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| Limitorque SMB MOV |
This document also provides detailed descriptions of Limitorque SMB actuators and Limitorque SB actuators with full assembly and subassembly breakdown and illustrations.
Document provided by NRC.gov
Theory of Operation for MOVs (Motor Operated Valves)
This document also provides detailed descriptions of Limitorque SMB actuators and Limitorque SB actuators with full assembly and subassembly breakdown and illustrations.
Document provided by NRC.gov
Configuring a Foxboro PH10 Sensor Using the Foxboro 876PH Transmitter
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| pH and ORP Sensor (courtesy of Foxboro) |
The sensors are available with a choice of temperature compensation and cable termination. They are available with an internal pre-amplifer for use up to 150 m (500 ft) and with a Smart sensor for use up to 100 m (328 ft) from the analyzer or transmitter. The sensors can be mounted to the process in a number of ways. They have a 3/4-inch external NPT connection on both the electrode and cable end. The sensors can be inserted directly into the process line or tank or mounted through a variety of accessories including bushings, tees, flow chambers, and ball valves/insertion assemblies.The sensors are available in both analog and Smart versions.
These industry-leading sensors are already proven in countless installations including chemicals, pulp & paper, all kinds of industry and municipal water/wastewater treatment, metals/mining, and food and dairy applications worldwide.
The Foxboro® brand Model 876PH is a 2-wire loop powered intelligent transmitter that, when used with appropriate electrochemical sensors, provides measurement, local display, and transmission of pH, ORP (Oxidation-Reduction Potential), or ISE (Ion Selective Electrode) concentration. The transmitter outputs a HART digital signal and a 4 to 20 mA analog output. Versions are available for use with both analog and Smart (digital) sensors.
This video demonstrates how to correctly configure a Foxboro® PH10 sensor using the Foxboro® 876PH Transmitter.
Form ore information, contact:
Mead O'Brien
www.meadobrien.com
(800) 892-2769
The Rack and Pinion Style Pneumatic Valve Actuator
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| Rack & Pinion Actuator (courtesy of Flowserve Automax) |
Pneumatic actuators can be further categorized as scotch yoke design, vane design, and the subject of this post - rack and pinion actuators.
Rack and pinion actuators provide a rotational movement designed to open and close quarter-turn valves such as ball, butterfly, or plug valves and also for operating industrial or commercial dampers.
The rotational movement of a rack and pinion actuator is accomplished via linear motion and two gears. A circular gear, referred to a “pinion” engages the teeth of a linear gear “bar” referred to as the “rack”.
Pneumatic actuators use pistons that are attached to the rack. As air or spring power is applied the to pistons, the rack is “pushed” inward or “pulled” outward. This linear movement is transferred to the rotary pinion gear (in both directions) providing bi-directional rotation.
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| Visual of rack and pinion (courtesy of Wikipedia) |
Most actuators are designed for 100-degree travel with clockwise and counterclockwise travel adjustment for open and closed positions. World standard ISO mounting pad are commonly available to provide ease and flexibility in direct valve installation.
NAMUR mounting dimensions on actuator pneumatic port connections and on actuator accessory holes and drive shaft are also common design features to make adding pilot valves and accessories more convenient.
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| Fully automated valve with rack and pinion actuator, solenoid, and limit switch. |
For more information on any pneumatic or electric valve automation project, contact:
Mead O’Brien, Inc.
www.meadobrien.com
10800 Midwest Industrial Blvd
St. Louis, Missouri 63132
Phone (314) 423-5161
Toll Free (800) 874-9655
Fax (314) 423-5707
Email: meadstl@meadobrien.com
Pneumatic Instruments
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| Pneumatic transmitters (courtesy of Foxboro) |
The indicator in this case would be a special pressure gauge, calibrated to read in units of process pressure although actuated by the pressure of clean compressed air from the transmitter instead of directly by process fluid. The most common range of air pressure for industrial pneumatic instruments is 3 to 15 PSI. An output pressure of 3 PSI represents the low end of the process measurement scale and an output pressure of 15 PSI represents the high end of the measurement scale. Applied to the previous example of a transmitter calibrated to a range of 0 to 250 PSI, a lack of process pressure would result in the transmitter outputting a 3 PSI air signal and full process pressure would result in an air signal of 15 PSI. The face of this special “receiver” gauge would be labeled from 0 to 250 PSI, while the actual mechanism would operate on the 3 to 15 PSI range output by the transmitter. As with the 4-20 mA loop, the end-user need not know how the information gets transmitted from the process to the indicator. The 3-15 PSI signal medium is once again transparent to the operator.
Typically, a 3 PSI pressure value represents 0% of scale, a 15 PSI pressure value represents 100% of scale, and any pressure value in between 3 and 15 PSI represents a commensurate percentage in between 0% and 100%. The following table shows the corresponding current and percentage values for each 25% increment between 0% and 100%. Every instrument technician tasked with maintaining 3-15 PSI pneumatic instruments commits these values to memory, because they are referenced so often:
Using the Foxboro model 13A pneumatic differential pressure transmitter as an example, the video below highlights the major design elements of pneumatic transmitters, including an overview of "maximum working pressure" versus "maximum measurement range" pressure.
