Showing posts with label temperature. Show all posts
Showing posts with label temperature. Show all posts

Tuesday, March 21, 2017

Industrial Temperature Control Basics

Process Controllers
Process Controllers used with thermocouples or RTDs
for temperature control (courtesy of Yokogawa)
The regulation of temperature is a common operation throughout many facets of modern life. Environmental control in commercial, industrial, and institutional buildings, even residential spaces, uses the regulation of temperature as the primary measure of successful operation. There are also countless applications for the control of temperature found throughout manufacturing, processing, and research. Everywhere that temperature needs to be regulated, a device or method is needed that will control the delivery of a heating or cooling means.

For industrial process applications, the temperature control function is found in two basic forms. It can reside as an operational feature within a programmable logic controller or other centralized process control device or system. Another form is a standalone process temperature controller, with self-contained input, output, processing, and user interface. Depending upon the needs of the application, one may have an advantage over the other. The evolution of both forms, integrated and standalone, has resulted in each offering consistently greater levels of functionality.

There are two basic means of temperature control, regardless of the actual device used. Open loop control delivers a predetermined amount of output action without regard to the process condition. Its simplicity makes open loop control economical. Best applications for this type of control action are processes that are well understood and that can tolerate a potentially wide variation in temperature. A change in the process condition will not be detected, or responded to, by open loop control. The second temperature control method, and the one most employed for industrial process control, is closed loop.

Closed loop control relies on an input that represents the process condition, an algorithm or internal mechanical means to produce an output action related to the process condition, and some type of output device that delivers the output action. Closed loop controllers require less process knowledge on the part of the operator than open loop to regulate temperature. The controllers rely on the internal processing and comparison of input (process temperature) to a setpoint value. The difference between the two is the deviation or error.  Generally, a greater error will produce a greater change in the output of the controller, delivering more heating or cooling to the process and driving the process temperature toward the setpoint.

The current product offering for standalone closed loop temperature controllers ranges from very simple on/off regulators to highly developed products with multiple inputs and outputs, as well as many auxiliary functions and communications. The range of product features almost assures a unit is available for every application. Evaluating the staggering range of products available and producing a good match between process requirements and product capabilities can be facilitated by reaching out to a process control products specialist. Combine your own process knowledge and experience with their product application expertise to develop effective solution options.

Thursday, December 22, 2016

Multifunction Calibrator Keeps Process Instruments "In Tune"

Genii 620 multifunction calibrator shown on pressure station
GE Multifunction Calibrator
Shown with pressure calibrator accessory
Courtesy GE Measurement & Control
Industrial process operations are populated with sensors, transmitters, and other measuring instruments of many varieties. This instrumentation is not installed without good reason, with each data point providing valuable and necessary information with regard to process status and safety. Regular maintenance and calibration of measurement instrumentation is a necessary part of maintaining quality, efficiency, and safety.

With so many different types and manufacturers of instruments, purchasing and maintaining calibration equipment can become and unwieldy process in itself. GE Measurement & Control meets the challenge by incorporating numerous calibration capabilities into a single high accuracy unit with flexibility and ease of use. The unit can simultaneously source and measure an extensive array of signals, providing capability to use a single calibrator for a long, maybe even complete, list of instruments installed at your site. Utilization of the multifunction calibrator can potentially reduce the total number of instruments in your calibration shop, with a commensurate reduction in cost, documentation, and time commitment to keep your calibration instrument arsenal ready for use.

A datasheet with all the details is included below. Browse the data sheet and reach out to a specialist with your calibration requirements and challenges. Work together to develop an effective solution for your operation.

Thursday, December 15, 2016

Versatile Thermal Dispersion Switches For Level, Temperature, Liquid Interface, and Flow Applications

flow level interface temperature switch for fluid process control
Sanitary version of  FLT93 FlexSwitch
Courtesy Fluid Components International
Thermal dispersion, as a method of process measurement, relies upon precise temperature measurement and, in some cases, the ability to measure heat input. The principal is fairly simple, based upon the relationship between two temperature measurement points in the subject fluid. One is heated by the control system in a known manner, the other is not. Whether measuring fluid flow, or functioning as a liquid level or interface switch, the relationship between the two temperature measurements can provide the needed information reliably, accurately, and without any moving parts in the measurement system.

Fluid Components International utilizes these physical principals in the operation of their FlexSwitch line of thermal dispersion measuring instruments. By combining modular components in various ways, the company offers switches suitable for applications across a wide range of industries.

