A flow meter (or flow sensor) is an instrument used to measure the linear, nonlinear, mass, or volumetric flow rate of a liquid or a gas. When choosing flow meters, one should consider such intangible factors as familiarity of plant personnel, their experience with calibration and maintenance, spare parts availability, and mean time between failure history, etc., at the particular plant site. It is also recommended that the cost of the installation be computed only after taking these steps.

First Steps to Choose the Right Flow Meter

The first step in flow sensor selection is to determine if the flow rate information should be continuous or totalized and whether this information is needed locally or remotely. If remotely, should the transmission be analog, digital, or shared? And, if shared, what is the required (minimum) data-update frequency? Once these questions are answered, an evaluation of the properties and flow characteristics of the process fluid, and of the piping that will accommodate the flowmeter, should take place. In order to approach this task in a systematic manner, forms have been developed, requiring that the following types of data be filled in for each application: Download the Flowmeter Evaluation Form.

Fluid and flow characteristics

The fluid and its given and its pressure, temperature, allowable pressure drop, density (or specific gravity), conductivity, viscosity (Newtonian or not?), and vapor pressure at maximum operating temperature are listed, together with an indication of how these properties might vary or interact. In addition, all safety or toxicity information should be provided, together with detailed data on the fluid's composition, presence of bubbles, solids (abrasive or soft, size of particles, fibers), tendency to coat, and light transmission qualities (opaque, translucent or transparent).

Electromagnetic Flowmeter (EMF)

Electromagnetic flow meters (EMF) have been used for continuous flow measurement in industrial applications for many years. They are ideally suitable for liquids with an electrical conductivity greater than 5 μS/cm. In addition to water and wastewater, other contaminated liquids are typical areas of application.

The underlying measuring principle of the EMFs is based on Faraday's law of induction. The coils of the flowmeter generate a magnetic field orthogonal to the flow direction. According to Faraday's law of induction, a conductive liquid passing through the magnetic field induces a current between the two electrodes, which can be used to measure the voltage. The higher the flow velocity, the higher the induced voltage. This voltage signal is converted into a standard signal (e.g. 4 - 20 mA or P) by the integrated electronics.

Our product range for flow measurement includes both "Insertion" and "Full Bore" EMFs in different versions. While the magnetic field in the "Full Bore" versions extends over the entire pipe cross-section, the magnetic field from the immersed sensor in the Insertion version is transmitted only to a part of the medium.

Metal Tube Variable Area Flow Meters

Durable and accurate flow meters for fluid measurement in high-pressure and extreme temperature applications.

Armored to deliver repeatable, reliable flow measurement in demanding high-pressure, high-temperature applications, metal tube flow meters ;from Brooks Instrument set the global standard for rugged durability and sustained accuracy.

Globally approved for use in hazardous environments, metal tube flow meter manufacturer Brooks offers a range of metal tube rotameters that include corrosion-resistant options for metering aggressive fluids and multiple connection options to make it easier to interface our meter into existing industrial systems. Engineered for long-lasting performance, Brooks high-pressure water or gas flow meters deliver excellent meter repeatability to help accurately measure and precisely control complex industrial processes.

Gas Flow Meter Types for Measurement

Most gas flow meters (differential pressure, turbine, positive displacement, vortex shedding) measure the gas flow at the actual operating conditions. This flow rate is ACFM (actual cubic feet per minute). However, it is more important to adjust or correct the flow rate for a particular pressure and temperature. This adjusted flow rate is often called STP (standard pressure and temperature) and is usually in units of SCFM (standard cubic feet per minute).

For this reason, most gas flow meters require pressure and temperature correction to convert the flow rate from operating conditions (ACFM) to standard conditions (SCFM).

Positive displacement meters require fluid to displace components mechanically and measure volumetric flow at the operating temperature and pressure. While they have sufficient accuracy, pressure and temperature compensation are needed to achieve mass flow, and since they have moving parts, the user must consider gas cleanliness. A PD meter may be called a PD flow meter or a volumetric flow meter. An example of a PD meter is the diaphragm meter.

Glass Tube Variable Area Flow Meters

When measuring liquid or gas flow at higher pressures and temperatures than is suitable for plastic, you can achieve accurate flow rates with robust glass tube rotameters (variable area flowmeters) from Brooks Instrument. With a broader range of flow rates available, glass tube rotameters are suitable for a variety of liquids and gases.

Resistance to thermal shock, pressure, and oxidation is the result of employing borosilicate glass tube bodies that can withstand pressures up to 13.8 bar (200 psi). Plus, corrosion-resistant material options for scales, floats, fittings, and valves accommodate a variety of applications, whether in the lab or in industrial processes.

Pressure Gauges

What is a pressure gauge?

Pressure gauges ;are instruments for measuring and displaying the pressure of a medium. Pressure gauges are pressure measuring instruments with elastic pressure elements, which have been used millions of times in various industrial applications. Depending on the area of application of the pressure gauge, Bourdon tubes, diaphragm elements, or capsule elements are used as pressure elements.

Which pressures do pressure gauges measure?

Pressure gauges measure gauge pressure, absolute pressure, and differential pressure. Furthermore, not only can WIKA pressure gauges be used for measuring positive gauge pressure, but also for measuring negative gauge pressure.

How does a pressure gauge work?

Pressure gauges work differently depending on the type. In industrial measurement technology, two different types of pressure gauges are used - Bourdon tube pressure gauges and diaphragm pressure gauges. They have different functional principles and are therefore suitable for different applications. With Bourdon tube pressure gauges, the pressure is measured by a Bourdon tube transmitting pressure directly to the pointer. Inside the case, there is a curved tube, into which the medium enters and causes the Bourdon tube to stretch. This stretching is transmitted to the movement via a link and a toothed segment and displayed on the dial as a corresponding deflection.

What is a solenoid valve and how does it work?

What is a solenoid valve?

The definition of a solenoid valve ;is an electro-mechanical valve that is commonly employed to control the flow of liquid or gas. There are various solenoid valve types, but the main variants are either pilot operated or direct-acting. Pilot-operated valves, the most widely used, utilize system line pressure to open and close the main orifice in the valve body. ;

While Direct operated solenoid valves directly open or close the main valve orifice, which is the only flow path in the valve. They are used in systems requiring low flow capacities or applications with low-pressure differential across the valve orifice.

How solenoid valves function

How a solenoid valve works is by controlling the flow of liquids or gases in a positive, fully-closed, or fully-open mode. They are often used to replace manual valves or for remote control. Solenoid valve function involves either opening or closing an orifice in a valve body, which either allows or prevents flow through the valve. A plunger opens or closes the orifice by raising or lowering within a sleeve tube by energizing the coil.

Solenoid valves consist of a coil, plunger, and sleeve assembly. In normally closed valves, a plunger return spring holds the plunger against the orifice and prevents flow. Once the solenoid coil is energized, the resultant magnetic field raises the plunger, enabling flow. When the solenoid coil is energized in a normally open valve, the plunger seals off the orifice, which in turn prevents flow.