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Q1 2016

Your Top 10 LEVEL Customers of 2015 MEASUREMENT Will Not be Your TECHNOLOGIES In The Process Top 10 of 2016 Control Industry þ What You Should Do

How to Two Birds with MEASURE One Stone FLOW RATE Level Indication with Level & Pump Control NEWPREDIG.COM Redesigned. Responsive. Resourceful.

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The Eclectic Engineer: How to Measure Flow Rate with Level Sensors 5

Two Birds with One Stone: Reader’s Level Indication and Pump Control with Brief The ProVu® Series 6 Your Top 10 Customers of 2015 Will Our first issue of 2016 is entirely dedicated to level measurement. Learn about various Not be Your Top 10 of 2016. What You topics on the subject including how to measure Should Do About It. flow rate using level sensors, level indication 9 and pump control using one device, and an introduction to level measurement technologies to guide you in selecting level instrumentation.

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We'd like to hear from you, our readers! Level Measurement Technologies Tell us how we are doing or recommend topics In The Process Control Industry for future articles. Send your feedback to 10 [email protected].

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4 The Eclectic Engineer How to MEASURE FLOW RATE with Level Sensors

Level sensors are capable of measuring more than just level. Flow rate measurement in an open channel, such as a stream, irrigation canal, or unpressurized sewerage pipe, can be accomplished using hydraulic structures known as weirs and flumes. These measure flow rate using the same technologies often applied to tank level measurement, such as bubblers, radar, and ultrasonic level transmitters. Both weirs and flumes function by constricting the flow of the channel and measuring how the fluid level is affected. Their physical characteristics, and therefore their effect on fluid flow, are known variables, so equipment that measures level upstream from the structure can use a series of mathematical equations to determine the flow rate.

Weirs function very similarly to dams in that they span the length of the Weir channel and constrict flow. There are Flume many styles of weirs, each meant for a different application, but they all allow fluid to escape through an opening and continue downstream. Fluid level is measured upstream from the weir. Flumes, on the other hand, typically consist of three sections: a constricting end, a throat, and an expanding end. The flume is partially submerged in the channel. The throat constricts the flow and the fluid level is measured at the constricting end.

5 ® Two Birds with One Stone ProVu Level Features Level Indication and ® Pump Control with the ProVu Series by Simon Paonessa

Level measurement and pump alternation control for up to eight pumps, control go hand-in-hand, whether it is advanced 32-point linearization for oddly making sure that your tanks stay full or shaped tanks, and automatic round that they don’t overflow. Traditionally, horizontal tank volume calculation. however, these two processes required As a level indicator, the PD6000 separate devices, a pump controller and PD6001 offer easy-to-read, dual- PD6001 and a level indicator. Precision Digital’s line displays with optional SunBright Feet & Inches ro u® P V Series combines both level LEDs which can be read in direct LED Display indication and pump control into one sunlight. The secondary display can device. Not only that, they also offer be used to show level measurement advanced multi-pump alternation control units, volume, or percent full. They functionality which can help maximize are available with up to four onboard For more information on the life-span of your pumps. mechanical relays and 4-20 mA analog multi-pump controllers visit: The ProVu® PD6000 is a bright, output for signal retransmission or pumpcontrol.com easy-to-read digital panel meter that output of some other variable. An accepts either a current (0-20mA, 4-20 available external expansion module mA) or voltage (±10 V, 0-5 V, 1-5 V) brings the total available relays to eight. analog input from any analog output As a pump controller, the PD6000 level transmitter. The PD6001 provides and PD6001 can use the available eight convenient level readings in a format relays to alternate the usage of up to operators are used to seeing, feet and eight pumps at programmed high or low inches. Both models feature multi-pump

6 ® ProVu Level Features

Multi-Pump Control 32-Point Linearization Round Horizontal Tanks Control and alternate Linearizes the level of Automatically calculates up to 8 pumps oddly shaped tanks volume

