BAL SEAL USER'S GUIDE - Bal Seal Engineering, Inc.
Contents
1. 4 4 3 GC graphite carbon filled PTFE General purpose material used when extrusion creep resistance is important while sealing ability and friction are secondary Resists deformation at high temperatures Not for general use in vacuum or inert gases 4 4 4 SP 45 polymer filled PTFE Low abrasion to mating parts General purpose material for use in contact with shaft housing made from 300 series stainless steel aluminum and other soft metallic or plastic materials Suitable for sealing most liquid media including moisture air at high speed low pressure with very high PV values FDA compatible Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 QM EIE REN Page 12 of 17 4 4 5 SP 50 polymer filled PTFE Low abrasion to mating parts General purpose material for use in vacuum air and inert gases in contact with soft materials like 300 series stainless steel aluminum and other soft metallic and plastic materials Ideally suited for high speed low pressure at very high P2. Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 ENGINEERING Page 7 of 17 PV Limits of Various Bal Seal Materials in Air at 170 fpm 52 m min and 70 F 21 C Air at 75 relative humidity 60000 50 000 z 105 S 50000 x S 40000 4 E E z 30000 mr 4 z 20 000 20 000 pes pes EE 42 42 x 20000 z am 410000 0 J T GFPA GFPMA GC G SP 45 SP 50 Graph 4A Bal Seal Materials PV Limits of Various Bal Seal Materials In Air at 900 fpm 274 m min and 70 F 21 C Air at 75 relative humidity 30 000 25 000 20 000 15 000 10 000 PV LIMIT LB IN X FPM N MM X M MIN 5 000 T GFPA GFPMA GC G SP 45 SP 50 Graph 4B Bal Seal Materials Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e
3. 0 0000 0 0030 0 0030 0 0000 101 63 and larger 0 00 0 08 0 08 0 00 Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 ENGINEERING Page 17 of 17 10 0 MEETING FORCE REQUIREMENTS Superior seal performance can be obtained by taking advantage of the special quality assurance testing procedures we offer Force testing can be implemented to maintain tighter tolerances and enhance the consistency of seal performance The specified seal force is met by changing the loading spring BAL Seal PTFE seals are available in various spring forces which determine to a great extent the sealing ability friction and duration of the seal The procedure and a typical computer printout of the frictional force of an individual seal are shown in Figure 4 Request Report TR 31 for information FIGURE 4 Frictional Force Testing Running Region Maximum SS Y E Py A bw Force line o ANS 8 J LL Pr uw Minimum Y Force line Plunger Travel Method o
4. 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 Rev E 10 23 01 BAL SEAL Page 4 of 17 1 0 INTRODUCTION Bal Seal Engineering Company is committed to conducting thorough research of our products and sealing technologies which influence the performance of BAL Seal PTFE seals This commitment helps us develop a diverse line of quality PTFE sealing devices that meet the high quality criteria required by today s seal user We believe that it is vitally important that the users of our seals have a thorough and complete understanding of the service conditions that affect BAL Seal PTFE seal performance so that you may can obtain the highest level of performance This report contains the abbreviated results of literally thousands of tests performed at Bal Seal Engineering on our products Wide ranging topics which affect seal service such as pressure temperature surface speed sealed media piston and bore materials coatings PV limits surface finishes jacket materials and lubrication that have been tested and analyzed are discussed here For further information about any item concerning the performance of BAL Seal PTFE seals or about general sealing technology contact the Bal Seal Engineering technical staff We will be happy to answer any questions or forward you one of our many technical reports dealing with specific topics of interest 2 0 SURFACE FINISH The performance of spring energ
