JPH0723853B2 - Liquid flow measuring device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a measuring device for use in measuring liquid flow,
More specifically, it relates to a flow measuring device arranged in the inlet conduit of a sewer manhole.

BACKGROUND OF THE INVENTION A large amount of money is spent each year for public efforts to isolate and reduce the heavy inflow of water into sanitary sewer systems. For many years, technical experts in this field have taken accurate and temporary measurements of sewage from sub-regions of the entire sewer system as the problem with the most serious inflow problems. We knew that it would be the most costly means of measurement to make.

As is well known in areas experiencing severe water inflow problems, it is common for sewers carrying sewage to operate under excess conditions during and shortly after rainfall. Unfortunately, it is almost impossible to obtain accurate flow rate data under the above conditions. The use of rudimentary flow measurement devices such as weirs and flumes to convert flow depth to flow is usually impractical for a variety of reasons. For example, the weir is accompanied by sedimentation on the upstream side and is polluted by rock fragments and the like. The measuring device according to these has to be made to fit the physical shape of each individual manhole and is difficult to adjust and correct under excess conditions.

Troughs such as the Palmer Bowlus flume and other Venturi flumes are generally imprecise at depths upstream of the flow exceeding 75% of the sewer diameter and cannot be used under excess conditions. An alternative is to measure the head loss (typically a fraction of an inch) between two manholes, using the Culvert and Manning laws to calculate the net flow. Naturally, this method would require making flow depth measurements in two manholes instead of one, thus doubling the cost of fluid measurement and uneconomical.

During the last decade, the design techniques of devices for measuring, recording and storing liquid flow depth (or pressure) information have evolved significantly. However, the flow depth or pressure is accurately converted into a flow rate under both open groove conditions that show free water flow and pipe conditions under which the pipe is completely filled (hereinafter referred to as full pipe excess condition). Nobody has developed a rudimentary sewage flow measurement device that can be carried in and installed.

[Problems to be Solved by the Invention] Generally, in the present invention, the inside of the sewer pipe is completely filled and flowed under the open groove condition in which the sewer system shows a free water flow below the complete depth. It is an object of the present invention to provide a device capable of measuring the flow in the sewer system under any condition where the manhole is submerged. It is another object of the present invention to provide a flow measuring device which can be carried in and installed in the sewer adjacent to the manhole temporarily and quickly. It also seeks to allow buoyant sewage solids to be carried through the device when the device is used under open channel conditions with free water flow. Furthermore, it is an object of the present invention to provide a flow measuring device capable of measuring with a relatively small head loss for forming the hydrostatic pressure difference used for calculating the flow rate.

Other objects and features of the present invention will be apparent from the following preferred embodiments described in detail with reference to the accompanying drawings.

In the device of the present invention, the outer surface is cylindrical so that it can be placed in the inlet tube, whereas an inflatable collar surrounds the cylindrical outer surface of the device, Is placed in the inlet pipe, and when the inflatable collar is inflated, a seal is provided between the portions to allow flow into the sewer through the device.

The inner surface of the device has a flow velocity through the device under open groove conditions that indicates a free water flow when the sewer pipe is partially filled, and the depth of water flow (hydrostatic pressure) at the upstream inlet part of the device. Is formed so that the relationship between and can be detected. In addition, the inner surface of the device has a hydrostatic pressure at the throat crest that limits the water flow of the device and a pressure at the upstream inlet part of the device under conditions where the pipe in which the device is installed is completely submerged in the water flow. It is formed in such a way that the difference relationship between hydrostatic pressure can be detected. Thus, flow data is obtained by known means using the relationship between hydrostatic pressure and flow rate.

Embodiment Referring to the drawings, FIG. 1 shows an embodiment of the present invention used for wastewater flow measurement including a cylindrical body 1 provided with an inflatable collar 2. The outer surface of the body 1 is cylindrical so that it can be placed in the inlet tube 3. The cylindrical outer surface of the body 1 extends over the entire length of the body 1, and the body 1 can be joined along a vertical plane perpendicular to its axis, from a sewer manhole 16 of normal diameter. The device can be inserted into a large sewer. Body 1
Has an annular groove that supports the inflatable collar 2. The inflatable collar 2 has a valve 4 and a valve stem 5 through which gas for inflating the inflatable collar 2 passes. The flow of water through the device passes through a tubular venturi member 6, which comprises an inlet portion 7, a constricted outer diameter throat portion 8 and an outlet portion 9.