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Dual-Scale Feet & Inches Display Display level in two Convenient level display scales in feet and inches

set points. When the level reaches the the next set point will activate a second first set point, the controller will activate pump. This will continue until all pumps the first pump. When the level then associated with the pump controller reaches the associated reset point, the have been activated. Additional relays active pump will be on the controllers can deactivated. The be used to activate next time this set [The] ProVu® Series external alarms or PD6000 point is reached, combines both level other systems if, Level Indicator and the controller will indication and pump control for example, the Pump Controller activate a different into one device... they also level measurement pump in the group. reaches an offer advanced multi-pump This spreads the emergency condition. alternation control... amount of system The advanced wear evenly among pump control and by Simon Paonessa - Technical Writer the pumps, rather than constantly level indication features of the ProVu® Precision Digital Corporation utilizing a main pump and leaving the PD6000 and PD6001 make combining backup pump to remain unutilized and level indication and pump control a deteriorated over time, potentially failing breeze. They help not only by providing when it is needed most. easily readable level indication and If a pump does not function convenient pump control, but also by properly or the rate of change is more extending the life of your pumps by way than a single pump can keep up with, of spreading out system wear.

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8 Letter from Sales

by Chuck Arcovitch US Distribution Sales Manager Precision Digital Corporation

Your Top 10 Customers of 2015 Will Not be Your Top 10 of 2016 þ What You Should Do About It

A Message for Precision and high tech companies, but for your You need to be able to answer these business as well. What it means for your questions, and you must be motivated to Digital Distributors business may not all be clear, but one change those numbers. thing that is for certain is that you cannot Your business is changing, and you count on your top 10 customers of 2015 The only way to change with the need to make sure you are promoting being the top ten customers of 2016, and changing world of 2016 and beyond is the products, services, and selling you cannot count on the same selling to change your approach. It’s no longer techniques that will keep you growing methods and sales calls resulting in the good enough to sell the same products in 2016. same business. to the same people. Precision Digital can help you. We can provide you with the At the time I am writing this, the price As the U.S. Distribution Sales tools, the messaging, and the products of a barrel of WTI oil is $38.50. A year Manager, I try to help our distributors you need in order to grow your sales in a ago, the price was $56.50; and even figure out what to do about this. How do changing market by helping you promote higher before that. While not everyone you, as a distributor, plan for change? new products for your existing customers’ may be touched by this kind of change, applications. We can also open up I am sure that other changes such as My answer to that question is that new applications for you with existing municipal budgets, new technologies, or you have to simply do more. You have customers. We make a great discussion even winter weather patterns will affect to visit new customers, knock on new point for bringing value directly to the your business. doors, and show existing customers new operators at new facilities. products. How many of your customers Jonathan MacDonald, founder and have seen a Precision Digital demo? How So, how do you plan for the speaker for TEN (Thought Expansion many of them have been walked through changes of 2016? You have to make a Network) is commonly quoted for his a catalog? Of your top customers, how commitment to doing more, and changing message: “Today is the slowest pace of many of them have you toured and how you sell. If you do, you’ll find some change we’ll ever experience.” Not only discussed their processes with them great changes can come this year to your is this true for people, marketing firms, on the plant floor, catalogs in-hand? bottom line.

9 A LEVEL PERSPECTIVE

LEVEL MEASUREMENT TECHNOLOGIES In The Process Control Industry

Few things are as ubiquitous in the Because of the importance of process control industry as the need to accurate level measurement and the measure the level of a process material myriad of different process materials in a container. Whether that material is requiring level measurement, an almost water, waste water, petroleum, sugar, equal number of unique methods for or any other form detecting level have of or solid, been developed. level measurement Instances of level Selecting the correct accuracy can be a measurement and control level measurement determining factor in technique for a both profit margins failure... can lead to tragic and particular application and safety. On costly consequences.... can seem like a December 11th 2005, daunting task in the malfunctioning level face of so many gauges were partially responsible for a options. All level measurement systems massive explosion at the Hertfordshire rely upon certain characteristics of Oil Storage Terminal in Hertfordshire, the process material, such as density, England. According to the Health and capacitance, , etc., and Safety Executive that investigated the each has its own particular advantages blast, “the tank was full, but gauges and and disadvantages. It is important to safety devices did not work.”1 A high understand the fundamental mechanics level switch that should have detected of the level measurement technologies the petrol level and cut off flow to the being considered in order to correctly tank failed to operate and workers didn’t specify the appropriate method (or notice that the tank was overflowing2. methods in the case of redundant This resulted in a 32-hour inferno which systems) for the application. injured 43 people and left many families homeless.