5. SEAL Rev E 10 23 01 iM T RIN Page 10 of 17 4 2 Influence of jacket material on friction The friction produced by a seal sliding against a counter surface is influenced by a variety of factors including jacket material A relative comparison of the friction produced by various BAL Seal materials is shown in Graph 5 For example the force produced by a seal made from UPC 10 was more than 2 4 times greater than the force produced by a comparable BAL Seal made from virgin PTFE when tested under the same conditions Force Factors of Various Bal Seal Materials 3 00 2 54 2 50 2 00 1 50 4 1 24 1 27 1 1 00 4 0 50 4 0 00 T G GC Graph 5 Sealing Jacket Material Estimated Friction Force Factors 128 128 134 1 34 SP 45 SP 50 GFPA GFPMA UPC 10 4 3 Effect of temperature on sealing jacket materials The operating temperature of the system has a very significant effect on the physical properties of the seal material The properties affected include extrusion resistance wear resistance tensile strength elongation and others As the temperature in the seal area increases the properties decline Significant changes in material properties occur soon after the temperature rises beyond room temperature 70 F 21 C The increase accelerates rapidly as the temperature approaches the temperature limit of the materials 550 F for PTFE based materials Graph 6 below shows how temperature affects the extrusion
6. resistance to wear moderate corrosion resistance approximately Re 74 7 8 Ceramics AbO and Cr203 Excellent resistance to wear very brittle Re 78 80 MATING SURFACE COATINGS Harder surfaces produce lower friction and lower seal wear Some of the stainless steels such as types 302 304 316 and 17 4 pH provide good chemical compatibility by only a moderate degree of hardness These materials are often coated with one of the following materials to provide an added degree of hardness 8 1 Hard chrome plating General purpose applications hard and thick low friction good resistance to wear limited corrosion resistance Rc 65 Request report TR 14 for more information 82 Dense chrome plating More demanding applications thin and hard improved corrosion resistance maintains a good surface finish Rc 70 Request report TR 14 for more information Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 Rev E 10 23 01 SIBAL SEAL Page 15 of 17 ENGINEERIN 8 3 Electroless nickel plating Gene
7. to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 BAL SEAL Rev E 10 23 01 Page 16 of 17 9 2 Piston Shaft and bore tolerances Because BAL Seal PTFE seals re spring energized they have the unique ability to compensate for wide tolerances However optimum results may be obtained when following the recommendations indicated in Figure 3 FIGURE 3 Piston Shaft and Bore Tolerances A DIA A B DIA Piston Shaft B Diameter Piston Shaft A Diameter Tolerance in inches mm Tolerance in inches mm Piston Shaft B Diameter Range in inches mm 0 000 to 0 376 0 0000 0 0005 70 0005 0 0000 0 00 to 9 35 0 00 0 01 0 01 0 00 o 0010 0 0000 0 03 0 00 0 367 to 1 500 0 0000 0 0010 9 55 to 38 10 0 00 0 03 i 1 501 to 2 500 38 13 to 63 50 0000 0 0015 0 00 0 04 o 0015 0 0000 0 04 0 00 1 1 2 501 to 4 000 o 0000 0 0020 o 0020 0 0000 63 53 to 101 60 0 00 0 04 0 05 0 00 4 001 and larger
8. BAL SEAL USER S GUIDE Factors That Influence BAL Seal PTFE Seal Performance Technical Report TR 78 Rev E 10 23 01 11 207 12 19650 Pauling Spinozastraat 1 Foothill Ranch CA 92610 2610 1018 HD Amsterdam p Tel 949 460 2100 The Netherlands Fax 949 460 2300 Tel 31 20 638 6523 Email sales balseal com Fax 31 20 625 6018 www balseal com Email sales balseal nl www balseal nl E NGI Ne fe E T MG TR 78 11 207 12 Rev E 10 23 01 DIBAL SEAL Page 2 of 17 TABLE OF CONTENTS 1 0 Introduction 2 0 Surface finish 3 0 4 0 5 0 6 0 7 0 2 1 2 2 2 3 Influence of surface on friction Influence of surface finish on BALTM Seal wear Surface finish and sealing ability Surface hardness Sealing jacket material 4 1 4 2 43 44 Estimated PV limit Influence of jacket material on friction Effect of temperature on sealing jacket materials Description of BAL Seal materials Operating conditions 5 1 Surface speed 5 2 Pressure 5 3 Fluid media Lubrication 6 1 Wet lubrication 6 2 Dry lubrication Mating surface selection 7 1 7 2 7 3 7 4 7 5 7 6 TA 7 8 302 and 304 stainless steels annealed 316 Stainless steels annealed 17 4 pH 15 5 pH and 13 8 pH stainless steel precipitation hardened 416 stainless steels hardened 440C stainless steel hardened 4140 and 4340 high alloy steels Tungsten carbide Ceramics AL203 and Cr203 Use or disclosure of data c
