ASME PTC 19.3 Wake Frequency Calculator
| Aspect | Information |
|---|---|
| Standard Title | ASME PTC 19.3-1974 (R2016) – Performance Test Code on Thermowells |
| Purpose | To provide guidelines for assessing the wake frequency of thermowells in fluid flow applications. |
| Scope | Covers the determination of wake frequencies, calculation methods, and assessment of thermowell vibrations. |
| Wake Frequency (St) | Wake frequency is a dimensionless parameter represented as St. It is a measure of the potential for thermowell vibration due to fluid flow. |
| Calculation Method | The standard outlines procedures for calculating the wake frequency (St) using fluid properties, thermowell geometry, and flow conditions. |
| Wake Frequency Limit (St Limit) | ASME PTC 19.3 provides guidance on acceptable wake frequency limits. The specific limit may vary depending on the application and industry standards. |
| Factors Affecting Wake Frequency | Factors influencing wake frequency include fluid velocity, thermowell diameter (D), thermowell geometry, fluid properties, and flow conditions. |
| Assessment of Thermowell Vibrations | The standard provides methods for assessing the severity of thermowell vibrations, including evaluation criteria and guidelines for mitigating vibration-related issues. |
| Recommendations for Design and Installation | ASME PTC 19.3 offers recommendations for the design and installation of thermowells to minimize the risk of flow-induced vibration. |
| Revision Status | ASME PTC 19.3-1974 (R2016) is a revised version of the standard, indicating updates and improvements. Ensure you refer to the most recent version for current guidelines. |
| Compliance and Use | Engineers, designers, and professionals involved in the design, installation, and assessment of thermowells in fluid flow systems should refer to ASME PTC 19.3 for compliance and best practices. |
FAQs
How do you calculate wake frequency? Wake frequency is not a standard term in engineering or physics, so I cannot provide a calculation for it without more context.
What is the wake frequency ratio of a thermowell? The wake frequency ratio (also known as Strouhal number) for a thermowell depends on its design and the flow conditions in which it is placed. Typically, it is calculated as follows:
Wake Frequency Ratio (St) = f * D / V
Where:
- St is the wake frequency ratio (dimensionless).
- f is the shedding frequency of vortices behind the thermowell.
- D is the diameter of the thermowell.
- V is the fluid velocity.
What is the ratio limit for wake frequency? The acceptable limit for the wake frequency ratio (St) depends on the specific application and industry standards. In general, a higher St value indicates a greater potential for vibration and stress on the thermowell. A commonly used limit is St < 0.2 for most applications, but this can vary.
How to calculate thermowell? Calculating the design parameters of a thermowell involves considerations like fluid properties, temperature, pressure, and flow conditions. It typically requires computational fluid dynamics (CFD) simulations or consulting industry standards and guidelines. There is no single formula for calculating a thermowell.
How do you calculate time in frequency? Time and frequency are inversely related. The formula to calculate frequency (f) from time (T) is:
f = 1 / T
Where:
- f is the frequency in Hertz (Hz).
- T is the time in seconds (s).
How do you convert clock period to frequency? To convert clock period (P) to frequency (f), use the formula:
f = 1 / P
Where:
- f is the frequency in Hertz (Hz).
- P is the clock period in seconds (s).
How to calculate frequency ratio? Frequency ratio typically refers to the ratio of two frequencies. It can be calculated as:
Frequency Ratio = Frequency 1 / Frequency 2
What is the frequency ratio? The frequency ratio is a dimensionless quantity that represents the ratio between two frequencies. It is often used in various fields, including physics, engineering, and music, to describe relationships between oscillatory phenomena.
How do frequency ratios work? Frequency ratios describe the relationship between two frequencies. For example, in music, specific frequency ratios between notes create harmonious sounds. In engineering, understanding frequency ratios can help design systems to avoid resonance and unwanted vibrations.
What is frequency ratio in vibration? In vibration analysis, frequency ratio refers to the ratio of the excitation frequency (e.g., the frequency of a machine’s operation) to the natural frequency of a vibrating system. It helps engineers assess the likelihood of resonance and structural vibrations.
What does a thermowell do? A thermowell is a protective tube or enclosure installed in industrial processes to protect temperature sensors (such as thermocouples or RTDs) from harsh conditions (high pressure, corrosive fluids, etc.) while allowing them to accurately measure temperature.
What are the guidelines for thermowell installation? Thermowell installation guidelines include considerations for proper immersion depth, orientation, material compatibility, and ensuring that it doesn’t obstruct fluid flow. Guidelines may vary by industry and application.
What is the rule of thumb for thermowell immersion length? A common rule of thumb for thermowell immersion length is that the thermowell should be immersed at least 3 to 5 times its diameter into the process fluid to ensure accurate temperature measurement.
What is the maximum temperature for thermowell? The maximum temperature for a thermowell depends on its material of construction. Common materials like stainless steel can handle temperatures up to 1000°C (1832°F) or more in some cases.
How to calculate frequency distribution? Frequency distribution is a statistical concept used to organize and analyze data. To calculate it, you need to count the number of occurrences (frequency) of each value or range of values in a dataset and present the results in a tabular or graphical form.
How to calculate frequency in Excel? In Excel, you can calculate frequency using the FREQUENCY function or by creating a frequency distribution table manually. The FREQUENCY function takes a data range and a bin range as inputs and returns an array of values representing the frequency distribution.
What is the standard of time frequency? The standard unit of time frequency is the Hertz (Hz), which represents one cycle (or oscillation) per second.
