WIIHH H! I” i * m.) CEO |\)_.a {THST " " f;_*§'-AUTDMATIC SPILLWAY GATES ‘ FOR ICE AND NON ICE “ ‘ ' CONDITIONS \ ‘ A ..\ THESIS FOR THE DEGREE OF B S R W Becker 1934 . x. ‘. _- .- -. \, . " f > ‘v . —. x -. ‘ 7;~ J ‘ _ < ‘ ‘ V ~ -' ‘ ., .' , wk , " r. ' x x .. - ~ - ‘. . A .‘ ~ . . " ;~' _ N . ~\ \ . W ' ‘ . ‘ ‘ ~ ~. ‘ \ N -. :1 N \ -. \ Automatic Spillway Gates for Ice and Non-ice Conditions i.Thesis Submitted to The Faculty of MICHIGAN SIAEE COLLEGE of AGRICULTURE.AND.APPLIED SCIENCE Bv R. W. Becker Candidate for the Degree of Bachelor of Science June 1954 AC"“I O‘JLEDELEN T To Mr. E. M. Burd of the Consumers Power Company of Michigan, for his willing assistance by furnishing imformation and suggestions. To Professor C. ML Sade of Lichi5 an State College for su55estions concernin5 Part IV of this pa;<)er. To the Detroit Edison Company for kindness shown at their Geddes Plant and Ann Arbor Office. 94-2788 INTENT This paper is intended to be a brief summary of automatic apillwav gates that have been, or are now being used with a fair degree of success. It is further intended to treat lightly ice conditions and methods of controlln g them, eSpecially in conjunction with the automatic gate. A new idea for an automatic crest gate will be worked out in the rough to illustrate what might be a useful princijile in automatic gating in the future. AUTOMATIC GATES Introduction The following definitions will be adhered to in this paper: An automatic gate is a gate which is Operated by the pressure of the standing or flowing water of the stream or pond. Furthermore this pressure must be controllable by a small amount of work for which only a few men and a short time are required. A.purely automatic gate is a gate which is Operated by the pressure of the standing or flowing water of the stream or pond. Furthermore this pressure must be controllable bv a mechanism responding to predetermined elevations of the head-water. This gate must be capable of Operating without the presence of an attendant. Throughout this paper references will be mentioned by the numbers they bear in the bibliography. In order to maintain simplicity,the Fargo Classifi- cation (Ref. 24) will be followed. All gates other than automatic or purely automatic will be mentioned but briefly. The Fargo Classification I Needle Dams II Sliding Gates A. Crest B. Deep Sluice III Pivoted or Hinged Gates and Flashboards At Bear Trap Gates B. Tainter, Sector, and Drum Gates IV Rolling Gates A. Cylinders B. Shutters of polygon section mounted between large wheels or rollers which travel inclined racks V Siphon Spillways PART I II III Gates fieedle Dams 1 Li a COT-T'V‘IT ’3 L‘ Ltd-L Sliding Crest Gates Slidin5 Gates for Deep Sluices Pivoted or Hinged Gates and Flashboards Bear Trap Gates The Old Bear Trap History The or y Design The Later Bear Trap Gates The ‘he The The The Tire The The The Du Bois Gate Carro Gate Girard Gate Du Bois Apron Gate Parker Gate Lang Gate Reversed Parker Gate harshall Gates Jones Gate Tainter, Sector, and Drum Gates Flashboards Rolling Gates Cylinder Type Shutter Type Siphon Spillways Ice, Ice Troubles, and Remedies Introduction Ice and Ice Troubles Sheet Ice Frazil Ice Anchor Ice Frozen Leakage Remedies for Ice Troubles EXplosives Heaters and Blowers Heat Filaments and Heat Lines Compressed Air Ice Prevention by Orientation Undersluices The Use of Chemicals Chopping Out and "Cracking“ Conclusion Conditions Combat Kethods Chart Comments J PA?" L wwooooooooooqqenbww 0103(5“l\'(\i‘~m 10 20 20 20 21 (‘4‘ 46 COhTiNTS PART PAGE IV A New Automatic Crest Gate s5 Operation and Discussion 25 Theory 24 Key to Symbols 24 Condition of Raising Gate 24 Condition of Keeping Gate Up 24 Condition of Lovering Gate 2 Condition of Keeping Gate Down 25 Summary of Conditions 25 Forces 26 The Weight 26 The Friction 2:6 The Friction 27 Water Over the Gate 2 The Head Loss 27 The Upward Water Pressure 2? Remarks on the New Automatic Gate 28 PART I Gates Needle Dams The needle dam is used most extensively in EurOpean countries. It cannot be classed as an automatic gate due to the large amount of labor required to Operate it. The chronological order of deveIOpment is: Poiree's Needles 1854 Vertical needles Boule Gates 1874 Square sections Curtain Dams 1876 Horizontal needles (Ref. 9 a 26) Sliding Crest Gates The stoney gate and similarly constructed gates, Operated by overhead cranes and hoists, are the most common sliding crest gates of today. They are obviously not automatic. There have been automatic sliding crest gates designed, however. A ood example is the Stickney Lifting Dam, designed by L1.t- Col. Amos Stickney, Corps of Engineers, U.S.A. for closing the navigable pass at Dam #6 on the Ohio river. The principle of construction of this gate is illustrated in Fig. l. The gate is raised by the pressure of the water stored in a reservoir upstream of the dam. The stOps, as shown, prevent the gate from.leaving the chamber. The gate is lowered by closing the valve leading to the reservoir, and Opening a valve to the stream below the dam. The gate drops by its own weight. The reservoir can be filled by natural flow when the river is at high stage. The Stickney gate is not always able to Operate as an automatic gate. This is true when for some reason, such as an emergency, the water must be pumped into the reservoir. Thus, a pump should be a part of the equipment. The Stickney gate has the following characteristics: a. Rapidity of movement b. Small leakage c. Automatic Operation d. Can Operate under any condition of the river e. Provides for safety of the Operators FIG] .I 1 0‘5 0. _ ' . - V I L. - a . r. ,.. '. —— ‘_v_,’. w L q.~ “I'M. . , {I II .. l. . - wk - o I. ‘l v ~0AL .d l 'I Verl‘lca/ Sac flan 577001: Y 1. IF rmc DAM H0. 2 + "'2/3' warfare Y: 2- Y3K: +1 ” / ‘5 [I’d- \\\ \““ [I / \\ ‘\ / // \ \\\ / \ ‘ I / \ \ / / \\ \\\ I, // lip \\\ \\\ / “1/ / X \ \\ I ’ \\ \ / 2 , \ \ / l‘ ' \ \ u q ‘A L h Y .0. Wm -- -_--__-_.4 A £11m DIAGRAM f5}? “01.0 BEA}? 7134p II Sliding Gates for Deep Sluices Although gates Of this nature are very extensively used, they are not of an automatic character. There are many different types of sliding gates for deep sluices, among which are some of the following: a. Stoney gates Ref. 2 a 27) b. multiple Leaf gates Ref. 1) 1. Old type, multiple slot 2. Cantilever type 5. Guillotine type c. Sliding gates with ice-flaps Ref. 1) d. Broome gates (inclined) Ref. 27) e. Sliding Vertical Cylinder gates (Ref. 27) Pivoted or Hinged Gates and Flashboards Bear Trap Gates The bear trap gates have been about the most successful of the automatic gates, and therefore merit considerable attention. The chronological order of their deveIOpment is as follows: 1819 Old Bear Trap Shown in Fig. 5 1862 Du Bois Gate Shown in Fig. 4 1868 Girard Gate Shown in Fig. 5 1870 Carro Gate Shown in Fig. 6 1881 Du Bois Apron Gate Shown in Fig. 7 1887 Parker Gate Shown in Fig. 8 1890 Lang Gate Shown in Fig. 9 1892 Reversed Parker Gate Shown in Fig. 10 1895 Marshall Gates Shown in Figs. 11, 12, 13, & 14 1900 Jones Gate Shown ianig. 