Continuous Liquid Level Measurement Technologies Used in Industry

Process measurement connectivity with wireless technology
is suitable for almost any application 

Although continuous level measurement technologies have the ability to quantify applications for bulk solids, slurries, and granular materials, this article will focus on level measurement technologies applied to liquid level measurement utilized in process control. A distinction should be made between continuous level measurement and point level measurement. Point level measurement acts like a switch, changing state when a single level condition is achieved. Called “transmitters,” continuous liquid level measurement devices employ technologies ranging from hydrostatics to magnetostriction, providing uninterrupted signals that indicate the level of liquid in a vessel, tank, or other container.

Hydrostatic devices focus on the equilibrium of dynamic and static liquids. There are three main types of hydrostatic transmitters: 1) displacer, 2) bubbler, and 3) differential pressure.

The displacer transmitters utilize a float placed within the liquid container. With its buoyancy characterized to the liquid and the application, the float, a connecting stem, and a range spring or similar counterbalance represents the liquid level in terms of the movement of the displacer (float). The displacement, or movement, of the assembly is converted into an electric signal for use by the monitoring and control system.

Bubbler transmitters are used for processing vessels that operate at atmospheric pressure. This method introduces a purge gas or an inert gas, e.g. air or dry nitrogen, into a tube extending into the liquid vessel. Precise measurement of the pressure exerted on the gas in the dip tube by the liquid in the tank is used to determine the height of the liquid.

Differential pressure (DP) transmitters rely directly on, in a basic explanation, the pressure difference between the bottom and top of the container. Precise pressure measurement is used to determine the height of the liquid in the tank. One of the most advantageous aspects of DP transmitters is that they can be used in pressurized containers.

Other examples of level transmitter technologies which are not hydrostatic devices include magnetostrictive, capacitance, ultrasonic, laser, and radar.

In magnetostrictive level transmitters the measuring device, a float, has a magnet that creates a magnetic field around a wire enclosed in a tube. Electrical pulses sent down the wire by the transmitter head produce a torsional wave related to the position of the float, which moves with changes in liquid surface level. The transit time of the torsion wave back to the sensing head is measured and the depth of the liquid, as indicated by the float position, can be determined.

Capacitance transmitters are best applied to liquids that have high dielectric constants. Essentially, changes in the capacitance of the sensor / tank / liquid assembly will vary proportionately with the liquid level. The change in capacitance is measured and converted to an appropriate electrical signal.

Ultrasonic level transmitters emit ultrasonic energy from the top of the vessel toward the liquid. The emissions are reflected by the liquid surface and them time required for the signal to return to the source is used to determine the distance to the liquid surface.

Laser level transmitters operate similarly to an ultrasonic level transmitter. However, instead of using ultrasound signals, they use pulses of light.

Radar level transmitters involve microwaves emitting downward from the top of the container to the liquid’s surface. The measured time for receipt of a return sign reflecting off the liquid surface enables calculation of the distance from the sensor to the liquid surface.

The precise measurement of transmit time for a wave or pulse of energy is employed in several of the technologies, the measurement of pressure in others. Each technology has a set of attributes making it an advantageous selection for a particular range of applications.

Analynk Wireless provides connectivity solutions enabling the wireless transmission of measurement data across the room, across the property, across the globe. Share your process measurement and control connectivity challenges with the experts at Analynk for a solution that is simple to implement and cost effective.

Wireless Communications Deliver Real Time Process Data From Remote Operating Sites

No distance is too near or far for industrial wireless
communications

Oil is where you find it, with many prospecting and production sites located where the communication options taken for granted in developed areas do not exist. Oil is big and serious business, with tremendous sums of money at risk on the prospect of reaping even greater returns. Every business operation, though, is of great importance to the stakeholders. Countless operations in little known industries and endeavors are located beyond the boundaries of modern communications infrastructure. 

If you want a data connection, bring your own.

Remote operating sites, whether for oil extraction or other purposes, will often be automated. Some decision making system or individual is responsible for the safe and effective operation of the remote site, or has a use or need for real time data being gathered at the remote site. Radio transmission is a viable, maybe the best, option for delivering real time data from a remote site to a central office.

• Transmission options for 900 MHz, 2.4 GHz, cellular, and satellite systems are readily available.
• Equipment operates on low voltage, low power. Suitable for solar or other remote site power source.
• No special instrumentation needed. Radio transmitting and receiving equipment interfaces directly with analog signals from common industrial process transmitters.
• No "across the land" cabling needed.
• Equipment can be configured to resist extreme environmental conditions.

Analynk manufactures transmission and receiving equipment that builds the bridge between remote sites and the home office. From elemental componentry to integrated, ready to run systems, Analynk specializes in wireless communications for industrial process control. Contact us with your wireless challenges. Whether an expansive multipoint, or a single point application, the specialists at Analynk can combine standard or customized products into a practical solution for every application.

