DE2424454B2 - Measuring plate for measuring the water flow by means of an overflow weir - Google Patents

Description

The subject of the invention is a MeQplatte with a triangular cutout, which can be used as an overflow weir in open 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:

Experiments showed that Ce is a function of h ρ,.
-; gunda is.

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

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

Kh = constant coefficient «0.85 mm
h = respective water height 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
hmax = maximum possible water height at the weir in m hmax = T

The object of the invention is to design a measuring plate with a triangular section from which = - or L and
p ρ

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

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

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 Storage costs for the manufacturer and user are reduced because you only have one measuring plate in stock needs to hold.

In the known methods of weir measurement, the water height h _e is measured at a distance of 3 to 4 h _max upstream in front of the measuring plate, outside the area of the lowering of the surface, in order to correctly record the flow in accordance with 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.

For installation in the channel, the measuring plate can 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,

Fig. 2 shows the measuring plate, built into a drainage channel,

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

The measuring plate 11 has an isosceles triangular section 12 of 90 °. Symmetrical to the triangular cutout, vertical marking lines 13 and horizontal marking lines 14 delimiting them in pairs are introduced into the plate 11. The U-shapes formed in this way are geometrically similar; the smaller measuring plates cut out along the U-shapes all have the same Ce values at a water height of h _muK .

3 4

In FIG. 2, the measuring plate 11 is provided with an edging for the channel walls 20, 21 and thus causes a safe

frame 15 surrounded in its isosceles seal. The frame 15 or

Recess 16 it is held.

elastic sealing strip 17 or a round jump or in lateral recesses in the duct walls

purring. On the outside, the frame has a circumferential 5 de 20,21.

fenden V-neck 18, in which an inflatable In Fig. 3, the built-in measuring plate is in a channel

Rubber hose 19 is inserted When inflating presses shown to the meaning of the sizes A _n h, hau * Kt

the rubber hose between the frames 15 and and T to show.

For this purpose 2 sheets of drawings

Claims (4)

Patent claims: 1. Rectangular measuring plate with isosceles triangular cut-out, used as a top weir for measurement of the flow in open channels and the 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 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 in that 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 Smaller measuring plates with the same Ce value for JW can be manufactured in the simplest way. This object is achieved according to the invention in that the weir measuring plate is provided in a known manner with an isosceles triangular cutout of, for example, 90 ° and that on both sides of the triangle tips several parallel, in pairs to Triangular points equidistant vertical marking lines are attached, which are bounded in pairs by a horizontal marking line so that the marking lines form symmetrically lying differently sized U-shapes to the triangle cut, which are geometrically similar.
It is thus achieved that the ratio values of