Testing by the guarded hot plate method fraunhofer. Figure 1 illustrates the layout of a typical guarded hot plate. Please contact us for more information about sweating guarded hot plate test method. Accuracy of a guarded hot plate ghp 83 metering area, the temperature gradient and the thickness of the specimen applying the steadystate heat transfer equation see next section. This method consists of placing textile fabrics and multilayer assemblies on a sweating hot plate for testing. The ghp principle is based on an absolute measurement method and therefore requires no calibration standards. The article begins with a general discussion of some of the characteristics of the conventional unit, noting especially the long time required to reach steady state conditions and the accuracy given in roundrobintests. With the guarded hot plate method, a material sample is heated from one side by an electrically heated plate. Pdf this work presents the development of an experimental setup for measurements on of thermal conductivity of solid materials, such as. Based on the wellknown, standardized guarded hot plate technique e.
There are four main types of instruments available to measure thermal conductivity. This work presents the development of an experimental setup for measurements on of thermal conductivity of solid materials, such as ceramics, polymers. Report on the cct supplementary comparison s2 on thermal. Samples of naval brass, stainless steel, aluminum alloy, leather, soft rubber, corkboard, and. Astm c177 19 standard test method for steadystate heat. Study calibrates guarded hot plate method of measuring. Thermal conductivity of insulations using guarded hot plates. A solid sample of material is placed between two plates. Pdf a theory for the square guarded hot platea solution of. Other test conditions such as air temperature and relative humidity may vary depending on the procedure utilized. Pdf development of a singlesided guarded hot plate apparatus. Accuracy of a guarded hot plate ghp in the temperature. Transient thermal response of a guardedhotplate apparatus. Guarded hot plate instruments consist of one or two cold plates, a hot plate and a system of guard heaters andthermalinsulation.
During operation the cold plates are maintained at some fixed temperature and the heat generated electrically in the hot plate and guard plate is adjusted so that the temperature difference between the. To find the thermal conductivity of a material by the two slabs guarded hot plate method. Pdf a theory for the square guarded hot platea solution. Skin model for textile testing october 2010 contact susie jahren tel. Ideally, the guarded hot plate and cold plates provide. This action was part of a series of supplementary interlaboratory comparisons including infrared spectral emittance and thermal diffusivity sponsored by the consultative committee on thermometry cct task group on thermophysical quantities tgthq. Another apparatus with a measuring surface of 120 mm x 120 mm is also available. The sweating hot plate instrumentation gives an assessment of heat and moisture vapor transport through the material into a controlled environment. Designed to measure both rct thermal and ret vapor characteristics in accordance with iso 11092 and astm. This work considers the influence of finite thermal contact resistances which exist in thermal conductivity measurements of homogeneous and poor thermal conductive materials using the guarded hot plate method.
Pdf development of a singlesided guarded hot plate. Pdf precision and accuracy of guarded hot plate method m. Standard practice for guardedhotplate design using. The lateral heat flow across the air gap was actively compensated for. Standard practice for guardedhotplate design using circular lineheat sources1 this standard is issued under the. Hot plate meter plate heating of both the metering plate and the guard ring of the guarded hot plate occurs through the use of multiple line source heaters. Type 5 guarded hot plate ghp apparatus in opened state for two specimen not displayed sandwiched between hot plate 1 and guard ring 2 in the center and the lower 3 and upper cold plate 4 from below and above.
Sweating guarded hotplate sweating guarded hot plate. Fox 600 ghp is especially wellsuited for thermal conductivity measurements at high temperatures, exhibiting unrivaled temperature and dimensional stability. The sweating guarded hot plate instrument, simulating the heat and moisture transfer from the body surface through clothing material to the environment, was designed for the measurement of thermal resistance and water vapor permeability of fabrics, relating to comfort characteristics of the garment. Properties by means of the guarded hot plate, american. Rather than using laminated metalsurface constructions, some hightemperature guarded hot plate designs have used ceramic plates with electrical heaters. Both hot plate and tailflick methods are used generally for centrally acting analgesic, while peripherally acting drugs are ineffective in these tests but sensitive to acetic acidinduced writhing test. Guarded hot plate series ghp 500, ghp 600, ghp 900 and ghp 900 s. It is a vacuum tight guarded hot plate system with a new design integrating state oftheart design, electronics and software. Schematic diagram of the guarded hot plate apparatus based on the design of the apparatus at dominion physical laboratory. The standard that applies to a ghp apparatus will depend on the specific setup of that apparatus. The sweating guarded hot plate instrument, simulating the heat and moisture transfer from the body surface through clothing material to the environment, was designed for the measurement of thermal. The hot plate test is a test of the pain response in animals, similar to the tail flick test. A guarded hot plate apparatus that can be operated up to c was constructed.
