A gas meter is a special flow meter that can measure the volume of gaseous fuels such as propane and natural gas. It is difficult to measure the volume of a gas because the volume measured is strongly influenced by pressure and temperature.
Definition of Gas Meter
Gas meter, a device to measure the quantity or rate of gas flow. Types of gas meters (based on operating principles) include displacement, speed, head, thermal, acoustic, and tracking. An example of the displacement principle is the bellow-and-diaphragm gas meter (shown in the diagram). This type is widely used in commercial and domestic gas services to measure the amount of gas delivered to users. A gas bellow meter measures the amount of gas that passes through it by filling and emptying, in order of order, one or more internal spaces with a known capacity. Calculating the time each space is filled and emptied gives the volume of gas being sent.
In a gas gauge the speed of the gas flow flows the impeller spoons on a rotor. The rotation of the rotor is directed to a dial mechanism that records the volume of gas being delivered. In a vortex speed gauge, the rotor is installed in an offset chamber in a short part of the flow pipe. Only a portion of the total gas flow is fed into this space, and the total quantity measurement is based on the movement of the rotor recorded. Speed gas gauges also include anemometer type gauges in which a rotating cup or propeller powers a small generator or drives a series of recorder registers.
The head-type gas gauge measures the amount of gas per unit of time. Measurements are based on a deliberate drop in pressure made, or head, between the two closest points in the tube in the meter. This pressure difference can be converted into flow rate. Devices used to produce pressure heads include orifice plates, venturi tubes, flow nozzles, and pitot tubes.
In a thermal type gas meter the heater (such as an electric heating coil) is placed in the gas stream, and the thermometer is installed on the upstream and downstream sides. Gas flow is measured in relation to the increase in the temperature of the gas flow or the amount of electrical energy needed to keep the heater at a constant temperature.
An acoustic gas gauge measures the rate of gas flow by comparing frequency shifts from two initially identical signals (one sent upstream, the other downstream) after it is reflected. The tracking-type gas gauge measures the flow rate by timing the passage of the radioactive material injected between two fixed detectors.
The specified volume of gas can be measured using a gas meter regardless of the quality or quantity of pressure of the gas flowing through the meter.
Types of Gas Meters
The volumetric flow rate of the gas is measured using various gas meters. The meter is designed to detect gas types and various streams. Some of the main types of gas meters are discussed in the following sections.
These gas gauges have four measurement chambers linked together to form units separated by diaphragms and deformable walls.
The diaphragm is connected through a rotating piston. The amount of gas passing through the diaphragm meter can be directly measured if the volume of each chamber is already known.
Diaphragm gauges can also be used with pulse generators to provide meter readings. However, leaks of moving parts and diaphragms are the main cause of measurement errors when using diaphragm gauges.
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Rotary Displacement Meters
Two rotating impelers placed facing each other inside the house unit form a rotary displacement meter. The impeler is positioned in such a way that its cross section is perpendicular to the spinning axis, and the gap between the impeler and the house is very small. The amount of gas can be measured directly if the volume of each chamber is known.
During measurement, gas molecules tend to travel through the meter continuously, which results in a pulse during calibration. Silencers can be used to avoid significant measurement errors. Gear systems, turbine wheels, extrusion parts, and enclosed housing units are the main components of turbine meters.
As the gas flows, the turbine wheels begin to spin. The rotation of the turbine wheel is proportional to the speed of flow. Therefore, the volume of gas can be calculated in connection with the rotation of the wheel.
Calibration of Gas Meter
The gas meter must be in good operational condition during use and must have a valid calibration certificate. It is important to calibrate the gas meter periodically to avoid significant errors.
General calibration practice involves setting a short recalibration period for a new gas meter, then performing sequential calibration. This allows deviations between each calibration to be estimated and the user can determine whether to increase or decrease the recalibration interval.
Gas Meter Measurement Metric
Gas measurement metrics depend on the information needed in the application and the convenience of the transaction. Gas energy, gas vapor pressure, its volume (or volume of liquid), or its mass can be measured. Factors such as temperature, pressure, and purity affect the properties of these gases.
It’s interesting how methods have evolved to measure the state of invisible matter (usually) and gases. Advanced gas measurement science has the most advanced technology in this era.
Natural gas (methane) is measured in volume (cubic meters or cubic feet) in resource wells. One cubic foot of natural gas is the volume of gas contained in 1 cubic foot, at standard temperature and pressure. Generally gas production measured from reserves ranges from thousands or millions of cubic feet. So, a trillion cubic feet of gas filled the 2-mile-long side cube!
However, the value of natural gas is based on energy content, measured in joules. About 4.2 joules is the heat needed to raise the temperature of one gram of water by one degree Celsius at a standard pressure of 101.325 kPa and standard temperature (15 degrees Celsius). The British thermal unit or Btu was a cousin unit of the joule empire. 1 btu is the amount of energy needed to raise the temperature of a pound of water by one degree Fahrenheit. The content of Btu gas is usually expressed as MMBtus (1 million Btus) or mcf (1000 cubic feet) or term (100 cubic feet).
”One cubic foot of methane gas at standard temperatures and pressures (60 degrees Fahrenheit and 14.73 pounds per square inch) contains exactly 1,000 Btus.”
Gas Meter Application
The following are the main applications of gas meters:
- It can be used in offshore and onshore drilling rigs to detect and measure the amount of gas.
- It can be mounted onto existing rig beacon lines to measure gas volumes under managed pressure drilling and unbalanced drilling operations.
Also Read: Electromagnetic Flow Meter for Calibration
Thus the article “Gas Meter: Definition, How It Works, and Applications” hopefully can answer and add knowledge to the readers to related articles, hopefully useful.