2 Features:(Functions and applications)
LUY precession vortex flowmeter is a new one which is much outstanding than others in our country. This technology has made up domestic shortcomings. It was regarded as a national key new product by State Economic and Trade Commission in 1995. With years of improvement and advancement, it can catch up with the other countries at advanced level.
The features of LUY precession vortex flowmeter are as follows:
a) It doesn’ have mechanical moving parts. It is anti-corrosion and reliable. It has a long service life. It doesn’t need special protection when working for a long time.
b) It adopts 16’s computer chips. It has a high integration, a small valum, a good performance, and a strong whole-machine function.
c) It combines flow probe, microprocessor, pressure sensor, and temperatur sensor into one. It adopts built-in combination to make it more compact. It can directly test the flow, pressure and temperature. It also can track the compensation and correction of compressibility aotomically.
d) It adopts double detection technology to improve the detected signal intensity and redtrain the distraction caused by pipeline vibration.
e) It adopts new special screen which reveals large numbers and is easy for people to read. It can directly display some parameters, such as valume flow under working condition, valume flow and totals under standard condition, medium pressure, and temperature.
f) It adopts EEPROM technology, which is convinent to set parameters, storage for long time, and can storage historical data for almost one year.
g) The conventer can output frequency pulse, 4-20mA analog signal. It possesses RS485 interface, which can network with the microcomputer directly. The distance of transmitting can be up to 1.2km.
h) The signal of pressure and temperature uses transmitter to input, which has high interchangeability.
i) The whole machine is low-power. It can be charged by the battery or external power.

2 Main function:
LUY precession vortex flowmeter can be widely applied for industries of petroleum, chemical, electricity, metallurgy, and urban gas-supplied to measure the flow of various gases. It is the first product for the distributed measure and traded measure of oil fields and town natural gas.

2 Ambient condition:
Ambient temperature: -30℃-＋55℃
Relative humidity: 5﹪-95﹪
Atmospheric pressure: 86Kpa-106Kpa

2 Working conditiong:
The range of medium temperature: -20℃-+70℃
Nominal pressure: 1.6、2.5、4.0、6.3Mpa

2 The criterion of flange’s connecting size is as follows:
1.6-4.0Mpa(DN20-DN150)    GB/T9113.1-2000
1.6、2.5Mpa(DN200)        GB/T9113.1-2000
4.0Mpa(DN200)             GB/T9119-2000
6.3Mpa(DN20-DN150)        GB/T9115.2-2000
[Flange’s connecting size]

2 Working Principle:
Through leading fluid the gas goes into the meter to integrate and accelerate it. The impulse of fluid make the blade own rotating torque. After overcoming the friction torque and fluid drag torque, the blades begin to rotate. The rotate speed of blade is steadily when you keep a balance among rotating torque, friction torque and fluid drag torque. The rotate speed is proportional to the fluid speed under a certain condition, so the rotate pal stance of turbine is proportional to the volume flow of fluid. According to faraday’s law, the location of detector loop will change by the period of rotation of turbine, and the loop production of pulse signal is proportional to the volume flow of fluid of it. Therefore, the frequency of pulse single is proportion to the volume flow of fluid, that is, f=K×Q/3600.  Through magnification, filter, and integration this signal delivers to the converter to be connected with temperature and pressure signal to deal with and show on the screen of LCD. The K not only stands for proportionality constant but the meter constant of flow meter. And the meter constant K is not only in conformity with the accuracy of turbine meters, but also the operation of turbine meters’ converter.

2 Operating principle:
The circulation section of flow sensor is similar to the molded lines of venturi tube. There will be a pair of spiraled guide vane on one side of the entrance. When the liquid goes into flow sensor, it will be forced to produce serious swils by guide vane. When the liquid enters into expansion section, the swirls effected by back flow start to spin to form gyro vortexed synchronous precession. The precession’s frequency is in proportion to the flow size., which is not effected by the physical property and density. When the detecting elements get the precession’s frequency which the liquid awirls secondly, it gets a good linearity in a large flow range. The signal with amplification, filtering and truing by preamplifier turns into pulse signal in proportion to flow rate. And then it will be sent to the microprocessor to integrate with the detecting signal, xuch as temperature and pressure. Last, it will show the result on the LED(the data of transient flow, intergrated flow, temperature and pressure).

2 The structure
The structure of procession vortex flowmeter is compact. It consisits of shell, bluf section, sensor(temperature, pressure, flow), rectifier, holder, and converter.[parameters]

2 Electrical performance index:
Shell’s protection grade: IP65
Anti-explosion’ mark:
Anti-explosion type: The marks are Exd II BT4 and Exd II CT4-T6( without ethyne)
Safety type: The mark is Exia II CT4-T6
Connection’s interface: The exit is M20×1.5 internal thread.
Electrical index:
Power supply:
Normal type
a. inside power3.6V DC average current＜80uA
b. external power24V DC(two-wire system) current4-20Ma
c. external power24V DC(three-wire system) current＜100mA
Intelligent type
a. inside power3.6V DC average current＜200uA
b. external power24V DC(two-wire system) current4-20Ma
c. external power24V DC(three-wire system) current＜100mA
Output signal:
Frequency’s signal
Frequency’s range 0-4000HZ
Pulse amplitude low level＜0.7V Level output VD-1V( VD is supply power’s pressure.)
Analog output
One pair current’s output of two-wire 4-20mA is adhere to one of the pressure, tempersture, working condituion’s flow and standard condition’s flow.
Two pairs current’s output of three-wire 4-20mA are adhere to two of the pressure, tempersture, working condituion’s flow and standard condition’s flow.
Communication interface RS485
Pressure loss
Flowmeter actural pressure loss’s calculation formula
△P1: flowmeter’s actural pressure loss
p: detected medium’s density(kg/m3)
△P: flowmeter’s pressure loss when the medium is dry air

2 Installation:
a) The sensor can be installated in the direction of vertical, horizontal, or other directions according to the flow’s mark.
b) When the tube is so long or close to the vibration sourcr, the upstream and downstream of the flowmeter should installate the supporter to eliminate the bad effects caused by the tube’s vibration.
c) The place of sensor’s installation must have a lot of space for the flowmeter’s inspect and repair. It aslo should satisfy the ambient requiremnts of flowmeter.
d) It should avoid of the interference of external high magnetic fields.
e) When used in the outside, it should be covered by something, which prevented from the sun and rain to protect its service life.
f) When the pipeline is tested, you should pay attenton to the pressure sensor’pressure range under the flowmeter’s pressure in order to protect the pressure sensor.
g) You should consider the effect of installation’s stress. The upstream and downstream of the flowmeter must be on coaxial cable, or it will produce shear pressure. When you choose the installation’s place, you should consider the thickness of seal cushion or put an elastic expansion joint on the downstream.
h) The welding slags and other sundries should be cleaned before flowmeter’s installation.
The requirements of anti-explosion’s installation:
a) The flowmeter should have reliable landing. The anti-explosion’s grounding should not be used together with the strong power system’s protecing grounding.
b) When tested the power, it will not be allowed to use alternating current.
c) The user musn’t change the explosion-proof circuit, component and qnti-explosion’ type under any condition.
d) If you want to open up the converter’s lid, you should cut off the external power firstly.