15 1918-1920 Lutz-Hulbert Gate (Have been unable to find a description of this gate) Of these gates, the three that are most commonly used in engineering structures are the Old Bear Trap, the Parker Gates, and the Lang Gate. The Parker and Lang gates are best for average conditions, but the 01d Bear Trap still has its advantages in remote and inaccessible places where skilled labor and metal work are hard to obtain, and where the expense must be very small. The Old Bear Trap ,History The first bear trap gate, known as the 01d Bear Trap, was invented by Josiah White. He and a business partner found it necessary to make the Lehigh river navigable for business purposes..After considerable study of the situation Hr. White devised a gate to be used in keeping the river at the desired elevation and thereby provide ample draft for his bargeS. Theory The Old Bear Trap is an automatic gate. It consists of two leaves, an upstream leaf and a downstream leaf, and an interior chamber. The chamber is connected to the water above and below the dam by two channels or ducts which may be Opened or closed independently of each other by valves. When the upstream.valve is opened and the downstream.valve is closed, the hydrostatic head above the dam raises the gate. When the upstream valve is closed and the downstream valve is opened, the weight of the gate plus any downward water pressure on the gate will close it. The gate may be held in any intermediate position by the proper adjusting of the valves. Design In order to have a workable gate under any given conditions of head and backwater, there are four dimensions whichwmust be related to each other in accordance with certain fundamental laws of.mechanics or hydraulics. These are the lengths of the two leaves, the distance between the hinges, and the height to which the dam.will raise. For low head conditions, the height which the dam.or gate will raise is taken as the basis of design, but in many other cases the distance between the hinges is used because it is limited by cost. A.0.Powell, U.S.Assistant Engineer, has derived formulas for the Old Bear Trap gate. (Ref. 19) From these formulas he has constructed curves for various thead and backwater, from.which the four essential dimensions can be taken. If a gate is built'using good engineering practice, to the dimensions of any one curve it will work for the conditions of that curve. A.modification of one of ur. Powell's curves will be derived and constructed at this point to illustrate the method used in bear trap gate design. To start with, it will be assumed that there is no backwater, and that the leaves have no thickness. The symbols used signify the following: (See Fig. 2) 5. I s The length of the upstream leaf Y - The length of the downstream.leaf z a The overlap when the gate is depressed Q - The distance between the hinges H“: The difference in head (upstream and downstream) E1=*The downward pressure P ==The upward pressure w = The weight Of a cu. ft. of water The two critical positions are when the gate is fully elevated and when it is depressed. The case of the gate depressed will be considered first. The downward force which.must be overcome is applied on the portion 2 only, as the rest of the upstream leaf is between equal pressures. From hydraulics, water pressure equals the area of the body acted upon times the head at the point of pressure times the unit weight of water. Also from mechanics, the sum of the moments, about any point, of a body in equili- brium equals zero. Therefore P1 acting through point ta‘ is as follows: (See Fig. 2) 22 x2-.. Pl:*I7H"(——i.) X.- Z The upward force used to raise the gate is applied on the whole surface of the downstream leaf. Therefore: P :g wYfi“ 2 2 P also acts through point 'a'. P2 must exceed P1, in order to be able to raise the gate. This excess can be definitely fixed to suit given conditions of friction etc. by evaluating 'n' in the following formula: “Ps'Pl Substituting the values of P1 and P2 tars-22 n(X - Z) Y- By definition: q=x+r-z Substituting and setting Q equal to unity, as it does not effect the relations between X, Y, and Z, the following value or expression for Y can be arrived at: n , l- -2 ‘2 l-n l-n ‘8 Also: x= W1 - My? - 2111 --’23-)‘+ 1 At this point 'n' may be evaluated and the equations for the various curves determined. Suppose that it is desired to have 1% times as much lifting force as downward force. If so, 'n' should be given the value of 2/3. Therefore by inserting this value in the prOper places of the equation for Y, it is found that: Y = 2 -( 31:2-4- 1 The curve shown on Fig. 2 was constructed from this equation. Any convenient point on this curve will serve as the vertex of the gate, and thereby determine the lengths of ‘X and Y to be used for a given Q. However, the highest point giving the maximum head for a given Q, is usually used, unless there is a definite reassn for desiring another point. It was previously stated that there were two critical positions for the gate. The case of the gate being depressed has been considered, so the next consideration is that of the gate being fully elevated. When the gate is in this position there is one requirement which.must be fulfilled. The angle between the leaves must be greater than 90 degrees plus the angle of friction, which means that it must be greater than approximately 100 degrees. . Backwater has not been considered in the above derivation, but could gage been enteied in by making the ' n for P a 11 t e more comp ex; . expresgfig Specific gravity of the gate may be adqusted one way or the other to some advantage. One leaf may be made buoyant to assist in raisingtfihe gite, and the other.made ssist in lowering e ga e. heavv I; :he above derivation it will be noted that the head (H“) drOps out, making it appear that the gate Will work for any head no matter how small. This may be so from a theoretical standpoint, but it is not true in actual _ practice. Mr. Powell finds that if the Specific gravity is 7. as low as 1.0, the gate will Operate under 6 inches of head or'more. As the specific gravity increases the minimum head required becomes greater. The Later Bear Trap Gates It is nOt possible in this short paper to go into each of the successive bear trap gates to any great extent, therefore a brief discussion will be presented in the way of a comparison with the 01d Bear Trap gate. All of the later gates Operate under the same fundamental laws as Mr. White's gate, and are in a sense of the word merely mechan- ical improvements or attempts at improvement. For this reason the comparison will be made by showing how they have overcome the various defects or weak points of the Old Bear Trap. These defects will be listed at this stage of the paper and referred to in the discussion by their respective numbers. (See Figs. 3 to 15) The defects are: I Friction between the leaves II Excessive distance between the hinges (This distance is approximately 3 times the head which can be handled, therefore requiring a sluiceway which is not of economic prOportions.) III Excessive strain on the leaves (This is due directly to defect II) IV Excessive stress at sudden stOpping (This requires an extra sturdy structure, increasing the cost.) V warping of the leaves (This is due to the uneven distribution of the water in the chamber When filling) VI Driftwood trap (Driftwood and otheridebris is caught in the exposed exterior angle.) VII Overlap of the leaves (Causing impact of the water on the lower leaf.) VIII Overlap of the leaves (Causing unnecessary lifting of water.) The Du Bois Gate The Du Bois gate is hardly an improvement over the 01d Bear Trap, but will serve as a variation. This gate overcomes defects (I,VI,VII, and VIII), but is subject to an equal amount of criticism for the sliding arrangement of the upsteam leaf. This arrangement causes a great deal of friction and is easily clogged by silt, submerged debris, or possibly anchor ice. Verf/ca/ Seer/on MR. Wm 75‘s 0L0 BEAR 7FPAP ~-—-—- --A.