10 Categorizing Level How to Measurement Narrow Down Technologies Options A good way to reduce the number of level measurement options is to categorize them into two broad categories: contact and non-contact. Then you can filter choices by the type of material they can measure.

Contact and Non-Contact Contact Non-Contact The characteristics of the process material being measured, such as tank size and shape, the and temperature that the process requires, amount of material agitation, available power, etc., must be taken into account when determining if a contact or non- contact approach is the right option. One must consider whether the material is corrosive or tacky and could possibly cause damage to the measuring device, whether it is volatile and a contact might create a safety hazard, whether the agitation, temperature, or pressure of the process material could affect the reading of or damage the contact sensor, and any other troublesome possibility. On the other hand, non-contact solutions may be outside of the budgetary constraints of the project or not provide the necessary level of precision. Granulars Interface Slurries Materials Materials that A surface Semiliquid Type of Material Measured that are in a are in a solid boundary mixtures of liquid state state and between liquid and Process materials that need and can have small enough two liquids fine solid level measurement can generally be different to be stored or chemical particulate classified as liquids, granular solids, densities in tanks phases slurries, and interfaces. Liquids vary greatly in density and can be under a wide range of and , depending on the process. These factors influence the types of level sensors that can be used. Interface level, or the point at which two liquids of different densities meet, requires special consideration over typical liquid level measurement. A lot of the sensor technology that can be successfully employed in measuring liquid will be unwieldy or simply unusable when measuring granules such as loam and stone dust, or slurries such as cement. For these reasons, it is important to understand the type of process material (at all stages of the process) you are dealing with prior to looking into level measurement options.

11 An Overview of Level Measurement Technologies Because for the sheer number of level measurement technologies, the following overview is not meant to be all-inclusive nor is it meant to cover every intricacy of the technology in question. It is meant instead to give a very high-level synopsis of some of the different types of technology available and how each functions as a measurement device. More detailed information regarding a specific measurement device can be found in the manufacturer’s documentation and should always be consulted prior to purchase as every device uses level measurement methodology differently. That being said, a broad understanding of how each technology category is meant to function will give you a proper head start when specifying level measurement sensors.

Contact Sensors on measurement accuracy3. When the number of reed relays placed in the measuring an interface, the top opening gauge. Other float sensor types rely on Level Sight Gauge of the gauge must be submerged the measurement of the extension and at the level of the top liquid and the retraction of a connected cable. This bottom opening must be at the level type of sensor, in principle, requires no of the denser liquid or else the level power to operate but is susceptible to measurement will be incorrect. Level failure from float jamming or clinging. sight gauges can only be used when measuring liquids, as granules and Displacer The first type of level measurement slurries cannot move fluidly through device to be considered here is also the gauge. There is also no way to the simplest. A level sight gauge incorporate any type of automation typically consists of a tube connected into the process using this type of at openings near the top and bottom of measurement device. the tank. The tube has a transparent face so an operator can see the level of Float Displacers are dissimilar from the process material. This is technically float devices in that they are denser a non-contact measurement because than the process fluid and suspended there is no sensor making contact with by a spring. They rely on Archimedes’ the process material. However, many Principle to detect changes in buoyancy of the same concerns about contact force, which is equal to the weight of sensors should be taken into account, the displaced fluid, caused by a rise such as agitation, corrosiveness, Other devices, such as floats and or fall in level. A sensor at the top of tackiness, temperature, pressure, etc., displacers, rely on the material’s specific the gauge measures the change in which could damage or obscure the gravity (density) to measure level. They apparent weight of the displacer body. viewing area. often use a gauge similar to the sight The level measurement is therefore a Though this method of level level (a tube connected to the side of product of the length of the displacer measurement may be considered the tank towards the top and bottom).. body covered by the process material 4 the most trustworthy because the Magnetic floats, a specific type of float and the specific gravity of the material . material level can actually be seen by level sensor, typically rely on reed Both displacers and floats require the operator, pressure or temperature relays placed lengthwise within the tube. much of the same considerations as differentials between the tank and When the float passes these relays the mentioned previously with level sight the viewing area can have an effect magnetic field trips them. Therefore, the gauges and special considerations for accuracy of such a sensor is limited by interface measurement.

