How to choose a suitable flowmeter? What should be noted respectively?

How to Start Selecting a Flow Meter

First you need to know what to consider when choosing a flow meter. Before you start choosing the right flow meter, it is necessary to understand what your application is for. Are you measuring gas, liquid or steam?

But let’s first explain in detail what flow meters are, how they work, what they are used for, and the criteria for selecting the best flow meter for an application.

What is a flow meter?

A flow meter is an instrument that measures the mass or volumetric flow rate of a gas or liquid. When referring to flow meters, you may come across a variety of terms such as flow sensor, mass flow meter, mass flow controller, flow controller , etc.

The basic purpose of a flow meter is to measure the flow of a gas or liquid between two points in a process. Sometimes it is necessary to control or regulate the flow of the medium . This is achieved by combining a flow meter with a valve to form a flow controller, in which case , in addition to measuring the flow, it can also be controlled to change the flow rate. Its output helps you better understand the process and make quick decisions to reduce flow in terms of product quality, process speed and cost reduction .

How does a flow meter work?

There are two basic types of fluid measurement , mass flow and volume flow measurement. For gas volume flow measurement , temperature and pressure are affected and expressed in volume units.

For example : milliliters ml/min or m³ / h.

When measuring mass flow, you will see mass units such as kg/hour or g/minute.

Additionally, since gases are compressible, it is more convenient to express mass flow rate in terms of standardized volume (such as milliliters per minute or cubic meters per minute).

Therefore, you can choose a mass flow meter or a volume flow meter depending on your application needs.

In addition to these two measurement types, there are different measurement principles each with its own specific advantages and disadvantages:

• Thermal measurement principle
• Coriolis measurement principle
• Ultrasonic flow measurement

Some flow meters are designed for gases, others for liquids. There is also a class of flow meters on the market that are not dependent on the properties of the fluid and can therefore measure both gases and liquids.

How does a flow meter work?

There are two basic types of flow measurement - mass flow and volume flow measurement.

For gases, volumetric flow measurement is affected by temperature and pressure and is expressed in volume units, such as ml/min or m3/h. When measuring mass flow, you will see mass units, such as kg/h or g/min. In addition, since gases are compressible, it is more convenient to express mass flow in standardized volumes, such as ml/min or m3/min. Therefore, you can choose a mass flow meter or a volume flow meter based on your application needs.

In addition to these two measurement types, there are different measurement principles each with its own specific advantages and disadvantages:

Thermal measurement principle

Coriolis measurement principle

Ultrasonic flow measurement

Some flow meters are designed for gases, others for liquids. There is also a class of flow meters on the market that are not dependent on the properties of the fluid and can therefore measure both gases and liquids.

What is flow?

Flow rate is often the most important specification to consider when selecting a flow meter. Fluid quantities can be displayed in volume, standard volume, and true mass units. Flow rate is the amount of fluid that flows through the measuring device per unit time.

What are the inlet and outlet pressures?

When choosing a flow meter, it is important to know if you need a low pressure drop. Pressure drop is defined as the difference between the inlet pressure and the outlet pressure. Additionally, flow meters have a maximum operating pressure. If you have a high-pressure application, you need to consider this pressure rating.

In the case of mass flow control, the inlet pressure (P1) and outlet pressure (P2) are required to select and size the most appropriate control valve.

What are ambient temperature and fluid temperature?

The temperature of the fluid and the environment of the instrument are the next factors to examine.

Changes in fluid temperature may affect the accuracy of the measurement. In the event of temperature fluctuations, select a flow meter with temperature compensation function.

Ambient temperatures that are too high or too low can also damage the flow meter's electronics during operation or storage. When you use a flow meter in a furnace or burner application or in an area with extremely low temperatures, it is important to check whether the instrument can withstand these extreme temperatures. Therefore, before selecting a flow meter, check the temperature specifications provided by the supplier.

Where is the flow meter located?

When choosing a flow meter, you must consider where it will be installed, whether it is indoors, outdoors, in a laboratory or in a specific industry. For laboratory applications, additional specifications may differ from those in the oil and gas industry.

• Protection level
• NEMA

You are installing a flow meter and require sector-specific certificates or approvals, such as ATEX or IECex certification (for use in hazardous areas) or FDA approval, etc.

What do you want to achieve with your flow meter?

When choosing a flow meter, you need to consider what is important in your application. What are you trying to achieve?

Performance and price

The most common criteria for selecting a flow meter are price and performance. If you prioritize price, you may end up with a basic instrument with below-average performance.

In addition to the price of the components, installation, maintenance, and repairs over time should also be included in calculating the total cost of ownership. The cost of running the flow meter, such as its power consumption, also adds to the overall cost of the flow meter.

Flow Meter Accuracy and Repeatability

When choosing a flow meter, you must consider the specifications of the flow meter. Accuracy and repeatability are important indicators to pay attention to.

Flexible application

Sometimes it makes sense to choose a flow meter that can be used in multiple applications. For example, when you need an instrument for a research project and you know that other projects will follow in the future, but you don't know what fluids will be used at that time. In this case, it may be beneficial to choose a flow meter that is fluid-independent and has a wide flow range.

If your application has high flow fluctuations, you may prefer a flow meter with a high turndown ratio. Turndown ratio is also often referred to as adjustable range. This represents the range over which the flow meter or controller can accurately measure the fluid. In other words, it is simply the high end of the measurement range compared to the low end, expressed as a ratio and calculated using a simple formula:

Turndown ratio = maximum flow rate / minimum flow rate.

What process conditions might be relevant to flow meters ?

How does the flow meter ensure that the medium is clean and pollution-free while monitoring data?

In the food and beverage and pharmaceutical industries, cleaning instruments is important to avoid cross contamination. Cleaning in place (CIP) is a method of cleaning the internal surfaces of pipes, vessels, equipment, filters and fittings. A typical CIP cycle includes multiple steps, including cleaning with hot cleaning agents and hot acids at temperatures up to 95°C. Steam in place, also known as sterilization in place (SIP), includes a stage in which the instrument is sterilized using saturated steam at temperatures up to 140 °C. Not all flowmeters are suitable for these cleaning methods, so this is an important factor to consider when applicable. Also note that these markets often require the application of FDA-approved seals as well.

Flow meter available space

installation space limited? Then choose a compact flow meter that does not require straight pipes at the inlet or outlet. There are ultra-compact flow meters on the market based on technology .

Installation of JUJEA flow meter

Before selecting a flow meter, it is important to examine where and how the meter will be placed in your installation. The accuracy of some instruments may be more affected by their mounting position than others. Other relevant aspects related to the installation of the flow meter may be interference caused by vibration, crosstalk, pressure shocks, and the effects of elbows, valves, and reduced pipe diameters upstream and downstream of the meter. These effects may also vary depending on the operating principle.