- N\\ Vcrf/ca/ Sect/on 77¢: Du B 0/5 6/! r: F764 O. The Carro Gate M. Carro's gate, being similar to the Du Bois gate avoids the same defects. It also has remedied the clOecinv difficulty, but introduces more friction and is more go 0 complicated to build, thus costing more. So all in all the Carro gate fails to be an improvement, but may be classed as another variation. The Girard Gate According to A.O.Powell, the gate patented by H. Girard is the first real improvement of the Old gate. This device has eliminated defects (I,II,III,V,VI, and VIII). The Girard gate, although not prOperly valued at the time Of invention, was the first to have a folding leaf. This feature is the key to the success of the more modern gates. The Du Bois Apron Gate hr. Du Bois' second gate, although introducing a little friction at the foot of the apron, does not have defects (VI and VII). It is heavier and costs a bit more than the 01d Bear Trap, but for many conditions may be considered as an improvement. The Parker Gate The'Parker'is in reality Girards' gate turned end for end, with a Du Bois apron added to it. This apron is now called an idler, and provides for the circulation of water through it to avoid unnecessary water pressures..All the defects except (IV) are eliminated in this gate. The absence of defects (II and III) is a very important improvement as the cost of the gate per foot of head is greatly reduced. This enables a stronger and more rigid structure and thereby practically eliminates defect (IV). A.very detailed discussion, including the derivation of formulas, of the Parker gate can be found in A.O.Powell's report in Ref. 19. The Lang Gate Mr. Lang substituted chains or rods for part of hr. Parker's upstream leaf and shortened up on the idler. This J \\ " \ ff“ “.- . A \ “arr/col Section CARPO 647-5 FIG. 6 Verfita/ \Secfion GIRARD CAT£ Ver/ica/ deaf/an 01150.45 GATE WITH AFRO/v Verf/ca/ Gecfion PARKER BEAR 777AP GATE \\ \ ‘\ V8 ’"7 [C a/ 6 c c 7/0 n 0 ”B 0 l6 0 A TE w ’7' H fl p R 0N 1:..- Me "2‘ "c ”I 6 QC ’2 O n p A R K t: R B EAR 7— R A p G ' A 75 9. .makes a lighter gate. but reintroduces sliding friction at the end of the idler. There are two Lang gates in Operation at the Geddes plant of the Detroit Edison Co. They operate with perfect ease, reSponding very readily to the working of the valves. The author was further informed that there is no great difficulty encountered with ice. According to Mr. Powell, it is hard to say which is the better gate, the Lang or the Parker. The conditions existing at any particular set-up usually determine which is more desirable. There is one small advantage which the Lang gate has over the Parker, and that is that it does not have the condition of unequal water pressures in the chamber at the vertex of the segments of the [lipstream leaf. By the addition of another set of chains or rods the Lang gate can be made reversible, that is; at a location where the flow of water is one way part of the time and the other way the rest of the time, this gate will serve its purpose for flow in either direction. This condition was encountered at the Sandy Lake Dam. (Ref. 29) The gate functions as a Lang gate in one direction, and when the flow is reversed it functions as an Old Bear Trap. The location of the additional set of chains or rods is shown in Fig. 9 by the dotted line between points 'a' and 'b'. The Reversed Parker Gate The Reversed Parker gate, as shown in Fig. 10, is nothing more than a Girard gate with an idler added to it. It therefore has the same qualities as the Girard gate, plus the obvious benefit of the idler. A.practical illus- tration of the use of this gate can be found in Ref. 18. The Marshall Gates W.L.marshall, major, Corps of Engineers, U.S.A., made several contributions to bear trap gate design. He patented his 51 and #2 gates about 1895. _(See Figs. ll and 12) Compared with the Parker gate, these gates differ essentially in that they fold out from,and not into the chamber. These gates introduce several new problems in forces. The size and the dimensions of the gates can be made such that the forces will do away with the necessity of stay-chains or steps. Er. Larshall and his assistant discuss the theory of these gates very freely in their report found in Ref. 19. ‘ « m_ Referring to the defects of the Old near Irap gate, it is found that the two Marshall gates mentioned above flu. L I ‘R.vb\~—\\~~\.‘\\Nu\\A-‘L‘_—‘~LMVS -‘fi , Downstream view of the "Lang" bear trap gates at the Geddes Plant of the Detroit Edison Company. Part of an emergency spillway is shown at the right. Downstream view of single gate showing minute flow trickling over. As can be seen in the picture at the tOp, very little leakage gets through these gates. . ,‘I Left: View of downstream valve control wheel at the Geddes Plant. The small motor turns the wheel. A button-switch in the power house controls the motor. The upstream valve wheels are shown in the backround. They are for emergency use only as pressure is usually maintained by water entering the chamber between the idler and the upstream leaf. Below: Downstream view of gates showing valve wheels. £76. .9 ‘, -- ‘--.‘~- nu- -—--—:=:-.—+—---------- " “ (' "I'M.-- --————_-..--.._-_ A ~---—-—- ...... . ' ---~-—--~——.—_- ' I 7/ ‘ //// ,x/ / // / '// %//////4///,’/l /, territo/ Sect/on LANG BEAR 7RAR GATE FIG. /0 .— —- _— , ' v ' w _ m. .7 _. .. /’/ _ / // /..// / / ////, Verfl’ca/ 6 sci/on Pi: VERSED PA RmsR GATE ta: 2 :x‘anv :1 (filial I]. 1L4. -_i__:+____.l_ ”I; ‘ F76. // ’- /////// 7M; ._:::.:::‘_‘:: _‘: : :': : 1“ “ ‘: 7' ’ : j;-}3 ”4'4 Vcrficq/ Jed/'0)? ////;A/// /‘,~‘/ , 4r - NARJHALL s BEAR 7RAP / F/& l! —— ——————.. —— .- _.___——_ _———- ‘-———-—_—- —--—.-—--—- L _____ ‘ _‘.__. /’////////// /// ,,/’ /// /// lav/cal Sect/on é} / //;/ // ”mama. is BEAR 77PAR ‘2 10. have eliminated (I,II,III,Iv,v, and VIII). A tnird Marshall gate is shown in Fig. 15. This gate is not fully automatic as it must have auxiliary jets of high head to raise the gate, due to backwater. . The result of an attempt by hr. Marshall to improve the Old Bear Trap, without too much alteration, is shown . a. , . .. - in rig. 14. The SpeCIal hinged roller evice eliminates defects (II and III). The dash-pot like connecting rods eliminate defect (IV). The proper distribution of water by several mains eliminates defect (V). The short idler practically eliminates defects (VI and VII). (See Ref. 16) The Jones Gate W.A.Jones, Lieut. 001., Corps of Engineers, U.S.A., shows in Ref. 19 a design for what he terms a "Reversible Weir with Short Base". It is reproduced in Fig. 15 of this paper. It is a series of gates that fold up in a very compact way, thus requiring a very small base, in compar- ison with other gates, for the amount of head taken care of. The Jones gate has defect (VII), and lacks simplicity. For conditions that demand a high head and a short base, this gate might be acceptable; but for other conditions some of the simpler gates are best, as simplicity is a key-word in engineering. For brief reports on bear trap gates see Refs. 4 and 9. Tainter, Sector, and Drum Gates The ainter gate (a form of sector gate) is a very commonly used gate. It is not an automatic gate, but perhaps could be made so by appying some of the principles that will be develOped later in this paper. (See heading WA New Auto- matic Crest Gate“) The so-called sector gate has its curved face down- stream. Fig. 16 shows a set-up for an automatic sector gate. (See Ref. 25) A snort eXplanation with some of the theory of this gate is as follows: For purely automatic action, the gate valve is closed, the inlet valve adjusted to a desired Opening, and the float adjusted to a desired elavaticn. The gate will then maintain the desired water level automatically, by r181ng wnen the siphon is broken and lowering when the siphon is Operating. The gate can be Operated as a drum gate by an attendant. through the use of the inlet and gate valves. In thisficaset they are Operated the same as the valves of a bear rap ga e. FIG. I4 ”WWW/f / // .. a I; / ’f . Kerf/ca/ Secfian MARSHAL/.3 Moo/nap GArE F/G. A5 — "- Vem'ca/ sect/on ‘ _ - __j _ QUE—.