12 point-measurement level switches are typically used to measure liquids Bubble Tube or continuous level measurement. and slurries9. Variations of this technique can be used to measure liquids, granular solids, Contacting Ultrasonic slurries, and interface levels8.

Resistance Tape Bubble tube level measurement relies on the specific gravity of the process material as well. With this type of contact sensor, a tube is submerged Vibrating or ultrasonic level into the process fluid and air or nitrogen switches work under the principle that is pumped through the opening, near the sensor will vibrate at its resonant the bottom of the tank. The resulting The mechanical force of a process frequency when not submerged in back pressure is proportional to the liquid can be used to measure level process material. If the frequency is liquid level and density5. In instances using what is known as resistance dampened, the material has reached the where submerging a tube into the tape. Two wires, one attached to a level of the switch. This technique works process liquid is impractical, air can be voltage source and the other to a with liquids, slurries, and granules, pumped in through an entry at the side precision resistor, are contained within although consideration should be made of the tank. This type of sensor can only a shielded, flexible probe. Hydrostatic for coating or corrosive materials. be used to measure the level of liquids. pressure pushes on the probe body Vibrating level switches will typically only If the process liquid in which the tube is and shorts out the submerged length be used for point level measurement, submerged remains at a constant level, of wire. The change in resistance is as opposed to continuous level any change in backpressure is due to correlated with the level of the process measurement, and trigger high and/or a change in density or interface level, liquid. These types of contact probes low alarms. The sensors themselves tend to be very delicate and changes in tend to be fragile because of the level of thus allowing for measurement of these 10 variables6. density can have a minor effect. They precision necessary .

RF Capacitance

Level Measurement Using RF Capacitance

RF Capacitance level sensors use mA mA the same operating principle as an electronic capacitor in order to gauge level. An electronic capacitor consists of two conductive metal plates separated Non-Conductive by some kind of insulating material. Materials Capacitance is the measurement of the amount of energy a capacitor can store. Using a method that is very similar to that of an electronic capacitor, the capacitance of a process material can also be measured and then correlated to the level. If measuring a non-conductive mA material, that material is used as the insulator part of the capacitor and the tank wall acts as the second conductive plate; if measuring a conductive Conductive material, the probe body is shielded Materials with an insulator and the material acts as the other conductive plate7. In either case, a rise in the level will correlate with an increase in the measured capacitance (over that of air). This technology can be used for either

13 Contact and Non-Contact Level Measurement Comparison Material Suitability Measurement

Type Liquids Granulars Interface Slurries Corrosiveness Agitation Tackiness Single-Point Level Continuous Level Level Sight Gauge ● ● ● Float ● ● ● ● Displacer ● ● ● Bubble Tube ● ● ● ●

Contact RF Capacitance ● ● ● ● ● ● Resistance Tape ● ● ● ● C Ultrasonic ● ● ● ● Radar ● ● ● ● ● ● ● ● NC Ultrasonic ● ● ● ● ● ● ● ● Load Cells ● ● ● ● ● ● ● ●

Non-Contact Nuclear ● ● ● ● ● ● ● ● Recommended applications

the direction of an object, waiting for Non-Contact Sensors that pulse to reflect off the object and return to the source, and measuring All level measurement Radar its time-of-flight. The distance between systems rely upon certain the pulse source and the object can be characteristics of the process calculated as the product of one-half the material... time-of-flight and the speed of light. For use in level measurement, a radar transceiver is suspended from the top of the tank and measures the Radar is a technology which distance to the top of the process was first extensively developed and material. The overall length of the tank deployed during the second World body can then be used to calculate War as a means of detecting aircraft, the level. As a non-contact sensor, ships, and other large objects. Since radar has the distinct advantage of the technology was introduced to not being affected by the process the civilian sector, many peacetime material’s state, such as agitation, usages of the technology have corrosiveness, tackiness, temperature, been established, including level pressure, etc. Radar can be used to measurement. Radar typically works measure liquids, slurries, and granular by emitting electromagnetic pulses in

