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Gas Measurement Unit - Gas Unit - LPG Measurement Unit - How is LPG Gas Measured?

The gas measurement for methane (natural gas) is measured by volume in cubic feet or cubic metres. One cubic metre of natural gas is the volume of gas enclosed in a cubic metre at standard temperature and pressure. The gas measurement of gas reserves is measured in thousands or millions of cubic metres.

A gas meter is a purpose built flow meter. A gas meter measures the volume of natural gas or LPG – liquified petroleum gas used. Gas meters are used by all gas utilities to measure consumption in homes, industrial and commercial buildings.

The gas unit used in the sale of gas is based on the energy content or calorific value of the gas, not gas volume. The typical gas units for energy content are British Thermal Units - BTU - megajoules (MJ) or therms, not cubic metres or cubic feet.

The distinctive properties of LPG mean that it can be measured in a number of different ways. These include gaseous volume (meter), liquid volume, weight, energy content and pressure. For example, LPG for homes is frequently delivered in 45kg gas bottles.

Gas measurement units (LPG measurement unit) are cubic metres, cubic feet, British Thermal Units (BTU), therms, and PSI as well as litres, kilograms, megajoules (MJ), tonnes and kilopascals (kPa) for gas measurement. The LPG (propane) gas is measured by weight in kilograms, pounds, tons or metric tonnes as gas measurement unit.

LPG gas is measured by weight when sold in gas bottles or cylinders. LPG gas is measured in tonnes when stored or transported in bulk tankers or vessels. LPG gas is measured in litres when it is sold by volume, with correction factors for temperature.

Gas is normally measures at STP - standard temperature and pressure (0°C at 1 atm pressure) or NTP - normal temperature and pressure (20°C at 1 atm pressure). Gas well production is measured in terms of thousands or millions of cubic metres or cubic feet.

Billion cubic metres (billions of m³) is the gas unit for measuring natural gas reserves. In the US, they would use trillion cubic feet (tcf) or billion cubic feet (bcf) as their LPG gas measurement unit. The gas unit for measuring gas well production is in millions of cubic metres (millions m³). These would be, by far, the largest LPG gas measurement units.

On a smaller scale, with a gas meter LPG gas is measured in cubic metres. If the gas units are billed in MJ or kWh, it’s calculated based on 3.6 megajoules equalling 1 kilowatt hour.

LPG is sold and weighed in gas bottles based on the weight of the contents. Bulk LPG is stored and transported in large quantities and LPG gas is measured in tonnes or US tons. Tanker delivered LPG gas is measured by volume in litres, with density corrections for temperature.

A liquid propane gas measurement unit for liquid volume, LPG gas is measured in litres or gallons for gas measurement.

The LPG gas measurement unit for the measurement of gas volume, such as natural gas volume, is cubic metres (m³) or cubic feet (ft³) gas units. For gas measuement, 1 ft³ is equal to 0.0283168 m³.

Megajoules (MJ), BTU or therms is the LPG gas measurement unit for energy content. For pressure, LPG gas is measured in kilopascals (kPa), Bar or pounds per square inch (PSI) is the gas measurement unit.

When measuring LPG by pressure, the term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the gas bottle. The pressure of the LPG gas is measured in kilopascals (kPa). “Bar” is yet another unit of measure for pressure. 1 Bar = 100 kPa, so it is metric based but not an SI unit of measure.

There is also measuring LPG by liquid volume, as LPG is a liquid when it is under pressure. When delivered by tanker hose or LPG dispenser, for autogas, the unit of measure is typically in litres. As the specific gravity of LPG – propane – is about half that of water, there are roughly 2 litres of LPG per kilogram.

LPG gas measurement is also done by volume (m3 or ft3), energy content (MJ, BTU or therms) and pressure (kPa, PSI or Bar) gas units.

