Not everyone knows that gas meters come in different sizes. Which one a business should get depends on its individual needs. From this guide, you can find out everything you need to know about gas meter sizes, including how they measure gas and what gas meters in different sizes can do. Understanding which gas meter size is the best for your business is crucial when setting up energy supplies and installing new meters at the business’s premises.
Basics of gas meters
A gas meter can be described as a specialized flow meter that measures the volume of fuel gases. These fuel gases include propane and natural gas. Gas meters can only measure Actual Volumes. There are three different Actual Volumes. If pressure and temperature are known, the actual volume can be converted to standard volume. There are three Standard Volumes that are the same.
When it comes to natural gas, one quantity of gas can occupy different volumes depending on temperature and pressure. That means that gas density changes when pressure and temperature change. That’s why the use of regulated volumes when referring to gas quantities is extremely important. The two common standardized volumes are:
- standard cubic feet (scf) – 1 cubic foot of gas at 0 °C and 14.6959 PSI
- normal cubic meters (Nm3) – 1 cubic meter at 20°C at 101.325 kPa
Based on the type and size of the meter they have different pressure, flow rates, and rangeability. The rangeability is also referred to as turndown and it describes the range in which a particular meter can accurately measure gas.
Types of gas meters
The volumetric flow rate of gas can be measured with many different gas meters. Each meter type can detect the type of gas and various flows. An overview of how the common types of gas meters are built can be found in the table below.
|Type of Meter||Description|
|Diaphragm Meters||have four measurement chambers linked together the measurement chambers form a whole separated by a deformable wall that is a diaphragm|
|Rotary Displacement Meters||consist of two rotating impellers that are placed opposite each otherthe impellers are placed inside a housingthe impellers don’t touch each other during the rotation|
|Turbine Meters||consist of a gearwheel system, a turbine wheel, an extrusion section and a sealed housing unitthe gearwheel system leads the meter’s index|
How does each type work?
- Diaphragm Meters
In Diaphragm Meters, both diaphragms are connected to each other and, through a rotating piston, they lead to the counter. If the volume of each chamber is known beforehand, the quantity of gas that passes through the meter can be measured directly.
Diaphragm meters are mainly used by domestic customers as they have low pressure (0-100 PSI) and low flow rates. They also have large rangeability (Qmax/Qmin = 160).
If a measurement error ever occurs it is likely to be caused by the leakage of both the moving parts and the diaphragm. The potential leakage can lead to a low flow range and cause lower meter readings.
Diaphragm meters sometimes come with pulse generators that transmit meter readings.
- Rotary Displacement Meters
The impellers in Rotary Displacement Meters are positioned so that the gap between them and housing is very small, no matter what position they are in. Similarly to the Diaphragm Meters, if the volume of each chamber is already known, the quantity of gas can be measured directly. Most of the time, you will know exactly what is the volume of each chamber in Rotary Meters.
Rotary Displacement Meters have medium Pressure (0-175 PSI in most models), and medium to high flow rates. They can also reach high rangeabilities (Qmax/Qmin = 250).
The downside of this type of gas meters is that they pulsate during measurement. That’s because gas molecules constantly run through the meter during calibration. The pulsations can sometimes result in measurement errors. To avoid that, you can use silencers. Another drawback of Rotary Meters is that they are sensitive to dust particles and their parts are very fragile. That’s why being careful during installation is very important.
- Turbine Meters
When gas flows through the meter, the turbine wheel starts to rotate. The rotation of the turbine wheel is proportionate to the velocity of the flow, so the quantity of gas can be measured according to the rotation of the turbine wheel.
These types of meters can include multiple pulse generators. Turbine meters have the highest Pressure (up to 1480 PSI) amongst all the meter types, and they also have high flow rates. Their turndown is poor compared with other meters.
Any measurement errors can be a result of the small mechanical damages caused by friction in the gearwheel system. Turbine meters are typically installed at premises where large gas quantities are used.
Each of the discussed meter types comes in different sizes. The overview of the sizing for each meter type can be found in the table below.
|Diaphragm meters||sized based on the actual gas flow ratesized using delivery pressure and required flowhave limited connection size optionsmost meters only have one possible connection size|
|Rotary meters||sized based on actual gas volume flowrate minimum flow rate is required to measure gas to save costs a smaller meter at a higher pressure can usually be used|
|Turbine meters||sized by volumetric flow rate have specified minimum and maximum flow rates|
To determine what size of the gas meter you need, you have to take into consideration several factors:
- Type of your premises – is it, for example, an office, a commercial building, or a small shop?
- Your highest demand for gas at any given moment – is also referred to as a gas load or maximum capacity.
- Distance from the gas meter to appliances – gas pressure lowers the more gas has to travel.
- The number and type of appliances that use gas – it’s possible that if you have a lot of appliances you will need a bigger meter.
What size gas meter do I need?
The gas load is different for each customer. Nevertheless, the highest demand for gas of a typical household is 30 kilowatts (kW). That varies, however, if a house has more rooms and more radiators.
Small businesses can have requirements similar to domestic customers. Commercial buildings, on the other hand, typically use much more gas. Medium-sized businesses often use between 70 kW and 150 kW, and the biggest ones 1000 kW or even more.
Diaphragm meters are the most commonly used. Almost all residential and small commercial customers use them. Diaphragm meters come in 7 sizes:
|Meter Type||Flow Rate kW||Capacity (SCMH)|
|U16||66 – 173||16||565|
|U25||174 – 271||25||883|
|U40||272 – 430||40||1412|
|U65||430 – 704||65||2296|
|U100||705 – 1083||100||3511|
|U160||1084 – 1733||160||5650|
Why is it important to get the right size of the gas meter?
When choosing a meter size, it is recommended that the maximum flow rate is no more than 80% of the maximum capacity of the meter. Otherwise, it might not work properly. It is impossible to choose one size of the meter that would be appropriate for all businesses. It is important that a meter can pass through the volume of gas your premises require. If you have the wrong size of the meter installed, the functioning of your business can be negatively affected. Replacing the wrong meter can be expensive and take a lot of time so before you install the first one, make sure it’s the right size.
Is a U16 gas meter domestic?
A U16 is a small diaphragm meter. It is usually used for commercial applications, but it can sometimes be installed also at domestic properties. The name consisting of ‘U’ and a number is applied to all Diaphragm Gas Meters and explains what the meter capacity is. It’s expressed in Standard Cubic Metres per Hour. That means that the capacity of a U16 meter is 16 cubic metres per hour.
What is a U6 gas meter?
U6 is a diaphragm meter that is the most common domestic meter. U6 refers to the capacity of the meter, which is 6 cubic metres per hour. It’s a low-pressure meter that has a flow rate of 0 – 65 kW.
How do I know what size gas meter I have?
When your meter is being installed, engineers will determine its size. They will calculate it based on the total capacity of the premises gas appliances. You can ask them about the size once the installation is finished. Later on, the gas meter’s capacity can be checked by looking at its label. It’s expressed in cubic feet per hour (cf/h). Typically installed gas meter sizes range from 175 cf/h to 275 cf/h.
What happens if my gas meter is too small?
If the meter is too small, your appliances might not be getting enough gas and they might not function properly. Similarly, your options to buy new appliances might be limited.
How do I upgrade my gas meter?
If you want to upgrade your gas meter, you need to call your utility provider. They can send a technician who will come and replace your old meter with a new, bigger one. Your utility provider can also help you calculate your total gas demand and based on that advise you what size of the meter will be the best.