— __-_—.—_-____ I -———-—— —- —_a "“‘ ::_::—"| /’//, //// , // dozvm' JHoRr BASE GA‘n.r General view of Tainter gates at Moores Park Plant in Lansing, Michigan. _ N \l ‘\_\~‘ A close-up of one of the above gates. Note the light wood construction, making the gate adaptable to the principle of Part IV of this paper. 11. The gate is designed to keep its crest above water until fully elevated, providing Pb is due to the head up- stream. Backwater pressures have no affect upon the eqilib- rium of the gate, as any water pressure on the curved face must act through the axis. The siphon is capable of varving P2 as much as the equivalent of 6 inches of head in either direction. This variation is sufficient to raise or lower the gate. The caisson (cross-sectioned in Fig. 16) has a drain pipe in it. This may be used to make small variations in the weight of the gate if necessary, by leaving it Open or closing it. The fundamentals of the hydraulic design of this gate are somewhat as follows: Let S = The leakage from the pit. (+or -) Let Y'= The water discharged by the siphon. Let D'= Displacement (The flow in or out of the Pit due to the movement of the gate) (+or -% Let Q = The water passing the intake. (Subscripts are used for various directions of movement.) For lowering the gate: Q13 S+Y~D For holding the gate down: Q2== S + Y For raising the gate: rile " '- “‘0 9+3 Assuming D is approximately the same in both cases: Y ‘= ED Therefore: Q1 ' Q5 If the effective head of the siphon is known and its efficiency is between 40 and 50 percent, D can be assumed and Y computed. Therefore for certain assumptions of S, the value of Q or Q5 can be figured..An Operating chart can be made coordinating the adjustment of the two valves with the adjustment of the float. Thereby water can be maintained in the pond at any desired elevation by the coreSponding adJust- ment. The drum or pontoon gate originated back in the time of the early bear trap gates, in fact the Brunet gate (See Fig. 17) was intended as a bear trap, but develOped later into a pontoon gate. (See Fig. 18) Many varieties of the Air Inlet Float - ---. -_-.----.--.-.o- MMWter_ ln/ef (vb/re ‘41: ‘ o .' "M .J _.__‘_ ._ .— ‘71 {vi '1‘“; 9173.4 :- .v' a a . ‘ .—-—-——_.. .’_’~.' ' ,\ ’2 fl 1:4"1'1‘3-2 - .23:- f' : ‘ ' 'o Jeri/ml Jecfion A uroMAr/c _ 55c rem 6A7: ' I t. O , A .hI‘II-'1 ‘ c \ . A. $5. FIG/7 Verfl'ca/ Section 8519}? 770429 CAT: Emma r Jew/on K-r/I'cv/ BIN/Nor PM Tea/v 0/! TE l2. drum gate have been designed, but they all work in a similar manner to the Brunot sate shown in Fig. 18. The principle of the drum gate is simple. Instead of the lifting force being mostly pressure from the head upstream as in the case of the bear trap gate, it is that pressure plus a buoyant force due to the low specific gravity of the gate. One good feature of the gate is the fact that it is all in one unit, and does not have a lot of separately moving parts. Flashboards The flashboard is an auxiliary gate used for obtaining additional head on the dam. It is usually made to break loose or trip if a certain height of water is surpassed. Some of the tripping types of flashbcards may be classed as automatic gates. .A flashboard of the type illustrated in Fig. 19 is automatic. It is hinged below the lower third pointof the gate; thus the water pressure trips it at a predesigned elevation. The handicap of such a structure is that it leaves too much obstruction in the path of the water and therefore is not good for use on streams containing any debris or having any ice runs. The gate is raised or set up again by an excess of weight in the lower part of the gate, which acts after the high water has subsided. Better arrangements are the two Swiss gates shown in Figs. 20 and 21. These gates offer less obstruction when they are tripped. Counterweights return the gates after high water has subsided. (For more detailed information on automatic flashboards,see Refs. 17, 25, 24, and 28.) Rolling Gates Cylinder Type The rolling cylinder is used a great deal for gates to be used in wide shallow Openings. The cylinder is able to withstand the stresses of wide Spams without being too heavy a structure. It is easily heated for ice conditions ,as it is an inclosed affair. The rolling principle also Imakes the gate lighter'to lift, as a component of the ‘weight is supported by the inclined rack. J.E.Jenkins of New York, patented an automatic roller gate, but the ,author has been unsuccessful in obtaining a description of it. F76. l9 Verf/cq/ Sad/'0)? 7;?IPP/N6 HAS/45 0,4317 FIG 20 Vertical Section OVERHEAD Comm? WEIGHT. l7. ASA/BOARD _,___ :e no. 2/ ’ '00. — -— ,~'-;~r , - 9 "a; "v If lb‘t‘.’.'\ l 1’,“ ,i | l I I a; . ' o‘-‘ —— — .\'.‘ a‘ul’: A I. '9’! . ' o C i“ ‘I:“ t h .5: . i”. \o'fi ‘1‘ I'. \u.‘ . ' r, . N' r: _ as: “1.. ; .n.- ‘53 a — 5. I "I 2: fl: 7" in 6\.‘.~' at. \' an '3?“ HIDDEN C ouA/rmwuém; final/50AM: Shutter Type A.medificatien of the rolling cylinder is the rolling sector or shutter. This gate is used where a complete cylinder would be to large to handle or require too much material to build. Siphon Spillways The siphon epillway is a purely automatic device for maintaining the desired water level on a pond. If prOperly designed and constructed it will Operate with very small variations in the water level. It has practical limitations however, such as the use of a suction head of no greater than 25 feet (54 feet theoretically). Its construction is rather expensive due to the form work necessary. It is not the best sort Of a device for the colder climates, as it quite readily clogs with ice, and therefore reduires more equipment for the prevention of such clogging. The siphon Spillway gives an increased discharge ever that Of the ordinary Spillway or weir. It is a very effective device if used in plants where the conditions make it readily ad'ptable. (For an illustrative description of a.modern set- up, see Ref. 27.) 14. PART II Ice, Ice Troubles, and Remedies Introduction In treating this subject, it will be divided into two parts: First, a short explanation of the various forms of ice and the difficulties they present. Second, same of the remedies used at the present time in engineering practice. A.thorough analysis of ice and ice conditions is out of the question in such a short paper, especially When this subject is only a part of the intent of the paper. However the high points will be touched upon, and the conditions affecting gates will be discussed in.more detail. H.F.Barnes,.Associate Professor of Physics, at EcGill Universitv, Montreal, has Spent a great deal of time in study and in research work on ice. His results are verv helpful to the engineer contending with ice conditions, and may be found in his text and other writings. (Refs. 14 and 15) The four principle types of ice that the power plant engineer must deal with are; frazil ice, anchor ice, sheet ice, and frozen leakage. Ice and Ice Troubles Sheet Ice Sheet ice occurs on the surfaces of the bodies of water. As the weather grows colder, the cold surface waters sink and the warmer waters rise. This