mun/awe QUKCK COUPLER PRESSURE'DROP': A ' ‘ ” ’ Thesis for theDégree mm. 7 ~ MICHIGAN STATE wvmsm g V JAMES BERMANN ' 1971 “41:11:! I; s. ._ .‘ JAIMA- -- ._ 1 ,9 L I B RA R 3-. ‘ Michigan Stan University (F‘Q‘CTQ ABSTRACT HYDRAULIC QUICK COUPLER PRESSURE DROP BY James Bermann This study was undertaken to investigate the pressure dr0p which occurs in hydraulic quick couplers due to the inherent restrictions to fluid flow. The application of hydraulic quick couplers is widespread in agri- culture and is of concern to those associated with the use of hydraulic equipment. The solution of the problem of misapplication of these com- ponents appears to be the planned use of Specific types based upon their flow characteristics. A few manufacturers supply with their couplers a set of test result data, upon request, which aids in the correct utilization of these handy and convenient units. Prior experience with hydraulic equipment and requests from users prompted a further investigation of the flow characteristics of the four basic types of couplers. Included in the investigation were pressure drOp and temperature rise of the fluid and coupler with relation to volume of flow. The basic test unit consisted of a Vickers PV-2032, 30 gpm hydraulic pump driver by a 10 hp electric motor Operating at a system pressure of 500 psi. The pump was capable of variable delivery volume from 0 to its maximum capacity by handwheel control. The pressure drOp test equipment consisted of a 120 inch differential pressure manometer capable of reading a maximum differential pressure of 68.75 psi. Associated with the mano- James Bermann meter was a set of hydraulic pressure gages of 500 psi capacity. The pressure gages were employed to check the total pressure drOp across the test couplings to determine whether the differential would exceed the limits of the manometer and flush the manometer fluid (mercury) into the hydraulic system. The hydraulic pressure dr0ps through the couplers tested showed a significant problem exists at high flow rates. One coupler showed a pressure dr0p of 325 psi at a flow rate of 23 gpm. The temperature differential measured in the fluid before and after the coupling was less than 3 degrees farenheit. Fluid temperature in the 60 gallon reservoir using SAE 10 hydraulic fluid rose a maximum of 11 degrees during 30 minutes of testing. The tests conclusively proved that eSpecially for high flow rates near or exceeding the manufacturers flow Specifications, large pressure drOps occur in most couplings tested. A test of pressure dr0p at 250 psi was performed on each coupling to determine if varying the pressure would have an effect on the pressure drop through the coupler. These tests showed no apparent changes in the total pressure losses. It can therefore be assumed that the initial tests were a true indication of the flow characteristics of that partic- Appmd Mi’ ZZZ/£41144 Major Professor Department Chairman ular coupler. HYDRAULIC QUICK COUPLER PRESSURE DROP By James Bermann A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Agricultural Engineering 1971 QC. 810/7" ACKNOWLEDGMENTS The author would like to express his sincere appreciation to all 'who assisted in any manner in the completion of this investigation. Special appreciation is afforded Professor L. K. Pickett for his suggestions and assistance in assembling components for the test device construction. Much appreciation is extended to Professor C. F. Albrecht for his moral support and encouragement. A Special "thank you" is given to Mr. John Ojala, Public Relations Manager, Vickers Hydraulics, Troy, Michigan, for his work in obtaining the test unit, hydraulic pump-electric motor-reservoir assembly. The author is grateful to the many hydraulic coupler manufacturers who supplied at no cost the various types of units to be tested. ii TABLE OF CONTENTS LIST OF TABLES . . . . . . . . . . . . . . . . . . LIST OF FIGURES . . . . . . . . . . . . . . . . . . INTRODUCTION . . . . . . . . . . . . . . . . . . . . OBJECTIVES . . . . . . . . . . . . . . . . . . . . . BACKGROUND INFORMATION AND TERMINOLOGY . . . . . . . Quick Disconnect Couplers . . . . . . . . . . . STATEMENT OF THE PROBLEM . . . . . . . . . . . . . . DESIGN AND CONSTRUCTION OF THE TEST EQUIPMENT . . Differential Pressure Manometer and Gage System Pump-Motor-Reservoir Assembly . . . . . . . . . Temperature Sensing . . . . . . . . . . . . . . Flow Measurement and Pressure Control . . . . . CONSIDERATIONS AND TEST PROCEDURE . . . . . . . . . RESULTS AND DISCUSSION . . . . . . . . . . . . . . . SUMMARY AND CONCLUSIONS . . . . . . . . . . . . . . SUGGESTIONS FOR FURTHER STUDY . . . . . . . . . . . LIST OF REFERENCES . . . . . . . . . . . . . . . . . APPENDIX 0 O O O O O O I O C O O O O O O O O O O O I iii 11 12 12 13 15 15 21 27 51 53 54 55 Table 10. 