Natural Gas Flow Meter-FAQ 

1. What is a flow meter?

The flow meter is a precision instrument used to measure the linear and volumetric flow of a pipe’s gas and liquid flow rate. The three main characteristics to determine the flow are:

• A positive displacement meter collects a fixed volume of gas or liquid, then refill and releases the fluid.
• One can determine the flow while measuring the rate of fluid over a known area.
• Some methods depend on the forces of the flowing stream as it calculates the flow indirectly and overpowers a known constriction.
• The accurate gas or liquid flow measurement ensures safe and environmentally friendly operation in many applications.

2. What is natural gas?

Natural gas is one of the most valuable energy sources for industrial and commercial sectors. It contains different compounds. Methane is the most significant component of natural gas, and it has one carbon atom and four hydrogen atoms. Natural gas is among the highly used energy source across the world. Natural gas is part of the combustion process.

It is essential to measure natural gas to optimize the combustion control of industrial boilers, furnaces, process heaters, etc. By monitoring the fuel rates to burners, you can optimize the air-to-fuel ratios. It will ultimately reduce the energy costs of natural gas and improve process efficiency.

3. What is a natural gas flow meter?

The natural gas flow meter is the device that measures airflow through the tube. The flow meter does not measure the volume of air passing; relatively, it measures the mass of air flowing at one particular time. The unit of measurement of the natural gas flow meter is in terms of kilograms per second.

The natural gas flow meter is applicable in various automobile industries for measuring the air through an internal combustion engine. Therefore, it is essential to measure natural gas accurately and efficiently. Air is the most commonly natural gas on Earth, consisting of nitrogen, oxygen, argon, and trace amounts of carbon dioxide, methane, hydrogen, helium, and neon.

The density of the air depends on the temperature and pressure. For example, at 90˚F and 5000 feet, and stress of 12.2 PSIG, the density will be 0.060 Ib/ft3.  So for ideal natural gas flow meter measurement, it is essential to calculate the density of natural gas at different pressure and temperature.

4. How do natural gas flow meters work?

The natural gas flow meter monitors and controls the flow of natural gas in various industrial applications. The two main components of the natural gas flow meter include temperature sensors and an electric heater. The electric heater adds the heat in the direct heat version. When the fluid passes through the pipe, RTD measures temperature rise.

You can measure the mass flow based on the temperature difference between meter coefficient, heat rate, and specific heat rate of the fluid. Many natural gas flow meters have heated tube flow meters that protect the sensor element from overheating and corrosion. However, when you mount the sensors externally to the piping, they respond slowly, and the relationship between temperature and mass flow becomes non-linear.

The bypass version of the natural gas flow meter is suitable for measuring more significant gas flow rates. There are two RTDs and a thin-walled capillary tube. When there is no flow, the temperature rises to 160˚F above the ambient temperature. When there is flow, the temperature shifts with the flow rate. The smaller size of the bypass tube minimizes power consumption and increases the accuracy of the measurement.

5. What are the types of natural gas flow meters?

There are different types and techniques to measure nature as a flow meter. You can select these types of natural gas flow meters according to your requirements. Nevertheless, all of them have their advantages and disadvantages based on their operating principles.

Thermal mass flow meter

This natural gas flow meter is also known as a thermal dispersion flow meter. It consists of instruments used to measure the total mass flow rate and primarily gases flowing through the closed conduits.

The thermal mass natural gas flow meter is an effective device to measure gases. The principle of operation directs the flow of material past a heating element, and you can measure its temperature before and after the heater. It consists of the main flow channel and flows sensor line. The flow sensor has a capillary, a heater, and a temperature sensor downstream and upstream of the heater.

A thermal mass flow meter provides high rangeability if you operate it in a constant temperature difference mode. This flow meter can operate in high-temperature and high-pressure environments.

The second thermal mass flow meter type is the capillary-tube type, which comprises a mass flow meter, electronics, and a valve. Though the principle of operation of both types is thermal, yet are so significantly different that two separate standards are required.

This natural gas flow meter can be quickly built by measuring the temperature differential across the silicon-based MEMS chips. The thermal mass flow meter is commonly used for general industrial gas flow applications in ducts and pipes. On the other hand, the capillary types are mainly used for the smaller flow of clean fluids in tubes.

Metal tube rotameter

Metal tube rotameter is an accurate flow measurement technique for high pressure and temperature applications and is an effective instrument for measuring natural gas and liquids. Metal tube rotameter is used widely because of its rugged structure and durability. In addition, it is corrosion-resistant that makes it the best option for the measurement of aggressive fluid.

Metal tube rotameter can measure the low process temperature ranging -198˚C and high process temperature of range 420˚C. It has the feature of a local operator interface with LCD for an easy and effective control system. It works on the variable area principle where the fluid raises afloat, increasing the fluid passage area. The float moves with a fluid and stabilizes when the weight of the float and hydraulic force are balanced.

Vortex flowmeter

Vortex flow meters for natural gas flow meters are the velocity meters used primarily in the industrial measurement of gas. This type of natural gas meter is a latecomer to the custody transfer approval game. Unfortunately, this later approval has made it quite tricky for this meter to catch up to other custody transfer meters.