14 solids. However, materials with high the level being at or above that sensor. conductivity tend to be better candidate Nuclear Though this technique is affected little for radar level measurement because by the physical state and properties they reflect more of the emitted radio of the material, it is typically only used signal. As such, conductive materials when all other options have been other than the process material within exhausted due to the dangers and the tank, such as agitators, can cause expense of using radioactive material interference with the radar signal. and the stigma associated with it. Nuclear type level sensors use radioactive isotopes, typically either Non-Contacting Ultrasonic cobolt-60 or caesium-137, to emit Summary gamma radiation into a storage The technologies described here container and sensors on the opposite barely scratch the surface of those side to measure the attenuation, or available to the industry (not to mention change in frequency modulation, of variations of these technologies). Due that radiation. Isotopes are atoms that to the nearly countless number of have the same chemical behavior as process materials and conditions in Non-contact ultrasonic level one another but a different number sensors use a very similar method all of the industries that require level of neutrons. Radioactive isotopes are measurement for their processes, an as radar sensors to measure level. those isotope variations which are However, instead of using radio waves almost equal number of methods for unstable under normal conditions and measuring level have been devised. they use sound waves and the distance decay into other elements. When these is calculated as the product of one-half However, understanding the differences atoms decay, they emit three different between and limiting factors attributed the flight time and the . kinds of radiation (alpha, beta, and Unlike the speed of light, the speed of to contact and non-contact sensors, gamma) which can be picked up and as well as the fundamental operating sound is temperature dependent, so measured by special sensors. Gamma the temperature of the tank must also principles of some of the more common 11 radiation is used for the purposes of level sensor technologies, should help be measured and taken into account . level measurement because, of all Like radar, they can also be used to when specifying what technique is three kinds, it is the best at penetrating best suited for a particular application. measure liquids, slurries, and granular materials13. solids. Process materials that produce Instances of level measurement and a stronger sonic reflection are more This technology can be used control failure, such as the events applicable to this type of measurement. in both single-point and continuous that unfolded at the Hertfordshire Oil Condensation, dust buildup, and level applications. In single-point Storage Terminal, can lead to tragic presence of additional objects within measurement, such as high and low and costly consequences that could the tank can all cause measurement alarms, a sensor is typically installed have been avoided. A level perspective inaccuracies12. parallel to the source of radiation on is vital to maintaining accurate process the opposite side of the tank and any control and ensuring continuous safety. change in frequency modulation over Load Cells a certain threshold triggers an alarm. Since radiation is released from all directions from a radioactive element, by Simon Paonessa - Technical Writer continuous level measurement involves Precision Digital Corporation using sensors along the length of the tank on the opposite side. Using Load cells, sensors normally used the attenuation detected through an to measure weight, can be used to empty tank as a baseline, any change gauge tank level. These sensors are detected by a sensor is attributed to attached to the support columns of a tank and measure the downward force applied on them by the mass of the container above. By taking into References account the weight of the tank when 1. Buncefield tank 'was overflowing', BBC News, 9 May 7. Magnetrol, Kotron® RF Capacitance, 2009, empty and assuming that the tank has 2006, stm> 8. Lipták, 430 straight sides, any change in the weight 2. How Buncefield fire unfolded, BBC News, 13 July 9. Lipták, 526 measured by the load cell can be 2006, 10. Ibid., 413 3. Lipták, Béla G., et al., Instrument Engineers' 11. Magnetrol, Ultrasonic Non-Contact Transmitters, correlated with a change in level. Load Handbook, Fourth Edition, Volume One: Process 4. Ibid., 465 12. Lipták, 412 liquids, slurries, and granular solids, 5. Ibid 13. Ibid., 515 but require the process material to be 6. Foxboro, Bubble Tube Installations for Liquid Level, Density, and Interface Level Measurements, of constant density. Load cells typically September 1988, are not used to measure interface level.

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Q1 2016

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