Friday, October 28, 2016

Industrial Process Temperature Sensor Comparison

industrial thermocouples
Array of thermoucouple assemblies
Courtesy Durex
It's always useful to have quick references for things. Durex, a globally recognized manufacturer of electric heating solutions, published the Temperature Sensor Element Selection Guide included below in a recent blog posting. It provides a consolidated comparison of the four primary temperature sensing devices used for industrial process control. Many will find it useful, so we share it with you here.

All the technical expertise needed for your process heating challenges is readily accessible at BCE. Share your heating challenges with experts, combining your process and application knowledge with their expertise to develop effective solutions.


Monday, October 24, 2016

Flanged and Screw Plug Electric Heating Assemblies for Industrial Applications

flanged tubular electric heater assembly
Flanged Tubular Electric Heater Assembly
Hotwatt
Electric heating, though not the most energy efficient means of delivering heat, provides some distinct advantages as a means of controlling the temperature or thermal component of fluids and solids throughout commercial and industrial settings.

Tubular elements are a common form of electric heater. Essentially a metal tube with resistance wire and electrical insulation inside, tubular elements can be configured into almost uncountable shapes and sizes. Manufacturers typically offer a range of standard sizes and ratings, but that should never deter you from making contact to discuss your ideas for a custom arrangement.

Two mounting schemes that are readily used on tanks or other vessels are the screw plug and flanged heater assemblies. In each case, tubular heaters are bent in a "U" shape and fitted into either a pipe flange or a threaded plug. A junction box encloses the electrical terminations for the heating elements, providing a single ended assembly that can be easily mounted to an industrial standard mechanical connection. These assemblies are useful for tank or vessel OEMs that wish to provide a fluid heating option to their customers.
tubular electric heaters screw plug mounting
Examples of Screw Plug Electric Heaters
Hotwatt

Electric heat enables a properly configured controller to proportion heat into a subject fluid across a wide range, from very small packets that could be fractional percentages of full capacity to the fully available output of the heater. The units are compact, rugged, and can be configured to accommodate a broad array of industrial environments and applications.

Selecting or specifying a unit is uncomplicated. Determine the amount of heating capacity needed, then select the assembly mounting type (flange, screw plug, or other). Select an element sheath material that is compatible with the process media and a termination enclosure that suits the surrounding environment. Application assistance is available from product specialists who are well versed in the available options and can help you specify an assembly that provides excellent performance and an extended service life.

Thursday, October 20, 2016

BCE Epoxy Vacuum Feedthroughs: When You Need to Pass a Signal Through A Vacuum Chamber Wall


Equipment manufacturers and scientific researchers are continually challenged with supplying power, fiber-optic, control, and monitoring cables into (and out of) sealed vacuum vessels. Whether due to space restrictions, special geometries, or number and type of conductors, standard glass-to-metal or ceramic feedthroughs never quite fit the bill. Unfortunately, because of limited options, many designers are forced to compromise and go for an off-the-shelf solution.

You don't have to compromise anymore.  EPOXY TO THE RESCUE. 

During the past decade, new epoxy compounds have been developed that rival glass and ceramic in performance. BCE is at the forefront of this development and leverages modern epoxy's unique properties to solve your feedthrough challenges.

With modern epoxy feedthroughs, any kind of standard or custom connector is sealed in a completely potted, high-performance, clear epoxy compound. Epoxy seals offer countless design options, and most amazingly, performance equal to or better than glass or ceramic. Better yet, pricing is very competitive and quick turn-around for prototypes and short production runs are not a problem.

BCE custom epoxy vacuum feedthroughs offer the best choice in application flexibility, cost, and high performance. Epoxy feedthroughs are the right product for today’s fast moving markets. If you have to pass an electrical, pneumatic, or fiber-optic signal through a vacuum chamber wall, THINK OF BCE!

Wednesday, October 19, 2016

Use Electronic Pressure Controllers in Your Research Process Loop to Eliminate Droop, Boost, and Hysteresis

(re-blogged with permission from Brooks Instrument)
Gas pressure control is critical in many applications like life sciences and chemical/petrochemical research where flow is an integral part of the process. Brooks Instrument electronic pressure controllers can be used as they require flow to function. Compared to using a mechanical pressure regulator, electronic pressure controllers eliminate droop, boost and hysteresis, offering stable pressure control.

There are two configurations available for pressure control – upstream and downstream. This terminology is somewhat unique to Brooks Instrument electronic pressure controllers.

