Water meter classification:
(1) Float type hydrometer
The principle is that the float senses the rise and fall of the water level. There are ordinary water level meters that convert the Angle provided by the float into incremental electrical pulses or binary coded pulses for long-distance transmission, digital water level meters, and digital sensing water level meters composed of miniature floats and many reed tubes. Mechanical water level gauges are widely used. Logging equipment is required for the application of float type water level gauge, which is only suitable for the use of low sediment content river with stable bank slope and small scouring and deposition of river bed.
(2) Optical fiber water meter
The optical fiber water level gauge comprises a water level gauge sensor part and a control circuit terminal part. Among them, the water level meter sensor part adopts the optical coupling regulation device and the cable connection to transmit the optical signal bearing the water level information. The control circuit terminal part adopts the laser modulation technology to send the modulated laser signal with different functions. Through modulation, comparison and detection, the accurate information of the water level is obtained. This principle realizes the whole light measurement, and does not use any charged devices outdoors, which can prevent electrostatic hazards and prevent lightning damage.
Also known as the contact water level meter, the use of the electric measuring needle on the weight to contact the water surface to send an electrical signal, so that the motor is turned or reversed, and the position of the water surface point is tracked at any time, so as to determine the water level. Generally, iron pipes are erected on steep bank slopes, and suspension hammers and suspension cables are raised and lowered in the pipes to drive recording or signal devices. The iron pipe inlet must have sand settling and still water facilities.
(4) pressure type water meter
Its working principle is to measure the water pressure and calculate the water level. Its feature is that there is no need to build static water logging, the sensor can be fixed at the bottom of the river, and the atmospheric pressure can be eliminated with the pressure tube, so as to measure the water level directly. There are two types of pressure gauges. One is the bubble type, which continuously transfuses gas in the pressure tube, and converts the water pressure into the mechanical Angle with an automatically adjusted pressure balance, thus driving the recording mechanism. The other type is the electrical measurement type, which uses a solid-state piezoresistive device as a sensor, and can directly convert the water pressure into a voltage modulus or frequency output, which is transmitted to the shore by wire for processing and recording.
(5) acoustic water meter
It is a reflection type water level meter, which uses the principle of reflection of sound waves against different interfaces to measure water level. It is divided into two categories: air medium and water medium. The air medium takes air as the propagation medium of sound waves, the transducer is placed above the water surface, and the sound waves are reflected by the water surface, and the water level can be calculated and displayed according to the echo time. The instrument does not touch the water body, and completely gets rid of the adverse factors such as sediment in the water, velocity impact and water grass. The water medium is a transducer installed at the bottom of the river, which emits sound waves to the surface of the water. Sound waves have high propagation speed and large distance in water medium, and do not need to build logging. Both gauges can be wired indoors for display or storage of records.