Happy Holidays from Miller Energy
Happy Holidays from everyone at Miller Energy. We hope 2019 is a great year for you!
ASCO Express Product Catalog
Download your copy of the ASCO Express Product Catalog here.
Contact Miller Energy for all your ASCO solenoid valve requirements.
908-755-6700
Water and Wastewater Treatment Applications for the Magnetrol R82 Pulse Burst Radar Transmitters
The Magnetrol R82 Pulse Burst Radar transmitter performs across a wide range of applications. The R82 is designed to provide radar reliable process measurement in challenging, vapor saturated environments, at the cost of what you pay for an ultrasonic device. For water treatment, the Magnetrol R82 Pulse Burst Radar transmitter provides continuous level measurement at the lift station and coagulant feed tanks, in settling tanks during clarification, in polymer, filter, and lime slurry tanks during filtration, and for open atmosphere water reservoirs where the control technology must withstand punishing weather conditions. In wastewater facilities, the R82 radar can control level at the lift station pump, open channel flow and screening system, monitor feed tanks containing chemical coagulants oxidants and phosphorous precipitation, measure splitter box in clarifier levels, control corrosion inhibitors, manage pH adjustment, mixed liquor and secondary clarifier levels, as well as activated sludge and digester level control.
Miller Energy, Inc.
https://millerenergy.com
Brooks Instrument Sponsoring $2000 Engineering Scholarship
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| CLICK THIS LINK TO LEARN MORE |
Brooks Instrument is committed to the next generation of engineers. Accordingly, they have established a $2,000 scholarship for a qualified student enrolled in an engineering program at an accredited college or university. Learn more here (https://www.brooksinstrument.com/en/about-us/scholarship).
Miller Energy Inc. Announces Acquisition of Fox & Dole Technical Sales
Miller Energy is pleased to announce the acquisition of Fox & Dole Technical Sales as of November 1, 2018.
Founded in 1974, Fox & Dole is a leading distributor of process instrumentation and controls serving Western Pennsylvania, West Virginia and Ohio. With over 100 years of combined experience, the merger of our two companies will offer our customers the most technical customer support and application expertise in the industry, an unparalleled product portfolio, and a continued commitment to outstanding customer service.
For more information, visit the news section of the Miller Energy web site.
Temperature Switches
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| Temperature switch (United Electric Controls) |
A temperature switch detects the temperature of some substance. Temperature switches often use bimetallic strips as the temperature-sensing element, the motion of which actuates one or more switch contacts. An alternative design uses a metal bulb filled with a fluid that expands with temperature, causing the switch mechanism to actuate based on the pressure this fluid exerts against a diaphragm or bellows. This latter temperature switch design is really a pressure switch, whose pressure is a direct function of process temperature by virtue of the physics of the entrapped fluid inside the sensing bulb.
The “normal” status of a switch is the resting condition of no stimulation. A temperature switch will be in its “normal” status when it senses minimum temperature (i.e. cold, in some cases a condition colder than ambient). For a temperature switch, “normal” status is any sensed temperature below the trip threshold of the switch.
Like all other process switches, temperature switches exhibit a certain amount of deadband in their switching action. A temperature switch that trips at 300 F rising, for example, will not reset at 300 F falling. That switch would more likely reset at some lower temperature such as 295 F. With mechanical switch designs, some amount of deadband is inevitable due to friction inside the mechanism. However, process switch deadband is actually a useful characteristic as it helps avoid repeated “nuisance” alarms from happening.
To understand this concept, it is helpful to imagine a scenario where the process variable is at or very near the trip point. For our hypothetical temperature switch with a trip point of 300 F (rising), imagine a situation where the process temperature is precisely 300.0 F. Any further rise in temperature will of course trip the switch (sounding an alarm). With no deadband, however, the switch will immediately re-set when the temperature falls back down to 300.0 F. This means the switch may possibly “cycle” back and forth between its trip and reset states with just a minute change in process temperature (300.0 F to 300.1 F and back again). If the temperature switch is activating an alarm every time it trips, it will create a series of alarm events prompting operators to repeatedly acknowledge the alarm. This is a nuisance to operations personnel, as it distracts them from addressing what they already realize is a process problem. It is better for the switch to trip at 300.0 F rising and remain in that tripped state until the temperature falls down to some degree substantially below the trip point. This way, the operators only receive one alarm event rather than multiple alarm events for each process temperature excursion.
Some mechanical temperature switches come equipped with a separate adjustment for deadband (also called differential). Setting this deadband adjustment in a mechanical temperature switch requires the technician to repeatedly subject the sensing element to a rising and falling temperature, to check that the switch trips at the proper setting and resets at the proper setting. This is analogous to cycling the process variable back and forth when adjusting the “zero” and “span” settings of an analog transmitter: checking to see that the transmitter repeatedly outputs a 0% signal at the lower range value (LRV) and a 100% signal at the upper range value (URV).
For discrete temperature-sensing applications demanding high accuracy and repeatability, electronic temperature switch circuits using thermocouples, RTDs, or thermistors may be used instead of a mechanical (bi-metallic or filled bulb) sensing element. The operation and configuration of discrete electronic temperature switches is very similar to that of continuous electronic temperature transmitters.
An example of an electronic temperature switch module is the United Electric One Series shown below:
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| UE Series One Electronic Temperature Switch |
With electronic temperature switches, the adjustment of deadband (differential) is both precise and flexible. Unlike mechanical switches where deadband is primarily a function of friction, and therefore liable to change over time as the device wears, electronic switching circuits may be precisely set for any trip and reset points along its measurement range, remaining very stable over time.
For more information about temperature switches, contact Miller Energy by visiting https://millerenergy.com or by calling 908-755-6700.
Text adapted from "Lessons In Industrial Instrumentation" by Tony R. Kuphaldt – under the terms and conditions of the Creative Commons Attribution 4.0 International Public License.
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