process reaches a limit when all the water has neared the freezing point. As more heat radiates from.the surface, the surface freezes into a sheet. This sheet becomes thicker as the heat con- tinues to radiate from.the water. Sheet ice is found mostly in quiet waters such as ponds, lakes, and the slower streams. It usuallv ranges from.a few inches to 5 or 4 feet in thick- HESS. Sheet ice is easier to handle than anchor or frazil ice as it is on the surface and is not so difficult to get at. Sheet ice is often desirable, as it prevents the forma- tion of the other types. The sheet tends to quiet the waters which along with the heat of friction under the sheet pre- vents the frazil and anchor ice from forming. If the condi- tions are very severe, any additional ice forming will do so in the way of thickening the existing sheet of ice. The main difficulties encountered with sheet ice are, the pressure exerted against the gate, and the ice break- up in the Spring. The pressure is usually the greatest sqrce Of difficulty, and has been known to break gates in several instances. The Spring break-ups causing damage, where the ice runs out Of the ponds, are only found in the more flashy streams. Ordinary conditions are such that the ice melts or rots in the ponds for the most part. Frazil Ice Frazil ice occurs in rapidly moving or violently agitated waters. It has needle-like crystals and is a slushy formation. These crystals, according to mr. E.M.Burd of the Consumers Power CO. of Michigan, are "ready to seize upon and matt over any Object in the current where it may slow down.“ Frazil ice has been known to be as much as 20 or 50 feet deep or thick; sometimes completely filling portions Of the pond or stream. (See Ref. 14) Frazil ice presents one Of the greatest difficulties for winter Operation. It masses behind the dam and gates and thoroughly clogs any moving parts by adhering to them Or wedging in them. In severe cases it prevents Operation for a period of time until the ice can be removed, thereby endangering the plant, the dam, and any prOperty or lives below the dam, should high water come on suddenly. Anchor Ice .Anchor ice, as its name indicates, is found at the bottom Of bodies of water. It forms about Objects which have become chilled, such as stones, metal, or concrete. This formation differs from frazil ice found submerged, in that it is very hard. Anchor ice is thought by some to be more troublesome after it has broken loose and floated to the surface, but in general this is not true. When on the surface it can be treated like broken sheet ice, but when submerged it presents difficulties Of an entirely different character. It forms about the submerged parts, eSpecially the metal ones, and prevents their movement. Being very hard, it takes more heat to melt than frazil. It is anchor ice that forms what is known as the "ice-gate" in the very cold climates. (Ref. ll) A.thick layer of ice forms behind the structural gate over its whole depth. ter the actual gate has been broken free and raised, the ice gate remains.makinr it imposible for the water to pass through. This ice gaténhas been known to remain for several hours before g1Vin¢ flay. Frozen Leakage .Considerable difficulty is encountered with gates freeZing tight. This phenomena is Often caused by the freezing of leakage about such parts as guides, hinges, and movable parts or joints. According to Mr. Burd, it is almost impossible to seal the gates so tight that there is no leakage whatever. "There is always some small leakage, and in the course of several months Of freezing weather this accumulates so much ice on the gates and so effectively freezes them.in position that to lift them is impossible without removing at least a part of the ice and doing some- thing tO break the seal." Remedies for Ice Troubles Explosives The use of dynamite or explosives in fighting ice conditions is Often necessary in sheet ice jams or in excessive formations of frazil ice. ,Mr. Barnes has experimented a great deal with the use Of ”thermit" in the place of ordinary explosives. His results can be summarized as follows: (See Refs. 12 and 20) Thermit is the trade name for an exothermo mixture of aluminum metal and iron oxide that is used ordinarily for welding. It attains a temperature Of from 2500 to 3500 degrees centigrade a few seconds after ignition, but only has a heat content of around léOO B.t.u. per pound. Although the heat content is low, thermit is very effective due to its extremely high temperature. Once ignited, the molten iron decomposes the ice (H20). The iron unites with the oxygen, liber- ating the hydrogen which burns in the free air causing a slow eXplosion which helps to further break the jam. The eXplosion mentioned is the slowest explosion known to Mr. Barnes. It is so slow that it is not injurious to structures in immediate contact, and it will not harm the fish in the pond or stream. Heaters and Blowers One method Of fighting ice at the gate prOper is the installing of an electric or a steam heater, supplemented by an air blower, in the gate. Unless the gate is housed in, this method is not economical as large quantities of heat 17. are lost. This method is quite applicable to Tainter, roller, and sector gates. It seems as if it might be used successfully in drum or pontoon gates, if not already ried. If a steam heater is used, it is usually supplied from the power house heating unit, and does not require any Special unit of its own. The following are some remarks taken from a report of the Rational Electric Light Association. (See Ref. 13) 1. This method works well alone. 2. This method can be Operated (electrically) with 16.5 watts per sq. ft. of gate area, and maintain a temperature of better than 32 degrees fahrenheit. 5. Air circulation is essential for the economic use of the heat. 4. The gate must be housed in if not of a hollow type for the economic use Of the heat. 5. Where there is a series of gates, only the end gates and possibly a center gate need be heated, as the currents caused by these gates being Open, will soon have the other gates Operable. (This statement appies to all heating systems.) Heat Filaments and Heat Lines The installation of electric heating filaments or steam lines in the embedded parts, such as guides or seats, is Often a very effective method of combating ice hazards. This method is used where comparatively thin gates, such as sliding gates, are found. It is also applicable to bear trap gates, by installing the electric coils or steam tubes just under steel plates in the sides of the peirs along the lines that the gate edges assume in the most frequented winter position. (This is usually with the gate fully raised.) The coils or tubes are also very effective when installed in,or near the upstream and downstream base hinges, eSpecially the downstream hinges. The use of electricity or steam as above described is very effective in preventing the leakage from freezing on strategic parts. (Ref. 11) Compressed Air The use of compressed air to prevent ice from forming on the face of the gate is quite successful. The followixc, concerning the same, has been stated by Mr. Burd: F A.very slight current of compressed air next to the bottom.of a gate, of merely sufficient pressure to cause it to escape 18. will set up sufficient circulation of the water so that very little ice forms on the face of the gate. This is quite an economical and effective method, and has been used extensively on the St. Joseph River and on the henominee River. Both the equipment required and the cost of Operation