Preso® differential pressure flow meters type Coin® NF
Flanged with NPT pressure taps for fluids, gases, steam, air and slurry
- High accuracy
- Low pressure drop
Lubricant oil, Gas, Water
from 1 up to 210000 l/min
from 0 up to 426 °C
from 0 up to 103 bar
Chemical industry, Oil industry, Gas industry, General industry
General information
The basic flow equation for the Coin® series is derived from Bernoulli's theorem (energy balance and the continuity equation). An engineered restriction creates a differential pressure that equates to a mass or volumetric rate of flow. Different height (H) over diameter (D) ratios are specified to handle different flow ranges. A Coin® flowmeter can solve your most difficult flow measurement applicatons. You get accurate, reliable results from the Coin® flowmeter. Due to its rugged construction, the Coin® flow meter can accommodate most flows, clean fluids, steam, gas, air, slurries, even the most abrasive and corrosive processes including high viscosity fluids.
Technical data
| Material | Stainless steel, carbonate steel or others |
| Pressure | Dependent on flange ratings |
| Temperature | Dependent on flange ratings |
Measuring principle
Diff. pressure flow meters/Venturi tubes
Due to the conical design of the venturi tubes, the flow of a fluid (gas, water, air) at the narrowest point of the low-pressure (p2 = dynamic pressure) results in the accumulation of the medium and at the outlet of the constriction the highest pressure is forming (p1 = static pressure). The pressure difference (incompressible, without friction) for liquids generated by the Bernoulli equation.
Pitot tubes also work on the basics of the Bernoulli equation. In contrast to the venturi tube, work is done with the help of a second tube which is oriented parallel to the flow of the medium, such that the flow impinging on a front pipe opening. In front of the tube is formed the dynamic pressure, behind the tube, the static pressure. This remains constant.
By different shaped pipe openings, measurement results can be affected. By the elliptical shape of the shaft, lowest permanent pressure loss (type Ellipse®) is achieved. In contrast trapezoidal pipe openings create strong vortex shedding in the measuring body and thus impede the flow, resulting in a very high flow resistance. All devices can be used both vertically and horizontally.