Common applications of magnetic flow meters: water, process and food industries

This measurement principle has been used worldwide for more than 50 years, as evidenced by the fact that the popularity of these flow meters has not diminished at all in many different fields.

In industrial settings, magnetic flow meters are most commonly used in water management systems, the process industry, the pharmaceutical sector, and the food industry. Modern magnetic flow meters are so robust that they can be used in mining and tunnel construction, under the harshest environmental conditions, and in virtually any type of application. Their typical routine use includes continuous flow measurement and control, filling and dosing, and custody transfer applications. These flow meters can measure many aqueous fluids: water, wastewater, sludge, pulp, paste, acids, alkalis, juices, fruit puree, etc. However, they cannot measure non-conductive liquids, gases, or steam.

Subsequent research and development in the fields of sensor design and signal processing have led to a product with a proven track record of reliable service, enabling easy integration into highly complex applications for high-level measurement, instrumentation, and control. The real-world examples highlighted below are sufficient to illustrate the status of these flow meters.

Application Example No. 1 – Water / Wastewater:

Magnetic flow meters have two main areas of application in the water management industry:

– Treatment and distribution of drinking water to consumers (aquatic facilities, domestic users, etc.).

– Control of water collection (both wastewater and rainwater) for purification in wastewater treatment plants for responsible return to the environment.

Laws and regulations governing water control in drinking water systems, sewage systems, and water treatment plants are becoming increasingly stringent, making detailed monitoring of water from its source to the consumer essential. Magnetic flow meters are the ideal choice for multi-point measurement in these systems and help identify and reduce leaks.

Task:

The operator of the wastewater treatment plant at an industrial complex wants to measure the volume of wastewater entering the plant. To do this, the operator needs information about the following aspects:

– Control of input flows, so that process management can be optimized in real time.

– Volume control for each individual source, so that the services supplied by the wastewater treatment plant can be located and billed to the customer according to their use.

Solution:

A magnetic flow meter is installed at each service connection point, between the user's premises and the main sewer line. The flow rates recorded by each magnetic flow meter are transmitted via electrical signals to the treatment plant's control system. Each flow meter also sends an electrical signal pulse indicating the total water consumption (water discharge). Approved weight and size magnetic flow meters, such as those from E+H, are widely used in water supply management for billing services to commercial customers.

Application Example No. 2 - Process Industry:

Many and varied are the demands that flow meters in the process industry must meet: resistance to aggressive fluids, requirements for use in risk areas, suitability for integration into instrumentation and process control systems, and a good cost-effectiveness ratio for their installation.

Task:

The chemical plant operator is to transfer a 33% hydrochloric acid solution from the storage tank to the production area. The operator has specified several other tasks in addition to volumetric flow rate measurement:

– The flow meter must be chemically resistant to reactive hydrochloric acid.

– The flow meter must be easily integrated into the existing instrumentation and measurement environment.

Solution:

A low-power, two-wire flow meter with lower installation costs than any conventional four-wire equipment (4-20 mA) / suitable for explosion-risk areas Ex 1/2 / digital interfaces for connection to a fieldbus device / Teflon coating and tantalum measuring electrodes to offer maximum resistance to the fluid.

Application Example No. 3 - Food Industry:

In the food industry, the technical characteristics of devices are just as important as their suitability for meeting the hygiene standards required by regulations. The suitability of systems for cleaning is critical in this context and is applied to measuring systems with the same rigor as to any other piece of plant equipment. This imposes durability requirements on the coating, which must be appropriate for the fluid being measured. The critical factors are as follows: a) Various production processes take place at or below ambient temperature. b) Typical temperatures involved in cleaning (CIP) and sterilization (SIP) processes range from +70 to +140 °C (160 to 285 °F). Alkaline/caustic or organic substances are often added to enhance the cleaning effect.

Fig: Flow measurement in the food industry. Photo: Promag H by E+H, manufactured with stainless steel

Task:

A yogurt manufacturer wants to inject molasses into their product as a flavor enhancer from a storage tank. The materials used in the system's construction must withstand the stresses of cleaning and sterilization processes and comply with EU quality standards (EHEDG) for food industry systems.

Solution:

A magnetic flow meter with longitudinally installed measuring tube (suitable for brush cleaning, without restrictions) / stainless steel head / PFA lining / all materials exposed to the fluid are FDA listed and comply with the requirements imposed by the 3-A certificate / the model complies with EHEDG requirements.