Flow Measurement Devices for HVAC-R
Flow Measurement Overview
Flow is defined as a quantity of material passing a given area in a unit time period. Flow measurement is used to calculate how much liquid, gas, air, steam or energy is moved, and is vital to understanding, among other things, system capacities and energy efficiencies. There are numerous methods used to measure flow and Siemens SITRANS F is a comprehensive line of flow measurement devices for all flow related applications.
Magnetic Flow Meters
The SITRANS FM magnetic flow meters are designed to measure the flow of conductive liquids in a full pipe. It works on the principle of Faraday’s law of electromagnetic induction where a voltage induced as a conductor is passed through a magnetic field. The mag meter flow tube creates the required magnetic field and the fluid passing through it is the conductor.
At zero flow there is no induced current, however, as the flow rate increases so too does the current which is registered by strategically placed electrodes that come into contact with the fluid being measured.
Very low permanent pressure loss
No moving parts
Process Variables have no effect on the measurement
Minimal straight run requirements
Clamp-on Ultrasonic Flow Meters
The SITRANS FU clamp-on ultrasonic flow meters consist of a flow display computer, ultrasonic clamp-on transducers, and mounting hardware and cables; configurations can also include temperature sensors for calculating thermal energy consumption. Clamp-on ultrasonic flow meters utilize either transit-time or Doppler technology – or in some cases, both.
Vortex Flow Meters
The SITRANS FX vortex flow meters are designed to measure flow of liquids, gases and steam in a pipe. The principle behind the operation of a vortex meter is the Von Kármán effect.
Low flow cutoff
Meters are usually sized smaller than the pipe to increase velocity
Moderate permanent pressure loss
Upstream pipe requirements
Differential Pressure Flow Meters
Differential pressure flow meters have been employed to measure the flow of liquids, gases and steam for many years. It is one of the oldest methods of flow measurement and the most widely utilized and accepted methods in the world.
There is a wide variety of primary flow elements – orifice, venturi, averaging pitot tubes, etc.- available to meet the needs of virtually any application.
Though not a flow measurement device, valve positioners are a critical component for regulating the flows of liquids, gases and steam. Valve positioners are devices that ensure the correct position of a control valve in relation to a controlling signal.
Siemens SIPART PS2 is an industry leader in intelligent positioners and has been providing accurate and trouble-free operation of all valve types for over 17 years.
Improved speed of response & accuracy over pneumatic and electro-pneumatic positioners
Very low bleed design reducing carbon footprint and cost of ownership
Standard control valve diagnostic reduces maintenance and provides system operating characteristics continuously to the BMS