Vortex Flow Meter with Cast Aluminum Alloy Shell

channel of flow rate measuring and micro processing unit, LCD driver circuit and other support circuit, and is equipped with output signal interface.           
4. Temperature pickup
With Pt100 platinum resistor as its sense organ, and with a certain range of temperature, resistance quantity shares correspondence relation with the temperature.
5. Pressure sensor
With Piezoresistive diffused dilicon connection circuit as its sense organ, its bridge arm resistance will make contemplated change under outer pressure, so under effect of certain energizing current, potential difference at both output terminal share a direct proportion with outer pressure.
6. Piezoelectricity crystal probe
It is installed at the laryngeal part of the dilating section of the shell and can detect frequency signal of eddy movement.
7. Swirl reducer
It is fixed at exit section of the shell to reduce whirling current and thus reduce compact on the performance of instruments of lower reaches.
 
Operating principles
Flow through section plane of flow sensor is similar to shaped conductor of venturi pipes (Figure 2).
 

Fix a helical guide vane at entrance side, when the fluid enters the flow sensor, the guide vane will force the fluid form fierce vortex. When the fluid enters the dilating section, the vortex will begin the second rotation under influence of reflux and will form gyro vortex precession. Frequency of the precession shares a direct proportion with flow rate, free from influence of the fluid's physical nature and density, therefore, precession frequency of the second rotation acquired by detecting element can obtain good linearity in a large scale of flow rate. Signals will be enlarged, filtered by the preamplifier and will change into pulse signal which shares a direct proportion with flow speed, then the signals will be sent to micro processing unit to be integrated together with detection signals of the temperature and pressure, finally, the measuring result will be displayed on the liquid crystal display (instantaneous delivery, integrated flux and temperature and pressure data).
 
Operating Principles of Flow Totalizer

Flow Totalizer is composed by temperature and pressure detection analog channel, flow sensor channel and micro processing unit, and is equipped with output signal interface, from which various signals are output. Micro processing unit of the flow Totalizer conducts temperature and pressure compensation due to the ideal gas law and automatically revises compressibility factor, the ideal gas law is as follow:
 
.........(2)
 
In this formula:
QN:  Flow volume in standard condition (m3/h);
QV: Flow volume in operating condition (m3/h);
Pa: Local atmospheric pressure (KPa);
P: Psig measured by pressure port of the flow totalizer (KPa);
PN: Atmospheric pressure in standard condition (101.325 KPa);
TN: Absolute temperature in standard condition (293.15K);
T: Absolute temperature of the measured fluid (K);
ZN: Air compression coefficient in standard condition;
Z: Air compression coefficient in operating condition;
Notes: when phosphorizer used and the subpressure is certain, ZN/Z=1, for natural gas, (ZN/Z)1/2=FZ is super compressibility factor. It is calculated according to formula of China National Petroleum Corp. standard.
 
Main Technical Parameters and Functions
3.1 Standards of Flow Totalizer, Basic Parameters and Performance Index (Table 1)
(Table 1)

Inside Nominal Diameter(mm)	Type	Range of Flow( m3/ h)	Operating Pressure ( MPa)	Accuracy Rating	Repetitiveness
20		1.2~15	1.6   2.5   4.0   6.3   10   16	1.0 1.5	≤2.5MPa  Aluminium alloy ≥4.0MPa Stainless steel  Lower than one third of the absolute value of the limit of intrinsic error
25		2.5~30
32		4.5~60
50	Type A	10~150
	Type B	6~75
80	Type A	28~400
	Type B	18~200
100	Type A	50~800
	Type B	40~600
150	TypeA	150~2250	1.6 2.5 4.0
	Type B	100~1200
200		360~3600

 
Notes: 1. Accuracy rating: system accuracy after temperature and pressure are revised;
2. A and B are used to distinguish different flow range of the same latus rectum.
 
Standard condition:
P=101.325KPa,T=293.15K
 
Conditions of usage:
Environment temperature: between-30 degree centigrade and 65 degree centigrade
Relative humidity: between 5 percent and 95 percent
Medium temperature: between -20 degree centigrade and 80 degree centigrade
Atmospheric pressure: between 86KPa and 106KPa