Gas Flow Measurement - Flow Meter Indonesia - Flow meter air, flowmeter solar, gas, Ultrasonic, Vortex, Electromagnetic


Minggu, 11 Januari 2015

Gas Flow Measurement

Gas Meter
Gas Flow measurement
Gas flow measurement is used to measure a fluid that has the characteristics such as gas and not only on a narrow understanding of gases such as natural gas and propane. The discussion here is the gas flow meter is used to measure the flow of a fluid in a form that has a gas, not a liquid and a solid. Therefore, applications for gas flow meter can be used for LPG​​, Compress air, CNG, Nitrogen, Oxygen, Air, Argon, a mixture of various gases and hot air or steam. With the character of the gas in which the determination of volume or weight is strongly influenced by the temperature and pressure of the gas is more difficult to make measurements when compared with liquid.
Several different designs of gas meters are commonly used, depending on the volume of gas flow rate to be measured, the range of flows anticipated, the type of gas being measured and other factors. he use of gas flow meter wide enough for both oil and gas sector, manufacturing, households, farms, laboratories, hospitals and mines. In determining the types and models of gas flow meter should be based on the function and the location where the gas flow meter is installed.  To needs at home, certainly not in the same hotel if used for industrial or hospital. Gas flow meter is used for combustion processes such as stoves, boilers, power plants, or burner must have a different character if the flow meter is used to oxygen, nitrogen, argon, steam and other gases are applied to production.

1 . Thermal Mass Flow Meter
Thermal mass flow meters generally use combinations of heated elements and temperature sensors to measure the difference between static and flowing heat transfer to a fluid and infer its flow with a knowledge of the fluid's specific heat and density. The fluid temperature is also measured and compensated for. If the density and specific heat characteristics of the fluid are constant, the meter can provide a direct mass flow readout, and does not need any additional pressure temperature compensation over their specified range.
Technological progress has allowed the manufacture of thermal mass flow meters on a microscopic scale as MEMS sensors; these flow devices can be used to measure flow rates in the range of nano liters or micro liters per minute.
Thermal mass flow meter (also called thermal dispersion flow meter) technology is used for compressed air, nitrogen, helium, argon, oxygen, and natural gas. In fact, most gases can be measured as long as they are fairly clean and non-corrosive. For more aggressive gases, the meter may be made out of special alloys (e.g. Hastelloy), and pre-drying the gas also helps to minimize corrosion.
Today, thermal mass flow meters are used to measure the flow of gases in a growing range of applications, such as chemical reactions or thermal transfer applications that are difficult for other flow metering technologies. This is because thermal mass flow meters monitor variations in one or more of the thermal characteristics (temperature, thermal conductivity, and/or specific heat) of gaseous media to define the mass flow rate

2. Laminar Flow Meters

Laminar flow meter is based on the utilization of pressure drop through the laminar flow element to measure the mass flow rate of the fluid. Laminar flow elements that form a very thin line serves to separate the turbulent flow of gas . With the reduced diameter of the flow channel will affect the pace will be laminar through the channel.  Laminar flow meter using the pressure drop created in the laminar flow element to measure the mass flow rate of the fluid . A laminar flow element taking turbulent flow and separated into a thin line . By reducing the diameter of the flow channel and affect the speed , the flow becomes laminar through the channel .
The pressure drop due to pass through the channel will cause a pressure difference will be measured using differential pressure sensor. By using the Poiseuille equation can be connected to the pressure drop volumetric flow rate . So that the rate of volume can be converted into flow rate using the density correction at a certain pressure and temperature.  Features of laminar flow meter : The pressure drop is proportional to the volumetric air flow rate, Wide dynamic range with no lower limit, High accuracy with linear scale, Low pressure drop, Fast response, Available small flow range.