One Transmitter, One Receiver, Multiple Process Signals

A16000 Multiple I/O Module
Analynk

Radio frequency (RF) communications can enable the establishment or cost effective, quick, process signal connections across very small or very large distances. A misconception arises, from time to time, that it is necessary to have a dedicated transmitter and receiver for each process signal. Analynk has a solution that provides for delivery of up to sixteen process signals over a single transmission path.

Wireless transmission of process control signals is steadily increasing in prevalence throughout commercial, institutional and industrial settings. The ease of implementation, with no long cable runs to plan, layout, install, protect, and maintain, allows wireless installations to fulfill application niches that may have been considered impractical in the past.

Analynk provides hardware that easily allows the transmission and reception of up to 16 I/O points using a single transmitter and receiver. The A16000 Expansion Module can be configured with up to four internal cards that accommodate various types of input and output signals. The process is similar to setting up the I/O on a PLC. Connect the process signals to the A16000, and the A16000 to one of Analynk's transmitter or receiver devices. Setup is straight forward and allows the installation to be operable in minimal time.

Share your wireless communications and signal transmission challenges with the experts at Analynk and get recommendations on how to best implement workable solutions.

Analynk Model A16000 RF Expansion Module from Analynk Wireless, LLC

Automation and Grain Processing

Grain processing benefits from automation and industrial wireless

The grain industry serves as an example of industrial process control, where standards are maintained at a constant rate for product delivery. Automation in grain processing provides both safety and efficiency by supporting the product delivery process. Historically, the grain production process has been hazardous, with industry workers subject to harsh conditions and potential risks associated with the grain, such as flammable grain dust. The transition from manual labor to automation has become the industry’s essential shift, with automation now a staple in harvesting, milling, and handling grain. The developers of automation components seek to mitigate production ineffectiveness and inventory miscalculations. Solids level transmitters, responsible for continuously monitoring the amount of grain in potentially hazardous environments, are a reliable replacement for employees at a silo’s peak.

Thanks to developments in technology, the implementation of sustainable automation does not need to come at the expense of company profit. A sole driver needs to control automation operations when dealing with grain handling, meaning that the number of employees put at risk via that stage in the process is substantially reduced. In order to keep track of inventory, automated management tracks not only the levels of grain inside silos but also where materials are located throughout the production facility. Grain sensors allow for the constant communication of how much grain is being moved through grain elevators and terminals. Instrumentation measures level, weight, and flow of solid grain while maintaining process protection.

Grain terminals allow for grain to be unloaded into hoppers, and then conveyors transfer those hoppers to the elevators. Cleaning drying, and blending machinery all employ automation, reducing the risks presented to employees. Truck and rail load-outs need to be close to target levels, because overloading or under-loading transport results in product loss. Preventing the loss of time and physical resources is a key element of automation. Radar transmitters cut through dust in silos to deliver reliable information back to the process operators. Ultrasonic instrumentation matches with point level technology to indicate when grain levels are high or low.

The handling and blending of raw materials can be monitored by solid flowmeters, with high accuracy still applicable in more compact spaces. A similar solid flowmeter ensures the accuracy of the flow rate and weight of solids measured in bulk, and can also be used in tandem with flow and weigh feeders to keep each individual load of grain consistently accurate. The applications of automation throughout the grain production process have evolved into a reliable means of reducing employee risk while ensuring accuracy and increasing throughput.

Grain operations cover large areas. A reliable, flexible, and cost saving way to establish the needed process control connections throughout the facility is via industrial wireless. Connections between measurement instruments and control units can be created across very long distances without the need to install conduit and cabling. Connections can be created quickly and reliably, with flexibility to increase throughput as more stations or sensors are needed. Equipment is suitable for general or hazardous locations. Contact an industrial wireless communications expert for help in developing connections on your project.

Diaphragm Seals Protect Industrial Pressure Gauges and Transmitters

Industrial pressure gauge with diaphragm seal installed
Courtesy Wika

Pressure measurement is a common element of industrial operations and control systems. Fluid processing can often involve media that is potentially harmful to pressure sensing devices. The media may be corrosive to the sensor material, or other media properties may impact the performance or usable life of the instrument. In process control environments, diaphragm seals play a role in protecting items like pressure sensors from damage by process fluids. The diaphragm seal is a flexible membrane that seals across the connecting path to a sensor and isolates the sensor from the process media. System pressure crosses the barrier without inhibition, enabling accurate measurement, but the process fluid does not. Typical materials composing diaphragm seals are elastomers, with a wide variety of specific materials available to accommodate almost every application.

In the operating principle of the diaphragm seal, the sealed chamber created between the diaphragm and the instrument is filled with an appropriate fluid, allowing for the transfer of pressure from the process media to the protected sensor. The seals are attached to the process by threaded, open flange, sanitary, or other connections. Diaphragm seals are sometimes referred to as chemical seals or gauge guards. Stainless steel, Hastelloy, Monel, Inconel, and titanium are used in high pressure environments, and some materials are known to work better when paired with certain chemicals.

