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The "Big Eight" Thermocouple Types

In the United States, each thermocouple class carries a notation defined by a single letter. The Instrument Society of America (ISA) pioneered this method, which was introduced as an American Standard in 1964 to avoid proprietary names. The American National Standards Institute (ANSI-MC96.1, 1982) and the American Society for Testing and Materials (ASTM 230-87) use the National Institute of Standards and Technology Monograph 125 reference tables as the basis for standardization. As noted in the ANSI and ASTM standards, the letter designations define the tables. Thus, they may be applied to any thermocouple with a temperature-EMF relationship that agrees within the tolerances defined in the standards, irrespective of the thermocouple's composition. 

Only a few of the approximately 300 different temperature measuring thermocouples defined and tested have achieved mass acceptance because they exhibit more desirable electrical and physical characteristics. Resultantly, these eight preferred thermocouple types are the most widely used in industrial, commercial, medical, and aerospace applications. 

1. Type B = platinum- 30% rhodium/platinum-6% rhodium - 0 to 1820°C *
2. Type E = nickel-chromium alloy/a copper-nickel alloy -270 to 1000°C*
3. Type J = iron/another slightly different copper-nickel alloy -210 to 1200°C*
4. Type K = nickel - chromium alloy/nickel - aluminum alloy -270 to 1260°C
5. Type N = nickel-chromium-silicon alloy nickel-silicon alloy -270 to 1300°C*
6. Type R = platinum- 13% rhodium/platinum -50 to 1768°C*
7. Type S = platinum- 10% rhodium/platinum -50 to 1768°C*
8. Type T = copper/a copper-nickel alloy -270 to 400°C*

* temperature range as per NIST Table I: Thermocouple Types Definitions.

Certain combinations of alloys, such as Type J and K, have become popular as industry standards.  Cost, availability, melting point, chemical properties, stability, and output are all drivers for thermocouple application. Different types of thermocouples are best suited for different uses/applications. Thermocouple selection also depends on the temperature range and accuracy needed. Other selection criteria include the chemical inertness of the thermocouple material and whether it is magnetic or not. 

For more information about thermocouples, contact Duro-Sense by calling 310-533-6877 or visiting https://duro-sense.com.

Shorter Lead Times Make Happier Customers

Customer satisfaction and loyalty can be closely tied to how quickly customers receive their orders. In terms of supply chain, lead time is a big part of any successful business. Reducing lead times as much as possible is vital to a company’s success.

Manufacturing lead time is the total time required to manufacture an item. From an operational standpoint, One should be aware that there are many different types of lead times:

• Material lead time is the amount of time it takes a customer to place an order with a supplier and receive it; from when the order was confirmed to when they have it on hand.
• Pre-production lead time is the amount of time required for the supplier to create a work order. This is sometimes called planning time. It primarily takes the form of paperwork.
• Production or Factory lead time is the actual amount of time the supplier needs to manufacture the product.
• Post-production lead time is the time required for a customer to receive an item from dock to inventory. Depending on the product, it could entail anything from inspection to quarantine time.
• Fixed lead time refers to a part of production or factory lead time that is not dependent on the order quantity.
• Variable lead time, is the part of production or factory lead time that is dependent on the order quantity.
• Cumulative lead time is the term used to describe the entire amount of time required, from order confirmation to the delivery of the product. It is the aggregate of material lead time and production or factory lead time

Accurately forecasting and reducing lead time is a vital element of any manufacturing operation. The need for a timely and accurate response to inquiries, on-time order completion, and the ability to respond quickly in an emergency must be at the core of a manufacturer’s ideals. They are keys to maintaining customer satisfaction, a competitive advantage, and a definitive reputation in the marketplace.

Duro-Sense has spent years researching, analyzing and implementing methods and procedures to continually improve our ability to work efficiently in pre-production and production, and to enable us to respond quickly and seamlessly to a customer’s requirements and unexpected emergencies.

Strategies including:

• Supply chain re-evaluation
• Domestic material sourcing
• Warehouse reorganization
• Creative inventory control
• Re-training and cross-training personnel
• Improved information flow and accuracy

This approach, has given us the ability to have more efficient and streamlined production and customer interaction, which leads to faster response time and shorter lead times. Duro-Sense has moved to the forefront of on-time delivery and the ability to seamlessly adapt to any urgent customer need.

Customers don’t like waiting. Production lead time can be the critical component in the success of your business. Like a bad movie, or a dull and tedious speech, shorter is always better. Choosing the right manufacturer is essential when trying to calculate lead time. After over four decades in manufacturing, Duro-Sense has developed valuable strategies regarding the most effective ways to reduce lead times without compromising quality. Let us prove it to you.

Duro-Sense Corporation
310-533-6877
https://duro-sense.com

Higher Quality Products Translates into Long-Term Success

Mistakes, failures, and recalls tend to attract people's attention and make them focus on the negative. They show us what a lapse in quality can mean to a company. The consequences of a lapse in quality tend to be much more prominent today than they have been in the past, due primarily to the complexities of today's economy and supply chain. However, despite the impact these types of failures could have on a company, they are only part of the story. While stopping losses like this from occurring is essential, focusing on them too much can skew a company's understanding of the true meaning of quality. 

Quality is about meeting or exceeding customer expectations. The value is greater customer satisfaction and higher productivity, greater efficiency in operations, even innovation and employee engagement. However, companies face many obstacles. Rising labor costs, material costs, freight costs, and many other costs inflate overhead and limit how much companies can spend on quality practices. Therefore, organizations cannot just be good at quality. They need to be smart about it, too. 