The Foxboro model 13A pneumatic d/p cell transmitters measure differential pressure and transmit a proportional pneumatic output signal.
The information above is attributed to Tony Kuphaldt and is licensed under the Creative Commons Attribution 3.0.
Mead O'Brien: Steam and Hot Water System Experts
Let Mead O’Brien help you create a sustainable Steam Trap Management Process!
- Trained Survey Technicians
- Traps located and identified, tagged with SS tag #, and data logged with up to 27 fields of useful data per trap
- Executive summary, Failed trap report with steam & dollar losses, detailed Log sheets, and Recommendations are all provided in a professional report.
- Monitoring options presented for critical service applications
- Steam flow measurement design
- Heat recovery potential
- Training options in a live steam lab
- Reduce steam & condensate losses
- Reduce loss of boiler chemicals
- Improve heat transfer performance
- Prevent coil and heat exchanger damage
- Minimize water hammer hazards
- Steam Distribution
- Process Heat Transfer and Control
- Condensate Return
- Heat Recovery Opportunities
- Process, Ambient & Combustion Air
- Steam Trap Surveys & Database Creation
- Humidification Assessment
- Application issues
- - Coil Freezing Issues
- - Poor Heat Transfer & Steam Control - Water Hammer Issues
- - High Backpressure
- Steam & Condensate Measurements, Control & Monitoring
Learning Systems:
- Armstrong University
- Over 125 web-based courses
- Mead O’Brien Live Steam Lab
- Content Tailored for Plant Need
Steam Trap Testing Guide for Energy Conservation
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| Annual steam trap testing schedule |
Below is a steam trap testing guide (courtesy of Armstrong International) to maximize efficiency and conserve energy. This guide discusses:
- Steam Trap Testing Procedure
- Tips On Listening
- Inverted Bucket
- Float & Thermostatic Trap
- Disc Trap
- Thermostatic Trap
- Sub-Cooling Trap
- Traps on Superheated Steam
Steam System Condensate - Save Big by Managing its Proper Return
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| Recover/return steam condensate |
Steam use in modern plants is everywhere. The condensate derived from its use is an asset that needs to be recycled. Older steam systems may have poor condensate return piping, or none at all. For these situations, creating or extending return lines should be considered. Steam traps in older systems are also suspect. Older traps are not as efficient or reliable as newer designs.
According to Armstrong International’s Senior Utility Systems Engineer Novena Iordanova, steam traps are very important in the condensate return/feedwater cycle. She believes the first purpose of a steam system is to deliver steam to a users defined area of need, and second, to return the resulting condensate back to the boiler. Unfortunately, in many cases the second goal is overlooked.
In older plants, a complete steam system evaluation, and many times an overhaul, is required. Professionals should be called in as plant maintenance staff typically doesn’t have the expertise required. The reasons for steam system degradation are common in the life cycle of plant operation. Over time, plant upgrades, new lines, expansion, and new equipment can have a significant detrimental effect on condensate return systems. The focus usually goes to the main headers and distribution, but condensate return doesn’t receive the same attention. The result can be a steam system that is no longer efficient - meaning high back pressures, water hammer, broken or freezing pipes, and leaks. At that point, the plant needs professional help for a complete system review.
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| Steam trap (courtesy of Armstrong) |
Frequent and regular inspections of steam traps are essential, but in reality they are many times postponed or rescheduled. Steam trap inspection is tough work. Traps are usually located in hard to see, hot, and tight areas. Over time, the difficulty (combined with the perceived low priority) degenerates to spotty inspection routines, higher trap fail rates and higher steam costs.
The good news is that steam trap monitoring systems now exist that can monitor the performance of steam traps and alert maintenance when things start to deteriorate. Steam trap monitoring systems report conditions that point to filature, and also alarm when things break down. Accordingly, maintenance is in a position to take preventive action, or make swift repairs. Any plant with a considerable number of stream traps should strongly consider deploying a steam trap monitoring system.
Steam trap monitoring systems monitor the thermal and acoustic characteristic of the trap and report any significant changes. Today many monitoring systems are wireless, and many operate on common plant communication systems such as WirelessHART, a communication protocol gaining worldwide acceptance.
Its important to mention here though, the on the most common mistake plant personnel make when it comes to their system is also one of the most obvious - insulation. The use of high quality, well maintained insulation, installed to allow access to steam components is critical. The energy savings alone from well insulated pipes and traps is argument enough for making the initial time and dollar investment for proper insulating.
If you’re a plant manager and are looking for significant measurable and meaningful ways to lower energy costs, you must consider a well planned and well executed steam trap management program.
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