Sanitary processes, such as food, beverage, and pharmaceuticals, use diaphragm seals to prevent the accumulation of process fluid in pressure ports, a possible source of contamination. If such a buildup were to occur, such as milk invading and lodging in a port on a pressure gauge, the resulting contamination compromises the quality and purity of successive batches. Extremely pure process fluids, like ultra-pure water, could be contaminated by the metal surface of a process sensor. Some pneumatic systems rely on the elimination of even the smallest pressure fluctuations, and diaphragm seals prevent those by ensuring the separation of the process materials from the sensors.

Diaphragm seals are not without some application concerns, and devices are now built to address and counter many potential issues related to the use of diaphragm seals with process monitoring instruments and equipment. Products seek to eliminate any and all dead space, allow for continuous process flow, and are self-cleaning thanks to continuous flow design. Some high pressure seals come equipped with anti-clogging features, accomplished by the elimination of internal cavities while protecting gauges. Multi-purpose seals reduce temperature influence and improve instrument performance while pinpointing and diffusing areas of high stress. These pre-emptive measures result in longer instrument life-cycles and improved performance while ensuring protection from corrosion.

There are numerous options and available diaphragm seal variants. Share your application specifics with a product specialist, combining your own process knowledge and experience with their product application expertise to develop an effective solution. Analynk Wireless manufactures industrial wireless communications equipment and process transmitters.

Tachometer Transmitter for Industrial Process Measurement and Control

Tachometer transmitters deliver rotational speed signals

Analynk Wireless, in addition to producing their line of products for establishing wireless connections among industrial process measurement and control devices, manufactures an extensive array of wired products. The wired products are useful in establishing similar connections between sensors and the devices or instruments that will utilize their output signals. The transmitters are available with a wide array of input and output combinations, as well as several enclosure options. Enclosures can be customized to meet specific installation challenges.

The tachometer transmitter will convert the pulse signal from a tachometer into a linear signal representing rotational speed. There are many applications where a frequency output from a tachometer or other sensor needs conversion to a 4-20 mA or other common signal for use by a monitoring instrument. Analynk provides transmitters to easily convert almost any sensor signal to a linear voltage or current output. A data sheet is included below that provides more detail about one of the many transmitters available from Analynk.

Share your connectivity challenges with the process signal transmission experts at Analynk. Effective solutions come through consultation and cooperation.

Tachometer transmitter for industrial process measurement and control from Analynk Wireless, LLC

Antennas In Industrial Wireless

Explosion proof antenna for industrial wireless
communications in hazardous locations
Analynk Wireless

Wireless field instrumentation has played a growing role in the process control industry since its introduction. Digital instrumentation has become the industry standard thanks to advantages in communicability, durability, cost effectiveness, and integration. WirelessHART maintains, and even exceeds, the operating efficiency of wired systems without sacrificing security. Other protocols for industrial communications also operate in the process control space, each providing an operable solution for wireless connectivity. All utilize a common signal path that is worth understanding, if you are involved in process measurement and control…radio

Communicating information over long distances through open space is achieved by radio systems using electromagnetic fields. The common radio wave comprises oscillating electric and magnetic fields to generate electromagnetic radiation. The three most common antenna designs are the half-wave dipole antenna, the quarter-wave whip antenna, and the five element yagi antenna. The dipole and whip antennas are engineered to adeptly receive electromagnetic waves from all directions perpendicularly aligned with their axes. The yagi antenna, on the other hand, boasts director and reflector elements to increase its directionality. Thanks to this directionality, the yagi is best applicable in radar and point-to-point communications. The dipole and whip, also known as omnidirectional antennas, are better in situations where equal sensitivity is required in multiple directions instead of a pinpoint system.

Supervisory control and data acquisition (SCADA) systems find uses for both yagi and dipole antennas. The dimensions of particular antennas are directly related to signal wavelength because radio antennas work at maximum efficiency when in conditions of electrical resonance. The actual size of the antenna allows for a certain electrical resonance frequency. Low frequency antennas are larger, and higher frequency antennas are smaller. A quarter-wave whip antenna designed as part of a 900 MHz transceiver application, in industry, would be around 8.3 centimeters. The same antenna design for an AM radio broadcast transmission operating at 550 KHz would be around 136 meters. These antenna parameters are specific to both the conditions the antenna operates under and the related frequency being measured.

Industrially designed yagi antennas are built to preserve the reliability of wireless monitoring, even in harsh environments. Oil and gas companies, water districts and progressive utilities can monitor Remote Terminal Units (RTUs) from a centralized location. The major challenge facing radio wireless monitoring today is the maximization of uptime in difficult environments. The challenge is being addressed by the development of antennas which can pair with National Electrical Manufacturers Association RTU enclosures. Protecting against dust and rain, wind, splashing water, and hose-directed water are some of the ways product developers are responding to industry reported client concerns. Additionally, industrial environments can present hazards that require the use of specially enclosed antennas to eliminate the potential for ignition of flammable atmosphere. Similarly, dipole antenna manufacturers are adapting to challenging environments by designing antennas specific to the application needs of industry customers.

Analynk Wireless provides solutions for establishing wireless connections in industrial settings. You can learn more about the company at their website.