OPERATING PRINCIPLE OF THE FLOWRATE TRANSDUCER
The transducer uses a vortex flow metering method. The oncoming liquid flow (gas) forms vortex in the flowaround body that propagate alternately along back of each flowaround body (Karman path). The frequency of vortex shedding from the flowaround body is proportional to the flow velocity of the moving fluid.
These vortices cause pressure fluctuations on both sides of the flowaround body which are fixed by the sensitive element.
The element senses the pressure pulsations at a breakdown of each vortex and converts them into an electrical signal that enters the electronic block. The electronic block after signal amplification, filtering, transformations and program processing forms the output signals of the tranducer.
The flowmeters of the explosion-proof modification ERVIP.NT-Vn are general industrial in the explosion-proof casing "d" designed in accordance with the requirements for explosion-proof electrical equipment of IIB, IIA subgroups according to GOST R IEC 60079-14.
Measured fluid - liquid (water, oil emulsion), gas (natural, associated)
and other non corrosive for flowmeter flowpath liquids and gases
Fluid parameters:
1. Temperature:
oC
- gas
from -40 to +50
- liquid
from -1 to +90
- high-temperature liquid
from +1 to +150
2. Excessive pressure
MPa (kgf / cm2)
up to 4(40)
3. Operating absolute pressure of gas
Pa
> 90
4. Density at normal conditions
kg/m3
> 0.6
5. Sediment content
mg/m3
< 50
6. Viscosity (for liquids)
m2/sec
< 500 × 10-6
Relative error limits of the transducer ERVIP DN 50/32 when measuring the volumetric flow rate:
Of liquid in straight sections:
2,0 - 2,5 m3 / h - ± 1,5%;
2,0 - 23 m3 / h - ± 1,0%;
Of liquid without straight sections:
2.0 - 2.5 m3 / h - ± 2.5%;
2.0 - 23 m3 / h - ± 1,5%;
For gas:
1.0 - 20 m3 / h - ±3%;
20-120 m3 / h - ±2.5%;
Usage of flowmeters in metering stations without straight sections is allowed with a reduction in the strength diameter of the flowmeter part (for example, DN 50/32 confuser). In this case, it is recommended to use the magnetically adjustable CMR-2Ex valve for flow rate control which provides the necessary flow velocity and flow rate through the flowmeter in the optimal range, and also excludes the influence of vibrational and acoustic noise.
The value of the volumetric liquid flow rate for various flowmeter sizes.
Flow Transducer type
DN pipe/DN meter., mm
Volumetric flow rate, m3 / h
Qmin
Qo
Qmax
ERVIP.NT-50/25
50/25
0.5
1.4
14.0
ERVIP.NT-50/32
50/32
2.0
2.5
23.0
ERVIP.NT-50/40
50/40
3.0
4.0
36.0
ERVIP.NT-50/50
50/50
< 5.0
6.0
57.0
ERVIP.NT-80/65
80/65
7.0
10.0
96.0
ERVIP.NT-80/80
80/80
8.0
15.0
145.0
Gas volume rate value
20.0
75.0
30.0
120.0
50.0
250.0
100.0
500.0
90.0
140.0
700.0
130.0
200.0
1000.0
Notes: Qmin - lower limit; Qo - nominal flow rate; Qmax - upper limit; DN pipe - nominal diameter of the connecting pipe; DN meter - nominal diameter of flowmeter.