The vortex flowmeter is a reliable flow measurement device in applications where there are moving parts problems. They are very widely used in industrial grade, brass, and plastic construction. The vortex flowmeter operates on the principle of Vortex shedding, where oscillating occurs when fluid passes the body.

The vortex flowmeter is the most popular natural gas flow meter and has 316 stainless steel bodies. The other flow meter parts consist of a bluff body, a vortex sensor assembly, and transmitter electronics. They are available in flange sizes from ½ inches to 12 inches.

Vortex flowmeter usually uses capacitance type sensors or piezoelectric for detecting oscillation in the bluff body. These sensors are modular and need little maintenance. You can operate them in a wide range of temperatures—the rangeability of the vortex natural gas flow meter changes with the change in viscosity. The inaccuracy of the vortex flowmeter is 0.5-1% of the rate for Reynolds numbers over 30,000.

Vortex flowmeter subsists in brass, manufacturing brass, and plastic building. Therefore, it is an excellent choice for uses where low costs are vital. Moreover, this flow meter has no moving parts and has a varied determining variety.

Gas turbine Flowmeter

The gas turbine flow meter is an instrument for measuring the velocity of liquids, gases, and vapors, such as water, hydrocarbons, chemicals, air, and natural gases. Using the gas turbine flow meter for non-lubricating fluids is not suitable because it will affect the flow meter’s accuracy.

Although the gas turbine flow meter is among the traditional flowmeter types, it is still the most popular way to measure low viscosity fluids’ gas flow and steady flow. It consists of a flow tube and a spinning rotor. With the media flows, force is applied to the rotor rings. As a result, the fluid causes the rotor to rotate at the angular velocity is proportional to the fluid flow rate. As a result, the gas turbine flow meter is less costly than other natural gas flow meter types.

6. What is the working principle of the natural gas flow meter?

The natural gas flow meter works on the principle of thermal dispersion method and constant measuring technique. While measuring the gases, the instrument uses no rotating or moving mechanism, so pressure drop is negligible. There are two sensors at the end of the meter probes. These sensors are resistance temperature detectors (RTD) and resistance thermometers.

The RTD has an integrated circuit that works as a flow sensor. The second RTD works as a reference sensor and measures the temperature of natural gas. When gas flows from the RTD, heat gets away because of the drifting gas molecules. When the sensor cools down, the energy goes away. Due to this, the temperature difference between the RTD and reference RTD changes. The power is restored by heating the flow sensor.

A mass flow meter alongside the LED display to provide clear and visible readings of the flow. The natural gas flow meter has accurate flow measuring features because it directly measures the mass flow. In addition, it has a 4-20mA output transmitter and a data logging facility.

7. What is the importance of natural gas flow meter?

It is essential to monitor the instantaneous natural gas flow rate from any industrial plant. Observing the natural gas flow will help in every consumption and wastage of resources. The conventional billing meter only provides you with the consumption over a fixed period. The natural gas flow meter, on the other hand, monitors flow rate and consumption. It offers honest feedback about the flow meter conditions, peak demand, wasted energy, and other inadequacies.

The natural gas flow meter is easy to install and efficiently measures the mass flow rate of the natural gas. It does not require additional pressure and temperature transmitters and has little or no pressure drop. In addition, you can get bright and visible graphic displays of the natural gas flow rate and consumption.

8. Why is natural gas measurement important?

The natural gas flow meter is essential for monitoring the management system, combustion control, and sub-metering natural gas. However, the most crucial advantage of measuring natural gas is energy consumption. Therefore, it is also essential to measure natural gas for regulating pressure to reduce emissions and consumption at individual levels.

Also, monitoring and assessing the natural gas provide better insight into the process efficiencies, unusual consumption, natural gas leakage, increasing consumption, and cost allocation in various operating areas. Sub-metering the natural gas helps in identifying the possible leakage and wear and tear of the equipment.

9. What are the advantages of natural gas flowmeters?

Natural gas flow meter helps monitor natural gas for more extensive natural gas lines and smaller gas lines and controls flow to boilers and heaters. The main concern in the natural gas flow measurement is the energy consumption because you get an idea of the natural gas requirements of the plant.

• Natural gas flow meter provides accurate measuring capabilities with fast reaction time and a turndown ratio of 100:1 with negligible pressure drop.
• The natural gas flow meter has extremely low-pressure drop and low-end sensitivity.
• The measurement of the natural gas flow meter depends on the technology of resistance temperature detectors (RTD) with platinum sensors.
• The installation and maintenance of the natural gas flow meter are easier. For example, you don’t need to cut into the pipe to put spool sections.
• The natural gas flow meter offers higher repeatability with little maintenance over the broad flow range.
• The natural gas flow meter is economical as it does not require installing temperature or pressure transmitters.

