Industrial Refractometers

Industrial Refractometers

Refractometry, a mixture of physics, material science, and chemistry, is a method that calculates the composition of known substances by measuring their respective refractive index (RI). The refractometer determines dissolved solids' concentration by making an optical measurement of a solution's refractive index (nD). The refractometer measures the refractive index nD and the temperature of the process medium. The calculation is based on the refraction of light in the process medium, called the critical angle of refraction, using a yellow LED light source with the same wavelength (580 nm) as the sodium D line (thus nD). In most solutions, the concentration of solute in a solvent can be determined by measuring the refractive index nD. The relation between the refractive index and the concentration depends on the solvent and solute, temperature, and wavelength.


Typical examples of industrial refractometry uses are:


  • The calculation of the salinity of water to assess its drinkability.
  • The analysis of dissolved solids in liquor production in pulp and paper production.
  • The assessment of sugar content ratios for food products and beverages.
  • The understanding of the hydrocarbon content of motor fuels. 


These are just a few examples. There are many more common industrial uses for industrial inline refractometers and thousands of unidentified potential applications. 


To discuss your application for refractometers in New England, contact Piping Specialties, Inc. / PSI. 


Piping Specialties / PSI Controls

800-223-1468

Level Measurement Solutions for Water Treatment

Level Measurement Solutions for Water Treatment

Several functional level measurement technologies have viable solutions for a broad range of industrial and municipal water treatment applications. Because of the variety of applications that exist and the varying application conditions, no one technology is best suited in all cases. 

POINT LEVEL VERSUS CONTINUOUS LEVEL INSTRUMENTS

Regardless of the application, there are two significant classifications of level measurement instrumentation: point level and continuous level measurement.

Point Level (On/Off) measurement indicates the absence or presence of level at a certain threshold (point) within a vessel.  Point-level switches perform as high level and spill prevention alarms, low level, pump protection alarms and pump control.

Continuous Level (Proportional) measurement indicates the level in a vessel over the full span of capacity.  These devices perform as process control as well as inventory control and management.

LEVEL CONTROL TECHNOLOGY CHOICES

The technologies used to measure level are affected differently by the varying process conditions. Below is a brief description of the different technologies commonly used in a water treatment facility.

RF ADMITTANCE/CAPACITANCE
RF Admittance/Capacitance employs a radio frequency signal and monitors for a change in capacitance. Either the presence or absence of material or how much material is in contact with the sensor, making it highly versatile and a right choice for a wide range of conditions and materials for point or continuous level measurement.

RADAR
Radar utilizes either Pulsed Wave or Frequency Modulated Continuous Wave (FMCW) through-air transmission that allows for an accurate non-contact reading of reflected electromagnetic signals.

MAGNETOSTRICTIVE
Magnetostrictive uses an electric pulse from ferromagnetic wire to accurately detect a float's position with embedded magnets.  As the pulse intersects the float's magnetic field, a second pulse reflects an electric circuit that accurately determines the distance and thus the level position.

CONDUCTIVITY SWITCHES
Conductivity switches measure the drop-in resistance when a conductive liquid contacts with two probes or a probe and a vessel wall.

ULTRASONIC (POINT LEVEL)
Ultrasonic (Point Level) measurement electronically resonates a crystal at a fixed frequency to generate sound waves that travel across an air gap to a second crystal.  As liquid fills the gap between the two crystals, the second crystal begins to resonate with the first.

ULTRASONIC (CONTINUOUS LEVEL)
Ultrasonic (Continuous Level) measurement uses a transmitter to generate an ultrasonic pulse and measures the time it takes for a reflected signal to return to the transducer to determine a liquid level.

GUIDED WAVE RADAR (GWR)
Guided Wave Radar (GWR) utilizes a Time Domain Reflectometry (TDR) technique by sending a highly focused electronic signal down a metallic rod or flexible cable waveguide. When the transmitted signal intersects the liquid's surface, it reflects along the rod or cable to determine the distance traveled. The level position is then easily inferred.

HYDROSTATIC
Hydrostatic measurement immerses a pressure transmitter with a sensing diaphragm and a sealed electronic circuitry that transmits an analog signal proportional to the liquid level above the sensor.

