Product Introduction
The product is a kind of sensor that measures flow velocity and flow rate in natural waters, channels or pipes.The flowmeter is divided into two parts: sensor and host, connected by cable.
To be able to measure flow velocity and flow rate in channels and rivers, the water level has to be 20 cm higher than the sensor.
To be able to measure flow velocity and flow rate in pipeline and culvert, water level has to be more than 20 cm higher than the sensor, tubing inner diameter has to be ≥500 mm.
1.1 Operating Principle
The sensor is fitted with two energy converters, one for transmission, one for receiving. On the premise that the sensor is facing the water flow direction, i.e. counter current direction:
1.When water is static, the transmission and receiving frequencies are the same.
2.The faster the velocity is, the faster frequency the sensor receives signal, and it will be higher than transmission signal.
3.The slower the velocity is, the slower frequency the sensor receives signal, and it will be lower than transmission signal.
On the premise that the sensor is on the water flow direction, i.e. current direction:
1.When water is static, the transmission and receiving frequencies are the same.
2.The faster the velocity is, the faster frequency the sensor receives signal, but it will be lower than transmission signal.
3.The slower the velocity is, the slower frequency the sensor receives signal, but it will be lower than transmission signal.
Hardware and software can calculate water flow direction and velocity.
The sensor has to be installed facing the water flow direction
1.2 Technical Parameters
Initials for Field Irrigation Doppler flowmeter: FIDF
Model no. for river channel flowmeter: GRCF
Non-full pipe flowmeter model: DTF
Structure: split type;
Measurement categories: velocity, flow, water depth, water temperature
Level of protection: IP68
Purpose: on-line measurement
Velocity measuring range: the standard is 0.04 m/s ~ 5.00 m/s (the sensor is 20 cm above minimum depth) ;Other velocity range can be customized.
The velocity measurement resolution: 1 mm/s;
Velocity measurement precision: ±2～4% of measuring velocity;
Water depth measurements: 0.02 m ~ 10.00 m; Resolution: 2 mm accuracy: ±0.5%;
Temperature range: 0～60ºC; resolution: 0.1ºC;
Flow range: 10 L/s ~ 99999999 cubic meters/hour
Power supply: battery, 12 VDC;
Output signal (battery): RS485;
RS485 output signal content: flow velocity, instantaneous flow, cumulative flow, water level and temperature；
Output signal (external power supply) : 4-20 mA;
4-20 ma output signal content: instantaneous flow rate；
Cable length between sensor and transmitter: 10 m;
Types of channels subjected to measurement: pipeline, channels, natural stream and rivers;
PH value requirement: PH between 6 ~ 8, no corrosive effect on sensor.
Liquid temperature requirement: 0 ~ 50 ℃；
Liquid pressure requirement: natural environment condition, 1 standard atmospheric pressure；
Power supply for flowmeter is 11 ~ 14 VDC, power supply current is 250 mA.
Continuous working power consumption: 14V×200ma=14V×0.25A=3.50W。
Softwares:
Data acquisition system 1 set low power consumption GPRS wireless data acquisition and transmission software
Integral management system 1 set low power consumption GPRS wireless data acquisition server software
1.3 Standard Measurement State
After powering up, flow velocity and flow rate will be provided after 60 s, then one set of data will be provided every 15~20s.
Under standard measuring status, signal 485 from sensor is directly connected with host. The host will output flow velocity and flow rate signals from 485 interface.
II. Product Installation
2.1 Installation condition and position inside channels
① Measurement in the rivers, channels can be conducted as long as the lowest water level is 20 cm above the sensor.
② Flowmeter sensor standard pressure is 100 kpa, namely pressure at 10 meters of water depth. If more pressure withstand ability is needed, please specify before issuing order, maximum pressure withstand achievable is 1000 KPa, i.e. at 100 m of water depth.
③ Ultrasonic Doppler flowmeter is applicable for water with less than 20 kg/m of solid contents, velocity of 5.0 m/s or less. Product can be customized if more flow velocity range is required, maximum velocity achievable is 10.0 m/s.
④ Ultrasonic Doppler flowmeter shall be installed at locations with steady flow. If flow is not smooth, in most cases is turbulent flow, will resulted in large measurement deviation.
⑤ On the upstream of ultrasonic Doppler flowmeter installation position, straight channel length 20 times of the channel width shall be set; and straight channel length 5 times of the channel width shall be set at downstream locations.
For some of the sites, due to channel condition limitation, the 20 times width requirements for upstream channel and 5 times width requirements for downstream channels cannot be met. The minimum requirement is straight channel 5 times of channel width on upstream and 3 times of channel width downstream. However, this will lead to increase of deviation, which is specifically determined by site condition.
