Saturday, July 6, 2019

The Basics of Pilot Operated Tank Relief Valves


When liquid is pumped in, storage tanks are pressurized and the current tank vapor is compressed. Tanks are also pressurized owing to higher ambient temperatures that cause the vapor of the tank to expand. Pilot operated pressure relief valves are mounted on tanks to mitigate harm caused by these growing tank vapors to avoid structural harm arising from overpressure.

Here is an outstanding animation, courtesy of Cashco, showing how a relief vent operated by a pilot valve protects a storage tank from overpressurizing during a pump-in condition or during rising ambient temperatures.

For more information on pilot operated tank relief valves, contact Arjay Automation at www.arjaynet.com or by calling (800) 761-1749.

Sunday, June 30, 2019

US Power Grids, Oil and Gas Industries, and Risk of Hacking


A report released in June, from the security firm Dragos, describes a worrisome development by a hacker group named, “Xenotime” and at least two dangerous oil and gas intrusions and ongoing reconnaissance on United States power grids.

Multiple ICS (Industrial Control Sectors) sectors now face the XENOTIME threat; this means individual verticals – such as oil and gas, manufacturing, or electric – cannot ignore threats to other ICS entities because they are not specifically targeted.

The Dragos researchers have termed this threat proliferation as the world’s most dangerous cyberthreat since an event in 2017 where Xenotime had caused a serious operational outage at a crucial site in the Middle East.

The fact that concerns cybersecurity experts the most is that this hacking attack was a malware that chose to target the facility safety processes (SIS – safety instrumentation system).

For example, when temperatures in a reactor increase to an unsafe level, an SIS will automatically start a cooling process or immediately close a valve to prevent a safety accident. The SIS safety stems are both hardware and software that combine to protect facilities from life threatening accidents.

At this point, no one is sure who is behind Xenotime. Russia has been connected to one of the critical infrastructure attacks in the Ukraine.  That attack was viewed to be the first hacker related power grid outage.

This is a “Cause for Concern” post that was published by Dragos on June 14, 2019.

“While none of the electric utility targeting events has resulted in a known, successful intrusion into victim organizations to date, the persistent attempts, and expansion in scope is cause for definite concern. XENOTIME has successfully compromised several oil and gas environments which demonstrates its ability to do so in other verticals. Specifically, XENOTIME remains one of only four threats (along with ELECTRUM, Sandworm, and the entities responsible for Stuxnet) to execute a deliberate disruptive or destructive attack.

XENOTIME is the only known entity to specifically target safety instrumented systems (SIS) for disruptive or destructive purposes. Electric utility environments are significantly different from oil and gas operations in several aspects, but electric operations still have safety and protection equipment that could be targeted with similar tradecraft. XENOTIME expressing consistent, direct interest in electric utility operations is a cause for deep concern given this adversary’s willingness to compromise process safety – and thus integrity – to fulfill its mission.

XENOTIME’s expansion to another industry vertical is emblematic of an increasingly hostile industrial threat landscape. Most observed XENOTIME activity focuses on initial information gathering and access operations necessary for follow-on ICS intrusion operations. As seen in long-running state-sponsored intrusions into US, UK, and other electric infrastructure, entities are increasingly interested in the fundamentals of ICS operations and displaying all the hallmarks associated with information and access acquisition necessary to conduct future attacks. While Dragos sees no evidence at this time indicating that XENOTIME (or any other activity group, such as ELECTRUM or ALLANITE) is capable of executing a prolonged disruptive or destructive event on electric utility operations, observed activity strongly signals adversary interest in meeting the prerequisites for doing so.”

Monday, June 24, 2019

Variable Area Flow Meters: An Overview

Variable Area Flow Meter
Variable area flow meters, also referred to as Rotameters, have diverse industrial processing applications that range from simple to sophisticated. The devices are easy to install, require no electrical connection, and provide direct flow rate reading. They provide fail-safe flow rate readings in a wide array of industrial applications.

Developed by German inventor Karl Kueppers in 1908, Rotameters measure the volumetric flow rate of liquids and gases. 

Important elements of a variable area flow meter include the tube and the float. Their operation is simple. The tube is fixed vertically and the fluid is fed from the bottom. It travels upward and exits from the top. The float remains at the bottom when no liquid is present and rises upward when fluid enters the tube. 