Astm c1043 06 standard practice for guardedhotplate. Jul 26, 2011 in 1912, dickinson conceived and built the first guarded hot plate apparatus at nist for this purpose. The general arrangement of a guarded hot plate apparatus has already been described in fig. The flow of heat through the metal hot plate itself, and the effects of temperature unbalance between hot plate and guard plate are both taken into account. Meter ep500e guarded hot plate apparatus is a test tool based on an embeddedpc for absolute value measurements on guarded hot plate method according to iso 8302, din en 19462, din en 12667 and astm c177 din 52612. These methods consisted of the astm guarded hot plate, the thermal comparator, and. Jun 23, 2015 there are currently three standards in place by astm which apply to the guarded hot plate method. Please contact us for more information about sweating guarded hot plate. Meter ep500e guarded hot plate apparatus measures the sample thickness d of the inserted sample.
Procedures for computing the preferred locations for circular heaters have previously been published in c 1043. Standard practice for using a guardedhotplate apparatus. Guarded hot plate apparatus is a measuring instrument for determination of steadystate heat transfer properties, thermal conductivity and thermal resistance, of flat slab specimens in accordance with international standards iso 8302, astm c177. This paper presents design, development, and testing of a custommade calibration environment for the calibration of temperature sensors applied in a guarded hot plate apparatus for thermal. Additional thermal conductivity values of foods measured by a guarded hot plate. C1043 06 standard practice for guardedhot plate design using circular lineheat sources, guarded hot plate apparatus, heat flow, line source heater, steady state, thermal conductivity, thermal insulation, thermal resistance.
Departmentofcommerce boulder,colorado803033328 may1988. Guarded hot plate apparatus for the investigation of thermal. Design concepts for a new guarded hot plate apparatus for use. The guarded hot plate ghp apparatus is traditionally recognized as the only absolute method for thermal conductivity measurement in steadystate of. Each of its components include stateofart technology representing the best available today in advanced materials and electronics. In civil engineering, the thermal conductivity is the most important quantity for thermal insulations and, as such, is in most cases determined with the guarded hot plate instrument in accordance with the applicable standards. There are 306 suppliers who sells guarded hot plate on, mainly located in asia. The objective of this thesis was the design, assembly, and test of a guarded hot plate apparatus for the measurement of the thermal conductivity of metals and nonmetals. Power for the guard ring is drawn fron the same dc unit that supplies the hot plate. The guarded hot plate ghp method is widely considered as the most reliable method to measure the thermal conductivity of insulating material due to its low uncertainty. Astm c177 is the standard test for measuring the thermal conductivity of a material by means of a guardedhotplate apparatus. To avoid edge losses, the apparatus is immersed in a liquid whose temperature is a few degrees lower than the mean temperature of the samples. Thermal modeling of multiplelineheatsource guarded hot.
The heat dissipated by the joule effect in the hot plate would travel to the cold plate through the sample, but also backwards and laterally on the edges of the hot plate. Finally, there is a section on certified reference materials. Rennex the use of thicker thermal insulation material with greater thermal resistance resulted in a. Construction and preliminary testing of a guarded hot plate. A number in parentheses indicates the year of last. Fully insulated guarded test chamber, designed for specimens with a thickness up to 200 mm available as 1 or 2plate measuring system according to iso 8302 chapter 1. Testing by the guarded hot plate mehtod test facility the standard guarded hot plate apparatus according to the single and double hot plate method have a measuring surface of 500 mm x 500 mm. A guarded hot plate apparatus for small circular samples has been developed for the temperature range from. Thermal conductivity by guarded hot plate apparauts s. Guarded hot plate apparatus for measuring thermal conductivity of liquids. In a guarded hot plate system a temperature difference. Pdf design and construction of a guarded hot plate.
Design and construction of a guarded hot plate apparatus operating down to liquid nitrogen temperature. This article describes the construction and properties of a new type of guarded hot plate apparatus for the investigation of thermal insulations. In operation, the heat from each lineheat source flows radially into the plate and is transmitted axially through the. Pdf an in situ temperature calibration of a guarded hot.
Ghp, configured for horizontal heat flow, is shown in fig. C1043 06 standard practice for guarded hot plate design using circular lineheat sources, guarded hot plate apparatus, heat flow, line source heater, steady state, thermal conductivity, thermal insulation, thermal resistance. Circular and square edge effect study for guardedhotplate. Testing thermal properties of textiles sciencedirect. However, the measurement uncertainty increases as testing temperature rise, making the influence of hightemperature conditions on the measurement results not quite clear. Sweating guarded hotplate is the most professional, stable and advanced thermal and evaporative resistance test instrument in the world. Shown below are two figures which illustrate the experimental setup for an early guarded hot plate apparatus. The ghp 456 titan is the ideal tool for researchers and scientists in the field of insulation testing. A circular main heater plate mh is surrounded by an annular guard heater plate gh with a narrow air gap in between. The guarded hot plate instrument measures the thermal conductivity of insulation products. Figure 2 shows the essential features of a guarded hot plate apparatus designed for operation near ambient temperature conditions in the singlesided mode of operation. The titan instrument guarded hot plate ghp 456 from netzschgeratebau gmbh is the only unit worldwide completely fulfilling the latest standards iso 8302, astm c 177, dinen12667.