Downstream vs. Upstream Pressure Control

downstream vs upstream pressure control diagram
Downstream pressure controllers maintain the pressure downstream of the device itself, increasing flow to increase the pressure and decreasing flow to decrease the pressure. For this reason, this is called direct acting. This configuration is commonly called a standard pressure regulator. A downstream pressure controller acts very similar to a typical mass flow controller because they are both direct acting.
Upstream pressure controllers maintain the pressure upstream of the device itself, increasing flow to reduce the pressure and decreasing flow to increase the pressure. For this reason, this is called reverse acting. This configuration is commonly called a back pressure regulator in the industry.

Selecting and Sizing an Electronic Pressure Controller

The following information is required to select and size a Brooks Instrument electronic pressure controller:
  • Process gas
  • Maximum flow rate being used to maintain pressure -The “sweet spot” for pressure control is between 100 SCCM and 5 SLPM.
  • Calibration pressure (maximum pressure to be controlled)
  • Reference pressure (for upstream controllers the reference pressure is the downstream pressure and for downstream controllers the reference pressure is the upstream pressure)
As long as flow is present in a process you will typically find the need for some type of pressure control. Vessel sizes up to 30 liters commonly use flow rates up to 3 SLPM during their process steps. Brooks Instrument pressure controllers are a perfect fit for these services, offering stable pressure control with no droop, boost or hysteresis, which are commonly experienced when using a mechanical pressure regulator.


Typical Bioreactor Process Using an Upstream Pressure Controller

Monday, October 17, 2016

Applying Precision Turbine Flow Meters

high precision turbine flow meter
Precision Turbine Flow Meter
Cameron Measurement Systems
Precision turbine flow meters are specially designed to accommodate a broad range of precise fluid measurement applications. They accommodate greater flow rates with lower pressure drops than other meters in their class. Some have a self-flushing design for longer sustained accuracy. The turbine's high-frequency digital output is suitable for interfacing with an assortment of readout and recording equipment. Some turbine flow meters have a symmetrical bi-directional design that supports reverse flow applications without a reduction in accuracy or capacity.

Operating Principle


(The following is excerpted from Model 700 Series Turbine Flowmeter User Manual, from Cameron Measurement Systems....with some editing)

Fluid flows over a diffuser section and is accelerated onto a multi-blade hydro-dynamically balanced turbine rotor. The rotor speed is proportional to the volumetric flow rate. As the rotor turns, a reluctance type pickup coil (mounted on the meter) senses the passage of each blade tip and generates a sine wave output with a frequency that is directly proportional to the flow rate.

The rotor is the only moving part of the turbine flow meter. The small lightweight rotor hubs ensure fast response to process flow changes. The rotor is hydro-dynamically balanced during operation, eliminating the need for mechanical thrust leveling. This low-friction design improves metering linearity and reduces wear and maintenance.

A variable reluctance generating pickup coil contains a permanent magnet and a wire winding. In some cases, the rotor blade of the turbine meter is made of a ferritic stainless steel such as grade 430. The movement of the rotor blade in proximity to the magnetic field of the coil tip produces an AC type voltage pulse within the coil winding. An alternate arrangement finds the ferritic bars embedded in the rotor shroud, where they can interact with the pickup coil. Increasing the quantity of bars on the shroud to outnumber the rotor blades provides more pulses per unit volume (resolution). This feature can be valuable when proving large-capacity meters with a small-volume prover. Shielded wire cable conveys the output of the pickup coil to compatible electronic instruments to indicate flow rate, record, and/or totalize the volumetric flow. The coil itself does not require electrical power to operate.

The meter may be factory-fitted with multiple coils for redundancy, indication of flow direction or pulse train verification. The pickup coil type and magnetic strength vary with application requirements.

The turbine flow meters are calibrated in a horizontal position. Therefore, the best correlation of calibration occurs when the meter is operated in this plane. However, the meter will operate satisfactorily in any position.

System Pressure


The maximum and minimum system pressures must be considered when applying the turbine meter. To obtain proper response, a back pressure should be applied to the meter. This back pressure should be at least twice the pressure drop of the meter at maximum flow. For liquid meters, the back pressure should be twice the pressure drop of the meter at maximum flow, plus twice the fluid vapor pressure.

Summary


Turbine flow meters, with their simple, durable construction and wide operating range, may be the right choice for a number of applications. As with all instrumentation, there are a number of factors to consider when making a selection. Share your flow measurement challenges and requirements with instrumentation specialists, combining your process knowledge with their product application expertise to develop the most effective solutions.


Thursday, October 13, 2016

Process Alarm Annunciators as Part of Cyber Security

industrial control alarm annunciator panel
Annunicator Panel
Courtesy Ronan Engineering
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.