Dynamic Compensation for Static Pressure Effects in Differential Pressure Measurement

DPharp Gauge Pressure Transmitter
Courtesy Yokogawa

Attaining the best available performance and accuracy from any measuring device utilized in an industrial process is always advantageous. The scale of most industrial processes is such that even small inaccuracies in process measurement produce financially tangible impact. Differential pressure measurement, with wide application in the industrial process sphere, can be improved with the addition of a means to compensate for the real world effects of static pressure upon instrument performance.

Yokogawa Corporation has developed a means to dynamically compensate for static pressure effects in field measurements. The brief technical presentation below will help you understand how static pressure effects can impact your field measurements, as well as how Yokogawa’s Real-time Dynamic Compensation works to offset its impact.

More detailed product and application information is available from your Yokogawa specialist.

Dynamic Compensation for Static Pressure Effects in Differential Pressure Measurement from Miller Energy, Inc.

Protect Valuable Pressure Gauges and Transmitters With a Pressure Limiting Valve

Pressure limiting valve provides gauge
or transmitter protection from spikes
Courtesy Mid-West Instruments

Pressure gauges and transmitters, commonly found in fluid process control operations, are vulnerable to damage from transient spikes in system pressure that may range beyond the instrument's working range. These pressure spikes can impact instrument calibration, or even render the instrument or gauge inoperative. The cost of replacing gauges or transmitters is substantial enough to warrant the use of protective devices to prevent exposure to pressure spikes.

Mid-West Instruments manufactures a line of pressure limiting valves specifically intended for use with pressure gauges and transmitters. The Model 200 pressure limiting valve prevents instrument over-range and has an adjustable needle valve to dampen pulsation. The valve and be used with all types of instruments and pressure gauges, is suitable for mounting in any position, and is available in a range of materials for body and seals.

The document below provides more product detail, as well as installation and setup instructions. Providing a useful measure of protection for pressure gauges and transmitters is a simple operation. Reach out to product application specialists for help in formulating effective solutions.

Pressure limiting valves for transmitter and gauge protection from Miller Energy, Inc.

"Bubbler Method" Liquid Level Measurement

An accurate pressure transmitter
is an integral part of  a liquid level
measurement system using the
"Bubbler Method"
Courtesy Brooks Instrument

Measuring liquid level in a tank or vessel can be accomplished in a number of ways, all of which require some arrangement of instrumentation to either infer the liquid level from the measurement of a related physical property, or directly deliver the liquid level visually using a scaled gauge arrangement. One indirect method of level measurement is often referred to as the bubbler method, so named because it employs a purging gas that continually vents from the bottom of a tube extending into a tank of liquid. Through a simple apparatus, the level of a liquid can be inferred by the amount a back pressure exerted upon the gas flowing through the tube.

Probably the greatest advantage of this method of liquid level measurement is that the liquid does not contact the sensing instrumentation. The only portion of the apparatus in contact with the liquid is a tube immersed into the tank. Basically, a purge gas flows through the immersion tube and may bubble out the immersed end of the tube, which is open to allow the contained liquid to exert a hydrostatic pressure on the purge gas. The back pressure on the gas that is exerted by the liquid contained within the tank will vary directly with the depth of the liquid. The back pressure can be correlated to a liquid level. Further calculations, which would include the tank shape, dimensions, and the liquid density can provide an indication of the volume and mass of the liquid. Here is an illustration of the setup, provided courtesy of Brooks Instrument, globally recognized leader in flow and pressure measurement and control. The illustration is from Brooks' January blog article.

Bubbler Method Tank Level Measurement Apparatus, showing application of some Brooks Instrument devices.

Below are data sheets detailing the components used in the system to control and measure the gas flow, and measure the back pressure on the immersion tube. There are other components needed for a complete system, but they are fairly generic in nature and easily obtainable. Contact a flow and level measurement specialist with your application challenges and work with them to produce effective solutions.

Bubbler Method Liquid Tank Level Measurement Instruments from Miller Energy, Inc.

Improve Process Safety Compliance With Safety Transmitters

Oil Refinery

Industrial processes often are characterized by substantial hazard through their operation. As operators, engineers, and designers, we are responsible for keeping those actual and potential hazardous conditions and occurrences in check. I recently wrote about safety transmitters that can be used to enhance safe industrial process operation and provide compliance with applicable standards.

I located a single sheet document that summarizes the features, benefits, cost savings, and compliance ratings for the safety transmitters from United Electric. You can get more detailed information on these devices and how to properly apply them in your process control scheme by contacting a product specialist. Combining you process expertise with their product application knowledge will generate a solid solution.

United Electric One Series Safety Transmitter from Miller Energy, Inc.