11. 12. 13. LIST OF TABLES Pressure Gage Calibration, 2 gpm Pressure Gage Calibration, 8 gpm Pressure Gage Calibration, 16 gpm Pressure Gage Calibration, 30 gpm Coupler Test Sheet, coupler A . . Coupler Test Sheet, coupler B . . Coupler Test Sheet, coupler C . . Coupler Test Sheet, coupler D . . Coupler Test Sheet, coupler E . . Coupler Test Sheet, coupler F . . Coupler Test Sheet, coupler G . . Coupler Test Sheet, coupler H . Coupler Test Sheet, coupler I . . iv Page 22 23 24 25 28 3O 31 32 33 34 35 36 37 q 14H - iii} I we .. LIST OF FIGURES Figure 1. Double POppet Hydraulic Quick Coupler . . . . . . 2. Sleeve and POppet Hydraulic Quick Coupler . . . . 3. Sliding Seal Hydraulic Quick Coupler . . . . . . 4. Double Rotating Ball Hydraulic Quick Coupler . . 5. Pressure Measuring Manometer and Gages . . . . . 6. Overall Test Apparatus . . . . . . . . . . . . . 7. Hydraulic Schematic of Test Apparatus . . . . . . 8. Coupling in Test Position (showing thermocouples) 9. Hydraulic Tester . . . . . . . 10. Pressure Drop Curve, coupler . . 11. Pressure DrOp Curve, coupler . . 12. Pressure Dr0p Curve, coupler . 13. Pressure Drop Curve, coupler . 14. Pressure Dr0p Curve, coupler . . 15. Pressure Drop Curve, coupler . . 16. Pressure DrOp Curve, coupler . . 17. Pressure Drop Curve, coupler . . 18. Pressure Drop Curve, coupler . . 19. Coupler Temperature Rise . . . . 20. Fluid Temperature Rise . . . . . 19 20 39 40 41 42 43 44 45 46 47 49 50 The findings in this thesis do not constitute a condemnation or endorsement of any manufacturers product, merely a study of representative types. vi INTRODUCTION It was in the middle 1930's when the tractor hydraulic system became popular. The use of remote hydraulic components followed soon, specifically being used to raise pull-type implements and angle offset disc harrows. In the post World War II days the advancements of wartime devel- Opments of hydraulics moved toward the agricultural industry. The trans- fer of hydraulic power to a detachable implement posed some problems as- sociated with the disconnecting of hydraulic lines from the power source, namely, the tractor. Tractor hydraulic power as a percentage of PTO power has increased from 20% in 1955 to 50% in 1964 (Zimmerman, 1966). The advantages of hydraulic power are numerous and the application of this type of power transmission is still expanding. Many agricultural machines exclusively use hydraulic power for all functions of that machine. Some of the components are detachable and interchangeable with a unit that is also hydraulically powered. One of the disadvantages of hydraulics besides low efficiency is most systems intolerance to dirt, foreign particles, and other pollutants. Quick disconnect couplers have been used where oil lines have been used in a Situation requiring frequent connection and disconnection. They have also been employed when it is desirable to have a self sealing con- nector on a line to eliminate the necessity of capping the line, to avoid the loss of oil and introduction of foreign material into the oil and system. - 4 x 11%|], Although the couplers are convenient, they do present a restric- tion to the flow of fluid. The Significance of this restriction is manifested by a drOp in pressure through the coupler with a resultant loss of efficiency in a dynamic application of fluid power. The couplers under high flow conditions have, in some cases become hot enough to preclude handling and Operation with bare hands. It is a logical assumption that most coupler manufacturers have tested their own units to determine the flow