How is LPG Gas Measured for Homes

When Liquefied Petroleum Gas – LPG – is used in the home, LPG gas is typically measured in kilograms. LPG gas in gas bottles is weighed and the price is based on the weight of the gas (e.g. 45kg). When produced, stored or transported, bulk LPG gas is measured in tonnes (e.g. 1,000kg).

Home LPG gas is also measured in litres of gas, if delivery is made by a tanker truck, instead of by gas cylinder exchange. The tanker truck has a gas meter attached to a hose reel that measures the gas as it is pumped into the customers' vessels.

A common way LPG gas is measured and selling LPG is by weight, in kilograms. There are different sizes of LPG gas bottles and the gas is sold based on the contents of a full bottle. Home LPG gas is measured in 45kg gas bottles.  BBQ gas is typically LPG gas measured and supplied in 9kg gas bottles. These numbers represent the weight of the gas, excluding the tare weight of the gas bottle.

LPG Gas Measurement Unit Chart

LPG Gas Measurement Unit Chart
Gas Type Attribute LPG Gas Measurement Unit
 LPG  Weight  kilograms, pounds, tons or tonnes
 LPG & Natural Gas
 Volume
 cubic metres (m³) or cubic feet (ft³)
 All Gases  Pressure  kilopascals (kPa), Bar or PSI
 Fuel Gases  Energy  megajoules (MJ), BTU or therms
 Compressed Gases  Volume  cubic metres (m³) or cubic feet (ft³)

LPG Gas Measurement

Gas measurement can be done with a gas meter measuring the volume of gas, scales measuring the weight of the gas bottle, pressure gauges measuring cylinder pressure or gas bowsers to measure the liquid volume for cars.

How is LPG Gas Measured - LPG Gas Measurement Unit

Gas measurement & calculated units of measure

The distinctive properties of LPG mean that it can be measured in a number of different ways. These include weight, liquid volume, gaseous volume, energy content and pressure. For example, LPG for homes is frequently delivered in 45kg gas bottles.

An LPG measurement unit can be litres, kilograms, megajoules (MJ), tonnes and kilopascals (kPa) gas units, as well as cubic metres, cubic feet, British Thermal Units (BTU), therms and PSI as the gas measurement unit.

LPG gas bottles are weighed, as they are priced based on weight. LPG is under pressure during storage and transportation and large quantities are measured in tonnes. Gas is also sold by volume, in litres or gallons, adjusted for temperature.

LPG gas is measured using an LPG gas measurement unit. For LPG (Liquefied Petroleum Gas) weight, the LPG gas measurement unit is in kilograms, pounds, tons or tonnes (metric tonnes). For LPG vapour - gas - measurement, the volumetric LPG gas measurement unit is cubic metres (m3) or cubic feet (ft3) gas units.

For gas measurement of LPG liquid volume, the typical gas measurement unit is litres or gallons.

LPG gas measurement unit of energy content is calculated in Megajoules (MJ), Gigajoules (GJ) or Petajoules (PJ), with the unit of gas measurement dependent on the gas quantities discussed.

BTUs or Therms are also the gas measurement unit for energy.

The gas measurement unit for gas pressure is calculated in kilopascals (kPa), Bar or pounds per square inch (psi) gas units.

LPG Gas Measurement Unit for Weight - Why LPG is Measured in kg

LPG gas measurement is in a kg gas unit because the volume and pressure can be affected by temperature. LPG (propane) expands at 1.5% per 5.55°C temperature increase. In other words, the density changes.

So, if the gas bottle was filled by volume on a hot day, it would have less gas, in kg, than a gas bottle filled on a cold day. That's why it is measured and sold in a kg gas unit.

Most auto LPG bowsers and tanker delivery trucks have an automatic correction factor so it can be delivered and/or sold in litres.

LPG gas measurement units for measuring and selling LPG is by weight, in kilograms. 

There are different sizes of LPG gas bottles and the gas is sold based on the contents of a full bottle. 

For example, LPG for homes is frequently delivered in 45kg gas bottles

BBQ gas is typically supplied in 8.5kg gas bottles. 

