Final Report - Summary of Thermal Testing of the Furnace Characterization Unit (FCU) for the Coast Guard

Nakos, James T.; Pantuso, J.; Bentz, J.H.

doi:10.2172/759456

Cited by 4 publications

(4 citation statements)

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“…Examples of systematic errors due to differing TC junction types are provided in reference [10]. Later sections and Appendix B provide more quantitative estimates of systematic errors in application typical of those in the RHF and LCBS.…”

Section: Systematic Errors Resulting From Installation Methods or Tc Typementioning

confidence: 99%

“…Results from reference [10] indicate noise was negligible. Additional experiments were recently performed (April 2003) during a set of foam characterization experiments.…”

Section: Electrical Noise From Rhf Power Systemmentioning

confidence: 98%

“…Additional data are available from reference [10] where extensive data were taken from a flat shroud. Twenty (20) TC pairs were mounted side-by-side where one was an intrinsic design and the other a mineral-insulated, metal-sheathed (MIMS) ungrounded junction design.…”

Section: Thermocouple Extension Wirementioning

confidence: 99%

“…The smaller errors were due to improved mounting techniques. Figures B-5 and B-6 show some of the data from reference [10], and The above examples are for TCs mounted on a flat stainless steel plate or "shroud" at RHF in abnormal thermal environments, and for fiberglass sheathed TCs attached to a thin metal case and to foam in normal environments. There are other configurations (e.g., "flame" temperatures at the Burn Site) where the systematic error caused by the TC type or installation method has not yet been properly quantified.…”

Section: Thermocouple Extension Wirementioning

confidence: 99%

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Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

Nakos¹

2004

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It would not be possible to confidently qualify weapon systems performance or validate computer codes without knowing the uncertainty of the experimental data used. This report provides uncertainty estimates associated with thermocouple data for temperature measurements from two of Sandia's large-scale thermal facilities. These two facilities (the Radiant Heat Facility (RHF) and the Lurance Canyon Burn Site (LCBS)) routinely gather data from normal and abnormal thermal environment experiments. They are managed by Fire Science & Technology Department 09132.Uncertainty analyses were performed for several thermocouple (TC) data acquisition systems (DASs) used at the RHF and LCBS. These analyses apply to Type K, chromel-alumel thermocouples of various types: fiberglass sheathed TC wire, mineral-insulated, metal-sheathed (MIMS) TC assemblies, and are easily extended to other TC materials (e.g., copper-constantan). Several DASs were analyzed: 1) A HewlettPackard (HP) 3852A system, and 2) several National Instrument (NI) systems. The uncertainty analyses were performed on the entire system from the TC to the DAS output file. Uncertainty sources include TC mounting errors, ANSI standard calibration uncertainty for Type K TC wire, potential errors due to temperature gradients inside connectors, extension wire uncertainty, DAS hardware uncertainties including noise, common mode rejection ratio, digital voltmeter accuracy, mV to temperature conversion, analog to digital conversion, and other possible sources. Typical results for "normal" environments (e.g., maximum of 300-400 K) showed the total uncertainty to be about ±1% of the reading in absolute temperature. In high temperature or high heat flux ("abnormal") thermal environments, total uncertainties range up to ±2-3% of the reading (maximum of 1300 K). The higher uncertainties in abnormal thermal environments are caused by increased errors due to the effects of imperfect TC attachment to the test item. "Best practices" are provided in Section 9 to help the user to obtain the best measurements possible.

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Section: Systematic Errors Resulting From Installation Methods or Tc Typementioning

confidence: 99%

“…Results from reference [10] indicate noise was negligible. Additional experiments were recently performed (April 2003) during a set of foam characterization experiments.…”

Section: Electrical Noise From Rhf Power Systemmentioning

confidence: 98%

Section: Thermocouple Extension Wirementioning

confidence: 99%

Section: Thermocouple Extension Wirementioning

confidence: 99%

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Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

Nakos¹

2004

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Understanding The Systematic Error of a Mineral-Insulated, Metal Sheathed (MIMS) Thermocouple Attached to a Heated Flat Surface

Nakos

2003

Thermal Measurements: The Foundation of Fire Standards

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Uncertainty assessments of temperature measurements performed at Sandia National Laboratories fire test facilities typically focus on measurements using mineral-insulated, metal sheathed (MIMS), ungrounded junction, chromel-alumel (Type K) thermocouples (TCs). These TCs are used to observe the temperatures of both heat sources and test objects in hydrocarbon fuel fires and simulated fires (typically up to 1200°C). Among the sources of uncertainty, errors associated with TC installation often prove to be dominant. For example, ungrounded junction, MIMS TCs have a systematic error when mounted on a flat steel plate (a commonly used configuration) when attempting to measure the plate temperature. A (relatively simple) model of an ungrounded junction MIMS TC mounted on a flat steel plate was developed. The purpose of this model is not to correct TC readings. Rather, it is to qualitatively understand the systematic error associated with the measurement and find ways to reduce the error through more effective mounting procedures or use of different junction types (e.g., grounded junction). Experimental data showing the errors are presented, as are details of the model and model versus experimental data comparisons.

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Fire Safety Test Furnace Characterization Unit

Keltner

Nash

Beitel

et al. 2003

Thermal Measurements: The Foundation of Fire Standards

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In standardized fire safety tests such as IMO Res. A 754 (18), ASTM E119, or ISO 834, the furnace temperature is controlled to a standard time-temperature curve [1,2]. The assumption is made that thermal exposure in these tests will be repeatable and can be described by the measured furnace temperature. The significant variations that occur in test results indicate this assumption is not well founded. Fire safety test results are influenced by both the temperature of the furnace and by heat transfer in the furnace. The heat transfer depends not only on the furnace temperature and how it is measured but also on the design of the furnace and the test unit. In developing engineering models of fire performance and performance-based codes, there is a need to understand both aspects of thermal exposure — temperature and heat transfer. To begin to address these problems, the U. S. Coast Guard's Research and Development Center authorized a study of furnace tests. The study documented important factors in current test methods that lead to large uncertainties in the fire safety test results. To attempt to understand and reduce these large uncertainties, the Coast Guard authorized the development of a Furnace Characterization Unit (FCU). The FCU was built, calibrated using a special electric heater at Sandia National Laboratories, and then used to characterize temperature and heat transfer in a large, gas-fired test furnace at Underwriters Laboratories. This paper reports the results of this multi-year effort.

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Final Report - Summary of Thermal Testing of the Furnace Characterization Unit (FCU) for the Coast Guard

Cited by 4 publications

References 1 publication

Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

Uncertainty analysis of thermocouple measurements used in normal and abnormal thermal environment experiments at Sandia's Radiant Heat Facility and Lurance Canyon Burn Site.

Understanding The Systematic Error of a Mineral-Insulated, Metal Sheathed (MIMS) Thermocouple Attached to a Heated Flat Surface

Fire Safety Test Furnace Characterization Unit

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