characteristics. Many have this data available. Still others may be reluctant to publish this information or simply do not have it available. Another interesting characteristic of the coupler flow patterns would be the misapplication or usage in a system where the manufacturers Specifications are exceeded. The use of a coupler that is too small or that has too high a pressure drOp is not easily noticed prior to actual Operation. It usually manifests itself as a cylinder that is slow in lifting or a hydraulic motor which will not develop its po- tential horsepower or related characteristics. OBJECTIVES In View of these problems, the objectives of this investigation are twofold. The first set of Objectives are: 1. The To construct and assemble a pump system which is capable of variable volume up to an arbitrary flow rate of 30 gpm and a pressure of a significant value to make valid determinations of pressure drop. To construct and assemble a measuring system or device which will lend itself to accurately determining the pressure drOps across test couplers as well as measuring, with reasonable accuracy, the flow rate through the couplers. Also it is ne- cessary for the investigation of temperature rise in the fluid through the coupling; to have a method of determining the fluid temperature both upstream and downstream of the test unit coupling. second set of objectives are: To measure, in a representative sampling of the four major types of quick couplers used in agricultural applications, the pres- sure drOp and temperature rise. To deveIOp a set of recommendations for the application of quick couplers by type. BACKGROUND INFORMATION AND TERMINOLOGY Quick Disconnect Couplers To simplify the classification of various types of quick couplers used in agricultural applications this thesis will use those already established (John Deere, 1967). The four basic types of quick couplers are: 1. Double pOppet 2. Sleeve and pOppet 3. Sliding seal 4. Double rotating ball Quick couplers usually consist of two halves; the body and the plug. The body usually has a Spring loaded seal as does the plug. This seal retains the fluid and protects it from contamination. As the plug is in- serted into the body the seals are forced Open to allow the free flow of fluid. A locking device holds the two halves together and seals them. The double pOppet coupler shown in Figure 1 has a self sealing pOppet in each coupler half. When they are closed or in the uncoupled position the pOppets seal in the oil as they seal out foreign material. When they are pushed into the coupled position, the pOppets are forced from their seats into an Open position. The coupler halves are locked into place by a series of steel balls in the body which are held in place by a Spring loaded outer sleeve. Some double pOppet couplers use large steel balls in place of the 4 OUKK COUPLERS COUPLED UNCOUPLED Figure l.--DOub1e Poppet Hydraulic Quick Couplers poppet which are spring loaded to Operate similarly. The traditional advantage of the use of the steel balls in place of the shaped poppet has been that the balls are considerably harder and resist wear. Wear of the pOppet tip has added to the flow restriction of double pOppet couplers as they age and become worn. It is conceivable that extreme wear could actually shut off the entire supply of fluid through the coupler. The majority of the listed manufacturers of quick disconnect hydrau- lic couplings use the double pOppet type design. It is assumed from ex- perience that this occurs due to the relative ease of manufacture and the related production cost. The sleeve and pOppet couplers, used almost exclusively in aircraft applications usually have a self sealing pOppet on the plug, and a sliding tubular valve and sleeve in the body. The extended sleeve shown in Figure 2, inserts first and gives an added margin of sealing against oil loss or dirt or air entry. One manufacturer of agricultural hydraulic equipment uses the sliding seal coupler or commonly called the sliding gate. In Figure 3 the coupler is shown to have a sliding gate which covers the fluid port in each half of the unit when it is disconnected. As the two halves are slid together the seals are forced from covering the ports. In most cases due to the design of this type coupling a c0pious amount of fluid may leak out. The coupler halves besides being locked together by their reSpective "tracks", are locked by a sliding bolt pin on one of the coupler halves. The double rotating ball coupler used by one manufacturer is shown in Figure 4. This particular coupler is an adaptation of the double pOppet type connector but utilizes an indented lever to Open the pOppetS after Figure 2.