Installation of wastewater meters

The provision of residential buildings with engineering communications is an important aspect of increasing the comfort of living. Living in an individual house is distinguished by a high water consumption for economic needs without subsequent utilization: watering the garden, garden, water consumption by people and animals, etc. In order not to pay for wastewater services for consumed water, installation of sewage meters is required. The meter will show that in reality, much less water goes into the sewage system than it enters the house.

The wastewater flow meter is a high-tech device that has electronic components in its design and ensures accuracy and reliability of measurements. The design of the instrument base and instrument assemblies allows working in chemically aggressive environments, without loss of reliability and accuracy of the measurements.

How do they work?

Sewer meters are divided into the following types, depending on what principle of operation underlies their work:

• ultrasound;
• electromagnetic;
• lever-pendulum.

According to the measurement method, wastewater metering devices are divided into two types:

• Accounting for the level of flow in the pipe. The amount of wastewater is determined depending on the size of the channel.
• Accounting for the flow rate together with the flow level of the effluent in the pipe. The amount of effluent is determined according to the “area-speed” principle.

Ultrasound Counters

High-precision devices designed to measure the amount of liquid sewage. Measurements are made using sensors using the square-speed method, which are easily installed in the collector. Used in open channels, self-flowing systems, non-pressure pipelines, in the industrial field for commercial accounting. When assembling devices with hydrostatic sensors, in addition to monitoring discharge volumes, the filling of the sewer network is monitored.

Installation is carried out in the pipeline or channels without carrying out additional construction works.

The operation of ultrasonic sensors is based on measuring the difference in the time of the passage of ultrasonic oscillations in the direction of flow of the fluid and against it. Sensors (piezoelectric transducers) are mounted on the measuring section, which initiate the excitation of these pulses.

The ultrasonic sensor is installed at an angle relative to the flow section. The speed can be measured by one or two beams of ultrasonic vibrations. The sensors work alternately, first as an emitter, then as a receiver. Fluid movement causes a change in the time of full propagation of signals along the stream and against it. Based on the received signals, the rate and volume of the effluent in the pipeline is determined.

The advantages of devices of this type lies in their versatility, the possibility of installation in pipelines of any geometry with a diameter of up to 9 m. Measurements occur in any direction of flow. The construction of additional wells or measuring chambers for the installation of the device is not required.

The disadvantages of the devices include the need for constant cleaning of sensors. Heterogeneity of effluent, the presence of bubbles, suspensions reduce the reliability of indicators. The measurement error reaches 5%.

Electromagnetic principle

These are simple but reliable instruments for measuring the volume of wastewater, including untreated. Apply on gravity and pressure sewer systems, provided that the pressure in the pressure sewage does not exceed 40 bar.

The principle of operation of flow meters is based on the measurement of the electromotive force (EMF), which occurs in wastewater when passing through an artificial magnetic field. The flow rate is directly proportional to the resulting emf, which is converted into a signal fed to the display device controller. Measurement of waste volumes is possible only if they conduct an electric current, since the action of the devices is based on Faraday's law (magnetic induction). The fluid that passes through the magnetic field acts as a moving core. It initiates an electric current, depending on the speed of movement of the effluent.

The advantage of electromagnetic devices lies in their versatility, they allow you to measure any type of liquid waste that conducts electric current, including untreated drains. Devices consistently show high-precision data, subject to the availability of a self-cleaning electrode system.

Tip! The disadvantages include unstable operation in the presence of strong electromagnetic interference. The cost of flow meters depends on the diameter of the pipe or channel, since the performance of the primary converter must always be full bore.

Lever-Pendulum Measuring Stock

Scope of devices - free-flow open and closed sewer channels. The principle of operation is to measure the level and average flow rate. Measurements are carried out continuously. Channel dimensions, information about the current value of the flow level allow you to calculate the current value of the transverse cross-sectional area of ​​the effluent. The volume of wastewater is defined as the product of the flow of sewage per unit of measurement time. The performance of the device is defined as the product of the flow cross section at its speed.

The device is a device with a lever fixed on the axis, on which a spherical float is rigidly attached. At the other end of the lever is installed the sensor of the angle of deflection of the lever relative to the vertical to the horizontal line. In the absence of stocks the lever is in a vertical position. In the presence of effluent float rises or falls, changing the angle of inclination depending on the level of effluent in the pipe. Through the indications of the angle of inclination is determined by the level of sewage.

To measure the speed used by another node, which is a rotary blade of stainless steel. The blade is fixed on the axis. One end of the blade freely sinks into liquid waste. On the axis of the sensor is fixed, which shows the flow rate at the angle of deflection of the blade, depending on the strength of the flow.

These devices provide high accuracy of the measured parameters of accounting for effluent regardless of the presence of contaminants in the pipe and other factors.

Before you choose a model flowmeter, you need to know what requirements are imposed on the sewage system and what type of water conduit is used.

Sewerage networks can be divided into open and closed. Closed networks are divided into pressure and non-pressure. For free-flow and open channels. The discharge flows through the pressure channels under the influence of pumps, in non-pressure and also open - by gravity due to the slope of the pipeline.

For measurement in pressure pipelines use instruments with sensors. Electromagnetic or ultrasonic flowmeters are selected on the basis of accounting for the estimated costs of wastewater.

Establishing accounting of wastewater in gravity pipelines is a more difficult task. Open or closed channels are characterized by the movement of sewage by gravity under the action of gravity at low speed.

Devices that measure only the level of a liquid give indications for the further calculation of the volumes of effluent taking into account the channel cross-section data. For open channels use lever-pendulum flowmeters.

More accurate results are given by devices of the second type, measuring according to the square-speed principle. The fluid level in free-flow channels is not constant. In a private house, the drain can occur periodically, there the drain will be unloaded most of the time, so data on the flow area and its speed over a period of time are used.

Ultrasonic and electromagnetic flowmeters are used to measure the speed in non-pressure closed channels. Specific models are selected depending on the diameter of the pipeline.

Sewage metering station

The wastewater metering station is a combination of measuring the flow of wastewater, a well, for the placement of metering devices and their maintenance, and the length of pipe on which measurements are made. Measuring instruments consist of a primary transducer (sensor) and a secondary transducer in which the processing, storage and display of measured information takes place. The well is constructed specifically in this section of the pipeline. The pipeline must be straight in the runoff measurement segment.

Before choosing the type of flow meter, it is necessary to assess the necessity and feasibility of installing a metering device and choosing the place for mounting the device.

When constructing a metering unit in an individual building, the place should be chosen to the point of connection with the common sewage system.

When choosing a measuring instrument, the device must record the values ​​of the flow of waste in the entire range of costs for the existing diameter of the pipeline. Accuracy of measurements should be high, the error is allowed no more than 5%. The accounting system should accumulate all information, provide information about the total cumulative volume, measurement periods and downtime. The power supply to the flowmeter must be uninterrupted with a spare power source.

The pipeline section where the metering device is installed must be straightforward. The flow meter should be located at the lowest part of the individual sewer network, where the maximum filling of the pipeline is located.

At each site requires a project that is agreed with the departments and organizations serving the sewer network. After receiving all permits and the project is a contract for subscription services.

Video

Ultrasonic wastewater flow meter in action:

See also:

Types of wastewater treatment systems

How to clean wastewater