The Role of the High and Low Pressure Ports on a Differential Pressure Transmitter

It's easy to misunderstand the role of the high and low pressure port on differential pressure transmitters. This video clearly explains their real meaning and role.

Thermo Scientific Ramsey

Thermo Scientific Ramsey manufactures industrial in-motion weighing, monitoring and inspection equipment used for process control and production control in a wide variety of industrial applications. Products include weighbelt feeders, belt scales, metal detectors, sampling systems, level indicators, conveyor safety switches. Below is an embedded copy of the Thermo Scientific / Ramsey Bulk Weighing and Monitoring Catalog. You can download a copy at the TECO website here.

Electromagnetic Flow Metering

Electromagnetic flow meters
Cutaways of electromagnetic flow meters - one
removed from service (right) and one
remanufactured (left).
Electromagnetic flow metering is widely used for conductive liquids, such as water acids and alkalis. It's also effective in many other process applications using clean, dirty, and process liquids and slurries. While electromagnetic flow metering is primarily used in full pipes, they can also be applied to partially full pipes and channels often found in effluent applications.

Electromagnetic flow metering is based on the principles of Michael Faraday's 1832 discovery. When a conductive liquid, such as water, is moved through a magnetic field a voltage is induced in the liquid at right angles to the magnetic field. The size of the voltage is directly proportional to the volume flow rate. This induced voltage is detected by sensors known as electrodes. These electrodes transfer the voltage signal to the processing electronics where it can be converted into a usable industrial standard signal.

It's important that the flow meter tube is non-magnetic, and austenitic stainless steel is the most commonly used material. It's also essential that the flow meter tube has a lining that electrically insulates it from the liquid inside, and provides a non-reactive barrier with any corrosive liquids being measured. Distinguishing between flow induced voltage changes, electrochemical noise, and plant induced noise, is a barrier to accurate electromagnetic flow metering. This can be particularly difficult in dirty and industrial applications. The choice of electromagnetic flowmeters with advanced noise suppression can mitigate unwanted noise and provide extremely high orders of accuracy as a result.

To ensure that your electromagnetic flow meters will be optimized for safety, longevity, and performance, the advice of a qualified flow instrumentation expert should be sought out. That expert will be able to help you with the best selection of the appropriate flow device for your specific application, be it electromagnetic flow meters or another flow technology.

Differential Pressure Flow Metering for the Chemical Processing Industry White Paper

Differential Pressure Flow MeteringFlow measurement is a critical aspect of plant operation in the Chemical Processing Industry (CPI). Users choosing equipment to meter the flow of liquid or gas processes must consider a wide range of factors to arrive at an optimal solution Experience has shown there are significant differences between meter technologies, with each type of device having its own advantages and disadvantages for processing facilities

Common Differential Flow Metering Methods:
  • Venturi
  • Cone Meter
  • Wedge Meter
  • Averaging Pitot Tube
In modern chemical plants, personnel need to make faster and better decisions by capturing, managing and analyzing the right data at the right time These facilities rely heavily on flow processes, and thus accurate and reliable measurement techniques are vital to the efficiency and safety of their operations.

Badger Meter, a premier manufacturer of industrial flow meters, has authored an excellent white paper explaining the use of differential pressure flow metering in the chemical processing industry. You can get the white paper at this link.

For more information, visit Thompson Equipment Company (TECO) at or call 800-528-8997 for immediate service.

Remanufactured Flowmeters, Instrumentation & Valves

TECO has the experience, trained technicians, and facilities to remanufacture your equipment to meet or exceed all OEM specifications and performance standards. Send us your old flowmeter, process instrument, or valve and we'll send it back to you as good as new.

Thompson Equipment Company

Magnetic Flowmeters for Fracing

Fracing illustration (USGS)
Hydraulic fracturing, or fracing, is the process of exploiting small fissures or cracks in rock layers deep under the earths surface, and increasing their number and size for the purpose of freeing up trapped natural gas. The process includes drilling horizontally in the bedrock and then forcing "frac fluid" into those cracks under very high pressure. The fracturing fluid is made up of water, a special type of sand (referred to as the proppant) and a mixture of chemicals.

Flow measurement is very important in fracing and requires instrumentation with long life and high accuracy.  Frac fluid is a very nasty slurry and it's flow measurement is challenging. Flow instruments are exposed to high pressures, erosive materials and corrosive chemicals.

FracingFrac sand is very erosive and the high pressure and corrosive chemicals complicate things exponentially. Any flowmeter used in fracing applications must not only be rugged enough to withstand these harsh conditions, but the flowmeter must also provide the accuracy required for reliable data reporting to supervisory agencies. Cost-effectively meeting accuracy and longevity requirements for these applications can be frustrating.

Magnetic flowmeters have always appealed to the fracing industry because of their unfettered flow path, availability of sizes and level of accuracy. Their downfall is their longevity. Standard, off-the-shelf magnetic flowmeters don't last in this environment and can't be considered an economically viable choice.

An excellent solution that provides all the the virtues of magnetic flowmeters, and overcomes the longevity and economics issues, are specialized magnetic flowmeters. Referred to as "severe service flowmeters" or "slurry flowmeters", they are designed with components matched specifically to withstand the mechanical and chemical abuse they will see.

Magnetic flowmeters, specialized for fracing, provide all of a "magmeters" desirable features with these critical enhancements:
  1. A ceramic sleeved liner made of magnesia partially stabilized zirconia. This ceramic can handle the abrasion and chemical attack with very little degradation.
  2. Highly polished, ultra-smooth Tungsten electrodes. The Tungsten provides outstanding wear resistance while the high-polish reduces electrical noise introduced in the electrode circuitry.
  3. Special coatings, or paints, to provide exterior protection.
Fracing flowmeterBy specifying magnetic flowmeters, specialized for fracing, not only do operators save money through increased uptime and decreased health, safety and environmental risk, but also through reduced costs related to flowmeter purchase and repair.

For more information on fracing magnetic flowmeters, contact Thompson Equipment Company (TECO) by calling 800-528-8997 or visit

Magnetic Flow Meters for Abrasive Service

Magnetic flow meters (magmeters) apply Faraday’s Law of Electromagnetic Induction to measure flow. They are specifically designed for conductive fluids like water, acids, caustic liquids, and slurries.

Magnetic flowmeters differ in materials, size, corrosion resistance, pressure and temperature performance. Properly applying magnetic flow meters for abrasive and/or erosive slurry measurement is one of the most challenging applications for plant engineers and maintenance managers to address. The proper combination of design components is critical.

If you have a challenging flow measurement application that involves abrasive or erosive media, contact TECO for assistance. A short conversation with one of our application engineers will save you a great deal of time and money.

Thompson Equipment Company