3. Coriolis Flow Meters
Coriolis Mass Flow meters s a mass flow meter that measures mass flow, density and temperature (volume flow calculated) of liquids, slurries and multi-phase liquids directly without going through calculation process based on other variables. The mass flow sensing element is composed of a pair of bent tubes, vibrators and displacement sensors. The trick here is to detect the Coriolis force applied on the tube by the flowing fluid inside the bent oscillating tube. In order to do that the vibrators vibrates the bent tubes at the natural frequency of the tubes. When there's a flow inside the tubes, the Coriolis force at work distorts the vibration of the tubes. This distortion can be measured using the displacement sensors. The amount of distortion is directly proportional to the mass flow of the liquid inside the tube. By accurately processing the displacement, the accurate mass flow is directly measured. Liquids, slurry and multi phase (liquid mixed with air bubbles or solids) can be measured. It boasts strong immunity to noise, high accuracy, wide turndown ratio, stability and reliability. Simple design allows for simple installation, operation and maintenance. It has no moving parts. And it doesn't require any special devise for installation and it doesn't require flow profile stabilization, meaning it doesn't require straightner or straight pipe sections either upstream or downstream. The wetted parts are made of stainless steel and therefore can be used for corrosive liquids.

4. Turbine Flow Meters
Turbine meters have found widespread use for accurate liquid and gas measurement applications. The unit consists of a multiple-bladed rotor mounted with a pipe, perpendicular to the liquid flow. The rotor spins as the liquid passes through the blades. The rotational speed is a direct function of flow rate. Electrical pulses can be counted and totallizer. Fluid flowing through the sensor shell, because of the impeller blade and to have a certain Angle, the fluid force makes the blade with rotational torque, to overcome the friction moment and fluid resistance, blade rotation speed stability after the moment balance, under certain conditions, the speed is proportional to the velocity of flow, magnetic conductivity due to the blade, it is in signal detector (composed of permanent magnets and coils) magnetic field, rotating blade cutting lines, periodically changing coil magnetic flux, so that the coil ends of inductive electric pulse signal, the signal after amplifier amplification plastic, form a continuous rectangular pulse amplitude, can be spread far to display instrument, show the instantaneous flow and cumulative amount of the fluid. Within the scope of the certain traffic, pulse frequency f and is directly proportional to the instantaneous flow rate Q of the fluid flowing through the sensor.
 It features :
  • Highly accurate and repeatible
  • Eexcellent long-term reliability Installation flexibility
  • Economic and cost-effective solution for applications requiring high accuracy
  • Only one moving part reduces maintenance cost
  • A wide selection of materials A wide selection of output options
5. Vortex flow Meters
Vortex flow meter is a internationally advanced new type of flow meter, it is developed based on Karman Vortex Street Theory. It is applicable to the measurement of super heated steam, saturated steam, general gas and liquid.

6. Variable Area Flow Meters
Variable Area Flow Meter also known as metal tube rota meter is a kind of measuring meter which the flow rate is changing along with the area and is widely used in the process control of industrial automation.It has the merit of little volume, broad measuring range and convenience for use.

  • Firm work, little maintenance and long life
  • Low requirements to straight pipe part
  • Broader ratio of flow rate 10:1
  • Two-wire LCD indicator; instant/accumulated display of flow rate are available; back light option.
  • Single axis and sensitive display
  • Rotation of non-contact magnetic coupling
  • Can be applied to hazardous occasions such as flammable and explosive ones
  • All-metal structure, fit for high temperature, high pressure and mediums with strong erosion.
  • Power supply such as two-wire system, battery, alternating current option
  • Multi-parameters calibration function
  • Function of date recovery, date copy and power-off protection

7. Ultrasonic Flow Meters
Ultrasonic flow meters use sound waves to measure the flow rate of a fluid. Doppler flow meters transmit ultrasonic sound waves into the fluid. These waves are reflected off particles and bubbles in the fluid. The frequency change between the transmitted wave and the received wave can be used to measure the velocity of the fluid flow. Time of Flight flow meters use the frequency change between transmitted and received sound waves to calculate the velocity of a flow.