US1067491A - Water-meter. - Google Patents

Description

J. E. SIMMANGE E J. ABADY.

WATER METER:

APPLIGATIO'N'LED JULY 26, 1910. Y

:L-@679 9L Peltenteclv July 15, 19113 lSuppose now that the waterlevel rises to the level P1 Q1, slightly above the level P Q, then, using the usua mathematical notation, letd A be .the'small'increase P P1 Q1 Q of the submergedarea, and let d 71,v -be-the small increase'Q Q'1 of the head. Then, by a formula well known in the differential calculas, from the above equation is immef 4diately deduced f placediby a'curve P3 P4 P5 so chosen that equation. yIt will be seen That is, i the breadth of the weir is inversely proportional to the square root lof the corresponding head." AThe curve Po PP,

is the graphic representation of the above that the curve is asymptotic to the axes .0 B, and O HQ That is, if the bottom of the, weir were a horizontal` straight line O B, theoretically, its ,Widthat the bottomv would be infinite. .But in practice a Weir isv never' required to measure a zero rate of discharge, but the capacity of the Weir may-be. specified to be from its maximum ratev of discharge to a 'minimum rate of discharge, whichmay be 10, 20, 40, 5 0 per cent. of the maximum, as

, the conditions may determine. Thus, if the capacity of the Weir is specified to be from its maximum vrate of discharge tol a minimum of 10 per cent. of the maximum, the water level may Vvary from the maximum P2 tothe lminimum P8, Fig-1. The portion n of the curve P3 P0 may therefore be 'rethe discharge is the 'same as given by the theoretical curve.

.- Theoutlin'e of the Aweir as described above and illustrated in Fig. 1, would be mathe- Amatically correct if the co-eiiicientsof discharge were 55,;.tice however,"it is found that thecoeicient absolutely invariable. *In pracof discharge varies slightly if the shape'of the issuing jet of water varies- It may therefore, be necessary to alter in a very slight degree the outline of the weir as above described to'counteract'the eHect of the variation of the co-eilicient ofdischarge. Any

necessary. correction would be determined experimentally.A Thus, if for values of the head greater than the minimum, the ce eicientof discharge (and therefore also the constant K) is found to increase slightly, the eorrespondingwidth at the surface level may be slightly decreased as compared with. that determined bythe above formula. li for still greater values of the head the ce efficientof discharge is found ie decrease. the corresponding width may be increased.

Butitis to -baobserved that for a Weir whose minimum discharge is 0.20v times the maximum, and whose shape 1s exactly that determi-ned bythe'formula, the greatest 'eriror may be` less -than one per cent. The weir .may be made Lsymmetrical about a vertical axis as shown in Fig. 2, or may have'one side a straight line, or again, one side. may be made to any convenient outline and the other side to an outline' vdeterniined by cutting ofi the `widths corresponding to the heads. 'as above described. Also the '.Weir may be made from two plates secured together by suitablefastenings. The said fastenings may be made so that the two plates are capable of slight adjustment reia tive to each other, lthe said adjustment roviding means for the final calibration o.` the Weir. Such a construction is represented in Fig. 4, in which the two plates composing the Weir-are denoted by'l and 2;' the said plates being adjustably secured together by bars 3, 4, provided with slots 5, fitted to re.- ceivecap screws 6,' threaded into the plates l and 2.

If the weir be formed in or fixed to the side or a4 suitable tank 7, and a fioat 8 be Aplaced on the liquid in the lupstream side ci' the weir as shown in Fig. 3 of the drawings, and the vertical movements of the iioat be recorded on a sutablc'chart or recorder Q driven at a uniform rate by clockwork, the horizontal divisions will represent units c? t-ime,and the vertical divisions, rates of diecharge. The area of the diagram inclosed by the datum line of the chart and the line drawnthereon by the float pen and the two extreme vertical ordinates will, during any period of time, be strictly proportional im the :quantity 4oiwater discharged during that time although the heacl may vary ce siderably duringtha-t period of time.

It is to be clearly understood that a ie l cording apparatus of the character described ilor is u ell known and has been proposed for use with weirs of the class referred to above, and therefore we make no claim to such. recording apparatus apart from its use in cou-- junction with Athe form of Weir which is the subject of the present invention.

What we claim is:

A water meter provided with a Weir notch having its width at the bearing surface level of the liquid between the maximum and minimum heads inversely poportional to 1n tesxmony whereof Weax our signatae squar@ 'mot of the conjesponding' head, tures in prese-nce of two witnesses;

its bottomfdge 'beow 'the datum level and JNO. F. SMMANU.- iislower pa beow the minimum level, l JACQUES ABADY. whereby thaxates of ischage Within the l fit-messes: maximum 'and minimum capacit-lss of the CEGIL ARTHUR GOQDWIN, notch Yae poportina abe heaf JAMES FOREMAN.

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