For example, in the figure below: because it is a mountain area, with turns of channels, which does not meet the straight channel requirement for upstream section, the actual flow velocity at installation point is 0.90～0.95 m/s, actual measured value is 0.65～0.80 m/s.
⑥ In case of installation location is downstream of gate (straight channel length is 30 times width or more), pay special attention of water surface and see if it is steady.
If the sensor installation location is already 30 times width away from the gate, but the water surface is still turbulent, then increase the distance until the water is steady. There is not limitation for this distance, it can be 60 times of the width or 80 times--until the water is smooth.
The figure below shows the actual installation position, which is 50 times width away from the gate until the water is steady. Installation point is at the red circled area in the figure below.
⑦ Determine installation height
Sensor's ideal height is 100 mm- 250 mm from the channel bottom, determined by minimum water level at the channel.
Sensors should be installed on the bottom of the channel, if channel bottom has a lot of sediment, mud, grass or a stone that may roll around, installation position can be raised slightly higher, in order to avoid the sensor being covered by sediment and aquatic plants , or stone impact damage.
⑧ Selection of horizontal installation position
Channels with less than 20 m of width, if its section is rectangular, then installation point is at 15-20% of the entire channel. This is because this location's flow velocity is closer to the average velocity than other locations.
Trapezoidal channel installation: sensors shall be installed in slope and bottom border, also known as "toe". At the same time: sensor is 20 cm below the lowest water level.
⑨ Sensor shall be facing water flow direction
⑩ For upstream waste or floating objects, grid shall be used to filter the upstream channel, and the distance between grid and sensors is more than 5 times of channel width.
2.2 Installation Position and Location within Pipelines or Culverts
① Installation in the pipelines can be conducted as long as the lowest water level is 20 cm above the sensor, pipeline inner diameter ＞500 mm for measurement. Measurement can be conducted even if the pipeline is not full. Select a place where the water flow is stable, the upstream of the installation position shall have a straight channel 20 times of pipe inner diameter, and a straight channel 5 times of pipe inner diameter downstream.
② Select locations with steady flow for installation. If flow is not smooth, in most cases is turbulent flow, will resulted in large measurement deviation. Two situations may occur: one, great turbulence in data records; two, measured data is smaller than actual value;
③ Take the sediment and sludge in the pipeline into account, if there is sludge, the sensor should avoid sludge during installation.
For upstream waste or floating objects, grid shall be used to filter the upstream pipeline, and the distance between grid and sensors is more than 5 times of pipeline inner diameter.
2.3 Installation Condition and Position in River Channel
① For wider river channels, such as natural rivers, flood discharge channels of large reservoirs, ship channels at dams, spillways of hydropower stations, flow rates from the two banks to the middle are large, and if the flow rate is to be measured, the flow rate is more complicated because at different position flow rates are different.
In this case, in addition to meet the conditions of installation in channel, generally require multiple point velocity data. 3 senors are required at least, one at each bank and one in the middle.
Such as dividing a river of 30 m wide into 10 equal sections.
② Ensure that the lowest water level in the dry season is 20 cm above the sensor, this does not include flow measurements conducted other than dry seasons.
③ Determine whether the site measurement point is suitable for installation: there are quite a few natural rivers, it is difficult to install with bracket, in order to install the sensor, it is necessary to use the excavator to block the water flow and form the site convenient for construction, in this case, Consideration should be given to using non-contact river flow meters to measure.
The site below is a typical case of a river flow meter that is less suitable for use with contact. There is no place where the bracket can be installed, and the construction was aided by the use of large machinery to make water in the water.
In this site, the sensor is difficult to be fixed, and the cable after installation can not be fixed at the bottom of the river channel. The cable is directly suspended from the water surface and is led to the instrument box on the shore side, problem is easy to appear under the large wind.
There is a rectangular section channel shown below, but the water in it is shallow, and rocks are washed away by water, which can easily damage the sensor. In such site, non-contact radar flowmeter is suggested to be adopted.
2.4 Bracket Installation and Wiring within Channel
Special Note: the flow rate of 0.20 m/s is set as standard, as the water flow speed is doubled every time, the destructive power to the surrounding objects is increased by 50-64 times!
① Ways of fixing sensor in channels
In the following installation, the outgoing line behind the sensor must be protected with PVC, PE or galvanized pipe, so that the cable will not be stressed due to the impact of water flow, nor can the cable be allowed to hang the floating objects or garbage.
On the premise that water cut-off, the sensor can be fixed on the cement floor at the bottom of the channel, and if the bottom of the channel is mud, it needs to be fixed by a cement platform.
In the channel with sludge and deposits, the installed cement platform enable the sensor to be higher than the deposit, making it harder for the sensor to be covered by the deposit.
Cables coming out from the back of the sensor are directly protected by tubing.
