Concepts of Process Instrument Calibration

Volumetric calibration rig

Measuring devices are an integral part of our lives nowadays, whether in everyday life or on the job. Take, for example, the scales at the supermarket check-out, the fuel volume measurement at the filling station pump, temperature measurement, velocity, flow volume and thermal energy, taxi meters etc. The wide variety of available quantities to be measured and measuring devices clearly illustrates the complex interplay between the quantity to be measured and the measuring device used. What does "accurate" actually mean in this context and how is this accuracy demonstrated? Why do we need accurate measuring devices?

Using the example of flowmeters, the following document will go into detail about these and other aspects of calibration and accuracy, and also looks at calibration standards from different countries around the world.

Concepts of Process Instrument Calibration from Instrument Specialties, Inc.

For more information regarding process instrumentation and calibration, contact:

Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104
www.isisales.com

Lightning and Surge Protection for Potentially Explosive Atmospheres

Protect your plant's hazardous area
from lightning strikes and surges.

During producing, processing, storing and transporting flammable substances (e.g. fuel, alcohol, liquid gas, explosive dusts), potentially explosive atmospheres where no ignition sources may be present to prevent explosion frequently occur in chemical and petrochemical industrial plants. The relevant safety regulations describe the risk for such plants posed by atmospheric discharges (lightning strikes). In this context, it must be observed that there is a risk of re and explosion resulting from direct or indirect lightning discharge since in some cases these plants are widely distributed.

To ensure the required plant availability and safety, a conceptual procedure is required to protect parts of electrical and electronic installations of process plants from lightning currents and surges.

The white paper below, provided by DEHN,  provides an in-depth strategy on plant protection and safety from lightning strikes and surges in hazardous areas.

Lightning and Surge Protection for Potentially Explosive Atmospheres from Instrument Specialties, Inc.

For more information, contact:
Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104

www.isisales.com
e-mail: offices@isisales.com

The Valtek Control Valve: Understanding the Components

Flowserve (Valtek) control valves

Valtek control valves are also known for handling the most severe services: cryogenic, superheated steam, volatile and corrosive fluids, erosion, high pressure drops, vibration, cavitation, flashing, and high noise levels.

Valtek valves are equipped with spring cylinder or spring diaphragm actuators that provide the thrust and speed necessary to manage any service. Valtek four-way analog and digital positioners provide accuracy and response to handle the most exacting applications.

This video gives the viewer an understanding of the major components.

For more information, contact:
Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104
e-mail: offices@isisales.com

Using Process Refractometers in the Processing of Sugar Cane

Sanitary process refractometer
(courtesy of K-Patents)

After sugar cane has been harvested, it must be processed in under 24 hours to avoid sugar loss by inversion to glucose and fructose. Traditionally, sugar cane processing requires two stages, milling and refining, but this two stages are slowly combining into on production facility. Process refractometers are commonly used to determine the concentration of a dissolved solids by making an optical measurement of a solution’s refractive index (nD).

In cane sugar refining and milling process, refractometers are used for accurate in-line Brix and concentration measurements with the purpose is to achieve high quality liquid and crystal sugars and to minimize costs of production. 

Specific uses of refractometers in sugar production are:

• Optimize extraction process and to minimize usage of water that needs to be removed from sugar juice later at the evaporator stage.
• Adapt product flow to the capacity of the evaporators in order to save energy.
• Make sure that liquid bulk sugar and molasses meet specifications.
• Control feed juice to adjust the concentration with the capacity of the separation columns. This leads to longer intervals between Recovering cycles and longer lifetime of the columns.
• Monitor supersaturation over complete strike of crystallization.
• Implement automatic and accurate seeding of the vacuum pan.

Refractometers (in red) used in sugar milling

Refractometers (in red) used in sugar refining

Download the complete Process Refractometer Application Note for Cane Sugar here.

For more information on process refractometers, contact:
Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104
e-mail: offices@isisales.com

The Ins and Outs of Isolation: A Guide to Selecting The Right Instrument Isolator

Isolators (courtesy of Acromag)

The primary function of the isolator is to eliminate ground loops that may exist between two or more instruments. A classic application isolates the control room equipment (computers, PLC, DCS etc.) from field devices which may have different ground potentials. In addition to break ing up ground loops, the isolators protect control room equipment from damaging transient spikes and noise generated in the field. Choosing the proper and most cost-effective isolator requires an understanding of the application and consideration of future expansion requirements.

Isolators are available in 2, 3, and 4 wire configurations. Isolators are further classified as input, output, or 3-way (input, output, power) isolators. Input isolation implies the input signal has no electrical connection to the output and power signals. Output isolation implies the output signal has no connection to the input and power. And similarly, 3-way isolation refers to a situation where there is no electrical path between the input, output, or power.

The technical paper below describes four types of isolators and typical PLC/DCS applications in which they are best suited. Each isolator produces a 4-20mA DC output signal corresponding to the 4-20mA DC input signal.

The Ins and Outs of Isolation: A Guide to Selecting The Right Isolator from Instrument Specialties, Inc.

Variable Frequency Drives and Energy Savings: More Than Just Fan and Pump Applications

Siemens Medium Voltage Drive

When discussing energy savings and variable frequency drives (VFD) the attention often focuses on a centrifugal fan or pump application. However, you should not overlook other applications which also have large potential energy savings and energy recovery. Applications involving regeneration, power factor correction, common bus applications or a combination of the three can also quickly achieve a significant reduction in energy use.

The paper below provides detailed insight into other application areas where VFD's provide substantial energy savings.

Variable Frequency Drives and Energy Savings: It‘s More Than Just Fan and Pump Applications from Instrument Specialties, Inc.

Self Regulating Heat Trace Guide

Self-regulating cable

Self-regulating heat tracing systems are the preferred choice for most complex pipe-tracing applications. This is due to their parallel construction, which allows them to be cut to length and spliced in the field, and their self-regulating output, which provides more heat where it is needed.

Self-regulating cable uses conductive-polymer technology in both monolithic (solid core) and fiber (polymeric fiber wrap) heating cables. The heating element is made of polymers mixed with conductive carbon black. This special blend of materials creates electrical paths for conducting current between the parallel bus wires along the entire cable length.

In each heating cable the number of electrical paths between the bus wires changes in response to temperature fluctuations. As the ambient temperature surrounding the heating cable decreases, the conductive core or fiber contracts microscopically. This contraction decreases electrical resistance and creates numerous electrical paths between the bus wires. Current flows across these paths to warm the core or fiber.

The document below provides an excellent detailed description of self-regulating cable, its application and selection.

Self Regulating Heat Trace Guide from Instrument Specialties, Inc.

For more information, contact:

Instrument Specialties Inc.
3885 St. Johns Parkway
Sanford, FL 32771
phone 407.324.7800
fax 407.324.1104
e-mail: offices@isisales.com

www.isisales.com