This standard is issued under the fixed designation C ; the number immediately 1 This specification is under the jurisdiction of ASTM Committee C on. ASTM C Standard Specification for High-Temperature Fiber Blanket Thermal Insulation. ASTM C Standard Specification for High-Temperature Fiber Blanket Thermal Insulation. standard by ASTM International, 05/01/ This document has.
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He has over 35 years of experience working in the thermal insulation industry. He is a registered professional engineer. He can be reached at gordon. Thermal insulation materials aatm commercially available in a variety of forms, shapes, and sizes, including blankets, boards, loose fill, pre-formed pipe, rigid foams, flexible foams, and spray foams. The materials appear to be simple but are highly engineered to optimize different properties, such as thermal performance, high-temperature performance, compressive strength, rigidity or flexibility, water repellence, flame spread prevention, inhibition of metal surface corrosion, and various health and safety considerations.
To meet quality standards, these materials must retain the same properties consistently from production batch to production batch. Additionally, qstm often must be made in a form that is relatively easy to install so as to be economical astmm their final application.
Exploring Insulation Materials – Insulation Outlook
Each different type of material is designed to perform in particular applications over a particular temperature range. Various organizations publish standards for thermal insulation materials and for testing and applying the materials. They sometimes coordinate internationally so each type of generic material meets minimum performance criteria. Standard test procedures are used to measure performance as determined by material properties. If two companies manufacturing the same generic material use different test procedures, it is challenging and perhaps even impossible for users to compare performance of the two materials.
Additionally, government organizations need to be able to specify materials using industry standards and reference standard test procedures. ASTM materials standards can list typical or limiting values as a guide for comparing available products and making informed purchase decisions. Understanding the methods used as the basis for different standards can help users choose their reference points appropriately.
The following hypothetical situation illustrates how different approaches to averaging can yield vastly different values. Jack and his sister Jill both started businesses on January 1, Their business histories over the first 11 years show striking similarities—and differences:.
Jill calculated her average three ways, getting different answers each time:. Jack calculated his average the same three ways, but he got the same result each time: Depending on the application, refractory insulation uses two types of thermal testing standards: These may present a situation similar to the Jack-and-Jill example.
ASTM C – Standard Specification for High-Temperature Fiber Blanket Thermal Insulation
Test asm C measures average thermal c982 taking two temperature points one at a very low temperature and one at a very high temperaturecalculating the average of those two data points, and designating that the average for the entire range.
If the thermal conductivity-mean temperature relationship is linear, or nearly linear, this approach will suffice. However, for a highly non-linear relationship i. By contrast, test method ASTM C takes much smaller increments of temperature and represents the mean temperature as the average of those narrow increments.
C lists thermal conductivity values in two sections, one as determined by C, and the other by C In most cases, the values for a specific grade at a specific mean temperature are significantly different.
Standard Specification for High-Temperature Fiber Blanket Thermal Insulation
Here is an example: As with all insulation materials, its thermal conductivity changes with mean temperature. C lists quite different thermal conductivity values one for each of the two methods for this grade, shown in Table 2. The C values range from 33 percent greater to 1 percent lower, depending on the mean temperature.
Why do the different thermal test procedures offer two different sets of results for the same material, tested at the same mean temperature? The answer appears to have two roots:. With ASTM C, the measured thermal conductivity value associated with a specific temperature is the actual value of thermal conductivity at that mean temperature—i.
Mathematically, it is the thermal conductivity one approaches, in theory, as the dT used in the measurement approaches zero.
The different approaches illustrate that the average thermal conductivity value over a large temperature range, in general, can be significantly different from the thermal conductivity value at the average temperature of that aztm. The C method was originally developed for rigid, higher density refractory materials with thermal conductivity values 3 to 10 times atm than those for typical thermal insulation materials.
Design limitations in the C apparatus limit the ability to make thermal performance determinations over the lower half of the C temperature range. As mean temperature increases, therefore, the correspondingly larger test temperature differences make it more difficult to devise effective thermal guarding techniques, resulting in greater measurement deviations due to increases in extraneous heat loss. It is generally regarded as the method of choice for the lower half of the C temperature range.
The two methods are thus complementary for application over the entire C temperature range. Material and test standards for thermal insulation materials provide valuable support to specifiers, designers, and users working with high-temperature products.
Thermal conductivity data tabulated in ASTM C is based on studies made more qstm 30 years ago; it may be time to reexamine the standard to enhance its usefulness. The guarded hot plate test method could be considered a primary resource for generating new thermal conductivity data, and C tests could be used for the top end of the temperature range.
It would be important to design a coordinated program to harmonize data by the two methods in the overlapping temperature range. Note that there are 11 data points, since each curve has a beginning and ending data point.
Their business histories over the first 11 years sstm striking similarities—and differences: Jill calculated her average three ways, getting different answers each time: She calculated total astk for all years and divided by Figure 1 shows these values graphically so they can be more easily compared.
The Laws of Average and Thermal Performance of Refractory Insulation Materials Depending on the application, refractory insulation uses two types of thermal testing standards: Figure 2 presents the same information graphically.
The answer appears to have two roots: Definition Difference—The thermal conductivity value listed by C is defined atsm than that for C, so one should not expect to find the same values listed. Different Tools Are More Accurate for Different Measurements—Despite the conflicting definitions, the two sets of numbers should be consistent after atsm appropriate mathematical adjustments are made; sstm they are not suggests that different methods are more accurate for different applications.
Definition Difference With ASTM C, the measured thermal conductivity value associated with a specific temperature is the actual value of thermal conductivity at that mean temperature—i. Choosing the Right Method for Given Conditions The C method was originally developed for rigid, higher density refractory materials with thermal conductivity values 3 to 10 times greater than those for typical thermal insulation materials.
Conclusions and Recommendations Material and test standards for thermal insulation materials provide valuable support to specifiers, designers, and users working with high-temperature products.
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