JPS6329213Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a perma-bolus friyum flowmeter (hereinafter referred to as P-B friyum) suitable for measuring the flow rate of fluid flowing in an underdrain, such as sewage, and particularly for small flow rates. Regarding improvement of time measurement accuracy.

P-B friyum is generally shown in Figure 1a,
It is formed as shown in b. FIG. 1a is a transparent perspective view, and FIG. 1b is a side view seen from the Z direction of FIG. 1a. In the figure, 1 is a tube body, and 2 is a bottom plate, which is fixed along the bottom surface of the tube body 1. Reference numeral 3 denotes a pair of side plates which intersect both sides of the bottom plate in the axial direction of the tube body 1, and form throat portions 3' in an inverted trapezoidal shape so as to be separated from each other toward the top of the tube. Bottom inclined plates 5 are formed on the upstream and downstream sides of the bottom plate 2 and are gradually extended so as to close the gap between the bottom plate 2 and the tube body 1. Reference numeral 4 denotes a side inclined plate which is gradually extended so as to close the gap between the side plate 3 and the tube body 1.

With the above configuration, the fluid flowing through the tube body 1 is constricted at the throat portion 3' and a critical flow is generated. The flow rate of the fluid flowing through the pipe body 1 can be calculated by measuring the water depth on the upstream side of the throat portion 3'.

The water depth can be measured using, for example, an ultrasonic level meter attached to a branch pipe 6 that communicates with the pipe body 1 at the top of the upstream pipe of the inclined plate 5 and has an axis perpendicular to the axis of the pipe body and the bottom plate 2. can be measured.

The above-mentioned general P-B Furium can measure the flow rate with an accuracy of about 3% error relative to the indicated value when the flow rate is large, but has the disadvantage that the error relative to the indicated value becomes large when the flow rate is small. . Japanese Patent Publication No. 56-41220 by the same applicant, as shown in FIGS. 2a and 2b, is a flow rate measuring device that improves the accuracy when the flow rate is small. Figure 2a,
In b, the same elements as in FIG. FIG. 2a is a side view of the tubular body 1 seen from the side perpendicular to the axial direction, and FIG. 2b is a sectional view taken along line AA in FIG. 2a. As is clear from the figure, in this conventional example, the first throat portion 3'
Another second throat portion 10 is provided on the bottom plate of the
is formed. When the flow rate is small, the unmeasured fluid flows through the second throat section 10, and when the flow rate is water, it overflows the second throat section and flows inside the first throat section 3'. With this configuration, accuracy errors in the small flow rate region are improved.

Figure 3 shows the relationship between the water depth H and flow rate Q of the fluid to be measured in a conventional general P-B frium and a P-B frium in which a second throat 10 is formed at the bottom of the throat portion 3'. It is a graph. In the figure, the dotted line indicates measurements taken with a conventional general P-B frium, and the solid line indicates measurements with a P-B frium with a second throat formed at the bottom. As is clear from the graph, the flow rate of the fluid to be measured is the dashed line M
If the flow rate is low in the range indicated by , the ratio of the change in flow rate to the change in water level.
Since dH/dQ increases and the error with respect to the indicated value decreases, highly accurate measurements can be performed.

However, the device in which the second throat portion is formed at the bottom of the throat portion has the following drawbacks.

(1) As is clear from the graph in Figure 3, accuracy improved in the range where the flow rate was low, but the flow rate gradually increased, and the water level changed at the boundary where the second throat overflowed and moved to the first throat. The non-linearity of the change in flow rate increases. Therefore, the linearity correction circuit on the converter side becomes complicated.

(2) Since the second throat portion is formed at the bottom of the first throat portion, the bottom of the first throat portion is raised. Therefore, the range that can be measured with the same tube diameter becomes smaller.

Generally, when measuring the flow rate of basin sewage, P-B
The sizing of Friyum is done by assuming the flow rate at the time of completion of the plan based on city planning and other measures. Therefore, for several years after the P-B frium is installed, it is often used at 1/5 or less of the maximum flow rate, and in this region, the error with respect to the indicated value becomes large. If another throat portion is formed at the bottom of the throat portion in order to reduce this error, the above-mentioned drawbacks occur.

The purpose of this invention is to eliminate the drawbacks of the conventional P-B frium, and when the flow rate is small, the throat for small flow rates can be attached and detached to the ready-made throat part, allowing accurate flow rate measurement regardless of the size of the flow rate. The purpose of this invention is to provide a P-B free form that can be used.

FIG. 4 is a diagram showing an embodiment of the present invention, and FIG.
FIG. 4b is a cross-sectional view of the main part of the throat portion taken along line BB in FIG. 4a and viewed from above. In the figure, the same elements as those in FIG. 1 are given the same reference numerals, and repeated explanation thereof will be omitted. Reference numeral 20 denotes a removable throat provided in a ready-made first throat part, and is fixed to both sides of the first throat part shown in FIG. 1 with bolts 21. As shown in FIG. 4C, the removable throat 20 is a substantially rectangular parallelepiped with one side cut off diagonally so that one end has an acute angle, and a fixing boss 22 is provided on the upper side. FIG. 4d shows a state in which the removable throat 20 is fixed to the side plate 3 of the ready-made throat part with bolts 21. In the figure, reference numeral 23 denotes a reinforcing member that is fixed to the side plate 3 by welding or the like.

FIG. 5 is a graph showing the relationship between the water depth H and the flow rate Q of the fluid to be measured when the removable throat 20 of the present invention is attached or removed. In the figure, the solid line represents the case where the removable throat 20 is installed, and the dotted line represents the case where the removable throat 20 is not installed.
As is clear from the figure, each curve is in a smooth state, so no complicated correction is required on the converter side. By changing the shape of the removable throat to match the city's population growth, a single P-B Freeum can serve multiple purposes.

As specifically explained above in conjunction with the embodiments, according to the present invention, by forming a removable throat on a ready-made P-B flueum, the fluid to be measured can always be measured under optimal conditions regardless of its flow rate. It can be measured and is advantageous in terms of cost.

[Brief explanation of the drawing]

Figures 1a and 1b show a conventional P-B frium, where a is a transparent perspective view and b is a side view from the Z viewing direction.
Figures 2a and 2b show other conventional examples, where a is a side view;
FIG. 3 is a graph showing the relationship between flow rate and water level in the conventional example shown in FIG. 2, FIGS. 4 a to d are views showing the embodiment of the present invention, and a is a side view. , b is a view of the B-B cross section of a seen from above, c is a perspective view of the removable throat, d is a view showing the state in which the removable throat is fixed to a ready-made P-B frium, and Fig. 5 is a view of the present invention. 2 is a graph showing the relationship between the water depth H and the flow rate Q of the fluid to be measured. 1... Pipe body, 20... Detachable throat, 22
...Fixing boss, 23...Reinforcement member.

Claims (1)

[Scope of utility model registration request] A permanent/bolus flueum flowmeter in which a throat portion is formed in a tube through which a fluid to be measured flows, and a level meter for measuring the fluid level in the throat portion is attached to the tube, at least A permanent/bolus frium flow meter characterized by having one throat section that is detachable and allowing the throat section to be selected depending on the flow rate.