Proper Thermowell DesignIt is critical to the safety of the process plant that thermowell vibration calculations (also known as: Wake Frequency Calculations/Analysis, or von Karman Calculations/Analysis) be performed for every thermowell, especially for new applications and for applications in which any of the characteristics of the process flow have changed.At your request, Daily Thermetrics will perform thermowell vibration calculations to ensure proper thermowell design. Furthermore, we can recommend the proper design solution to overcome a high velocity issue.Proper thermowell design is a very important topic, especially to those who have experienced thermowell failure out in the field due to stress and vibrations resulting from improper thermowell design. Thermowell failure can cost the end user hundreds of thousands of dollars in lost production time. Moreover, the legal implications involved in such an event are both time consuming and costly. It is much less costly to properly design a thermowell up-front using the proper tools (thermowell vibration calculations).Daily Thermetrics has been designing and manufacturing thermowells since 1973, and we currently employ the latest thermowell vibration calculation method, ASME PTC 19.3 TW-2016 to verify the thermowell design for each specific application. Unlike the older, outdated ASME PTC 19.3 version, the ASME PTC 19.3 TW-2016 takes into account the characteristics of the actual process with which the thermowell will come into contact. The process density, viscosity, and even the nozzle project length are now key inputs in this calculation method (ASME PTC 19.3 TW-2016).Calculation methods such as those developed by J.W. Murdock or even J.E. Brock can be performed by Daily Thermetrics upon special request, but it is important to note that these older methods fail to consider all of the criteria incorporated by ASME PTC 19.3 TW-2016.Thermowell TraceabilityA very important feature we offer (free of charge with every order) is 100% full traceability for every thermowell manufactured by Daily Thermetrics. We do this using a unique serial number etched onto each thermowell. Also etched onto each thermowell we manufacture is our company name and telephone number. This allows the end user to know who manufactured it, and using the serial number, we can tell you when you ordered it, what the part number is, who welded it, who inspected it, and, more importantly, we can provide material certifications for the thermowell (and flange) by using the serial number. The thermowells we manufacture are therefore fully traced, both in the labor aspect, as well as the material aspect of each.Remember: Currently, the industry uses only tag numbers to identify a thermowell. However, the tag number never changes, no matter how frequently the thermowell is replaced with a new one. Having a unique serial number for each thermowell ensures vendor accountability for each and every thermowell.
Achieving that goal begins with a sample probe wake frequency calculation based on static and dynamic stresses relative to process temperature and pressure. Flow-induced vibration, for instance, can lead to fatigue failures. And erosion from particulates weakens probe integrity. You want to avoid both with the correct calculations.
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Well, using a thermowell as an example, factors such as wall thickness, unsupported length, root and tip diameter, process fluid velocity, and thermowell natural frequency, as well as criteria such as Strouhal Frequency and Reynolds Number may all be part of the calculation. From a practical standpoint, calculating sample probe wake frequency under a range of process conditions is the shared domain of instrument engineers and process engineers.
Swagelok is your expert source for helping refineries in Northern California design, install, and maintain fluid systems critical to their operations. Our Field Engineers and certified technicians apply decades of experience in solving unique fluid processing challenges. A consultation relieves you of the complexities of sample probe wake frequency calculations and ensures your sample probe designs support safe, cost-effective operations.
This family of Spike2 v7 scripts and sampling configurations allows you to perform long-term recordings of blood pressure, heart rate and sympathetic activity and to analyse baroreceptor reflexes and heart rate variability. The scripts are suitable for use with a range of laboratory animals and can record data from up to 8 animals simultaneously when used together with telemetry systems.HRBP8b.s2s derives systolic, diastolic and mean blood pressure, heart rate and respiratory rate from each blood pressure trace. Data from up to 8 animals can be analysed on- or off-line. Results are recorded continuously or according to a user-defined schedule, e.g. 10 minutes per hour. Data can be auto-saved to a new file at regular intervals (e.g. every 24 hr.) in order to achieve virtually continuous recording over days or weeks.MergeFiles.s2s /SplitFiles.s2s These utility scripts allow you to splice auto-saved data files end to end before further analysis and to split data related to different animals into separate data files.sBRG.s2s This offline script calculates baroreceptor reflex sensitivity based on spontaneous fluctuations in blood pressure.SigFit.s2s Fits sigmoid curves (4 and 5 parameters) to heart rate and blood pressure data derived from steady-state experiments.HRV1.s2s Performs frequency domain analysis of heart rate variability.Poincaré s2s Performs non-linear analysis of heart rate variability.HRBPtable.s2s Generates tables of results suitable for further analysis with spreadsheet software.Baro5.s2s This is a library of script functions required by the SigFit script.This family of Spike 2 scripts require v7.12 or higher.
The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Is a cross-platform software package for econometric analysis, written in the C programming language. It is free, open-source software.You may redistribute it and/or modify it under the terms of the GNUGeneral Public License (GPL) as published bythe Free Software Foundation.
Thanks to the good people on the comp.lang.c of old andgtk-app-devel-list@gnome.org for expert advice on manyissues. Thanks to Richard Stallman of the Free Software Foundationfor all his work in developing and promoting free software, and morespecifically for agreeing to "adopt" gretl as a GNU program.
Finally, although we have designed the free website above to be enough for basic needs, we also aim to cater for the more sophisticated needs of many of the energy professionals, multi-site organizations, academic/government researchers, and energy-software developers who use our system. If you could benefit from additional data, data for lots of locations, or automated access to data (in large or small quantities), please take a look at our overview of Degree Days.net products to see how they can help.
When fluid flows past a thermowell, the change in fluid momentum creates a turbulent wake behind the well. Vortices form in this wake, and shed from alternate sides of the well. The vortex shedding frequency (or Wake frequency) is linear with flow velocity and inversely proportional to thermowell tip diameter.
These vortex-induced forces, which cause thermowell vibration, are normally small with the magnitude of the vibrations generally negligible. However, as the wake frequency (fw) approaches the natural frequency (fn) of the thermowell (within 20%), it can shift and lock-in to the natural frequency. When fw = fn, the thermowell goes into resonance, and vibrating forces increase rapidly. The resultant vibrations can cause mechanical failure of the well.
The Murdock calculations (and companion ASME PTC 19.3) consider only the oscillating lift force as the cause of thermowell vibration. The ratio of wake to natural frequency is restricted to a maximum of 0.8 to eliminate the possibility of resonance.
Although the oscillating drag force is small, it can force the thermowell into resonance at lower velocities because it occurs at twice the wake frequency. For high-density fluids (liquids and high pressure steam), the Murdock analysis is not adequate. When the oscillating drag component is included, the velocity rating can be reduced by up to 50%.
The calculations included herein are modified to include in-line resonance due to the oscillating drag force, correction for the magnification ratio and use of the actual natural frequency of the well rather than the estimated value.
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