FLOAT SWITCHES
Float switches rely on a low-density float mounted in a vessel that magnetically couples to a limit switch. A change in fluid height actuates a switch by moving the float.

VIBRATION/TUNING FORK
The Vibration/Tuning fork is piezoelectrically energized and vibrates at a frequency of approximately 1200Hz, and as the process media cover the fork, the frequency shifts. The internal oscillator the frequency shift by and converts it into a switching command.

POINT LEVEL SOLUTIONS

Advanced RF Admittance/Capacitance point level devices are the most versatile of the point level technologies, especially with process media that can coat the sensor. They provide excellent spill/overfill protection. They are simple to install and have no moving parts, making them virtually maintenance-free. Their robust design and circuitry make them an ideal solution for many water treatment applications.

Both tuning forks and ultrasonic gap switches provide reliable high- or low-level measurements in various applications. For non-coating conductive liquids, conductivity switches provide economic priced measurement while float switches appear in many basic applications at very cost-effective prices.

CONTINUOUS LEVEL SOLUTIONS

Mechanical systems such as floats and bubblers require extensive maintenance and are less reliable and accurate than electronic systems. Hydrostatic systems afford better reliability and are simple to use, and can transmit data to another receiver for remote monitoring, recording, and control.

RF Admittance/Capacitance level is a time-proven and one of the best available technologies for indication and control. RF technology inherently provides the highest accuracy and repeatability in interface measurements. Variations in the makeup of upper and lower phases of a liquid have no appreciable effect on system accuracy. Recalibration is not required.

For short-span measurements, RF Admittance technology provides one of the most preferred readings. As the level of measurement span decreases, the more appropriate RF technology becomes. In spans of only a few inches, RF systems can repeatedly produce accuracies of 1/32ths of an inch. RF has the added benefit of not being limited by “dead zones” inherent with many popular technologies often selected for measurement ranges larger than 5 feet.

Non-metallic tanks pose no technical problems for Ultrasonic, Magnetostrictive, Hydrostatic Pressure, Radar, and GWR (Guided Wave Radar) technologies. The GWR approach is suitable for vessels with internal obstructions and uses lower energy levels than airborne radar technologies. Non-contact technologies, such as Radar and Ultrasonic, can have measurement ranges up to 130 feet. 

For long-range measurements or headroom limitations, flexible sensors offer insertion lengths up to several hundred feet for Hydrostatic Pressure and RF Admittance technology products. Loop-powered GWR (TDR)-based products allow measurement ranges up to 115 feet in selected applications. Magnetostrictive technology provides an accuracy of 0.1% of measurement span in flexible sensor designs up to a maximum range of 70 feet.

Piping Specialties / PSI Controls
800-223-1468

Sizing Calculator for LINK-SEAL® Elastomer Sealing System Available

Sizing Calculator for LINK-SEAL®

LINK-SEAL® modular seals are the premier method for permanently sealing pipes of any size passing through walls, floors, and ceilings. As they pass through barriers, any cylindrical object becomes quickly and persistently secured by the patented Link-Seal® modular seal design.

LINK-SEAL® withstand hydrostatic testing up to 20 PSIG (40 feet of static head) and is used on plastic, metal, and concrete pipes. Electrical and telecommunications cables are sealed within conduit as they enter vaults or utility holes. Link-Seal® also closes the annular space between carrier pipes passing through casings against the entry of water, soil, or backfill material. 

LINK-SEAL® provides a handy calculator to assist in sizing and choosing your LINK-SEAL® sealing system. You can find the calculator here.

Piping Specialties / PSI Controls
800-223-1468

Valve Positioners

Valve Positioners

Valve positioners control a valve's position (ball, butterfly, and globe) such that a given process will achieve specific desired flow parameters. They perform this by determining the error between the optimum valve position and actual valve position. With specialized sensors mounted on the valve stem or actuator shaft, these sensors compare the magnitude of error between the setpoint from the control system and the actual process value. The positioner's corrective output is sent electrically or pneumatically to a valve actuator, which moves the valve in the corrective direction. 