To achieve the proper balance, companies must think about quality systematically. The first step is to listen to the voice of the customer clearly, while at the same time stabilize their operating system. Once these applications take hold, the next step is to strengthen corporate and individual accountability and interdepartmental collaboration for quality, including new quality performance standards. These standards affect product design and supply chain management. The next step in this process is to have quality influence an organization's decision-making to the point that it changes the corporate culture and becomes essential to every aspect of operations. The outcome is quality becomes the basis for the company's reputation. 

At a fundamental level, quality is about meeting or exceeding a customer's expectations. Organizations cannot just be "good at quality." For meaningful success, quality must be the foundation of their reputation. 

Duro-Sense Corporation has spent a great deal of time, energy, and expense to build that reputation for unsurpassed quality. Our company developed a quality management system to satisfy our customers' needs better and improve the company's management and operation. Our quality system, DSQ-2000, follows the international standard ISO 9001. ISO 9001 is a quality standard whose goal is to imbed a quality management system within an organization, increase productivity, reduce unnecessary costs, and ensure the quality of processes and products. In addition to ISO 9001, DSQ-2000 also meets the requirements of AS 9100. AS 9100 is an aerospace specification that fully incorporates ISO 9001 while adding additional requirements relating to quality and safety. After both of these standards, we have also established compliance with the current versions of the following standards relating to different aspects of quality: ANSI/NCSL Z540, BAC 5621, AMS2750, ISO 17025, ISO 10012, ASTM E220, ASTM E230, ASTM E207, ASTM E29. 

Quality is integral to how we operate. Likewise, we flow down these quality requirements to our supply chain. To mitigate the quality risks and costs involved in sourcing, we have implemented an audit process for all existing and potential suppliers. Doing so ensures that our supply chain delivers high-quality products, operates efficiently, and supports continuous improvement. In effect, they become an extension of our company and must strive to meet the exacting standard we hold ourselves and our clients retain us. 

The American Heritage Dictionary defines quality as "inherent or distinguishing characteristics, a degree or grade of excellence." The ISO definition of quality is "The totality of features and characteristics of a product or service that bear on its ability to satisfy stated or implied needs." Duro-Sense defines quality as "a mark of uncompromising standards and high achievement for which we strive every day." 

Duro-Sense Corporation
310-533-6877
https://duro-sense.com

Thermocouple Stability - Understanding Drift

Base-metal thermocouples, ANSI standard Types J, K, T, E, have innate thermoelectric instability related to time or temperature-dependent instabilities in many of their chemical, physical,  and electronic properties. 

When a thermocouple is used to measure the temperature of a particular environment, it can be expected that the measured voltage does not change if the temperature of that environment remains constant.  Actually, the voltage can change over time, even though the temperature of the environment remains constant:  this phenomenon is called DRIFT.  Drift is a source of error in thermocouple measurement. 

Drift occurs because of metallurgical changes in the conductors during the operation of the thermocouple.  Because these changes are time dependent, the voltage change from the expected value, called drift, is also time dependent.  An example of drift is shown below, in Figure 10, for a 1.5mm bare wire Type ‘K’ thermocouple exposed at 500ºC.  The change in voltage is reported as a function of the exposure time. 

Metallurgically, drift can be distinguished in the following:

• Surface modifications, which are related to changes in the conductors because of interactions between the conductors and the environment around the them.
• Bulk modifications, which are related to changes in the volume of the conductors.

Some examples of surface modifications can be identified below: 

• Oxidation (bare wire configurations)
• Depletion of elements from the conductors [bare wire/mineral insulated metal sheathed(MIMS)]
• Contamination from the environment (bare wire/MIMS configuration)
• Interaction with the insulator (MIMS configuration)
• Interaction with the sheath (MIMS configuration)

In relation to bulk modifications, the following phenomena can occur: 

• Phase transformations
• Short/long range ordering transformations
• Grain growth
• Residual strain and dislocations annihilation
• Recrystallization

Duro-Sense Corporation
310-533-6877
https://duro-sense.com

References 

{1} R.E. Bentley, “Long-term drift in mineral-insulated Nicrosil-sheath type K thermocouple”. Sensor and Actuators A, 24(1990) 21-26

Balancing Creativity, Design, Engineering, Cost, and Quality to Meet a Customer’s Unique Specifications Is the Ultimate Challenge

Custom temperature sensor production is the design, engineering, and manufacturing process of goods based on the unique specifications of a customer, including build-to-order parts, one-offs, short production runs, as well as mass customization. If you can't produce it, developing an idea for a product is meaningless. An understanding of design, materials, application and budget is required to manufacture your product correctly. 

There are, however, many unknowns that can drive up expenses and create confusion. Between design and engineering, materials and applications, production and installation, there is often a knowledge gap. At Duro-Sense, we add a knowledge layer that fills these crucial gaps because we bring a unique blend of design, application engineering, product expertise, and teamwork. By making it easier for engineers, designers, manufacturers, and clients to communicate and work together towards project success, we deliver enhanced value to any project.

Duro-Sense Corporation
310-533-6877
https://duro-sense.com

Fast Selection Criteria between Thermocouples and RTDs

Both RTD and thermocouple probes monitor temperature, but which one is right for your application?

What temperature range are you trying to monitor?

Generally, if the temperature is above a hundred and fifty degrees Celsius, a thermocouple would be used. For anything below a hundred and fifty degrees Celsius, choose an RTD.

What is the required sensor accuracy? 

RTDs provide more accurate readings with repeatable results. Choose RTDs when temperature accuracy and repeatability are critical. 

What is the purchase budget?

Thermocouples can be up to three times less expensive than RTD sensors, making thermocouples the right choice when purchasing large quantities or requirements on tight budgets.

Use these three criteria to narrow down your selection process. There are many other differences between thermocouples and RTDs you need to understand before selection and application.

Always consult a temperature sensor application expert before installing or specifying a thermocouple or RTD where failure can cause harm or personal injury.