--Sleeve and Poppet Hydraulic Quick Coupler Figure 3.--Sliding Seal Hydraulic Quick Coupler the plug and body have been disconnected. This type of coupler is connected by inserting the line plug into the body with the lever so positioned to preclude fluid loss, and then is turned to force Open the poppet balls, allowing the Oil to flow. When the coupler is disconnected, pulling the line plug rotates the lever to close the valve balls mini- mizing the loss Of oil. The coupler halves are locked by a ring of small steel balls similar to the double pOppet type coupler. When the line connected to the line plug is pulled it puts pressure on the sleeve that the coupler assembly is mounted in. When this pressure is exerted it rotates the release lever and disconnects the plug as it closes the ball valves thereby releasing the line to the coupler without damage. Similar devices are available for the other types of couplers although they are not an integral part of the manufactured assembly. Many of the couplers used in agricultural applications are manufac- tured with pipe thread connections to facilitate use with standard fit- tings and pipe used for water systems. This standardization of thread dimensions has greatly broadened the use of the quick coupler to include areas besides oil hydraulics. Of the various sources consulted there was little information avail- able on the flow characteristics of the various types Of couplers. A few manufacturers had extensive test result data. Others could do no more than say the maximum flow and pressure recommended is as follows, with no reference to pressure drop. 10 OPERAHNG LEVER CLOSED OPEN '""7_':..-r‘«‘<“:-J~.rv'1..gal-“v" " ‘ - Figure 4.--Double Rotating Ball Hydraulic Quick Coupler STATEMENT OF THE PROBLEM When the previous information is reviewed and related library research is concluded it is evident that the problem of coupler pressure drOp measurement and study is one that could prove valuable in hydraulic component application and use. The requirements of the investigation Should be as follows: 1. 2. IS there a significant pressure drOp in hydraulic quick couplers? Do the different types of couplers using the same size connect- ing conduits vary in pressure drOp? (Which type has the greatest or least drOp?) Is there a significant temperature rise in the fluid due to the restrictions caused by quick couplers? Is the equipment constructed to investigate the flow character- istic adequate and accurate enough for valid data accumulation and analyzation? 11 DESIGN AND CONSTRUCTION OF THE TEST EQUIPMENT Differential Pressure Manometer and Gage System Most manometer applications involve the use of water as the fluid media with total pressures of less than 150 psi. Under these conditions glass or clear plastic tubing is sufficiently strong to contain the pres- sure and still afford a reasonable degree of clarity for reading. When mercury is used as a manometer fluid and pressures approach 500 psi it is necessary to seek other materials to contain the manometer fluid and related pressures sensed. Mercury has a Specific gravity of 13.546 and a density of 847 pounds per cubic foot. Due to its density and melting point, it affords a rela- tively ideal application to manometer use. (Marks, 1958) The U-tube man- ometer expresses the difference in pressure in the tube arms as a total difference of the fluid levels in the arms. The tubing selected for use in the test application was nylon pres- sure tubing having an outside diameter of 1/4 inch, and an inside diameter of 0.150 inches. The test burst pressure was 2500 psi. Although the tub- ing was not transparent it was translucent enough to be read easily. The test pressures did not exceed 500 