9. DNESS The hardness of the surface in contact with a BAL Seal PTFE seal has a significant effect on seal wear Adhesion is lower between a soft PTFE seal and a hard mating surface resulting in reduced friction Test results indicate that harder surfaces promote less wear See Graph 3 Refer to TR 30 Wear Rate of BAL Seal GFP Materials vs Various Coatings for complete details Wear Rate of Bal Seal GFPA vs VariousSurface Hardness 4 8 RMS 3 6 7 2 Ra E gt 16 1 9 16 1 9 Z ed S E 14 1 7 o a 3 5 a Ig 12 1 4 D 10 1 2 7 4 d 8 0 9 0 8 lt 6 0 7 8 c T 4 05 e a4 ga 2 ee mE 10 41 73 Surface Hardness Rockwell Scale Graph 3 4 0 SEALING JACKET MATERIAL The selection of the seal material should be based on a variety of considerations including the sealed media friction requirements pressure and velocity wear life requirements operating temperature cost lubrication and other factors Request report TR 8A for a complete description of the physical and mechanical properties of many BAL Seal materials 4 1 Estimated PV limit The PV limit is the medium value representing the product of pressure and velocity Ib in x fpm or N mm x m min The PV limit is extremely important in selecting the proper BAL Seal material to obtain maximum reliability and performance based on fluid medium The PV limit of the seal material will be furnished with a design proposal
10. ICULAR PURPOSE AND ALL OTHER WARRANTIES IMPLIED OR EXPRESSED ARE EXCLUDED AND SHALL NOT APPLY This document provides product options for further investigation by Buyers Users having technical expertise The Buyer User through its own analysis and testing is solely responsible for making the final selection of the products and for assuming that all performance safety and warning requirements for the application are met It is recommended that Buyers Users run evaluation testing under actual service conditions to determine whether proposed BAL Seal products are suitable for the intended purpose Nothing contained herein or in any of our literature shall be considered a license or recommendation for any use that may infringe patent rights LE 17 PATENTS The items described in this report include products that are the subject of the following issued United States patents 5 979 904 5 994 856 6 050 572 5 984 316 6 161 838 and others as well as foreign patents or products where patents are pending LE 88G Copyright 2001 BAL Seal Engineering Co Inc U S A Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638
11. V value FDA compatible 4 4 6 GFPA graphite reinforced PTFE Excellent wear resistant material for higher temperatures pressures and speeds Excellent performance in water and other aqueous solutions Can be used in continuous duty at high pressure with adequate backing Very high PV limit Limited use in vacuum or inert gases 4 4 7 GFPMA molydisulfide fiber filled PTFE Vacuum inert gas usage excellent wear resistance with properties similar to GFPA High extrusion resistance 4 4 8 UPC 10 polyethylene based Excellent material for use in water aqueous media and very low temperatures Excellent wear and extrusion resistance Moderate friction Suitable for scraping applications Limited to temperatures to 170 F 75C 5 0 OPERATING CONDITIONS 5 1 Surface speed Dynamic friction generally increases as the surface speed becomes greater This causes high temperature at the sealing interface which may result in greater seal wear The surface speed should be as low as possible to reduce frictional heat and lower the PV Select a BAL Seal material with a high PV limit Pressure x Velocity for high surface speeds 5 2 Pressure As pressure increases the force pressing the seal against the mating surface increases This results in greater friction which may increase seal wear The system pressure should be kept at the lowest possible level to reduce the PV and obtain optimum seal performance If seal friction is too great select a BAL Se
12. Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl SIBALSEAL ENGINEERING SP 50 not sidbebyje for this media PV Limits of Various Bal Seal Materials In Water at 170 fpm 52 m min and 70 F 21 C TR 78 11 207 12 Rev E 10 23 01 Page 8 of 17 140 000 294 140000 gt 110 000 z E 120000 230 90 000 x lt lt 100000 4 as 189 5 80000 ete gt 60 000 14 m 126 x 60000 z 400004 20000 5000 bo 10 5 o i i T UPC 14 G GC GFPMA SP 45 SP 50 GFPA Graph 4C Bal Seal Materials PV Limits of Various Bal Seal Materials in Water at 900 fpm 274 m min and 70 F 21 C 350 000 300 000 z 630 300 000 x 2 250 000 220 000 E 462 z 170 000 200 000 160 000 357 amp 336 X 150 000 2 100 000 100 000 d 210 210 m 100 000 E al gt 50 000 a 0 T T T T G UPC 14 GFPMA GC SP 45 SP 50 GFPA SP 50 not suitable for this media Graph 4D Bal Seal Materials Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam T
13. al material with a lower frictional force factor 5 3 Fluid media Liquids around the seal remove heat from the sealing interface and reduce temperature Reducing interface temperature improves seal performance Some liquids also provide a lubricating film which tends to reduce friction and improve seal performance Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SBAL SEAL Rev E 10 23 01 NEERING Page 13 of 17 6 0 LUBRICATION The surface finish should vary depending on the lubricating conditions present When the lubricating film is thick as it is during hydrodynamic lubrication the surface finish may be rougher because the seal does not come into contact with the mating surface When the film is thin as it is during boundary lubrication the finish of the mating surface should be smoother due to the greater area of contact between the seal and mating surface 6 1 Wet lubrication The friction and wear behavior of a BAL Seal PTFE seal in a lubricated environment is dependent upon the extent of th
14. e 5 of 17 DIBAL SEAL INEERING 2 2 Influence of surface finish on BAL Seal wear The finish of the mating surface influences the abrasive wear to which the seal is subjected Abrasive wear occurs when a rough hard surface slides over a softer surface Wear occurs in the form of plastic chips cut from the surface of the seal Test results indicate that smoother surfaces produce lower wear rates by reducing abrasive wear See Graph 2 Graph 2 Wear rate of BAL Seal GFPA material vs various surface finishes Wear Test Surface Speed 55fpm 17 m min 35 4 15 Loading Stress 55 Ib in 4 Bar m o Wear Rate in Air g PV 3025 T 30 3 56 Ib in x ft min eo gt 7 5 N mm x m min 2 gt e 25 2 46 f Mating Surface Hardness Rc42 s Ox Mating Surface Material 17 4 PH a 20 3 37 Stainless Steel d Mating Surface Finish 1 6to 111 1 o 15 1 76 11 00 tei microinches RMS BS 9 50 1 30 149 1 4 to 100 m 10 1 19 m 1 12 Ambient Temperature microinches Ra x lt 3 62 0 75 Ambient Relative Humidity 70 F 21 C Z I 5 0 59 0 43 Duration ES 75 RH T BAL Seal Material 5 hours E o GFPA F 1 6 4 2 6 7 8 3 21 1 111 10 z 0 1 4 3 8 6 0 7 5 19 0 100 0 l2 Mircroinches RMS Microinches Ra Counter Face Surface Finish 2 3 Surface finish and sealing ability Although many factors affect leakage the sealing ability of a PTFE seal is g
15. e lubricating film separating the seal from the mating surface One of the three types of lubricating conditions may be present in any application See figure 1 Figure 1 Lubricating Conditions Hydrodynamic Lubrication Mixed Lubrication Boundary Lubrication No Seal Mating Surface Contact Partial Seal Mating Surface Contact Partial Seal Mating Surface Contact i d rd qtti Metal Sealing Surface Metal Sealing Surface Metal Sealing Surface Height of Height of Lubricant Film Height of Lubricant Film Lubricant Film RMS Ra RMS Ra Low Pressure Low Speeds High Speed High Lubricant Viscosity Low Lubricant Viscosity Low Temperatures High Temperature Moderate Operating Conditions High Pressure Surface Finish Surface Finish Surface Finish RMS Ra 6 2 Dry lubrication Dry lubricants should only be used when wet lubricants cannot be used Dry lubricants are used to reduce friction by minimizing adhesion between the seal and mating surfaces They provide a film that reduces the shearing action that occurs between two moving surfaces There are three basic types of dry lubrication that are generally compatible with BAL Seal PTE seals graphite for most general purpose applications molybdenum disulfide for use in vacuum or with gas and PTFE for applications requiring excellent chemical compatibility and very low friction 7 0 MATING SURFACE SELECTION Some of the piston shaft and bore materials typically com
