1. overview
1.1 the instrument is designed and manufactured according to the national standard GB/T11828.1-2002. It is widely used in surface water, ground water and dam piezometric level measurement.
1.2 the instrument is a single buoy type self collecting water level gauge (hereinafter referred to as water level gauge). When the water level meter works, there is only one cable in the well pipe, which affects the float to track the change of the water level, and realizes the automatic measurement of the water level.
1.3 this type of instrument is suitable for use in places where the bore diameter is not less than 70 to 150mm, and the buried depth is from 10 to 500m, and the central axis of the well pipe must be straight, and the inner wall of the well pipe must be smooth and without concave convex obstacles.
1.4 the instrument water level encoder is a low torque, anti lightning type (micro switch contact power of 5A/250V) absolute encoder, and gold-plated waterproof aviation plug seat, the instrument performance is stable and reliable, no temperature, time drift.

2. composition and working principle
This type of instrument is composed of a water level encoder, a measuring wheel, a measuring cable, a float and a self closing device composed of cable; cable self closing device is composed of a lifting wheel, shaft hoist, hoisting cable, fixed pulley and the movable pulley group, hammer, upright support plate, bottom plate, protective cover and other components; instrument level encoder is mounted on the upright branch board, measuring wheel installed in the shaft encoder level; self winding shaft cable collecting device is installed on the support plate; a hoisting wheel mounted on the winch shaft end; a movable pulley block is arranged in the hammer; fixed pulley installed on the supporting plate through the respective bracket; starting end installed on the hoist cable winch the other end of the shaft, turn around a fixed pulley 1 and a movable pulley 1, 2 fixed pulley and the movable pulley 2 upward through the mounting hole and the supporting shaft supporting shaft fixed on the instrument; protective cover connected with the bottom plate through four fixing screws. Measuring cable winding in the groove of the rolling wheel, the terminal along the wire through hole connected with the float counterclockwise around the water wheel down through the bottom of the instrument; self closing cable device is to produce a constant force for measuring cable tension, automatic retractable, the float work in the normal water depth of eating.
Its working principle is: water static, static float on the water hammer in the corresponding instrument hover height, the encoder output value and the water height values; when water level drops, the float with the change of water level downwards along the well tube center, and pull the measuring cable to go down to the measuring wheel counterclockwise at the same time, rotate and drive wheel hoisting winch shaft to rotate clockwise, enhance the weight to the corresponding height, water level variation and water level corresponding to the encoder output value; when the water level rises, float to follow the water level rise along the well tube center to move to the corresponding position under the hammer, a hoist cable driven winch the shaft and the rolling wheel counterclockwise straightening and recovery of the measuring cable, causes the measuring wheel clockwise, the water level and water level rise change of encoder output value corresponding to the amount, complete automatic water level Tracking measurement.
The instrument level encoder output code for Gray code is 10 ~ 13bit, connected by a multi core aviation plug and cable to the external monitor or computer, can measure the water level from 10 to 80m.
When the instrument is used to measure the groundwater level, when the buried depth is more than 80m, the extra long part of the suspension cable should be connected with the special light suspension cable.

3. logging construction requirements
3.1 general logging is composed of a plurality of fixed length steel pipe (or engineering plastic pipe, cement pipe) which are connected together, each well pipe length is 2 ~ 6 meters long, the joint of each pipe must be smooth and free of obstacles, the gap of the joint should be less than or equal to 2mm, the joint wall height difference should be less than or equal to 1mm, axis geometry the well pipe should be bent is not allowed in a straight line.
3.2 well pipe diameter size is generally not less than 70 mm diameter, inlet area of about 1/10 can not seal the wellhead, between the section of well pipe joint.

4. main technical parameters
4.1 water level variation: 0 - 10m:0-20m; 0-30m; 0-40m; 0-80m;
The 4.2 level encoder resolution: 1 cm
4.3 measurement accuracy: less than 0.2%
4.4 float diameter: 40mm; 50mm; 100mm optional
4.5 output signals: gray 10 ~ 13bit (RS485 or 4-20mA interface matching)
4.6 environmental temperature: -10 ~ 85 C
Relative humidity was less than 90% (40)