick Flame Persistence (ISO 14935) Factory Mutual 6930 Std –Spray Flammability Test Status Mineral oil Class H 380 Fail Not tested (probable fail) Polyalkyleneglycol Class F 420 Fail Approved Vegetable ester Class H 420 Fail Approved Polyol ester (1) Class H 440 Fail Approved Polyol ester (2) Class G 455 Not tested Not tested Polyol ester (3) Class H 435 Fail Specification tested Phosphate ester Class E >704 Pass Approved Water-glycol fluid Class A >704 Pass Approved hydrocarbyl portion of the molecule and, if the procedure is followed as specified, a small amount is actually added to the test fluid in the bomb) Thus any heat released may involve not only the heat of combustion but also the heat of formation (or heat of reaction) with water and therefore the data are not comparable with heat of combustion from other fluids falling within the scope of this method • Some chemicals, e.g., phosphate esters are very difficult to combust completely by conventional bomb calorimetry Successful methods use very small quantities (5 ll) of fluid, e.g., by microcalorimetry There is no known evidence to confirm that phosphate esters show “complete” combustion by the ASTM D240 procedure which involves substantially greater amounts (0.5–1.0 g) It should be apparent from the above that neither approach to the measurement of the fire resistance of hydraulic fluids is completely satisfactory and in fact they produce conflicting results Table shows the effect of testing the same products by the different protocols [24] Can the Conflict be Resolved? Obviously the conflict between the two standards needs to be resolved and agreement reached on the tests used to assess fluid fire-resistance In the absence of such an agreement, end users may select a product that does not have the level of fireresistance necessary for their application A Change in Terminology? As indicated earlier, one aspect that must be seriously considered is whether the continual use of the term fire-resistant can be justified for all fluid types This, in itself, is misleading In the past the use of terms “fire-retardant” and “less flammable” have been used for some fluid types, for example by Factory Mutual Research, 195 196 STP 1573 On Fire Resistant Fluids and the latest revision of ISO 12922 refers to the HFDU Class of fluids as less flammable In reality, the only fluids that can justify the term fire-resistant are the high water-based fluids where the water content is >80 % One possibility would therefore be to divide the fluids into the following classes: – Fire resistant: (Fluids which, under standard test conditions, are extremely difficult or impossible to ignite and not propagate flame.) This definition would cover mainly ISO classes HFAE and HFAS (where the water content is >80 %) – Fire retardant: (Fluids which, under standard test conditions, are difficult to ignite and not significantly propagate flame.) This definition would cover ISO classes HFB, HFC, HFDR, and HFAE/S fluids where the water content is 550