psi and the fluid temperatures were below 100° F. It was expected that further use of the equipment at the termination of these tests may exceed the test values. Tygon tubing with 12 13 a listed burst of 1800 psi and temperature tolerance of 221° F. is much more tranSparent but has an elongation of 400% at high temperatures. (U.S. Plastics Corp., 1970) The ends of the nylon tubing were joined to standard 1/8 inch black pipe with nylon pressure tube fittings. The fittings had a standard gage nut securing the tubing to the fitting on one end and male pipe threads on the other. The force to pull out the tubing from the compression type fitting was 35 pounds at 1700 psi. The manometer was isolated from the pressure connections by two hand valves in the 1/8 inch pipe line. Two 500 psi pressure gages were mounted near the manometer outlets with common connections and isolation valves. Tape repair blades cut to length were nailed to the wooden uprights to form the manometer scale. In Figure 5, the center gage was placed for future use in determining maximum pressure to be applied to the manometer using a 1.7 safety factor, relative to manometer tube fitting failure. Two line levels were fastened to a plate on the base of the manometer- gage assembly to be used in conjunction with the four leveling screws lo- cated on the corners Of the base, as illustrated in Figure 5. The entire unit was then mounted on casters for ease of positioning and movement. Pump-Motor-Reservoir Assembly It was estimated that the maximum flow necessary to test couplers used on agricultural equipment would be near 30 gpm. Due to the estimated safe working pressure of the manometer tube fittings it was determined that 500 psi would be an acceptable test pressure. Figure 5.—-Pressure Measuring Manometer and Gages 15 A Vickers PV-2032, 30 gpm, piston type variable diSplacement pump, was secured along with a 60 gallon base type reservoir. If it is assumed that the pump efficiency is 70% the following holds true: psi x gpm x 0.000583 efficiency Pump Input hp 500 x 30 x 0.000583 .70 12.49 hp Assuming that an electric motor will run at overloads near 25%, a 10 hp, 3 phase, 240 volt, 1150 rpm motor was connected to the pump Shaft with a flexible coupling. Standard motor protection and control was utilized with a magnetic control push button. Temperature Sensing Due to the expected temperature ranges of from 80 to 120 degrees Fahrenheit, iron-constantan thermocouples were used in conjunction with a two channel chart recorder. The thermocouples were epoxied into brass 1/8 inch pipe fittings and inserted into the main flow line, one immed- iately in front of the test coupler and the other immediately behind it, as shown in Figure 8. Flow Measurement and Pressure Control A standard portable hydraulic tester was utilized to measure the flow rate and to apply line restriction downstream of the test coupler thereby controlling system pressure. This unit as shown in Figure 9, l6 Figure 6.--Overall Test Apparatus TEST Figure COUPI. R i 9 W X '—-—'—’fi f MANOMETER 7.—-Hydrau1ic Schematic of Test Apparatus .CPA NO ‘ofil L-_-—-————l 14 L 18 also has a fluid temperature gage which was used to determine fluid temperature rise during the tests. Hydraulic Fluid The fluid used was Military Specification hydraulic oil of SAE 10 weight, having nomenclature MIL-H-46001A. AmeasoooEuwcu wcfizoswv :oHuHmom ume cg wcflfiasoonn.w muswwm “mumme ofifiomucmmun.¢ wusmflm .IL“ 0— ,1”: .. 11.21; .I v ’3: 1.11 X. .- cI. «kw-Lt. n.7,? anta(u ( . . < 1. :ll ,7. .1: I a ..A.-:.. I L 6 3 (8023 «023:- =uso mono whammmumuu.oH muowwm 75:: 30.:- . .XL _ 0.. ..P._ n I I' I I' I I Til I7'7 I rVI I71 11 I I I ‘r I Or..— ...a. scan muammuus 40 on P p b - an as P....~..L.«_..L 1H m uwfiasoo .m>u:o mono musmmmumuu.HH muswwm 7:10. 30.. u n— — a n - — p b, — b J A 1 Ian TI 3 r on. was... 1 assumes; 1 no». 1 recs 41 o pmfiasoo .O>psu mono wpsmmmpmuu.NH wuswwm than. 30.: On an ON n— O— n p p - nib,_FIP - — — .1 PIP -r b - — — —, b - _— P — — ~.h , 11. _ d u #11 (d T. I LIOm 1 I IIOO— I 1 lIOn— r. lIOON :ua. 50¢: assuage; 42 a" P,—. W - p p o wmaaooo .m>u:u aouo muzmmmumuu.mH musmwm .Ean. 30am cu — T-Ib, - -T P 41 a. o— PL.Fr..b q . ‘- ‘ h (In. On I I' I I I I I I 100— ...a. scan unanmuut 43 m unwasoo .m>uso mono whommmumnu.qH muswwm :53. 