are very moderate. This plan does not, however, keep ice from forming on the downstream face of the gate due to leakage past the seal." In the report in Ref. ll, there is mentioned the practice of electrically heating the air before it is bubbled out into the water. In a summary given in Ref. so, a method of using heated air from the generators is described. Also an A.S.C.h. report, found in Ref. 10, contains imformation on the use of warm compressed air for preventing ice-thrust. (Ref. 10 contains quite an extensive bibliography on ice conditions.) The H.E.L.A. report (Ref. lo) advises against the use of the compressed air system by itself, except in rare instances. They find that it is not sufficient to meet the situation except as an auxiliary unit to some other heating system. Ice Prevention by Orientation The following is from a letter from hr. Burd: "It makes a good deal of difference which way the gates face; that is, if the po d is on the northerly side of the gates then the gates get the full south sun and this helps in keeping them free from ice. Thus, the orientation of the dam warrents careful thought if it is to have an emposed gated Spillway." This is a good point to keep in mind if designing a power project, in a climate where ice must be contended with. Often in the preliminary survey several prospective locations are considered, and eliminated one by one until the best remains. If the stream.is a winding one, the direction of the sun plays an important part in the elimination of possible sites. Undersluices The prOper use of the undersluice is advantageous to a plant confronting ice conditions. If the inlet is well under the surface, it will not be subject to ice unless an extreme case of frazil is encountered. There are two reasons, usually, why a system.of undersluices should not be built to do away with all the other gates. First, 18 the high cost of the concrete form work; second, is the fact that such a system would require a very elaborate arrangement of floats and undergates to keep the water at a constant level. howa ever, the undersluice works well as a means of las ssing an ordinary amount Of wete while the gates are beir* freed from ice. This is a safeguard against a washout when high water uneXpectedly catches a plant with frozen gates. The Use of Chemicals Often a sli ght change in temperature can reverse conditions; that is, can destroy the ice just enough to m& e the ga es Ope‘able. This is eSpecially true with frazil ice. However, instead of raising the temperature by one of the aforesaid heating systems, it is found quite convenient, sometimes, to lower the freezing point. This is done by distributing certain chemicals over the ice around the gates. The following have been found to work quite satisfactorily in rotting the ice: sodium chloride, calcium chloride, calcium carbide, crude sulphuric acid, and crude hydrochloric acid. These chemicals can be use ed to a still better adve ntage if mi: {ed with sand or gravel before applying. This will draw the heat from the suns rays. (See Ref. 20) Chopping Out and "CraCxiing" In many cases it is imiossible to spend money on heating equipment, eSpecially if the plant is a small one. If labor is cheap and easily available, the gates can be kept chOpped out. In severe weather chOpping is necessary in a small amount at plants having heating systems. A.method of avoiding much of this undesirable labor is known as “cracking” the gate. The gate is opened a small amount and cracked free whenever the ice begins to get a hold on it. In severe weather this has to be done as often as once a day. The gates best adOpted to such procedure are the automatic gates as they require no eXpense or labor to Operate. Thus, the automatic gate, eSpecially the bear trap, fights its own ice conditions and is kept free to Operate without a lot of auxiliary heating equipment. Pafi' III Conclusion In this conclusion, the ice conditions and the methods Of combating ice difficulties will be classified, and a chart will be presented. This chart is for the purpose of helping the designing engineer make his choice of a gate, from the standpoint of added cost involved in overcoming ice difficulties. Conditions As stated before, the condition of leakage is always present. It ma< be cut down considerable by the proper use of such devices as felt or rubber seal strips, rubber compound in the hinges, or the "s aunohing rod." (Ref. 24) Thus, the possible ice conditions may be divided into two classes, both containing leaaage. They are as follows: I. The open forebay, including; Leakage Frazil ice Ancnor ice closed forebay, including; Leakage Sheet ice 3 5—. P (I‘ II. Combat Methods In the preceding part of this paper, 8 Specific methods of combating ice were presented. They will be listed below for the convenience of referring to them, and for eXpense comparisons. A ninth item will be added to the list for reasons to appear later. The eXpense that is under consideration is the added eXpense of fighting the ice, and not the initial eXpense of the gate and foundations. This added expense is of two types, initial installation cost of extra equipment, and Operation cost of this equipment or'any destructible materials. 1. Use of eXplosives Has Operating expense) 2. Heaters and blowers Has initial expense and Operating expense) 3. Heat filaments and (Has initial eXpense and heat lines Operating expense) 4. Compressed air 5. Orientation of dam 6. Undersluices ?. Chemicals 8. Cracking 9. Extra equipment to prevent formation of ice in valves, 21. (Has initial expense and Operating eXpense) (Kay or.may not cause extra eXp ens e ) (Has initial expense, and possible Operating expense if power driven undergates must be Operated) EHas Operating expense) Has Operating expense for non-automatic gates, but NO EXPENSE for AUTOLATIC earns) (Has initial eXpense and Operating eXpense) channels, and chamr bers Chart CONDITIONS OPEI FOREBAY CLOSED FOREBAY GATES Frazil Leakage a Leakage Sheet Anchor Non-automatic sliding gates 5 l or 4 3 4 Automati c sliding gates 8 l & 9 8 8 Bear trap gates 8 & 9 8 8 Non-automatic Tainter, sector, and drum gates 5 l or 2 5 2 Automatic sector and drum gates 8 & 9 8 8 Rolling gates 2 or 5 l or 2 2 or 5 2 or 4 r ._ (.23. The purpose Of the chart on the preceding page is not to point out which is the best gate to use. It is to be used as an gig in choosing a gate for a given project, giving due consideration to the added expense caused by the provisions necessarv for overcoming ice hazards. The numbers refer to the list of methods on pages 20 and 21. The gates used in the chart do not.make a complete list, but are sons of the most common types from the ice standpoint. The methods indicated for the various gates and conditions are suggested as to what might be the best under the circump stances. There may be exceptions there the suggested methods will not hold. Comments From the inspection of the chart, it can be concluded that in general automatic gates are best for closed forebays and non-automatic gates are best for Open forebavs. This is only so far as ice costs are concerned. There may be other costs, such as the cost of the gate prOper or the foundation, that would make it advisable to use a gate of higher ice expense. The orientation of the dam (method 5) may make it possible to Operate without extra methods for combating leakage. If the climate is not too severe and this is so, the arrangement as given in the chart will be some different. This should be considered when choosing the gate. Undersluices (method 6) can be