  • Flow
  • Level
  • Flow and temperature
  • Level and temperature

Features throughout the product line include:

  • Dual trip points and relays
  • SIL 2 rated, ultra reliable
  • 3 year warranty
  • Broad agency approvals
  • Suitable for full range of pipe sizes
  • Apply in fluids to 850 °F (454 °C)
  • No moving parts to foul, clog or maintain
  • All welded elements
  • Easy to install and set-up
  • Highly sensitive and accurate
  • Threaded, flanged, packing gland installation
  • Integral or remote mounted electronics
  • Choice of enclosures
  • Field selectable AC or DC power
More information about the FlexSwitch line of thermal dispersion based switches is provided in the document below. For best results, share your project requirements and challenges with a product application specialist. Combine your process knowledge with their product application experience and develop effective solutions.

Monday, January 11, 2016

Process Control - Five Categories of Instrument Protection

Industrial process temperature and pressure gauges
Instrument protection is a key element of process design
and equipment layout
The performance of every process is critical to something or someone. Keeping a process operating within specification requires measurement, and it requires some element of control. The devices we use to measure process variables, while necessary and critical in their own right, are also a possible source of failure for the process itself. Lose the output of your process instrumentation and you can incur substantial consequences ranging from minor to near catastrophic.

Just as your PLC or other master control system emulates decision patterns regarding the process, the measurement instrumentation functions as the sensory input array to that decision making device. Careful consideration when designing the instrumentation layout, as well as reviewing these five common sense recommendations will help you avoid instrument and process downtime.

Process generated extremes can make your device fail.

Search and plan for potential vibration, shock, temperature, pressure, or other excursions from the normal operating range that might result from normal or unexpected operation of the process equipment. Develop knowledge about what the possible process conditions might be, given the capabilities of the installed process machinery. Consult with instrument vendors about protective devices that can be installed to provide additional layers of protection for valuable instruments. Often, the protective devices are simple and relatively inexpensive.

Don't forget about the weather.

Certainly, if you have any part of the process installed outdoors, you need to be familiar with the range of possible weather conditions. Weather data is available for almost anywhere in the world, certainly in the developed world. Find out what the most extreme conditions have been at the installation site....ever. Planning and designing for improbable conditions, even adding headroom, can keep your process up when the unexpected occurs
Keep in mind, also, that outdoor conditions can impact indoor conditions in buildings without climate control systems that maintain a steady state. This can be especially important when considering moisture content of the indoor air and potential for condensate to accumulate on instrument housings and electrical components. Extreme conditions of condensing atmospheric moisture can produce dripping water.

Know the security exposure of your devices.

With the prevalence of networked devices, consideration of who might commit acts of malice against the process or its stakeholders, and how they might go about it, should be an element of all project designs. A real or virtual intruder's ability to impact process operation through its measuring devices should be well understood. With that understanding, barriers can be put in place to detect or prevent any occurrences.

Physical contact hazards

Strike a balance between convenience and safety for measurement instrumentation. Access for calibration, maintenance, or observation are needed, but avoiding placement of devices in areas of human traffic can deliver good returns by reducing the probability of damage to the instruments. Everybody is trained, everybody is careful, but uncontrolled carts, dropped tools and boxes, and a host of other unexpected mishaps do happen from time to time, with the power to inject disorder into your world. Consider guards and physical barriers as additional layers of insurance.

Know moisture.

Electronics must be protected from harmful effects of moisture. Where there is air, there is usually moisture. Certain conditions related to weather or process operation may result in moisture laden air that can enter device enclosures. Guarding against the formation of condensate on electronics, and providing for the automatic discharge of any accumulated liquid is essential to avoiding failure. Many instrument enclosures are provided with a means to discharge moisture. Make sure installation instructions are followed and alterations are not made that inadvertently disable these functions. Moisture also is a factor in corrosion of metal parts. Be mindful of the extra degree of protection provided by special coatings or materials that may be options for your instruments.

Developing a thoughtful installation plan, along with reasonable maintenance, will result in an industrial process that is hardened against a long list of potential malfunctions. Discuss your application concerns with a knowledgeable instrument sales engineer. Their exposure to many different installations and applications, combined with your knowledge of the process and local conditions, will produce a positive outcome.

Monday, October 19, 2015

Welcome to Flow-Tech's Maryland & Virginia's Process Control Blog

Virginia and Maryland Process Control
Serving Maryland and Virginia
Flow-Tech, Inc. has been specifying and applying process instrumentation and control valves in the Maryland and Virginia markets for over 40 years. Flow-Tech's outstanding growth in sales and reputation is directly a result of our consultative sales approach, delivered by our team of knowledgeable and experienced Sales Engineers.

We see this blog as an extension of that process where today's customer can learn and discover at their own time and place, narrow the selection of products and vendors, and then  arrange for me focussed presentation with a salesperson.

This blog will be populated with post we think you will find interesting and education in the area of process instrumentation and control. It will be updated frequently, so please check back often.