What is the difference between clock frequency and period? Clock frequency (in Hertz, Hz) represents the number of clock cycles in a second, while period (in seconds, s) represents the duration of one clock cycle. They are inversely related: Frequency = 1 / Period.
What is the formula for frequency and amplitude? The formula for frequency (f) and amplitude (A) in the context of simple harmonic motion is:
y(t) = A * sin(2πft)
Where:
- y(t) is the position of the oscillating object at time t.
- A is the amplitude (maximum displacement from equilibrium).
- f is the frequency in Hertz (Hz).
Is frequency and time period same? No, frequency and time period are not the same. Frequency is the number of cycles or oscillations that occur in one second, measured in Hertz (Hz). Time period, on the other hand, is the time it takes for one complete cycle to occur, measured in seconds (s). They are inversely related: Period = 1 / Frequency.
What are the 3 types of measures of frequency analysis? The three common measures of frequency analysis are:
- Absolute Frequency: The number of times a specific value occurs in a dataset.
- Relative Frequency: The proportion or percentage of times a specific value occurs relative to the total number of data points.
- Cumulative Frequency: The running total of frequencies as you move through a dataset.
What is the ratio of frequency and time period? The ratio of frequency (f) and time period (T) is:
f = 1 / T
What is the ratio between periodic time and frequency? The ratio between periodic time (T) and frequency (f) is the reciprocal of the frequency:
T = 1 / f
Why is frequency 50 or 60 Hz? The choice of 50 Hz or 60 Hz as the standard frequency for electrical power systems is historically based on engineering and practical considerations. Different regions of the world adopted these frequencies for historical reasons, and they have become the standard. 50 Hz is common in Europe and many other parts of the world, while 60 Hz is prevalent in North America.
What is the formula for the natural frequency? The formula for the natural frequency (ωn) of a vibrating system, such as a mechanical or electrical oscillator, is given by:
ωn = √(k / m)
Where:
- ωn is the natural frequency in radians per second (rad/s).
- k is the stiffness of the system.
- m is the mass of the system.
What is the frequency ratio in engineering? In engineering, the frequency ratio often refers to the ratio of two frequencies, typically in the context of resonance analysis or the relationship between excitation frequency and the natural frequency of a system.
What is the difference between pitch and frequency? Pitch and frequency are related but not the same. Pitch is a perceptual quality of sound associated with its perceived frequency. Frequency is the physical measurement of the number of oscillations or cycles per unit of time. Higher frequencies are typically associated with higher pitches.
What is the relationship between pitch and frequency? Pitch and frequency have a linear relationship. Higher frequency sounds are perceived as higher pitch, while lower frequency sounds are perceived as lower pitch.
What frequency ratio gives an interval of a perfect fourth? In Western music theory, a perfect fourth corresponds to a frequency ratio of 4:3. This means that the higher note has a frequency 4/3 times that of the lower note.
What is the formula for the frequency of a vibrating wire? The frequency (f) of a vibrating wire or string can be calculated using the formula:
f = (1 / (2L)) * √(T/μ)
Where:
- f is the frequency in Hertz (Hz).
- L is the length of the wire or string.
- T is the tension in the wire or string.
- μ is the linear mass density of the wire or string.
What is the formula for vibration? The formula for vibration depends on the specific context and system being analyzed. In general, vibrations are described using equations of motion and can involve parameters like mass, stiffness, damping, and external forces.
How many vibrations per second is Hz? One Hertz (Hz) is equal to one vibration or cycle per second.
When not to use thermowell? Thermowells should not be used when accurate temperature measurements are not required, or when the process conditions are not harsh enough to warrant their use. They add cost and complexity to temperature measurement systems, so their use should be justified by the application.
What are the disadvantages of thermowell? Some disadvantages of thermowells include increased response time for temperature measurement, potential for measurement errors due to heat conduction through the thermowell, and the possibility of thermowell corrosion or damage in harsh environments.
What is Pt100 in thermowell? Pt100 is a type of resistance temperature detector (RTD) commonly used in thermowells. It is made of platinum and has a resistance of 100 ohms at 0°C. Pt100 RTDs are known for their high accuracy and stability.
What is the IEC standard for thermowell? The IEC standard for thermowells is IEC 60584-2, which provides guidelines for the selection and use of temperature sensors, including those used with thermowells.
What is RTD in thermowell? RTD stands for Resistance Temperature Detector. It is a type of temperature sensor often used in thermowells. RTDs measure temperature by correlating the resistance of a platinum wire with temperature changes. They are known for their high accuracy and stability.
What do you fill thermowell with? Thermowells are typically empty or filled with an inert gas to prevent moisture or corrosive gases from entering. Some applications may require special fill materials for specific purposes, such as thermal conduction or insulation.
What is the neck length of the thermowell? The neck length of a thermowell is the portion of the thermowell that extends beyond the process connection and into the fluid. Its length can vary depending on the specific thermowell design and application requirements.
What is the lowest acceptable hot holding temperature? The lowest acceptable hot holding temperature for food safety typically varies by jurisdiction and type of food. In many cases, the temperature should be maintained at or above 135°F (57°C) to prevent bacterial growth.
What is the maximum allowable temperature? The maximum allowable temperature depends on the specific material and application. In general, common materials like stainless steel can withstand temperatures up to 1000°C (1832°F) or more in certain conditions.
What is the difference between immersion and insertion? In the context of thermowells, “immersion” refers to how deeply the thermowell is immersed into the process fluid. “Insertion” is a more general term that can refer to placing a temperature sensor or probe into a thermowell or directly into a process without a thermowell. Immersion typically provides better protection for the sensor.
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