Installed with stainless steel bracket:
2.5 Bracket Installation and Wiring within Pipe
If installation is carried out within the pipe, do not have to stop supplying water, lay down the bracket from the top of pipe for fixation. General pipe, within 2000 mm, can be installed in center, sensor shall be fixed at the bottom of pipe with bracket. Bracket shall be made in "L" form, sensor shall be fixed at the bottom of L-shaped bracket, deep into the pipe, facing the water flow direction.
If there is silt deposit at the bottom of pipe, lift up the sensor or tilt it to either side of the pipe.
As shown in the figure below, the installation is carried out within a Φ1000 mm pipe, the cable of sensor is led to the host through a vertical galvanized tube:
Installation Diagram of Φ1000 mm Effluent Discharge Pipe:
2.6 Installation Notes
●Before fixing sensor to base, wrap the sensor with over 2 mm-thick rubber cover which can be replaced with car inner tube to separate the sensor from metal clamp and base.
●Outgoing lines of sensor must be protected with PVC, PE, PR and galvanized pipe to avoid cracking, separation under the long-term impact of water flow and scratch or cut by objects. With the protective tube, cable is led out of water in downstream direction of sensor along bottom or inner wall of channel.
●Outlet on the back of sensor shall be protected and fixed to reduce the long-term impact of water flow. Protective tube can be applied to withstand the impact of water flow. Water flow may directly break the cable or wear out the jacket of cable.
●As there is ventilation duct within the communication cable of sensor, the bending degree shall be no more than 80°. After leading the communication cable out of water, connect it with common cable to make the ventilation duct open downwards to avoid blocking.
The 485 and 12VDC cables on the sensor must be separately combined with two pieces of 2-core shield cables.
●Don't pull or swing the cable or strike the sensor shell. Don't hang weight on the cable. Cable must be fixed on the cement wall of channel without swinging.
●Power can only be supplied through battery or solar energy. If applying 220 VAC mains power supply, convert it into 12 VDC current with linear power supply, instead of switch power supply.
●If flow velocity is larger than 1.0 m/s, the strength of bracket shall be over 3 times the current strength to ensure that it will not be carried away or broken by rip current. Diagonal bracing shall be made in the horizontal direction to keep the sensor stable without displacement, shaking or drifting.
●If cable needs to be lengthened, gas cable shall be applied to ensure that the lengthened part will not be leaking, bent or blocked under high humidity and low condensation conditions. 12 VDC cable can be lengthened to 200 m with 0.75 mm2 two-core shield cable. 485 output cable can be lengthened to 200 mm with 0.75 mm2 two-core shield cable.
2.7 Installation Steps
① Fixed bracket shall be mounted first to ensure the stability and reliability at the maximum flow velocity of two times.
② Sensor shall be fixed on the installation base.
③ All protective tubes for crossing wiring of sensor shall be fixed. Tube in water shall be fixed with at least one clamp every 0.5 m. Outlet behind the sensor shall be specially protected and fixed to ensure that protective tube can completely withstand the impact of water flow and protect the outgoing line of sensor.
Or outgoing line of sensor will be broken.
④ Send order through laptop to check the measuring data
⑤ If flow velocity is close to the actual value, combine 485 line with RTU or other receiving devices on-site.
⑥ Clean the garbage in upstream of sensor.
The Doppler ultrasonic flowmeter uses the physical principle of Doppler frequency shift to measure the speed of water flow. Therefore, the Doppler ultrasonic flowmeter is suitable for measuring fluids containing solid particles or bubbles, and is not suitable for measuring pure water. The scope of use includes: natural rivers, artificial rivers, farmland channels, urban sewers, enterprise sewage outlets, sewage treatment plants, etc. It is suitable for environments that require continuous and accurate measurement of flow velocity and flow rate, and has significant advantages such as convenient installation and maintenance, high reliability, and high precision.
● Flood Disaster Monitoring Sewage Discharge Natural Rivers
● Municipal water supply and drainage ● Water loss/infiltration monitoring ● Irrigation process monitoring
● Estuary and tidal studies ● Fisheries/hydraulic ● Coastal erosion studies
● Underdrain flow monitoring● Road drainage monitoring ● Canal flow research
● River process monitoring
Trumsense Technology is an ultrasound technology company integrating R&D, production and sales. Focusing on the R&D and production of ultrasonic material (liquid) level meters, liquid level difference meters, open channel flow meters, mud level meters, sensors, transducers and other products, it occupies nearly 45% of the ultrasonic liquid level and material level industry market.
Mainly engaged in ultrasonic material (liquid) level meter series, pressure level / transmitter series, flowmeter series.
The main application fields of the product: sewage plant water works, mines, water conservancy, power plants, chemical plants, steel plants, printing machinery manufacturing plants, etc., liquid level measurement in various industrial fields, especially sewage treatment, acid and alkaline liquid measurement.