The float inside the tube moves in proportion to the rate of fluid flow and the area between the tube wall and the float. When the float moves upward, the area increases while the differential pressure decreases. A stable position is reached when the upward force exerted by the fluid is equal to the weight of the float. A scale mounted on the tube records the flow rate of the liquid. Usually, the flow can be adjusted manually using a built-in valve. 

Types of Variable Area Flow Meters 

Variable area flow meters can be categorized by the type of tube they use, which relates to their ability to withstands various pressures, temperatures, process media, and cost. Process connection size and wetted part materials vary as a function the rotameter type and construction. 

Glass Tube Variable Area Flow Meter - The basic glass variable area flow meter consists of borosilicate glass tube while the float is made of either glass, plastic, or stainless steel. The most common combination is a glass tube and metal float. This is suitable for a measure the flow rate of liquid of low to medium temperatures and pressures. 

Applications: Analytical instrumentation; Industrial processes; Chemical production; Pharmaceutical production; Oil & gas extraction; Refining processes; Fuel cell research; Water treatment systems.

Metal Tube Variable Area Flow Meter - Metal tube variable area flow meters are another type that is suitable for temperatures and pressures beyond the physical and mechanical limits of glass tube versions. They are generally manufactured of stainless steel, aluminum, or brass. The piston position is determined by the mechanical and magnetic followers that can be read from the outside of the tube. They are suitable in situations where applications conditions would damage the glass metering tubes, such as steam applications.

Applications: Purge liquid or gas metering; Liquid, gas, or oil flow measurement; Chemical injection; Rotating equipment flow measurement; High-pressure flow meters for offshore oil platforms.

For more information on rotameters, visit this Arjay Automation web page or contact them by calling (800) 761-1749.

Wednesday, June 5, 2019

Guided Wave Radar Level Transmitters

Guided wave radar transmitters are widely used across different industries. These devices with their simple installation and trouble-free operations help industrial companies save time and money. They are ideal for a large number of process applications ranging from simple to complex.

How Do Guided Wave Radar Transmitters Work?

Guided wave radar transmitters rely on microwave pulses. Since microwaves are not affected by dust, pressure, temperature variations, and viscosity, this type of transmitter produces highly accurate results.

A low-energy microwave pulse is sent down a probe, and a part of it is reflected back when the pulse hits the process media. The liquid level is directly proportional to the time-domain reflectometry. The time when the pulse is launched and received back is measured to determine the distance from the surface of the media.

Types of Guided Wave Radar Level Transmitters

Guided Wave Radar Level Transmitter
Single Element Design
(NIVELCO)
Guided wave radar level transmitters are available in different probe configurations. Selecting the
right probe is important for successful implementation of the device. While manufacturers offer a range of guided wave radars, most are derived from the three basic probe configurations: single element, twin element, and coaxial.

Single element probe — The single element probe is the most widely used and least efficient device. The device is popular since it is more resistant to the coating of the liquid.

Twin element probe — The twin element probe is a good, general purpose probe that is generally used in long-range applications. They are ideal in situations where flexible probes are important for successful reading.

Coaxial probe — The coaxial probe configuration is the most efficient guided wave radar level transmitters. The probes are used in more challenging low-dielectric applications.

Benefits of Guided Wave Radar Level Transmitters

Guided Wave Radar Level transmitters provide a range of benefits in different applications. The concentration of the measuring signal is strong and clean. This is due to the narrow path of the signal propagation that reduces the chances of impact by stray signals due to obstacles or construction elements inside the tank.

Another benefit of guided wave radar level transmitters is that they are easy to install. No mounting holes are required to install the device. This results in cost savings for the organization. The waveguide can be formed to follow the tank’s contours or mounted at an angle.

The device is ideal in situations where an interface measurement is required. The measuring signals can penetrate the medium deeply, resulting in more accurate results. The waveguide technology is suitable for applications where the medium is subjected to heavy vapors, foam, and dust.

Guided Wave instruments can detect changes in dielectric consents on the boundary of a property. The device can be configured to detect level at both the top and the bottom of a layer of emulsion.

Industrial Application of Guided Wave Radar

Guided wave radar level transmitters are increasingly being used in process industries. The sensors are used in situations that previously employed ultrasonic, hydrostatics, and capacitance. The accuracy specification of the basic model range is up to ±5mm, while the accuracy of the advanced models is up to ±2mm.