10. What are the disadvantages of the natural gas flow meter?

• The natural gas flow meter is sensitive to gas composition.
• Accurate field Calibration is a delicate process.
• You can only measure gases with low pressure.
• There is a need for excessive power requirements in large pipelines.
• You can only use natural gas flow meter for fluids with good electrical conductivity.
• The accuracy range is only ±1% over a flow range of 5%.
• You can get the condensation of moisture on the temperature detector that can lead to corrosion.
• The coating on the sensor can affect the heat transfer, and the meter can read low.
• You can use natural gas flow meter for measuring corrosive fluids and gases.

11. What are the applications of a natural gas flowmeter?

Natural gas is the explosive mixture of various low molecular hydrocarbons and non-hydrocarbon gases. It is used as a fuel and produces raw materials for chemicals such as ammonia, ethanol, hydrocarbon fuels, methanol, nitric acid, etc.

The natural gas flow meter is widely used in various applications, such as measuring emissions from steam generators and boilers, gas measurement for air decomposers, landfill gas, ethanol distillation, and flue gas monitoring. Natural gas flow meters are increasing because they can handle large line sizes to measure gas flow. Another common application of the natural gas flow meter is biomass gasification.

Overall, the natural glass flow meter proves to be the cost-effective solution for measuring gas flow and providing optimal production and control. Its technology is fastest growing in new environmental measurements. The properties of low flow sensitivity, low pressure down, and thermal dispersion make natural gas flow meters an attractive alternative in challenging environments.

12. What is the working of the Coriolis natural gas flowmeter?

A natural gas flow meter provides reliable measurement and controls the consumption of natural gas. The Coriolis natural gas flow meter is the industry standard for achieving a high level of accuracy. In addition, it is easy to install with little maintenance. The main advantage of using a Coriolis natural gas flow meter is that you don’t need an inlet or outlet run for installing it.

You can install it horizontally or vertically. If you are mounting it vertically, the fluid should go up, and the temperature is lower. However, the temperature is high when you mount it horizontally, so install it with your head down. Coriolis natural gas flow meter is the direct flow measurement method that uses the deflection force of the fluid through an oscillating tube.

13. What are the specifications of the natural gas flow meter?

The natural gas flow meter is a critical technology for the accurate measurement of natural gas. It helps monitor the gas levels in boilers, ovens, furnaces, gas burners, etc. The specifications of the natural gas flow meter include:

• The natural gas flow meters are available in various sizes, ¾ inches, 1/2″, 1″, 2″, 3′, 4″, 100mm, 6 inches, 10 inches, 12 inches, and maximum 6000mm.
• Various process connections include flange, thread, inline natural gas turbine flow meter, insertion natural gas flow meter, etc.
• The pressure rating can be as low as 10 PSI, and it can detect natural gas leakage. The pressure rating can measure a low flow rate with a high-pressure rating of 150 LB, 300LB, 600LB, and 900LB.
• The output is 4-20mA with the actual result for alarm purposes for HART natural gas turbine flow meter.

14. What are the factors to consider while choosing the natural gas flow meter?

The natural gas flow meter is an essential device used in coal mining, nitric acid plants, burners, organic plants, petroleum refining plants, etc. Before purchasing the natural gas flow meter device, first, understand the application of this technology.

What type of natural gas will it be measuring? Are you looking for a flow meter that can measure single gas or mixture of gases? What are the process temperature, flow range, and pressure requirements? Are you going to measure dirty, corrosive, or clean gas?

What types of upgrades or calibrations are needed? For example, is your natural gas flow meter required to work in an extreme environment? And under what regulations?

What purpose does the natural gas flow meter serve? It is essential to understand whether you need a natural gas flow meter for sub-metering, monitoring, or custody transfer. Also, whether you need to measure volumetric natural gas or mass flow rate? How much are you willing to spend on the purchase of natural gas flow meter?

You need to answer these fundamental questions, make a list of your requirement and then purchase the natural gas flow meter accordingly.

15. What are the factors that affect the prices of natural gas flow meters?

Many factors determine the prices of the natural gas flow meter. You choose the natural gas flow meter based on your specifications and budget. Generally, the larger the natural gas flow meter, the higher are the prices. For example, the price of a 6″ natural gas flow meter is much higher than a 1″ flow meter.

The prices are also determined by the natural gas flow meter working principle. There are different natural gas flow meters: thermal gas flow meters, Coriolis mass flowmeter for measuring gas, and turbine flow meters for measuring volumetric flow rate. Each of these natural gas flow meters has varying price ranges.

If you customize the natural gas pressure rating according to your requirements, it won’t be cheap. You have to pay higher if you need a natural gas flow meter with ASME pressure or a 600 LB class. The functions of the natural gas flow meter can also influence the prices. These functions include HART communication, lithium battery, EVC (temperature and pressure correction), etc.

Conclusion

The natural gas flow meter is an economical and cost-effective solution for monitoring the natural gas in your applications. BSCT provides easy to install natural gas flow meters that are reliable, accurate, and repeatable.

If you are looking for a natural gas flow meter for your specific applications, you can contact us. We will guide you in purchasing the suitable flow meter that fits your applications. Our team of professionals will be there to assist you in every possible way.