Safety Transmitter for Temperature and Pressure in Industrial Processes

One Series Safety Transmitters
Courtesy United Electric Controls

United Electric Controls has developed a safety transmitter that combines transmitter, safety switch, and display gauge in a single, easily deployed device. The One Series Safety Transmitter includes the manufacturer's patented self diagnostics, along with diverse and redundant signal processing that feed algorithms to detect and respond to internal faults and process abnormalities.

The safety transmitter provides a local switch that can be used for rapid emergency shutdown at the point of measurement or detection, eliminating the need to communicate with other safety controllers and await a response. The safety relay output is programmable and can handle high voltages and currents associated with shutting down control valves, compressors, and other industrial equipment.

In addition to the safety relay output, the One Series Safety Transmitter provides logic outputs that can be employed in voting logic schemes often used to produce warnings prior to a shutdown. For reliability, the unit employs no moving parts and includes self diagnostics with a local display of device status.

There is a whole lot more to learn about these "Safety right out of the box" industrial pressure and temperature transmitters. The product brochure is provided below, but you can get the latest and most detailed product and application information from a specialist in industrial process measurement and control.

United Electric One Series Safety Transmitter from Miller Energy, Inc.

New Product From United Electric - Hybrid Transmitter for Industrial Use

Series One HART Transmitter
Courtesy United Electric

By mid November, United Electric will begin shipping its new One Series hybrid transmitter-switch models that include HART® Communications Protocol. The newly designed product offering includes a transmitter-only model, as well as another model providing a transmitter plus two solid-state relays. Monitoring pressure or temperature in harsh, hazardous and heavy industrial process measurement and control settings is the target application for these loop-powered transmitters. Models will include UL and ATEX approvals for Divisions 1 & 2 (Zones 1 and 2). With the introduction of the One Series, UE is declaring a number of older models obsolete. You can get a listing of the newly obsolete models from your local UE distributor.

The new combination transmitter and switch model provides a HART® 7 loop-powered transmitter, and includes two programmable solid-state relays, an improved backlit LCD display, and a separate IAWTM health status discrete output.The transmitter-only model is a HART® 7 loop-powered transmitter and also features an improved backlit LCD display.

Some operational benefits, quoted directly from United Electric's product announcement documentation:

• With HART® 7 capability, all of the functions available with the two-button keypad are also available via the HART® Communications Protocol. Using a HART®-compatible hand held communicator or a PC with a HART® modem and appropriate asset management software, users have the ability to quickly configure the One Series, including the switching parameters, and save the configuration in their library for cloning additional controls with the same parameters. We believe this is the only Division 1 electronic switch on the market with HART compatibility!
• If the units are connected to a control system with HART® IO allowing bi-directional communication, configuration can be performed remotely, without the need to remove the enclosure cover in a Division 1 (Zone 1) area.
• Using a HART® capable asset management system, the comprehensive diagnostic functions of the One Series can determine the health status 24x7, saving time and money while allowing operators to focus on other critical issues.
• For cybersecurity purposes, the HART® communications can be set to read-only mode that prohibits parameter changes from unauthorized users and creating a potentially dangerous condition.

You can explore these new products in more detail with your United Electric distributor, taking advantage of their freshly acquired new product knowledge. Find out how the advanced new features of the One Series transmitters can enhance the operation and management of your industrial process.

Process Measurement and Control Essentials – Industrial Pressure Transmitters

Industrial Liquid Level
Transmitter
Courtesy Yokogawa Corp.

The measurement and control of fluid pressure is ubiquitous throughout many industrial processes. Measurements of pressure, directly and indirectly, provide real time information about what is happening in places that cannot be seen, such as inside a pipe, tank, or machine. The very nature of “process” suggests movement and change, the control of which is necessary to produce a consistent desirable outcome. Industrial pressure transmitters employ specific technologies and physical principals to derive a measurement of process pressure, then deliver or transmit, the measured value to a controller or recording device.

Fluid pressure tells a process operator much about what is currently happening. The pressure variable can be used to determine, among many industrial process elements:

• Degree to which the process is conforming to a recipe or specification
• Whether machinery is performing within its specified operation range
• If conditions of the process remain within the bounds established for safety
• A quantity measurement of flow, mass, or volume

Differential Pressure
Transmitter
Courtesy Yokogawa Corp.

Global industrial processes have widely varying physical arrangements, operating environments, and measurement requirements. Manufacturers of industrial pressure transmitters have responded with an immense array of transmitter technologies, arrangements, and configurations. When selecting the best suited pressure transmitter for your application, consult a sales engineer and consider some of the following:

• Signal requirements – Type, distance, possible sources of interference
• Device environment – Hazards, extreme conditions of temperature or corrosion
• Accuracy and stability of measurement
• Response time to changes in the process condition
• Ratings and certifications required for the device
• Configuration, arrangement, and mounting aspects of the transmitter device

Explore the differing technologies and how they can be best applied to implement or improve your process. Experienced sales engineers can be a useful sounding board for discussing your needs. Take advantage of their extensive experience with a wide array of process applications.