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Name:  Variable Metal Rota Flow Meters  Line Diameter:  DN15  DN100 

Accuracy:  0.5% At Liquid, 1% At Gas, 1.5% At Steam  Compensation:  Temperature / Pressure / Temp. & Pressure 
Connect:  Quick Connect Flange  Pressure Rating:  PN1.0 Mpa To PN40 Mpa 
Option:  Weight Flow Or Cubic Flow  Flow Direction:  Horizontal 
Metal rota high pressure air flow meters for lubrication oil, variable area type flow meters Pipe size DN15100
Operation principle
The variable area, also called metal flowmeter's flow sensing element consists of a vertical tapered tube expanding from bottom to top and a float set moving up and down along the tapered tube axis. Working principle shown in Figure 1, the measured fluid from the bottom up through the conical tube 1 and the float 2 formed ring gap 3, the upper and lower ends of the float to produce differential pressure to form the floating force of the float when the lift is greater than the submerged fluid The weight of the float, the float will rise, the ring gap area increases, the annular gap at the immediate decline in fluid flow velocity, the float lower differential pressure decreases, the role of the buoy lift force also decreases until the lifting force is equal to immersed in the fluid In the float weight, the float will be stable at a certain height. The height of the float in the conical tube and the flow through the corresponding relationship.
The basic equation of volume flow Q is:
When the float is nonsolid hollow structure (put the weight adjustment), then
Where α  instrument flow coefficient, due to float shape varies;
ε  gas expansion coefficient measured gas is gas, usually due to the small coefficient of this correction is ignored, and has been included in the flow coefficient through the calibration, such as liquid, then ε = 1;
△ F  Circulation area, m2;
g  local acceleration of gravity, m / s2;
Vf  float volume, if extended body should also include, m3;
ρf  float material density, kg / m3;
ρ  measured fluid density, such as gas is the density of the upstream crosssection of the float, kg / m3;
Ff  working area of the float (maximum diameter) crosssectional area, m2;
Gf  float quality, kg.
Circulation area and the relationship between the height of the float as shown in equation (3), when the structural design has been set, then d, β are constant. There is a quadratic term in h, we can not ignore this nonlinear relationship. Only when the cone angle is small, can we regard it as approximate linearity.
m2 (3)
Where d  maximum diameter of the float (ie, working diameter), m;
h  float from the cone diameter equal to the maximum diameter of the float rise height, m;
β  taper cone angle;
a, b  constant.
Model selection
LZ－□－□－□－□－□－□
Code  Description  
Type code  LZ  metal rota flow meter 
Display  Z  local display 
D  remote reading  
Diameter  15  DN 15mm 
25  DN 25mm  
40  DN 40mm  
50  DN 50mm  
80  DN 80mm  
100  DN 100mm  
150  DN150mm  
Special function  N  normal 
F  anti corrosion  
Media to be tested  L  liquid 
G  air 
Data sheet
Diameter(mm)  Flow range  Pressure loss  
Anticorrosion  Normal  air(m3/h at 0.1013Mpa)  water L/h  air  water 
15  15  0.070.7  2.525  7.1  6.5 
0.111.1  4.040  7.2  6.5  
0.181.8  6.363  7.3  6.6  
0.282.8  10100  7.5  6.6  
0.44.0  16160  8.0  6.8  
0.77.0  25250  10.8  7.2  
1.010  40400  10  8.6  
25  1.616  63630  14  11.1  
25  3.030  1001000  7.7  7  
4.545  1601600  8.8  8  
7.070  2502500  12  10.8  
50  11110  4004000  19  15.8  
50  18180  6306300  8.6  8.1  
25250  100010000  10.4  11  
80  40400  160016000  15.5  17  
80  60600  250025000  8.0  8.1  
100  1001000  400040000  13.0  9.5  
100  2002000  630063000  11.0  10 