These numbers represent the gas measurement of the weight of the gas inside the bottle, excluding the tare weight of the gas bottle. 

Gas measurement of larger quantities of LPG is in tonnes (1,000kg).

In the US, the LPG gas measurement would be in pounds and US tons (2,000 pounds). 

For example, a typical BBQ gas bottle in the US contains 20 pounds of LPG.

LPG Gas Measurement Unit for Liquid Volume - How LPG is Measured as a Liquid

LPG is a liquid when it is under pressure. When delivered by tanker hose or LPG dispenser, for Autogas, the LPG gas measurement units is typically in litres. 

As the specific gravity of LPG – propane – is about half that of water, there are roughly 2 litres of LPG per kilogram. 

The exact weight to liquid conversion depends on the composition of the LPG, relative to the propane and/or butane content. 

It is also temperature dependent.

The temperature of the LPG must be known to calculate measurement by volume. 

LPG liquid meters have an automatic temperature correction process. 

See the table below for propane gas measurement conversion values.

Once again, the US gas measurement is different, this time being in US gallons. 

One gallon equals about 3.8L. 

Measurement of Gas Volume - How LPG is Measured Volumetrically

Measurement of gas volume would be in either cubic meters (m3) or cubic feet (ft3) gas units. When it is not under pressure, LPG exists in its gaseous or vapour form. As with other gases, the gas measurement unit for volume of LPG is measured in cubic meters (m3).

In the US, they use cubic foot (ft3) as the gas measurement unit.  One ft3 is equal to 0.0283168 m3.

LPG Gas Measurement Unit for Energy Content

The LPG gas measurement unit for energy value or calorific value of LPG is frequently expressed in Megajoules (MJ). Larger quantities are expressed in Gigajoules (GJ). Petajoules (PJ) gas units are used when huge quantities are being discussed, as in national consumption or production.

In the US they use BTU.  BTU, or British Thermal Unit, is another gas measurement unit of energy based on the Imperial System.

One BTU is the energy required to raise the temperature of 1 pound of liquid water by 1°F, at sea level. 

1MJ equals 948BTU, so to get an equivalent number of Megajoules, just divide the BTU rating by 948.

LPG Gas Measurement Unit for Vapour Pressure:

LPG Pressure Temperature Chart

As previously mentioned, when LPG is stored in a gas bottle, it is under pressure.  The LPG gas measurement unit for LPG gas cylinder-bottle pressure is measured in kilopascals (kPa).

The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the gas bottle. 

“Bar” is yet another gas measurement unit for pressure. 

1 Bar = 100 kPa, so it is metric based but not an SI unit of measure.

LPG Pressure Temperature ChartLPG vapour pressure can vary greatly based on temperature.

(LPG Pressure Temperature Chart shown)

The level of fill in the gas bottle comes into play when the LPG is being used, as it affects the rate of vapourisation. 

As LPG is a liquefied gas, the vapour pressure inside the cylinder will remain the same from full until the last of the liquid LPG is vapourised. 

Then the LPG gas cylinder-bottle pressure will fall quickly as the last of the LPG vapour is used, as well.

The use of LPG gas cylinder-bottle pressure as a measurement in LPG use is very limited. 

A steady pressure only shows that liquid LPG is inside the cylinder, but not how much liquid is left.

In the US, the vapour pressure gas measurement unit is pounds per square inch (psi). 

Psi is defined as 1 pound of force applied per square inch.   

As a comparison, 1 psi = 6.89476 kPa.

LPG conversion table

Final Thoughts on Gas Measurement and LPG Gas Measurement Unit

Gas measurement of LPG relates to the context in which you are interested.  It also depends upon the country in which you live.  Most small LPG cylinders, the LPG gas measurement unit for weight is kg or pounds. Most large tanks are filled and invoiced using the gas measurement unit litres (or gallons).

 

 

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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.