As shown in FIG. 2, the shape of the throat portion 8 is circular or polygonal on the surface in the cross-sectional direction orthogonal to the direction of the sewage flow. The space between the cylindrical main body 1 and the venturi member 6 is hollow, the main body 1 is made of a porous material, and air or liquid enters the space between the main body 1 and the tubular venturi member 6. It's designed to allow you to come and go. The holes may be of any size, shape, number, etc., as long as the structural integrity of the device is not compromised. The space between the body 1 and the tubular Venturi member 6 is filled with a granular solid material. The solid material may be of any type or composition, as long as there are at least a large number of voids between the granular solids.

In achieving the objects of the present invention, the term tubular venturi member shall serve the function of the modified venturi flume and also the complete sewer when the sewer in which the device of the present invention is installed is running at less than full flow. Means a device that fully fulfills the function of a Venturi tube when filled and flowing. The term tubular venturi member also refers to (1) acting on the device to maintain its measuring function even at low liquid flow rates, and (2) at approximately the same flow rate as when the upstream tube is filled with liquid. Throat part 8 confined to be filled with
Means a device with a constriction that satisfies the requirement of maintaining its measuring function during the transition from the open groove to the full pipe flow.

The modified Venturi flume creates a flow at the precise depth in the open groove near the constricted throat portion 8 due to the constriction in the open groove, and the depth of water flow and liquid flow in the open groove upstream from this constriction. It is technically possible because it is known that the proportions are distributed so that there is a relationship between them. Further, the tubular Venturi tube 6 forms a constricted part in the closed pipe, promotes the fluid flow in the pipe and lowers its hydrostatic pressure, and (1) the hydrostatic pressure of the liquid flow upstream of the venturi pipe and the liquid passing through the constricted part. It is also technically possible to make a ratio distribution such that there is a given relationship between the difference between the hydrostatic pressure of the flow and (2) the liquid flow rate.

A flange 10 is formed on top of the outer surface of the cylindrical body 1 and a level indicator 11 is supported on the head of the flange 10. The level indicator 11 has a bubble level type with a cross line for indicating the level of the base of the level indicator 11 with respect to a horizontal line perpendicular to the axis of the main body 1. The level indicator 11 has a reference line parallel to the bottom surface of the throat portion 8 when the throat portion 8 has a polygonal cross section, and a throat portion when the throat portion 8 has a non-polygonal cross section. 8 is oriented to provide a reference line parallel to a horizontal line tangent to the bottom surface.

The sidewalls of the tubular venturi member 6 are formed by vertical plates connected to the inner surface of the body 1 such that the inner surface of the cylindrical body 1 forms the top and bottom walls of the tubular venturi member 6. . In this embodiment, the side wall of the tubular venturi member 6 looks like a chord that is perpendicular and parallel to the cylindrical wall of the body 1 when viewed in a cross section taken perpendicular to the axis of the body 1.

A pressure sensor 12 is supported below the inner surface of the inlet portion 7. The pressure sensor indicated by reference numeral 13 is supported by the crest of the throat portion 8. From the standpoint of achieving the object of the present invention, the term crest shall mean the top or the crown or the vicinity thereof.

These pressure sensors 12 and 13 are piezometers or piezoelectric type pressure transducers.

Referring to FIG. 3, the pressure signals from the pressure sensors 12 and 13 are transmitted via the channel switching conductor 14 to the signal converter 15.
Be transmitted to. The signal converter 15 converts the signal into a flow rate and stores the flow rate data.

A known mechanical device is used as the signal converter 15. It is known that a bubbler type mechanism can be used to convert the difference between the hydrostatic pressure at the inlet and the hydrostatic pressure at the throat portion 8 of the tubular venturi member 6 into a liquid flow rate. It is also known in the art that a bubbler type mechanism can be used to convert the hydrostatic pressure at the inlet to the Venturi flume to a liquid flow rate. Bubbles are emitted from the end of the tube immersed in the liquid by the bubbler type mechanism.
A bellows or the like is used to measure the pressure required to maintain a predetermined amount of bubbles. The pressure is proportional to the depth at which the end of the tube is submerged. The differential pressure, or the difference between the two pressures, can be sensed by measuring the deflection or movement of the bellows diaphragm with one pressure exerted on each side of the diaphragm. The hydrostatic pressure of the throat section 8 is the same as the ambient air pressure until the throat section 8 is filled with liquid. In this embodiment, the flow rate is measured and the flow rate is mechanically transferred to the means for recording these data. The recording means is
Includes ink pens and paper charts or needles and pressure sensitive charts.