30.. u on an ON .5... Op .5. — (P —I p p p p — — _— fl _. — —, n —T P p (P — _ p P p - I I I ’I I °I I ‘I I I I' I I I I I I I I On 00— On— l r, C’ C) G! ._nu. scan uuammmua m umfiasoo .m>uoo aouo mummmmpmuu.mH mwsw.m .530. 30.. n. 00 mm ON n— O— n P - P h. — b. — — .p - P\.,.P — p - _. — - P.— p n, p q _ lid .d d 44 I °I I I I I71' I I’ I I I I I I I I7 I I On 00— On— A.aa. .:U¢O unammmut 45 on p b p b an n d o pmaaooo .w>uso mono mpsmmmum-n.0H mpstm .510. 30.. a ON a— P.- I— p - b\_—\b . 0.. I I If Ian loo. ._.a. scan unaunuag an. l7 I I I I I I7 I I I OON onor(Pfl) 46 ll,lJ A .1 I l J . 1_J I'II IIII I II I7 I I' I If I I IIWI I I ’I l I I I I 5 IO 15 2O 25 F Low (990") Figure 17.--Pressure DrOp Curve, coupler H PRESSURE ononpsi) 100‘ l J. I l l l l 47 I l 1 ‘I I l l I l I 17 I I Fl I I 1F*l l 5 10 15 now (9 pm) Figure l8.--Pressure Drop Curve, coupler I .fiJ 48 The coupler temperature rise, as indicated in Figure 19, is a mea- surement of the change of surface temperature during the duration of a test sequence; usually 30-32 minutes. Coupler C Showed the greatest net increase although the temperature extremes, 65 and 92 degrees, were not considered excessive. Again, due to the large reservoir capacity, it was assumed that the aforementioned expected high temperatures of the coupler itself were not reached. Coupler C, a relatively common double poppet, % inch pipe thread, cadmium plated steel unit, had a higher pressure drOp in relation to others of the same type. Coupler F had the lowest net temperature increase although its recorded pressure drOp was not greatly different than others of the same type. 'The physical mass was relatively the same as other double poppet, steel units, and its appearance had no distinguishing marks. The mean and median net temperature rises of all couplers tested closely match those of couplers G and H, with minor variation. This, by no means, is a valid assumption, because of the nature of the tests and the doubt of obtainment of a true random sample of couplers. The fluid temperature rise during the tests were recorded as Shown in Figure 20, with an average rise noted of 8 degrees which is also the median. By analyzation of the patterns it is evident that coupler A was tested at one period of time. The next series of consecutive tests in- cluded units B, C, and D. Following these were the final series including couplers F, C, H and I. DEGREES 95 75 65 60 1 IIL'LII l I I 7 7.. -1 L .1. 49 Figure 19.--Coupler Temperature Rise DEGREES F. _l O 0 J I 95 85 80 Figure 20.--Fluid Temperature Rise SUMMARY AND CONCLUSIONS A review of the present literature and Specifications of hydraulic quick couplers indicates that the selection of these units may be based purely on the type of connecting fitting and its Size. Initial tests with a representative type of commonly used agricul- turally applied couplers show that in some cases a serious pressure drOp could be experienced. The results Of the tests indicated that: Pressure drops may reach as much as 300 psi at 30 gpm. Although the extreme pressure drOps may be a result of misappli- cation there was no method or indication of the expected losses until actual use occurred. Coupler H and I appeared to be low pressure drOp couplers. High pressure drOps in a unit may not especially be indicated by a marked increase in fluid temperature or the surface temperature of the coupling in a large reservoir capacity system, due to the heat dissapating capabilities of the fluid. The physical appearance of the sealing and locking mechanism does not necessarily indicate its pressure drOp characteristics. The sliding seal type of coupling had the lowest resistance to flow and the lowest pressure drOp Of the units tested. The sleeve and pOppet type coupler had the highest pressure drOp. 51 52 The sliding seal type coupler therefore is recommended for use in flow applications where minimum pressure drOp is desired at a relatively high flow rate and oil loss during connection and disconnection is not critical. The pOpular double pOppet coupler is recommended over the sleeve and poppet type unit