LS10 type propeller flowmeterDetailed product description：

The LS10 propeller flowmeter is a hydrological measurement instrument suitable for measuring the average velocity of water flow at predetermined measurement points in general rivers, channels, pipelines, culverts, etc., in order to determine the flow rate of the section.

Main technical instructions
1. Speed measurement range: V=0.10~4.0m/s;
2. Working water depth: When using a measuring rod, the actual water depth should not exceed 1.2m; when using a hanging rod to fix it on a lead fish, the water depth is generally not greater than 24m;
3. Working water quality: freshwater (containing moderate minerals) or turbid water containing sediment;
4. Continuous working hours: ≤ 10h;
5. Starting speed of the instrument: V0 ≤ 0.08m/s;
6. Mean square deviation of the verification formula: m ≤ 1.5%;
7. The number of revolutions of the propeller between each second signal: 20 revolutions.

Working principle and calculation method
The working principle of the LS10 propeller flowmeter is that when the water flow acts on the sensing element of the instrument, the propeller produces a rotational motion, and there is a certain functional relationship between its rotation rate "n" and the flow velocity "V", V=f (n), which is determined through experimental verification of the water tank. The experiment shows that when the flow velocity is above 0.1m/s, the calibration formula of LS10 propeller flowmeter is a linear relationship.
Each instrument calibration result is accompanied by the following calibration formula:
V=bn+a (corresponding to the original standard V=Kn+C)
Where:
V - Flow velocity (m/s);
N - propeller rotation rate, equal to the ratio of the total number of propeller revolutions N (N=20 times the number of signals) to the corresponding speed measurement duration T, i.e. n=N/T (1/s);
B - Hydraulic pitch (m) (corresponding to the original standard K);
A - Instrument constant (m/s) (corresponding to the original standard C).
The values of b and a are related to factors such as the pitch of the propeller and the frictional resistance of the support system. Therefore, the parts in this part must be used and maintained carefully, otherwise it will affect the accuracy of the flow meter test.
According to regulations, the speed measurement duration T can be selected from two options: 100 seconds and 50 seconds. Generally, 100 seconds is chosen.

instrument structure
The main structure of the LS10 propeller flowmeter is divided into three parts: rotating component, body frame component, and tail wing component (see attached figure for details).
（1） Rotating components: According to their working principles, they can be divided into two parts: induction and contact mechanisms.
1. Induction part: composed of induction elements - propeller (1) and its supporting system - front axle sleeve (27), pressure cap (2), bearing (26), inner spacer (25), outer spacer (24), propeller shaft (3), screw sleeve (22), rear axle sleeve (23), etc.
A propeller is a three bladed propeller made of engineering plastic. There is a screw hole in the center of the propeller that is directly screwed onto the front shaft sleeve (27). The slender shaft tenon extending from the front end of the front axle sleeve is the most precise key part of this instrument. Be sure not to withstand severe vibrations or collisions during use, otherwise it is prone to bending and deformation. If there is obvious jumping phenomenon of the propeller during rotation when it is subjected to collision during use, it should be sent to the production plant for repair before continuing to use.
2. Contact mechanism: It is a device that closes a switch and converts the number of revolutions of the propeller into an electrical pulse signal.
The contact mechanism includes: screw sleeve (22) embedded in the rear axle sleeve, gear (5), gear shaft (4), contact wire (6), fixing screw (7), contact shaft sleeve (20), and plug (8). Precautions for rotating components:
1. Add lubricating oil. When installing the support system, instrument oil should be injected into the inner cavity of the front shaft sleeve, with an oil volume of about 1/3 of the hole height. Slowly insert the support system into the hole so that the bearings and contact mechanism are completely immersed in oil, which facilitates the normal operation of the instrument.
2. Apply butter: When measuring flow in rivers with high sediment content or deep currents, in order to avoid water and sand entering the instrument, a layer of butter should be applied outside the screw thread of the front shaft sleeve when installing the rear shaft sleeve. Before applying butter, the instrument oil overflowing from the front shaft sleeve should be wiped clean, otherwise the butter is easily dissolved by the instrument oil and loses its function of applying butter. At the same time, attention should be paid not to accidentally insert cotton fibers and other debris into the bearing, otherwise it will affect its normal rotation, especially reducing sensitivity.
After tightening the rear shaft sleeve, use your fingers to smooth out the squeezed butter. If the water is clear, the flow is slow, and the water is not deep, and there is no water or sand ingress during the use of the instrument, then the work of applying butter does not need to be carried out.
The rotating parts are the most important part of this instrument, so special care must be taken during use and disassembly. After use, they must be washed clean with gasoline, refueled, and properly placed in the designated position of the instrument box.
（2） Body frame components: mainly composed of body frame (14), terminal post (12), lining tube (10), socket sleeve (15), socket (16), fixing screw (13), shaft fixing screw (17), waterproof washer (18) and other parts.
（3） Tail wing components: composed of fixing screws, tail wing screws, tail pillar, and tail wing.
The tail wing of the LS10 rotary propeller flowmeter is an elongated planar rudder used to balance the instrument and cater to the flow direction