Wednesday, October 26, 2016

Pneumatic Volume Booster Function

pneumatic volume booster
Pneumatic Volume Booster
Fairchild
A volume booster is used in a pneumatic control system to relay a low flow signal as one with greater flow volume. The common configuration is to provide a 1:1 ratio between the input and output pressure, keeping the input and output signals the same pressure. Products are available that deliver different ratios.

The general purpose of a volume booster is to provide a relay between a system with low flow volume and one with higher volume requirements. A typical example is a pneumatic actuator. The flow available through the pneumatic signal line may be insufficient to deliver the response rate desired from the pneumatic actuator. A volume booster, with control over an independent air supply, solves this challenge with increased flow volume at the same pressure as the control signal.

Volume boosters are simple in operation. The input signal applies force to one side of a diaphragm, the output pressure to the other. An imbalance between the two applied pressures will cause the diaphragm to move, changing the position of the valve and the outlet pressure until the two forces are again in balance. Little maintenance is required when the units are properly installed and supply air is of good quality.

The unit pictured is from Fairchild, a well recognized manufacturer of industrial pneumatic components, and provides a 1:1 ratio. There are some key points in the selection process, so reach out to a product specialist with your pneumatic system challenges and requirements. Combining your process and facility knowledge with their product application expertise will produce effective solutions.


Wednesday, October 12, 2016

Conductivity Controller For Boiler Applications

Multivariable water quality controller
Conductivity controller for boiler applications
Lakewood Instruments
Modern boilers using the Rankine cycle require feedwater and make-up feedwater quality maintained within certain limits with respect to alkalinity, conductivity, and other factors in order to maintain boiler operating efficiency and minimize maintenance requirements.

Controlling the feedwater quality can be accomplished with the addition of controlled amounts of the right chemicals to regulate various aspects of water quality. Another method is to purge, or blowdown, the boiler in a measured fashion that allows fresh feedwater to replace overly contaminated water. Filtration, which I generally deem to include ion exchange, reverse osmosis, and mechanical filtration, is a third method. All deal specifically with a limited scope of contaminates that have an impact on boiler operation and longevity.

Boiler blowdown can be used to limit the amount of total dissolved solids in the boiler drum water. As water boils, the dissolved solids in the water concentrate in the remaining liquid water. Blowdown purges a portion (or all) of this water, allowing the addition of water, presumably treated, with substantially lower total dissolved solids.

Boiler blowdown has an energy cost, since the replacement water must be heated to the design condition. It follows that executing this procedure should be undertaken when necessary, but not more frequently. A conductivity monitor and controller can accomplish properly timed blowdown cycles. The system consists of a conductivity sensor and a control unit that provides all the necessary functionality in a single integrated package. A data sheet is included below for one such unit from Lakewood Instruments.

Share your boiler operation challenges with an instrumentation specialist an explore how a properly instrumented steam system can provide operational savings and extended time between failure.




Thursday, October 6, 2016

Process Control - Annunciator Panel as Cyber Defense Measure

Process control annunciator panel
Standalone Annunciator Panel
Ronan Engineering Company
There are numerous applications for annunciator panels, stations, and equipment throughout the various industrial markets. One such application, arising and growing with the connectivity of industrial control systems to the internet, is in the cyber defense arena.

Industrial control systems are increasingly internet connected, making them vulnerable to cyber attack. There was a time when all that was necessary for plant or operation security was installing a perimeter fence around the property and posting a guard at the gate. Our industrial control systems are now subject to mischief or malicious attack from locations and parties unknowable and worldwide.

Do you know of ICS-CERT? If involved in industrial control, you should. It is the Industrial Control Systems Cyber Emergency Response Team, a part of the Department of Homeland Security that provides operational capabilities to defend control systems against cyber threats. You can follow them on Twitter, @ICS-CERT, and monitor the vulnerabilities and threats that they discover in the industrial control sphere. New items are added almost daily, naming specific vulnerabilities uncovered in named systems and equipment. Chances are that you will discover some of the equipment in your plant listed.

Annunicator systems and equipment can be employed as an isolated "watcher", monitoring process performance and providing alerts when conditions exceed specified limits.
A major impact of a potential cyber attack scenario is that, as operator, you can no longer fully trust what your software based internet connected control system is telling you, or whether it is doing everything it should and only those things that it should. An annunciator system, isolated from the primary control system and the internet, monitoring critical process conditions, incorporates a substantial level of safety against cyber attack.

There is more to be learned. Browse the document included below for a detailed visual demonstrating the set up of annunciators that can be isolated from your network. Share your process control challenges with specialists, and combine your process and facility knowledge with their product application expertise to develop effective solutions. And start following @ICS-CERT on Twitter and build your awareness and knowledge of industrial control cyber threats.