Flow measurement Kinds and units of measurement

Flow measurement is the quantification of bulk fluid motion.Flow can be measured in various ways using a device called a flow meter. Common flow meter types with industrial applications are as follows:

• Obstruction type (differential pressure or variable area)

• Reasoning (Turbo)

• Electromagnetic

• Positive displacement flow meters, which accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow.

• Hydrodynamics (vortex shedding)

• Anemometer

• Ultrasonic flow meter

• Mass flow meter (Coriolis force).Flow measurement methods other than positive displacement flow meters rely on indirect calculations of flow by the force exerted by a flowing stream of water overcoming a known constriction.Flow can be measured

Flow measurement 

Kinds and units of measurement 

Flow measurement is the quantification of bulk fluid motion. Flow can be measured in various ways using a device called a flow meter. Common flow meter types with industrial applications are as follows:

• Obstruction type (differential pressure or variable area)

• Reasoning (Turbo)

• Electromagnetic

• Positive displacement flow meters, which accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow.

• Hydrodynamics (vortex shedding)

• Anemometer

• Ultrasonic flow meter

• Mass flow meter (Coriolis force).

Flow measurement methods other than positive displacement flow meters rely on indirect calculations of flow by the force exerted by a flowing stream of water overcoming a known constriction. Flow can be measured by measuring fluid velocity over a known area. For very large flows, flow can be inferred from changes in the concentration of dyes or radioisotopes using tracer methods.

Kinds and units of measurement

Both gas and liquid flow can be measured in terms of physical quantities such as volume or mass flow in liters per second or kilograms per second respectively. These measurements are related to the density of the material. The density of a liquid is almost independent of conditions. This is not the case with gases, whose density depends largely on pressure, temperature, and to a lesser extent on composition.

When a gas or liquid is transferred because of its energy content, as in natural gas sales, flow can also be expressed in terms of energy flow, such as gigajoules per hour or BTUs per day. Energy flow is volume flow times energy content per unit volume or mass flow times energy content per unit mass. Energy flow rate is usually derived from mass or volumetric flow rate by using a flow computer.

In an engineering setting, volumetric flow is usually represented by the symbol , and mass flow by the symbol .

For fluids with density, mass and volume flow rates may be related to .

Gas

Gases compress and change volume when they are pressurized, heated or cooled. A certain volume of gas under one set of pressure and temperature conditions is not equivalent to the same gas under different conditions.Will refer to the "actual" flow through the meter and the "standard" or "basic" flow through the meter in acm/h (actual cubic meters per hour), sm3/sec (standard cubic meters per second), kscm/h ( thousand standard cubic meters per hour), LFM (linear feet per minute) or MMSCFD (million standard cubic feet per day).Gas mass flow can be measured directly, independent of pressure and temperature, using ultrasonic flow meters, thermal mass flow meters, Coriolis mass flow meters or mass flow controllers.

Liquid

For liquids, different units are used depending on the application and industry, but may include gallons (US or Imperial) per minute, liters per second, bushels per minute, or when describing river flows, cumecs (cubic meters per second) or acres per day . In oceanography, a common unit for measuring volumetric transport (such as the amount of water transported by currents) is the sverdrup (Sv), which corresponds to 106 m3/s.Gases compress and change volume when they are pressurized, heated or cooled. A certain volume of gas under one set of pressure and temperature conditions is not equivalent to the same gas under different conditions. Will refer to the "actual" flow through the meter and the "standard" or "basic" flow through the meter in acm/h (actual cubic meters per hour), sm3/sec (standard cubic meters per second), kscm/h ( thousand standard cubic meters per hour), LFM (linear feet per minute) or MMSCFD (million standard cubic feet per day).Gas mass flow can be measured directly, independent of pressure and temperature, using ultrasonic flow meters, thermal mass flow meters, Coriolis mass flow meters or mass flow controllers.

Liquid 

For liquids, different units are used depending on the application and industry, but may include gallons (US or Imperial) per minute, liters per second, bushels per minute, or when describing river flows, cumecs (cubic meters per second) or acres per day.In oceanography, a common unit for measuring volumetric transport (such as the amount of water transported by currents) is the sverdrup (Sv), which corresponds to 106 m3/s.