As a control valve accessory and the interface between the control system and valves, positioners play a vital role in ensuring the process loop's performance. The valve positioner adjusts the valves' opening, thereby varying the valve's flow rates, from completely shut or wide open to anywhere in between. An example of this type of positioning control will include mixing hot and cold water to achieve a specified downstream temperature requirement. By controlling the valve's opening and closing, process control parameters such as flow, pressure, level, and temperature are maintained

Piping Specialties / PSI Controls offers a full range of positioning equipment, including pneumatic, electro-pneumatic, intrinsically safe, explosion-proof, and Smart type positioners.

Piping Specialties / PSI Controls
800-223-1468

Level Measurement for Water in Sewage Pools

Level Measurement for Water in Sewage Pools

This application takes place at a large power plant well known for its "Green Approach" and it's commitment to ensuring a clean and healthy atmosphere in and around the plant. 

The branched sewer system of the power plant requires instant maintenance and control. The plant uses water to operate the turbine. This water and other wastes move to the city’s wastewater treatment plant through the sewage system.

Some of the sewers are dispersed in remote locations around the plant, making it difficult for personal maintenance personnel to approach and repair damage on time. Plant technicians were looking for a solution to control the sewers better and avoid cases where wastewater might overflow. 

The sewage pool readings had to be transmitted to the central DCS because the sewage system connects to a central control room. The plant needed a 24/7 watch and an on-site guard to gain maximum control over those sewers. 

Technicians also stressed that wastewater flooding was inevitable because it takes time for the equipment to handle blockages. This flooding has caused severe damage to the environment. It was essential to control the wastewater level in the sewers to avoid cases such as these from reappearing. 

The Drexelbrook Usonic - The Solution 

After a lengthy examination of several possibilities, the plant decided to install two Drexelbrook USonic systems in its sewage pools. The ability of USonic to produce non-contact, continuous, and accurate readings of the water level in the pools gave the engineers of the plant a clear picture of the pools' status. 

Its compact size and integral construction simplify its installation, offering an efficient solution in no time at all. The USonic had no problem providing 12ft water level readings with a measurement range of up to 30 ft.  It can map obstacles in the pool and memorize interfering signals with its scan distance function. 

The USonic was linked to the central control system via 4-20mA, allowing the plant engineers to control the water level in the sewers constantly. The engineers know that the sewers would maintain the correct water level, and the system would be alerted in an emergency. 

Summary

The two USonic systems installed in the power plant give complete control over the sewers' water level to the plant's engineers. The systems' ability to display continuous level readings around the clock improved maintenance crews handle the sewage system.

To detect sudden blockages and avoid environmental damage on time, they can now save time. The plant received an immediate return on investment due to its compact size and reduced price.

Piping Specialties / PSI Controls
800-223-1468

Key SIL (Safety Integrity Levels) Terms

Safety Integrity Levels

The global value of SIL (Safety Integrity Levels) to the process industries has increased significantly over the years. For many companies, SIL is still an elusive term sometimes misunderstood and implemented incorrectly. To fully understand SIL and its consequences, it is essential to comprehend the necessary words, acronyms, and phrases often used and how they relate to the pursuit of functional safety.  The following are some of the most commonly used:

Dangerous failure

Failure with the potential to bring the safety instrumented system into a dangerous or non‐functional state.

FMEDA

Failure Modes Effects and Diagnostic Analysis

HFT

Hardware Fault Tolerance, ability of a hardware to continue to perform a required function in the presence of faults or errors.

MTBF

Mean Time Between Failures

PFD

Probability of Failure on Demand, Probability of hazardous failures for a safety function on demand.

Safety Function

The ability of a system to carry out actions necessary to maintain a defined safe state for a process, equipment, or a plant.

Safety‐Related System

A safety‐related system performs the safety functions that are required to maintain a safe condition (for example, a flow meter, a burner, and a PLC).

SFF 

Safe Failure Fraction, percentage of failures that do not have the potential to put the safety‐related system in a hazardous state.

SIL

Safety Integrity Level, IEC 61508 defines four Safety Integrity Levels (SIL1 through SIL4). Each level corresponds to a level of probability for the failure of a safety function.

SIS 

Safety Instrumented System, implementation of one or more safety instrumented functions.


Piping Specialties / PSI Controls
800-223-1468

Terms and definitions courtesy of Kurz Instruments