The signal converter 15 can also use a known electronic device. It is known in the art that piezoelectric devices produce an electrical signal proportional to the pressure acting on them. In addition, a digital integrator circuit calculates the flow rate intermittently and is provided with a hydrostatic pressure at the inlet of the Venturi Flume meter and / or a differential pressure across the Venturi tube, which is programmed to be stored in electronic memory. What is possible is also known in the art.

[Operation] Returning to FIG. 1, a portable wastewater flow measuring device supported again in the sewer will be described. A cylindrical body 1 with an inflatable collar 2 is inserted in the open end of an inlet tube 3. The body 1 is rotated within the inlet tube 3 until the flange 10 is at the relative level, as indicated by the level indicator 11. A gas pressure source is attached to the valve stem 5 to introduce gas through the valve 4 into the inflatable collar.

In this embodiment, the inflatable collar 2 is inflated and bulges between the cylindrical outer surface of the body 1 and the inner surface of the inlet tube 3 to hold the body 1 in a fixed position, Provides a liquid tight seal between.

As shown in FIG. 3, the channel switching conductor 14 is
The main body 1 is connected to a signal converter 15 which is temporarily fixed to the top of the wall of the manhole 16. The pressure signals from the pressure sensors 12 and 13 are transmitted to the signal converter 15 via the channel switching conductor 14. The signal converter 15 calculates the liquid flow rate, but the pressure signal is used to store the flow rate data.

As described above, the portable wastewater flow measuring device for installation on the pipe at the entrance of the sewer manhole is disclosed.
Liquid flow measurements can be made by taking measurements between sewers adjacent to a sewer manhole under both open channel and full pipe conditions, which show free water flow.

The embodiments disclosed above are merely illustrative and not restrictive, and the present invention should not be construed as being limited to the particular forms disclosed herein. It is intended that the invention encompass all of the various modifications of the embodiments of the invention that have been selected to achieve the objects disclosed herein, without departing from the spirit and scope of the invention.

EFFECTS OF THE INVENTION The device of the present invention is superior to the prior art in that floating solids are carried through the device under free water flow conditions but do not affect the accuracy in liquid flow measurements. is there.
The device of the invention also has an improved function over the prior art in that the location in the manhole where the device is installed extends above the sewer crest where the device is installed,
The flow restricting surface of the device is not permanently fixed to the wall of the tube, is provided in a compact shape, and a piezoelectric pressure transducer can be used to sense hydrostatic pressure by any of the bubbler pressure sensing mechanisms. It is an improvement over the prior art.

[Brief description of drawings]

1 is a schematic longitudinal side view showing a portable wastewater flow measuring device according to the present invention installed in a sewer manhole, and FIG. 2 is a schematic end view longitudinally taken along line II-II in FIG. FIG. 3 is a schematic vertical sectional side view showing a sewer manhole in which a carry-in sewage flow measuring device is installed. 1 ... Main body, 2 ... Inflatable collar, 3 ... Inlet pipe, 4 ... Valve, 5 ... Valve stem, 6 ... Venturi member, 7 ... Inlet part, 8 ... Throat part, 9 ... Outlet Portion 10 …… Flange, 11 …… Level indicator 12,13 …… Pressure sensor, 14 …… Channel switching conductor 15 …… Signal converter, 16 …… Manhole

Claims (2)

[Claims] 1. A pipe-shaped Venturi member is provided in the conduit in such a manner that the liquid is freely passed through the conduit while the conduit is blocked, and the flow in the conduit connected to the sewer manhole is measured. A device configured to do so, wherein the tubular venturi member includes a throat portion narrowed along an axis in a flow direction and constricted on an inner surface, the throat portion serving as a flow path continuous from an inlet portion of the venturi member. It is defined, and in the region of the inlet part and the region of the throat, the pressure of the liquid flowing in the conduit is not filled in the pipe, and the pressure condition is filled in the pipe. A pressure sensor for detecting the pressure is provided in the area of the inlet portion and the area of the throat portion, and the throat portion is provided with the inlet portion due to an increase in the flow in the conduit. A liquid flow measuring device in which the inlet portion and the throat portion are dimensioned with respect to their cross-sections with respect to their respective longitudinal axes, so that they are filled with liquid substantially simultaneously with the minutes. 2. The pressure sensor is provided at a first pressure measurement point of the inlet portion and a second pressure measurement point of the throat portion, and the first pressure measurement point is on a side opposite to the throat portion. The fluid flow according to claim (1), wherein the second pressure measurement point is disposed near a bottom portion of an end portion of the inlet portion at, and the second pressure measurement point is disposed near an upper portion of the throat portion. measuring device.