in high flow applications because of the high pressure drOp in sleeve and pOppet type couplers. Also, double poppet couplers are less expensive and more readily available from most agricultural machinery dealers. The Sleeve and pOppet couplers do lend themselves to an applica- tion where they may be coupled under pressure more easily than the other types. The double rotating ball coupler, being an adaptation of the ball type double pOppet unit, has similar characteristics to those of double pOppet couplers, and therefore carries the same recommendation. SUGGESTIONS FOR FURTHER STUDY The following suggestions are provided to assist in the direction of any further studies which might relate to hydraulic quick coupler pressure drops. 1. The use of various fluids employed in agricultural applications of hydraulics with respective temperature extremes encountered should be investigated. 2. Coupler connection and disconnection under varying pressures would indicate suitability for comprehensive use. 3. A universal method of marking couplers with expected flow characteristics and application data would prove useful. 4. An economic justification of coupler type selection and appli- cation is necessary. 53 LI ST OF REFERENCES 10. 11. LIST OF REFERENCES Deere and Co., Fundamentals of Service-Hydraulics, Moline, Illinois, 1967 Faisandier, J., Les Mechanismes Hydrauliques (French), pages 157-158, Dunod, Paris, 1957 Fitch, Ernest C., Fluid Power and Control Systems, McGraw- Hill, New York, 1954 King, Horace William, Handbook of Hydraulics, McGraw-Hill, New York, 1954 Marks, Lionel S., Mechanical Engineers Handbook, McGraw- Hill, New York, 1958 Stewart, Harry L., Hydraulic and Pneumatic Power for Production, page 5-17, Industrial Press Incorporated, New York, 1970 Stewart, Harry L., and John M. Storer, Fluid Power, Howard Sams and Co., New York, 1968 United States Plastics Co., Catalog, Lima, Ohio, 1970 Vickers Hydraulics Machinery Division, Industrial Hydraulics Manual 935100, Troy, Michigan, 1962 Yeaple, Franklin D., Hydraulic and Pneumatic Power and Control, McGraw-Hill, New York, 1966 Zimmerman, M., "How Much Hydraulic Horsepower?", Implement and Tractor, Volume 81, Number 11. 54 APPENDIX 10. 55 PROCEDURE FOR LOADING MANOMETER Lay the entire manometer assembly on its Side with the upper ends lower than the rest of the unit. Disconnect the plastic tube fittings from the manometer exposing the upper open ends of the U tube to the atmOSphere (caution: any fluid in the tube will run out onto the ground.....heated mercury is potentially poisonous). Blow compressed air through the U tube being careful to catch any residue which is expelled in a suitable container. Attach 2 feet of 3/16 I.D. surgical tubing to the lower leg of the U tube by Slipping it over the manometer tubing a distance of % inch. Attach 6 inches of 3/16 I.D. surgical tubing to the upper leg of the U tube by slipping it over the manometer tubing a distance of % inch. Attach a 50 cc. hypodermic syringe to the upper surgical tubing with the syringe fully compressed. Stick the end of the lower tube into a container of mercury below the fluid level. Pull a negative pressure on the system by retracting the syringe plunger....hold it in the retracted position. Slowly raise the container of mercury, making sure the end of the tubing does not break the surface of the fluid, until the desired level of mercury is Obtained in the U tube. When the desired level is reached, quickly pinch the end of the lower tubing near the place where it joins the manometer U tube. 11. 12. 13. 14. 56 Slowly raise the manometer on its side until the tube leg is high enough to keep the mercury from running out as the surgical tube is unpinched and both surgical tubes are removed. Replace the nylon tubing fittings and tighten them. Raise the manometer to its normal working position and bleed any transient mercury from the pipe lead lines by Opening all valves on the manometer gage assembly and Opening the plumbing unions near the base of the pressure gages. If any bubbles appear in the manometer tubing repeat the above procedure. . . m .1 {sigh-E]! . a . I, . u . a. - ..bl. J... j I .. MTl'l'fliifililjfllilifl[11111111111111ES