Flow Meter - Differential Pressure Flow Measurement

Flow Meter - Differential Pressure Flow Measurement

SITRANS FP product line from Siemens provides a comprehensive solution for differential pressure flow measurements. This technology is versatile and suitable for a wide range of applications, including liquids, dry or humid gases, and steam. Its robust yet adaptable design has made it a primary choice for flow measurement in various industries.

SITRANS FP product line provides extensive flexibility for your processes. It represents more than just a mere replacement for the previous orifice program, as it's an entirely new setup. With a new digital sizing process, it minimizes effort during presales and ensures full traceability in aftersales. The differential pressure portfolio includes the pitot tube measuring system SITRANS FPS300 and the differential pressure sensors (orifices) SITRANS FPS200, compliant with ISO 5167 standards.

SITRANS FP230/FPS200 Primary Elements (ISO 5167)

SITRANS FP330/FPS300 Averaging Pitot Tube

SITRANS FP230/FPS200 Primary Elements (ISO 5167)

Primary differential pressure devices, also referred to as differential pressure transducers, are standardized mechanical flow sensors produced in compliance with EN ISO 5167. By narrowing the line diameter, these devices create a differential pressure that is directly proportional to the flow rate. A differential pressure transmitter then converts this pressure into a current signal or flow value.

The relationship between the differential pressure and flow is determined through a calculation specific to the primary differential pressure device. These devices are ideal for single-phase media such as gas, steam, and solid component-free liquids. Their standardized nature and suitability for various media make them versatile and reliable for flow measurement applications.

Catalog Sheet SITRANS FP230/FPS200

Operating Instructions SITRANS FPS200

Brochures Pressure Measurement

Brochures SITRANS P Portfolio

Flow Measurement Catalog

Process Instrumentation Brochures

Application

Technical gases
Compressed air
Fresh and combustion air
Steam/Heat quantities
Heat transfer fluids
Water

Design

Basics: Orifices for flow measurement

Orifice plates are usually differentiated by their type of installation, type of differential pressure tapping and the shape of the orifice.

The characteristic differential pressure is created by the orifice bore which is the defined circular opening. It is usually of square edged concentric type according to ISO 5167-2 positioned in the middle of the pipe.

The main features are a sharp edge, a cylindrical bore of a certain length and a conical bevel tapering to the rear. Alternatively, the relevant standards provide for deviating designs, which are used for applications with highly viscous (e.g. quarter-circle nozzles) or contaminated media (e.g. segment orifices).

The standard design is permitted by the standard for an inner diameter of the pipe between 50 mm and 1000 mm. For pipes with smaller inside diameters, standards such as ISO 15377-TR or ASME MFC-14M which go beyond these standards must be taken into account. Orifice plates for pipes with small inside diameters are usually designed as meter tubes.

In order to reduce the uncertainties of these meter tubes, the devices can be calibrated on a flow test bench if required on request.

Accuracy	Uncertainty at design flow:
Accuracy	Typically 0.5% … 1.2%
Media	Steam, liquids, gas
Operating conditions	Pressure: up to PN100
Operating conditions	Temperature: acc. EN1092-1 / ASME B16.5
Installation conditions	Inlet: depends on β-coefficient (typically 16 … 44 x inner diameter)
Installation conditions	Outlet: depends on β-coefficient (typically 6 … 8 x inner diameter)
Design	Acc. to ISO 5167 (2003)
Design	Acc. to PED 2014/68 EU
Approvals	Ex, SIL, … acc. SITRANS P320

Benefits

Suitable for universal use across the globe and widely accepted in all industries
Very robust and can be used in a wide range of nominal diameters
Suitable for high temperature and pressure ranges
Low uncertainty of measurement
No wet calibration required as they use an internationally standardized flow rate measurement procedure
Differential pressure transmitter can be used over a long distance from the measuring location
Differential pressure method is well known and has a large installed base
SITRANS P differential pressure transmitter is easy to parameterize again if process data change. They are adapted by recalculating and assigning new parameters to the transmitter or, in case of an orifice plate with annular chamber, by using a new orifice plate

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SITRANS FP330/FPS300 Averaging Pitot Tube

SITRANS FP330/FPS300 averaging pitot tube offers a range of impressive features! Its robust technology and straightforward measurement principle make it suitable for versatile applications, even under challenging conditions. The easy installation, long-term measuring stability, bidirectional flow measurement capabilities, and integration of temperature and pressure measurement certainly make it a standout choice for various scenarios.

Catalog Sheet SITRANS FP330/FPS300 Averaging Pitot Tube

Operating Instructions SITRANS FPS300

Operating Instructions SITRANS P320/P420 with 4 to 20 mA/HART

Brochures Pressure Measurement

Brochures SITRANS P Portfolio

Flow Measurement Catalog

Process Instrumentation Brochures

Application

Technical Gases
Compressed Air
Exhaust Air
Fresh and Combustion Air
Heat Transfer Fluids
Water
Exhaust Gas
Steam/Heat Quantities

Design

Basics: Averaging pitot tubes for flow measurement

Mounting by insertion into the pipe (no flange-to-flange instrument)
Differential pressure generation through forced flow
Variation of the classic "pitot tube" through multiple metering orifices (so-called "averaging pitot tube")
Design follows manufacturer guidelines, not standardized

Designs

Averaging pitot tube for gases and liquids (7ME161)
Averaging pitot tube for steam applications (7ME162)
Averaging pitot tube with FASTLOK (7ME163), to remove sensor during operation without interruption of process

System Design

Compact design for dry gases and liquids without integrated temperature measurement
Compact design for wet gases with or without integrated temperature measurement as well as for dry gases and liquids with integrated temperature measurement
Compact design for steam with or without integrated temperature measurement
Remote design for dry or wet gases, liquids and steam

Accuracy	Linearity: RE > 20,000: 1%
Accuracy	Repeatability: RE > 20,000: 0.1%
Media	Steam, liquids, gas
Operating conditions	Pressure: up to PN100 (flange)
Operating conditions	Temperature: -100 °C … 490 °C
Installation conditions	Inlet: 7 x inner diameter
Installation conditions	Outlet: 3 x inner diameter
Design	Acc. to PED 2014/68 EU
Approvals	QAL1
Approvals	Ex, SIL, … acc. SITRANS P320

Benefits

Easy to retrofit (no rebuilding of the pipe)
Easy to install
Good for large nominal diameters
Wide range of application (media, nominal diameters, process conditions)
Minor measurement inaccuracy
Special designs possible for special applications
Also work in rectangular ducts and pipes

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