Guangdong urban sewer Bacher trough open channel flowmeter

Product Overview:

Guangzhou Dichuan Instrument Co., Ltdparshall flumeOpen channel flowmeterUsed in conjunction with a measuring weir to measure the flow rate of water in an open channel. It is mainly used to measure the flow rate of sewage discharge outlets in sewage treatment plants, enterprises and institutions, urban sewers, and channels in agricultural water conservancy. Due to the fact that our company's instruments use ultrasonic waves to pass through the air and measure in a non-contact manner. Therefore, under conditions of sticky and corrosive liquids, it has higher reliability and durability than contact type instruments.

Principle Description

Basher Channel Open ChannelflowmeterIt consists of two parts: an instrument for measuring liquid level and a water tank made according to the documents published by the metrology institute. The liquid level instrument directly measures the height of the liquid in the channel or water tank. When used for measuring flow in open channels, a measuring weir groove is installed on the open channel. The measuring weir channel converts the flow rate in the open channel into the height of the liquid level. Measure the water level in the measuring weir tank with instruments, and then measure the corresponding water level in the measuring weir tank—Calculate traffic based on traffic relationships.

Guangdong urban sewer Bacher trough open channel flowmeter

1Principle of Ultrasonic Liquid Level Measurement

The ultrasonic pulse emitted by the transmitting ultrasonic transducer is propagated through the propagation medium to the measured liquid surface, reflected, and then returned to the receiving transducer through the transmission medium. The time for the ultrasonic pulse to propagate in the transmission medium from transmission to reception is measured. Based on the speed of sound in the transmission medium, the distance from the transducer to the liquid surface can be calculated. Thus determining the liquid level. Therefore, we can calculate the distance from the probe to the reflecting surfaceD ＝ C*t/2(to be divided by2 Because sound waves actually go back and forth from emission to reception,D It's distance,C It's the speed of sound,t It's time. The liquid level value can be obtained through subtraction operation.

2The principle of measuring flow rate in water measuring weirs and channels

The larger the flow rate in a smooth open channel, the higher the liquid level; The smaller the flow rate, the lower the liquid level (as shown in the figure). The flow rate can be calculated by measuring the water level. The correspondence between flow rate and water level in a regular open channel is influenced by the slope ratio and surface roughness of the channel. Install a measuring weir groove in the channel to generate throttling effect, so that the flow rate in the open channel has a fixed correspondence with the liquid level. This correspondence mainly depends on the structural size of the measuring weir groove, minimizing the impact of the channel as much as possible.

When using a Bacher trough open channel flowmeter, it is necessary to know the water level of the dosing weir trough during installation-Traffic correspondence relationship. Basher groove knows the throat widthbYou can use the corresponding formula to calculate the water level-Traffic correspondence relationship.

The right angled triangular weir is also calculated for water level using the corresponding formula—Traffic correspondence relationship.

Rectangular weirs also have corresponding formulas. But it also depends on the size of the installed channel to determine the water level-When it comes to flow relationship, rectangular weir and channel widthBOpening widthbUpstream weir heightpof

If the calculation of the water level in the measuring weir tank-If you are not familiar with the traffic, you can use theMeasuring weir troughNotify our company of the parameters, and we will assist in the calculation. Attention should be paid to providing both the above and the determined water level simultaneously-Parameters related to traffic relationships.

Basher trough open channel flow measurement weir trough

When choosing the type of measuring weir, consideration should be given to the flow rate inside the channel, the flow state of the water in the channel, and whether free flow can be formed. According to the different flow rates, we can choose different weir channels.

①Large traffic less than40 rise/It is recommended to use a right angled triangular weir;

②greater than40 rise/It is recommended to use the Bacher slot in seconds;

③The upstream channel is relatively short, and the large traffic is greater than40 rise/It is recommended to use a rectangular weir.

If conditions permit, it is better to choose the Bacher groove. The water level of the Bacher trough-The flow relationship is calibrated by the laboratory, and the requirements for upstream channel conditions are relatively weak. Water levels of triangular and rectangular weirs-The flow relationship comes from theoretical calculations, which can easily lead to additional errors due to neglecting some usage conditions.

Use fiberglass to make measuring weirs or troughs. The dimensions of triangular and rectangular weirs should be accurate, and the surface facing the inlet side should be smooth; The dimensions of the throat section of the Bacher groove should be accurate, and the surface inside the groove should be smooth.

Installation of Basher trough open channel flowmeterMeasuring weir trough

①. The centerline of the measuring weir should coincide with the centerline of the channel to prevent water flow from deviating when entering the measuring weir.

②. After the measuring weir channel is filled with water, the flow state of the water should be free flowing.

The water level downstream of triangular and rectangular weirs should be lower than the weir crest; The submergence degree of Bacher trough should be less than“Bacher slot parameters”The critical submergence level.

③. The upstream of the water measuring weir should be larger than5 A straight section that is twice the width of the channel, allowing the water flow to smoothly enter the measuring weir groove. The standard is“There are no waves on the water surface”There is no lateral deviation or the impact force formed by the slope of the channel.

④. The installation of the measuring weir groove on the channel should be firm. The connection with the side walls and bottom of the channel should be tight and not leak water. Make all the water flow through the measuring part of the measuring weir. The measuring position of the water measuring weir plate is the weir mouth; The measuring part of the measuring tank is the throat section inside the tank.

Sexual, at room temperature, without volatile gases.