considered as a precaution to be used with any gate for the more severe conditions. It therefore does not effect the choice Of the gate very much. It should be considered, however, before the final choice of the gate is made. The use of chemicals (mothou 7) does not effect the choice of he gate very much, but may be used to advantage in many situations with practically any gate. It is well to keep in mind that a combination of gates might be the solution to the ice problem at some particular location. It has been practice in some Of the hichigan plants to use a group of several Tainter gates. One or two of the end Tainters would then be housed in and heated. This of course is added expense, and it might be feasible when designing a project to install an automatic gate in place of an end Tainter. This principle might be applied to other situations. (The credit for this suggestion should go to Llr. Bu rd. ) r: '2 at). PART IV A.Eew.Automatic Crest Gate Operation and Discussion The purpose of presenting the following few pag es of discussion on a flew Automatic Crest Gate is mainly to illustrate a principle of automatic gating. For this reason the drawings are not detailed and contain just the necessary features to aid the discussion in illustrating the previously mentioned principle. The theory given is by no means complete, although it does give some idea of what forces must be considered in the design of such a gate. The gate as shown in Fig. 22, is a purely automatic gate. It should Operate entirely under its own power if prOperly installed and regulated. The water in the upstream.pond is always in contact with the underside of the piston. It is intended that the piston be of such a size that,when the pond level is at or above the Spillway crest, the pressure on the underside of the piston will raise the gate. The gate will then remain up until the pond level exceeds a predetermined elevation. This elevation is determined by adjusting an overflow box in the peir. When the water overflows into this box it exerts a pressure on the upperside of the piston by the way of an overflow pipe. This added downward force causes the gate to lower. The piston, on its downward journey opens the outlet cover. (fig. 23) The outlet pipe is smaller than the overflow pipe, therefore as long as there is overflow the gate will remain down and allow water to go over the epiliway. when the Iond has subsided a'ar in to the desired elevation, the overflow will cease. The wei gnt of the water flowing over the crest will hold the gate down until most of the water above the piston leaves the chamber throu h the outlet pipe.,At a certain predesi;.ned point the upward water pres ssure will (Uciu dominate and the gate will rise. It will rise all the way, deepite the small amount of water remaining in the overflow pipe, because as it goes up the weight of water flowing over the tsp of the gate decreases, thus lessening the total of the downward forces. (When the piston goes up the outlet cover Springs over the outlet, thus preventing the water under the piston from leaving the challber.) The tendency of the ga t: is to keep the pond at a desired elevation, which is usually at a point on the same level with the tOp of the ate when it is up. FIG. 22 L714 pi?!" Sic/”wait C reef Dawn arr-em V 1.. 34.; “Na. I h:v v': .;- ., :- ”Lat/#2! ,Pipe ’,-' .,.,_ v.4. 3£crlo~ ”(ROUGH SPILL my 0F Ms-v AyronAr/c Clear GA TE FIG. 26’ ..0. 0-.“ -’ 0-...-. ‘ “.3111: ooooooooooooo c .04 o a no--- on 9. .:’.':Im. “—— ..---...-...---.-...-.--.. . -....-.-. ........ --- -.-..-.-. 1 Outlet -——-.=r—t 1 1‘ L‘j—q ‘ a: Curb)“ Ca var Sprinf .9 - 3v ‘ ' ” - I 1 " ‘-‘.‘7" ’. s." :~v ~¢ 'f-s’.‘o “’34.. "¢;?£.l\ ((1 1:“ ¢ ’1 ,I ‘l‘ I 0‘ ~‘, ’. ,51 f a. .‘. ‘2‘: “‘- VA ' r . . . - ‘ ' ' '43:! 3'» '~ r" v ' v . . fa," - ~~ *‘ ~. L‘. '9 Q I J ‘0‘ l a ~~J ( ’ fl v (0 61.0.5: - up VIEV of PISTON . CHAMBER “it. Theory Key to Symbols 3 = fieight of gate, piston, and rod in lbs. - 'fieight of gate in lbs. ‘3 Area of gate in sq. ft. :- d’eight of rod in lbs. 2 Weight of piston in lbs. Friction of gate, piston, and rod in lbs. F U - a e pm; I ‘4 .- ‘e "01"” riction of gate due to water pressure in lbs. pward water pressure on piston in lbs. 8 Diameter of piston in ft. = .head on piston when up in ft. 8 Distance gate moves in ft. = Weight of cu. ft. of water in lbs. T Downward force due to Spill-water in lbs. 3 Downward water pressure on piston in lbs. hlz head loss in either pipe in ft. rrs Radius of piston rod in ft. (2"th _, $13634 \ - - - .- Condition of Raising Gate The minimum U (Umin) which must raise the gate is when the pond level is even with the Spillway crest. The greatest U (umax) is when the pond level is even with the tOp edge of the overflow box. The latter condition is the one to design for as the downward forces to be overcome are greater due to the weight of the water flowing over the gate. Therefore the condition necessary to enable the gate to rise when the pond is at the desired level is: ® Umax > w +Fmax+ fmax + imax + hl Condition of Keeping Gate Up When the gate is held at raised position, the only downward force is W, and the only upward force may be as .9 Therefore' U “'1' fldgba 1' ‘ ° min > a + 4 'n’dgba (2) Or: may“. 2 .'"~ f“ an, Condition of Lowering Gate ahen water begins to overflow, the force H is aided by the new force D and the gate lowers. The ouposing un- ward forces are U,F,f, and h—. The condition for lowerinr . ._ J. c.) 13 therefore: "' + Dinin > bmin+ ”max + fihéix +111 0 H” T“ "1 J ‘ @ OI" fl + ”max > U, + ”max + inax +111 (Individual forces will be explained later.) Condition of Keeping Gate Down The for es tending to keep the gate down are w and T. The only upward force is U. Therefore the condition is: Cy? -. 7-.“ v “I + Jhlr‘,‘r + *l‘lw’: > Um,“ ‘- 1 0 fl ' ' ‘ ’ {P r (a ‘7 K . ' - ' . fir @ O . ‘43 b > Uiflwx " *IJAWI 8- Suamary of Conditions In order to haVe a date which will operate in the right way, the four conditions of expressions 1,3,5, and 4 must be satisfied. It is obviors that a value of Umax: large enough to satisfy eXpression 1, will be large enough 7“ for CXQIGSSiOH 2. Likewise the value of eaax must be found from eXpressicn a in order to satisfy both expression 5 and eXpression 4. The upper area of the piston is smaller than the under area because of the piston rod. Therefore: Unlax . D‘nax'ffil‘rh’l4' (3)8. Substituting for Umax in eXpression 3: W 'l’ D” a d 7 fl . _ ~ map}; > #11318); +flrr(fl+b)d+ FJHELX". fma}:+nl Therefore: @ w ) FineJL+fn1-"‘ +hl+ur§(11+b)a This condition will obviously be so unless the gate Q L“. is counte wei 5hted. Therefore, if the value of Umax satisfiesI empression 1, all four expressions will oe satisfied. (Expression 5 sets a very definite limit on the use of the counterweight.) In order to ev luate Umax. each of the terms on the right must be determined. Apparently this is not too simple a matter and requires much of the design detailing. Therefore the terms will only be discussed briefly in this paper. The Weight (W) The weight of the 5&te depends on the type ofb ' ate used.Tnis wei:ht can be accurately figured when the :ate is detailed. For a rough estimate, the formula for Stoney gates given in Ref. 21 may be converted to the english system giv1n5= the weig ht in lbs. wg-= 24.2A‘+,0448A‘ The weig ht of the rod is easy to determine when the length is known and the approx Aimate load on it has been found. An empirical formula would perhaps be some constant times some power of the length: Wr ‘3 k(h"’ b)x The weight of the piston will perhaps have to be assumed, as the diameter of the piston is still unhnown. This weight varies as a constant times some power of the piston diameter: - X I; := lid ‘9 The total of the downward weights is: W = wgcrwr-+wp The Friction (r) This friction is due to the piston rings, the rod éguides, and the gate seals. It cannot be figured very Jclrmely'until the design has been detailed. If assumed, it sfldould not be more than a few hundredths of W, as the :frictional forces are parallel to the wei Dnts. Careful ciesign and constrution should practically eliminate this force. (F) The Friction (f) rnn ' .fl .7 1 ' ° i, ". ' 4.