What is Zero Adjustment , Span Adjustment and Linearity Adjustment

Summary

This instructional video delves into fundamental terms in instrumentation and calibration: zero adjustment, span adjustment, and linearity adjustment. It explains 'span' as the difference between upper and lower range values, using examples like a pressure transmitter and a level transmitter to clarify. Span adjustment sets the instrument's upper limit, while zero adjustment, also known as offset, establishes the lower limit. Linearity adjustment ensures equal response across the range, crucial for mechanical instruments. The presenter encourages viewers to ask questions for further clarity and to subscribe for more informative content.

Takeaways

• 🔍 The video discusses common terms in instrumentation and calibration, focusing on zero adjustment, span adjustment, and linearity adjustment.
• 📏 'Span' is defined as the algebraic difference between the upper and lower range values (URV - LRV).
• 📈 An example of span calculation is provided with a pressure transmitter having a calibration range of 0 to 400 kPa, resulting in a span of 400 kPa.
• 🌊 Another example explains span with a level transmitter's calibration range of 20 to 50 inches H2O, yielding a span of 30 inches H2O.
• ⚙️ Span adjustment is used to set the upper limit point or 100% mark of the instrument range by giving a 100% input signal and adjusting the output to 100%.
• 🔄 Zero adjustment, also known as offset adjustment, is used to set the lower limit point or reference point of the instrument with a 0% input signal, adjusting the output to 0%.
• 🔧 An instrument requiring zero adjustment is identified when the output is 2% for a 0% input signal.
• 🔗 Linearity adjustment ensures equal travel above and below the 50% mark on the instrument range, typically applied to mechanical instruments with gearing or lever mechanisms.
• 🤔 The video encourages viewers to ask questions in the comment box if they have doubts about the discussed concepts.
• 📢 The host invites viewers to share and subscribe to the channel for more informative videos on instrumentation and calibration.

Q & A

What is the definition of 'span' in the context of instrumentation and calibration?

In the technical world, span refers to the algebraic difference between the upper and lower range values, which is calculated as URV (Upper Range Value) minus LRV (Lower Range Value).

How is the span value of a pressure transmitter with a calibration range of 0 to 400 kPa determined?

The span value of this pressure transmitter is determined by subtracting the lower range value (0 kPa) from the upper range value (400 kPa), resulting in a span value of 400 kPa.

What is the span value for a level transmitter with a calibration range of 20 to 50 inches of H2O?

The span value for this level transmitter is calculated by subtracting the lower range value (20 inches) from the upper range value (50 inches), resulting in a span value of 30 inches of H2O.

What is span adjustment and how is it used?

Span adjustment is used to set the upper limit point or 100% mark of the instrument range. It involves providing a 100% input signal to the instrument and adjusting its output to 100%.

What is zero adjustment in the context of instrument calibration?

Zero adjustment, also known as offset adjustment, is used to set the lower limit point or reference point of the instrument. It is done by giving a zero percent input signal to the instrument and adjusting its output to zero percent.

Can you provide an example where an instrument would require zero adjustment?

An instrument would require zero adjustment if its output is not at zero percent for a zero percent input signal, such as when the output is two percent for zero percent input signal.

What is linearity adjustment and in which types of instruments is it commonly applied?

Linearity adjustment is used to ensure equal travel above and below the 50% mark on the instrument range. It generally applies to mechanical instruments with gearing or link and lever mechanisms, or those with Bourdon tubes, diaphragms, or bellows.

Why is it important to understand the concepts of span, zero, and linearity adjustments in instrumentation?

Understanding these concepts is crucial for accurate calibration and performance of instruments, ensuring they provide reliable and consistent measurements within their operational range.

How can viewers get more information or ask questions about the topics covered in the video?

Viewers can ask questions or seek further clarification by leaving a comment in the comment box below the video.

What is the call to action for viewers who found the video informative?

Viewers who found the video informative are encouraged to share it with friends, subscribe to the channel, and not miss out on future informative videos.