DE2424454C3 - Measuring plate for measuring the water flow by means of an overflow weir - Google Patents

Description

The subject of the invention is a measuring plate with a triangular cut-out as an overflow weir in open areas Channels and channels are installed and used to measure the flow

According to ISO recommendation No. 1438, the flow rate for the weir measurement is as follows Calculate equation:

= Ce .A

Experiments showed that Ce is a function of h ρ
-; Yy

It means:

Q = flow rate in mVh

Ce = runoff coefficient

g - acceleration due to gravity in m / s ²

λ = opening angle of the triangular section

Ac = h + Kh - effective water level in m (in front of the weir)

Kh - constant coefficient «0.85 mm
A = water level measured at the weir in

m
ρ = height of the apex of the triangular section above the base of the inlet channel

B = ' Width of the measuring plate or the channel
Λ ™, «= · maximum possible water height at the weir in m himn = T

The object of the invention is to design a measuring stick with a triangular cutout from which smaller measuring plates with the same Ce width for hmax can be manufactured in the simplest possible way For example 90 ° is provided and that on both sides of the triangle tips several parallel vertical marking lines that are equidistant in pairs to the triangle tips are attached, which are bounded in pairs by a ίο horizontal marking line so that the marking lines form differently sized U-shapes symmetrically to the triangle cutout, which are geometrically similar are.

It is thus achieved that the ratio values of
J ₁ Td

or - and - ^ -
PPB

and the angles cc are the same for all measuring plates and therefore the Ce values are also the same.

Corresponding to the respective channel width, this standard measuring plate is now placed on a U-mark cut out a smaller plate.

The width of the U-markings is graded according to the channel widths that usually occur.

The measuring plate can also be used for any intermediate values of the channel width using the U mark can be cut so that the Ce value is the same

When manufacturing panels made of plastic, the geometrically similar U-markings can be used in Pressing or spraying the plates can also be embossed.

In addition to the metrological perfection, the measuring plate according to the invention has the advantage that the

j5 Storage costs at the manufacturer and user are reduced, since you only need to keep one measuring plate in stock.

In the known methods of weir measurement, the water height A _c is measured at a distance of 3 to 4 h _mas upstream in front of the measuring plate, outside the area of the lowering of the surface, in order to correctly record the flow according to the ISO recommendation.

In the embodiment according to the invention, taking into account the lowering Kh, the measuring scale for the flow is attached to one or both edges of the triangular section, so that the surface of the water flowing past serves as a pointer.

The measuring plate can be installed in the duct with

■ so be surrounded by a border frame, the opposite the canal is sealed by an inflatable rubber tube inserted all around the outside.

The invention is to be explained in more detail with the aid of the drawing.

F i g. 1 shows the geometry of the measuring plate,

F i g. 2 shows the measuring plate installed in a drainage channel,

F i g. 3 shows a built-in measuring plate with a longitudinal and cross-section through a drainage channel.

Mi The measuring plate 11 has an isosceles Triangle section 12 from 9C °. Symmetrical to the triangular cutout are in the plate 11 vertical Marking lines 13 and these pairwise delimiting horizontal marking lines 14 introduced. The so

The U-shapes formed in h5 are geometrically similar; the along the U-shapes cut out smaller measuring plates all have the same Ce-Wertc in one Water level of A ",,".

i g. 2 is the measuring plate 11 with a mount 15 surrounded, in whose isosceles hamming 16 it is held rather sealing strip 17 or a round one. The outside of the frame has an all-round V-cutout 18 into which an inflatable hose 19 is inserted When inflating presses; r rubber hose between the frame 15 and the channel walls 20, 21 and thus causes a secure seal. The frame 15 or the measuring plate 11 on a walled-in channel projection or in lateral recesses in the channel walls 20.21 must be held.

In Fig. 3 shows the built-in measuring plate in a channel in order to show the meaning of the variables Λ « h, h _m2X , Kt, and T.

For this purpose 2 sheets of drawings

Claims (4)

Patent claims: 1. Rectangular measuring plate with isosceles triangular cut-out, used as the upper drop weir for measurement of the flow in open channels and the one opening angle of the triangular section of, for example, 90 °, characterized in that that on the measuring plate on both sides of the triangle tip several parallel, in pairs to the Equidistant, vertical marking lines (13) are attached to the apex of the triangle, which are marked in pairs by a horizontal marking line (14) are limited so that the marking lines to the triangular cutout (12) Form symmetrically lying, differently sized U-shapes that are geometrically similar. 2. measuring plate according to claim 1, characterized gekennreichnet, that it is made of plastic and that the U-mark when pressing or spraying the Measuring plate is embossed with 3. measuring plate according to claim 1, characterized in that one or both edges (22) of the Triangular section (12) are provided with a flow measuring scale, so that the surface of the flowing water at the edge of the weir serves as a pointer. 4. measuring plate according to claim 1, characterized in that it is provided with a mounting frame (15) is surrounded, the outside of a circumferential, inflatable to seal against the duct wall Rubber hose (19) carries