16. enerally proportional to fluid viscosity Media with reduced viscosities i e gases versus liquids are more difficult to seal This can be compensated for to some extent by improving the finish of the mating surface A smoother finish creates greater sealing contact between the seal and mating surface thus improving sealing ability See Table 1 Table 1 Suggested Surface Finishes Medium Dynamic Surface Static Service Gases and Liquids At Cryogenic Temperatures Gases Air N2 Oz etc Liquids Hydraulic Fluid Water etc 2 to 4 Microinches RMS 1 8 to 3 6 Microinches Ra 6 to 12 Microinches RMS 5 4 to 10 8 Microinches Ra 8 to 16 Microinches RMS 7 2 to 14 4 Microinches Ra 4 to 8 Microinches RMS 3 6 to 7 2 Microinches Ra 12 to 32 Microinches RMS 10 8 to 28 8 Microinches Ra 16 to 32 Microinches RMS 14 4 to 28 8 Microinches Ra Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 Rev E 10 23 01 BAL SEAL Page 6 of 17 INEERING 3 0 SURFACE HAR
17. f Measuring Linear Force Force vs Plunger Travel of Individual Seal View A View B 11 0 SUMMARY The performance of a BAL Seal PTFE seal is not dependent on just one or two operating conditions but on a variety of factors working simultaneously Selection of a BAL Seal PTFE seal for a particular application requires a complete understanding of these factors At Bal Seal Engineering Company we continuously test our materials springs and seals to find out how service conditions affect performance and to discover new ways to improve seal design We hope that by using the information contained in this report seal users can improve the performance of their products Please contact the Bal Seal Engineering technical staff for any additional information Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl
18. he Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 ENGINEERING Page 9 of 17 PV Limits of Various Bal Seal Materials In Oil at 170 fpm 52 m min and 70 F 21 C 300 000 240 000 250 000 4 504 200 000 z 200 000 420 z 420 200 000 i 157 000 t 330 ES z 130 990 120 000 252 oo 100 000 252 x 210 g 100 000 oO 60 000 a 52 000 126 109 2 50 000 4 0 T UPC 14 G GC GFPMA SP 45 SP 50 GFPA Graph 4E Bal Seal Materials PV Limit of Various Bal Seal Materials In Oil at 900 fpm 274 min min and 70 F 21 C 600 000 0 000 1093 500 000 350 000 350 000 400 000 735 735 280 000 290 000 609 588 609 200 000 100 000 PV Limits LB IN X FPM N MM X M MIN T G UPC 4 GFPMA GC SP 45 SP 50 GFPA Graph 4F Bal Seal Materials UPC 14 not suitable for these conditions Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL
19. ing into contact with BAL Seal PTFE seals are discussed here with some of their various applications 7 1 302 and 304 stainless steels annealed Moderate service conditions good chemical compatibility high rate of seal wear Rc 20 to 30 annealed Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 QM EIE RIEN Page 14 of 17 7 2 316 stainless steel annealed Moderate service conditions excellent chemical compatibility high rate of seal wear Rc 20 to 30 annealed 7 3 17 4 15 5 and 13 8 pH stainless steels precipitation hardened Good chemical compatibility moderate friction and seal wear Rc 36 to 41 when hardened 7 4 416 stainless steel hardened Good Chemical compatibility Rc 55 when hardened 7 5 440c stainless steel hardened Moderate corrosion resistance low friction and seal wear Rc 60 when hardened 7 6 4140 and 4340 high alloy steels Moderate corrosion resistance moderate friction and seal wear Rc 50 when hardened 7 7 Tungsten carbide Very good
20. ized BAL Seal PTFE seals is governed to a great extent by the finish of the mating surface over which the seal slides The surface finish has a significant effect on friction wear and sealing ability Detailed reports on surface finish include TR 4 The Influence of Surface Finish on BAL Seal Performance TR 29 Methods of Obtaining Surface Finishes and TR 51 Measuring Surface Finishes 2 1 Influence of surface finish on friction In general PTFE seal wear is proportional to frictional force lower friction results in reduced wear Test results indicate that improving surface finish may reduce friction See Graph 1 Graph 1 Frictional Force vs Surface Finish Force Test Parameters Shaft Dia A 0 1875 in 4 762 mm Stroke Speed 4 in min 102 mm min Stroke Length 0 5 in 12 7 mm Frictional Force Grams 2 0 4 0 8 0 16 0 32 0 1 8 3 6 7 2 14 4 28 8 Microinches RMS Microinches Ra Surface Finish Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 Rev E 10 23 01 Pag
