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

https://psi-team.com

800-223-1468

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

https://psi-team.com

800-223-1468

Key SIL (Safety Integrity Levels) Terms

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

https://psi-team.com

800-223-1468

Terms and definitions courtesy of Kurz Instruments

Happy Holidays from Piping Specialties / PSI Controls

 

The Operation of the Cash Valve B Series, Type E-55, Type PBE-1, Type PBE-2, and Type PBE-5

Cash Valve is a leading manufacturer of pressure regulating and back pressure valves offering products for steam, air/gas, liquid, and cryogenic applications. Products range in size from 1/8" - 2" for threaded NPT connections and up through 6 inches for flanged configurations. Temperatures range between cryogenic up through 800°F, and materials of construction are offered with iron, brass, bronze, carbon and stainless steel depending on your application.

For more information about Cash Valve, contact Piping Specialties, Inc. by calling 800-223-1468 or by visiting their web site at https://psi-team.com. 

A Free Technical Paper Explaining Refractive Index

Refractive index measurement is a measurement of the speed of light in a medium. The speed of light (usually denoted by c) is 299 792 458 m/s in a vacuum. In other media, the speed of light is lower, and the refractive index (R.I.) of a medium is how much slower the light's speed is in the medium.

The detection of liquid concentrations by optical means is not new. The law of refraction was mathematically formulated first by Ibn Sahl in 984 but not known in Europe. Instead, its discovery misattribution goes to the Dutch astronomer and mathematician Willebrord Snellius (Snell), who rediscovered the law and published it in 1621. The first laboratory instrument to accurately measure liquids' refractive index was developed by Ernst Abbe in 1874.

This technical paper, courtesy of Vaisala K-Patents, is a technical explanation and understanding of the refractive index.

For more information about industrial refractometers, contact Piping Specialties / PSI Controls by calling 800-223-1468 or by visiting their web site at https://psi-team.com.

Valve Condition Monitoring

As corporations worldwide are increasingly concentrating on their bottom-line margins, there is an increased drive towards efficiency and productivity in industrial operations. Operators are also looking to respond to industry concerns about aging assets. All manufacturing activities are continually motivated to improve performance and productivity to boost profit margins and optimize bottom-line returns. This drive takes place in many industry sectors against a backdrop of increased health, safety, and environmental issues and the need to make changes to old assets that can sometimes run beyond their original design lifespan.

Reducing the number of unscheduled plant shutdowns is an essential way of fulfilling these targets. Unplanned shutdowns are mostly related to worn-out machinery and are attributable to exceeding process equipment's longevity in many instances. Operators may avoid expensive shutdowns and increase production uptime with a regular maintenance schedule and a condition monitoring solution that minimizes maintenance spending and improves plant safety. Asset tracking, asset management, and predictive maintenance solutions are, therefore, becoming increasingly common.

Valve condition monitoring's goal is to detect and prevent possible failures before causing unsafe conditions and unplanned downtimes.

Since valves are a critical component of any flow-based operation, valve efficiency is an essential factor to check when trying to avoid unplanned maintenance, or worse, shutdowns of plants and the resulting loss of batch output.

Although some operators already deploy condition monitoring on control valves and critical valves, many valves are often left unmonitored, particularly those used for on / off and shutdown applications. Although the technology for controlling these valves is available, operators are discouraged from such an investment because of the prohibitive hardware and installation cost. 

Although some valve manufacturers have touted various valve testing and monitoring systems, many proposed solutions can pose operational, financial, and/or technical implementation problems. This is because they are usually considerably more expensive than conventional methods or require new electrical systems and hardware to accommodate and enhance the monitoring software. Suppose automation is at the most basic level, such as that needed with on/off valves. In that case, the transformation is relatively low in value. The time and resources involved in implementing a useful monitoring solution can be challenging to justify. However, the consequence is that vast numbers of on/off valves are not supervised and pose a significant risk of valve failure.

By implementing this technology cost-effectively on all automatic valves, a plant will provide production efficiency and avoid unspecified delays and unsafe conditions. Valve Condition Monitoring is useful to all operating phases of the plant and thus provides the ability to increase all current and future installations' performance and safety. If you are considering updating your plant's valve monitoring strategy, contact a local expert who can guide you through all the ups and downs. The information they provide is truly invaluable. 

Piping Specialties / PSI Controls

https://psi-team.com

800-223-1468