The device is generally used in industries to take level readings. The readings are used for local indication and visualization in control systems.

Moreover, guided wave radar level transmitters are also used for managing liquid inventory, determining safety limits, dry run protection, and leak detection. Other applications of guided wave radar level transmitters include communicating low limits to suppliers, automated ordering systems, and streamlining the logistics process.

Guided radar level measurement is also suitable for bulk solids. The surface type is not restricted to liquids since the reflected waves are guided easily through any medium. Foam formation and turbulent liquid surfaces and different angled surfaces (as is the case with bulk solids) don’t influence the accuracy of the reading.

Selection of Guided Wave Radar Level Transmitters

Selection of guided wave radar level transmitters should be based on the requirements of the task. Generally, the rigid single element probe configuration is ideal for angled installations for flowing liquids. The dual flexible wire probe is suitable for most other common applications.

A coaxial probe configuration is recommended for liquids that are cleaner with low dielectric constant and with turbulence on the product’s surface. This type of guided wave radar device is also recommended for installations where the probe is near the tank wall or other obstacles.

Make sure that the device can withstand the range of temperature within the tank. Most GWR devices are rated up to 850 deg F or 450 deg C. You should select a device with added signal strength since this will result in increased reliability and accuracy of the devices.

Guided wave radar level transmitter with dynamic vapor compensation is recommended where a high level of accuracy is required under a high-pressure environment. The measurement taken from the device can compensate for changes in vapor dielectric, which results in improved accuracy.

Other factors that should be considered include mounting and proximity. Single probe configuration can be installed almost anywhere. But the single probe configuration can only to apply to specific situations.

Lastly, the probe length of the device should be of the right length. The length should be according to the measurement rate. This is an important consideration as it can help in ensuring accurate reading with minimum chances of an error.

Guided Wave radar level transmitters can also be used with an agitator. However, certain things must be considered prior to use the device. The probe must be prevented from contacting the agitator blades. Make sure that you confirm the ability of the probe to withstand the force inside the medium. This is important since turbulent on the surface may decrease the accuracy of the measurement. You can install the device in a bypass chamber or stilling well for an agitated tank.

For more information about guided wave radar transmitters, contact Arjay Automation. Call them at (800) 761-1749 or visit their web site at https://arjaynet.com.

Sunday, May 26, 2019

Bridging the Gap between HART Devices and IIoT, the Industrial Internet of Things

Manufacturing Plant of the Future

The typical process control model that involves decision making for the process at the local or centralized level by PLCs (Programmable Logic Controller) or BPCS (Basic Process Control System) is quickly changing. These systems installed yesteryear were never intended to deal with or even realize the amount of data they would have access to in the near future. There are certainly newer ERP, MES and asset management systems that collect some of this data now, but the more critical challenge that local manufacturing facilities face is manpower. Because streamlining of costs and overheads has left many manufacturing facilities with just enough personnel to keep the plant running, facilities no longer have the extra time, personnel and resources required to analyze data. For this reason we are seeing third party companies, and even some of the larger process control vendors, offer leasing or annual agreements that involve collecting, storing, and analyzing all sorts of process data. This data is part of a larger predictive analytics strategy that can not only forewarn operators of impending problems to come, but is also being used to optimize the process itself. This type of cloud automation looks to gather as much data as possible to reduce operating expenditures and future capital expenditures for future plant builds.


So the challenge remains: how do existing and new manufacturing facilities find a cost effective way to get critical plant floor data up to higher level information systems? The answer is to take advantage of the digital HART data you already have installed but either didn’t know it was there or couldn’t afford the equipment upgrades to gain access to it.

This white paper, courtesy of Moore Industries, will outline how the flow of process and diagnostics data from smart HART digital field instruments can now be shared with mid and higher level control, asset management and data information systems without having to upgrade expensive process control interface equipment. Additionally, features and considerations of devices that enable this sharing of data will be reviewed and suggested.

Table of Contents
  • Plant of the Future
  • HART Protocol’s Persistence
  • HART Primer
  • HART Revisions and Compliance
  • HART Dynamic and Device Variables
  • HART Hosts and Revisions
  • HART Interface Options
  • Employing the Extracted HART Data
  • Cybersecurity Considerations
  • Configuration of IIoT Devices
For more information, contact Arjay Automation, LLC. Call (800) 761-1749 or visit https://arjaynet.com.