21. ontained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 ENGINEERING Page 3 of 17 8 0 Mating surface coatings 8 1 Hard chrome plating 8 2 Dense chrome plating 8 3 Electroless nickel plating 8 4 Plasma coating 8 5 Gas nitriding 9 0 Design considerations 9 1 Radial clearance 9 2 Piston shaft and bore tolerances 10 0 Meeting force requirements 11 0 Summary The information descriptions recommendations and opinions set forth herein are offered solely for your consideration inquiry and verification and are not in part or in whole to be construed as constituting a warranty expressed or implied nor shall they form or be a part of the basis of any bargain with Bal Seal Engineering If any sample or model was shown to or provided by Buyer User such sample or model was used merely to illustrate the general description and type of goods Such use is not to be construed as a warranty that the goods will conform to the sample or model Furthermore THE IMPLIED WARRANTY OF MERCHANTABILITY AND FITNESS FOR A PART
22. ral purpose applications good surface finish good resistance to wear excellent chemical compatibility for bores Rc 50 as plated Rc 62 after heat treating Request report TR 16 for more information 8 4 Plasma coating High speed applications abrasive environments very hard low abrasion to seals Rc 73 Request report TR 3 for more information 8 5 Gas nitriding Best overall properties very hard and tough requires heat treating at 1050 F 566 C shafts or bores Rc 70 9 0 DESIGN CONSIDERATIONS 9 1 Radial clearance The radial clearance between the piston shaft and bore has a significant effect on seal performance As system pressures and temperatures increase the clearance must be reduced to minimize the possibility of extrusion Some very general guidelines are indicated below Extensive testing conducted by Bal Seal Engineering Company has led to the development of recommended clearances based on pressure temperature and seal diameter seal cross section seal material and other factors A suggested radial clearance will be provided with every seal design proposal Figure 2 Radial clearance between the piston shaft and bore E Pressure Maximum Radial Clearance PSI Bar Inch mm 150 10 0 0040 0 10 500 35 0 0040 0 10 1000 70 0 0035 0 09 3000 210 0 0030 0 08 At higher pressures tighter E clearances are required Use or disclosure of data contained on this sheet is subject
23. resistance of some BAL Seal materials Use or disclosure of data contained on this sheet is subject to the restrictions contained in the disclaimer located in the Table of Contents of this report Bal Seal Engineering Co Inc e Foothill Ranch CA USA 92610 2610 e Tel 949 460 2100 Fax 949 460 2300 e Email sales balseal com e Web www balseal com Bal Seal Engineering Europe B V e Amsterdam The Netherlands e Tel 31 20 638 6523 Fax 31 20 625 6018 e Email info balseal nl e Web www balseal nl TR 78 11 207 12 SIBAL SEAL Rev E 10 23 01 ENGINEERING Page 11 of 17 120 98 0 100 4 80 4 45 9 45 5 Percent Extrusion T G GC GFPA 70 F W200 F r1400 F Graph 6 4 4 Description of BAL Seal materials 4 4 1 T virgin PTFE General purpose material used where or when low friction and chemical compatibility are important It is limited to light duty service and can be used in vacuum and inert gases BAL Seal T PTFE is subject to cold flow and exhibits high wear in water aqueous media BAL Seal T PTFE is compatible with most fluids and gases except molten sodium etc Excellent retention at cryogenic temperatures 4 4 2 G graphite filled PTFE General purpose material used when more extrusion creep resistance and less wear than PTFE are desired BAL Seal G material is compatible with most fluids and gases except strong oxidizers and certain concentrated acids Not for general use in vacuum or dry gases
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