Pdf precision and accuracy of guarded hot plate method. Standard practice for guardedhotplate design using circular. Sweating guarded hotplate complies with iso 11092, astm f1868, astm d1518, etc. Sweating guarded hot plate test method sciencedirect. Exact measurements of this material property are essential for understanding. The guarded hot plate ghp method is the standard technique for measuring thermal conductivity of solid materials in the range from about 0. The guarded hot plate method has been standardized by both the international organization for standardization 1 and astm international 2. Schematic diagram of the guarded hot plate apparatus based on the design of the apparatus at. Details of two guarded hot plate apparatuses designed and constructed at npl over the last decade or so, one to measure insulations up to 250 mm thick at or around room temperature and the other to measure insulations and refractories at temperatures up to 850 c, are given. The guarded hot plate ghp technique for measuring the temperaturedependent thermal conductivity of. In the singlesided mode of operation, auxiliary thermal insulation is placed between the hot plate and the auxiliary cold plate, replacing one of the specimens shown in fig. Design, construction and validation of a guarded hot plate apparatus for thermal conductivity measurement of high thickness cropbased specimens samuel dubois1, frederic lebeau1 1dept.
The temperature of the test plate, guard section, and bottom plate is maintained at 35 0. Design, construction and validation of a guarded hot plate. The temperature at any point in the sample or in the heater plate may be determined. An arrangement of the main mechanical components of a ghp, configured for horizontal heat flow, is shown in fig.
Design concepts for a new guarded hot plate apparatus for. Astm c1043 16 standard practice for guardedhotplate. An automated hightemperature guardedhotplate apparatus. The fox series provides endusers with unique features and the widest range of. Standard test method for steadystate thermal transmission properties by means of the guarded hot plate, american society for testing and materials, 1916 race street. There are currently three standards in place by astm which apply to the guarded hot plate method. The lowtemperature guarded hot plate, which has metal surface plates and a definite guard gap see 3.
Later, while traveling in europe, he learned that poensgen in germany had been using a guarded hot plate for thermal conductivity measurements since 1910. Circular and square edge effect study for guardedhot. Resistance in thermal conductivity measurements using the guarded hot plate method nenad stepanic1,a, nenad milosevic1 abstract. With the guarded hot plate method, which will be presented in the following, the heat flow is generated by an electric heater and the resulting temperature difference is measured.
Thecoldplatesareliquidcooled heat sinks, the hot plate is electrically heated. Accuracy of a guarded hot plate ghp old city publishing. For a material to be classified as a thermal insulator, it must exhibit low thermal conductivity throughout this test which, though not identical, is comparable to iso 8302. Ste, gembloux agrobio tech, university of liege, belgium corresponding author, supported by a f. Sweating guarded hotplate sweating guarded hot plate testex. Sweating guarded hot plate test method request pdf. Standard practice for guardedhot plate design using circular lineheat sources1 this standard is issued under the. In 1912, dickinson conceived and built the first guarded hot plate apparatus at nist for this purpose. Solvason thermal properties section division of building research national research council of canada ottawa, canada kia or6 abstract this paper presents a summary of an investigation of the precision and accuracy achievable with the nrcc 450 mm square ghp. It offers optimum accuracy in the available temperature range. The fox series provides endusers with unique features and the widest range of possible configurations to meet every measurement need. Thermal conductivity of insulations using guarded hot plates, including recent developments and sources of reference materials david salmon centre for basic, thermal and length metrology, national physical laboratory, teddington, middlesex tw11 0lw, uk email.
Precision and accuracy of guarded hot plate method. The sweating guarded hotplate, often referred to as the skin model, produces accurate, repeatable measurements of the thermal resistance and vapor permeability of textiles in accordance with. Circular and square edge effect study for guarded hot plate and heatflowmeter apparatuses show all authors. Sweating guarded hotplate skin model for clothing comfort. Back and lateral guard zones are then necessary to neutralize these leaks. Standard measurements allow the following dimensions of the test specimens. Correction on the influence of thermal contact resistance.
C17719 standard test method for steadystate heat flux measurements and thermal transmission properties by means of the guarded hot plate apparatus thermal testing thermal resistance thermal transmission. Sweating guarded hotplate the sweating guarded hotplate, often referred to as the skin model, produces accurate, repeatable measurements of the thermal resistance and vapor permeability of textiles. A theoretical treatment is given for the action of the guarded hot plate apparatus used for measuring conductivities. Iso 8302, astm c177, din en 12939 or din en 12667, the system features unrivalled performance over an. Iso 8302, astm c177, din en 12939 or din en 12667, the system features unrivalled performance over an unmatched temperature range. To make sure that the heat released in the hot plate is passed only through the sample, the hot plate is surrounded by guard heaters and. Nbs lineheatsource guarded hotplate for thick materials.
Pdf additional thermal conductivity values of foods. Construction and preliminary testing of a guarded hot. They differ in technique, sample size, testing time, capability and methodologies of measurement. Circular and square edge effect study for guarded hot plate and heatflowmeter apparatuses.