‘ .. . .—. A lulo friction is one to the pressure or the water against the gate. It varies with the amount of gate area 7“ J . .3 .,,__ J- 5‘ .. '- ,, "‘ -,\_..‘ ,- -.,,A.. , .. --.\l -r' .r . 8.}.LJEDSCC. t0. tAL. QWC‘LI. #1143“ Stone; iJiJC QLLLU 1“,“leg Li. roller train, it snoald not exceed: 1" r- . 01w Hater Over the Gate (T) This force varies from zero to one of considerable magnitude. It is Quite inportant in Operating the gate. It is greatest when the gate is down and the water has just ceased cveri‘lo.'.'ing into his overflow pipe. T is equal to the weight of the ;ajxxrcrirectly over the gate, therefore the thichness of the gate is quite important. Obviously, T cannot be determined until the length, thichness, and rise of the gate are known. The head Loss (hl) The head loss of a pipe varies with the sguare of the velocity. The velocity need not be very hisn to Operate this gate, therefore the loss should be very small. With a good choice of pipe sizes, the loss should be less than .Oth., and therefore could be neglec ed in the design of the piston. ' 1 "I' .4- "I rw-i. 1 " YT The Upward water Pressure \o) This pressure is due to the hydro-static head of the pond. It is a maximum when the gate is down and decreases as the gate is elevated. A little study of r15. he will bear this fact out. The formulas for Upax and Umin are: fld2(h +b)a Uhax a fidaha U 1.“: ml“ 4 All the values-except 'd” can be determined along with the terms on the right side of eXpression l. There- fore"d"can be solved for. Remarks on the Kew Automatic Gate At many installations of automatic crest grtes of the Stickney type, the available head is greater than that used to Operate the gate. This requires a very large surface to apply the pressure to. In the new gate just presented, this area is reduced considerably by the use of a long red and a piston which make use of most of the available head. There- fore for high head (30 to ldoft.) develOpments, the new gate should be economical as the piston would not have to be so verv large. The new gate as shown, should work quite well in a dam such as the Calderwood Dam.(?ef. 1) It should not cost more and perhaps not as much as it eliminates two gantry cranes and their accessories. The present set-up at the Calderwood Dam requires two or three hours to Open or close all the gates,and uses considerable power to run the cranes. This new set-up would mahe it possible to Open or close all the gates in a few minutes, and would require no power other than that furnished by the water itself. The new gate as shown in Fig. as would not be very economical for very low heads. (50 ft. or less) The reason is that it would require too large a piston. However, if an arrangement of counterweights is added, the size of the piston would be greatly decreased, and the gate will have a more practical aspect for low heads. This addition of counterweights requires quite a little study to determine just what they should weigh. (See eXpression d) The additional eXpense for form worh required for the New Automatic Crest Gate should not be ery great. The work consists of a rectangular tunnel, some gate pits, and channels in the peirs. The pipe can be laid with the concrete. Of course the strength of the dam.must be considered before designing such openings in it. For this reason the whole idea might work out better in a hollow dam. Comparing the cost of the new gate with other gates, both automatic and non-automatic, would be quite an under- taking, and is out of the question in this paper. The new gate, however, can be placed in the class of the other automatic gates, and is thereftre advantageous for ice operation due to its ability to "craoh." (Adxiliary valves on the -inlet and outlet pipes would make the gate Operable in a similar manner to the bear trap gates.) It may be possible to adapt the principle of the “piston“ to the modern Tainter gate. A simple sliding con- nection of some sort would be necessary to permit the red to move vertically while the gate swings in its arc. The overflow pipe and mechanism could be abolished if desired, and the gate Ope“ated by the previously mentioned auxiliary valves. 1 Thus, if the principle of the ”pispon" is wcrhatle, it will make possible an automatic Tainter gate. By the use of the auxiliary valves, a minimum amount of added equipment is necessar:. This added equipment may not cost any more than enclosing a Tainter gate and installing a leatin; device. With such an automatic gate the advantages of a Tainter gate may be had, ice may be overcome by the costless Operation of "cracking," and power or labor will be saved in Operating the gate. m- ,.'. —-‘\v-‘ ran .31.“) Reference Number l. 10. ll. 12. 13. P ,. \c'. 17. 18. 13. BIBLIOGRAPHY Subject batter and Source Types of Gates Used on Dams in EurOpe Power v75n23 pp852—853 Gate Handling at Calderwood Dam hngineering News Record v106n19 pp754-757 Bear Trap Gates ,A short discussion of the theory and design giving the various types, their history and advantages. Engineering hens Feb. 1895 Text "Design and Construction of Dams" by Wegmann 8 n edition Section of book on Movable Dams BOOK contains a very complete bibliography. Ice Control at Power Plants .d short sum- mary of ice remedies containing a very complete bibliography. A.S.C.E. Transactions VJS ppllSé-llél heating Gates hetnods used where conditions are quite severe. Engineering Record v70 p691 Thermit Announcement Power v65 p531 Ice Cont‘ol at Power Plants {A very complete report of the N.E.L.A. Power Plant Engineering vfiunG pp366-568 Text “Ice Formation" by H.T.Barnes A good physical treatise on ice. Thermit and Ice Jams _ Examples of blows with discussion. Franhlin Institute Journal v203n5 ppSll-d54 Larshall Bear Trap Gates Engineering News hay 1893 p542 Automatic Plashboards Engineering Record Larch 13oz Lake fiinnibigoshish Dam Reversed Parker Engineerin; Record September 1J0; Bear Trap and Drum Gates A very complete discussion in 7 articles of automatic gates, giving complete history and theory. Journal of Association of Engineering Societies June 1%36 pprV-zol Thermit and Ice Relief Short review of thermit and other chemicals for rotting ice. Power Plant Engineering v3nn13 pp75d-757 Gates in General Worlds Power Conference Reports 350 for 1926 Reference Eumber 22. BIBLIOGRAPHY Subject hatter and Source Ice Troubles .A good summary. Power Plant Engineering v30n24 pplz4l-1542 Counterweignted Gate Engineering Record June 1926 Classification of Gates -Fargo Suggestions on heating, counterweighting, and sealing. Municipal and County Engineering v58n4 pp157-159 Floating Crest_Gates Siphon sector Sate. Engineering News Record January 1918 heedle Dam Engineering News July 1898 Text "Water Power Engineering” by H.K.Barrows A.very modern chapter on gates. Davis Island Dam Scientific American Supplement August 1891 pp12985-12984 ' Sandy Lake Dam. Reversible Lang gate. Engineering Record February 1895 IIIHH “I" I“ l‘ V H III 1 5 8 9