NIST Measurement Services:

 Heat-Flux Sensor Calibration 

NIST

Special 

Publication 

250-65 

Benjamin K. Tsai, Charles E. Gibson, Annageri V. Murthy, Edward A. Early, 

David P. Dewitt, and Robert D. Saunders 

U.S. Department of Commerce 

Technology Administration 

National Institute of Standards and Technology 
 

NIST Special Publication 250-65 

NIST MEASUREMENT SERVICES: 

Heat-Flux Sensor Calibration 

Benjamin K. Tsai, Charles E. Gibson, Annageri V. Murthy, Edward A. Early, 

David P. Dewitt, and Robert D. Saunders 

Optical Technology Division 

Physics Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-0001 

May 2004 

U.S. DEPARTMENT OF COMMERCE 

Donald L. Evans, Secretary 

Technology Administration 

Phillip J. Bond, Under Secretary for Technology 

National Institute of Standards and Technology 

Arden L. Bement, Director
 

National Institute of Standards and Technology Special Publication 250-65 

Nat. Inst. Stand. Technol. Spec. Publ. 250-65, 37 Pages, (May 2004) 

CODEN: NSPUE2 

NIST PRINTING AND DUPLICATING OFFICE 

GAITHERSBURG, MD: 2004
 

 iii

PREFACE 

The calibration and related measurement services of the National Institute of Standards 

and Technology are intended to assist the makers and users of precision measuring 

instruments in achieving the highest possible levels of accuracy, quality, and 

productivity. NIST offers over 300 different calibrations, special tests, and measurement 

assurance services. These services allow customers to directly link their measurement 

systems to measurement systems and standards maintained by NIST. These services are 

offered to the public and private organizations alike. They are described in NIST Special 

Publication (SP) 250, NIST Calibration Services Users Guide. 

The Users Guide is supplemented by a number of Special Publications (designated as the 

"SP250 Series") that provide detailed descriptions of the important features of specific 

NIST calibration services. These documents provide a description of the: (1) 

specifications for the services; (2) design philosophy and theory; (3) NIST measurement 

system; (4) NIST operational procedures; (5) assessment of the measurement uncertainty 

including random and systematic errors and an error budget; and (6) internal quality 

control procedures used by NIST. These documents will present more detail than can be 

given in NIST calibration reports, or than is generally allowed in articles in scientific 

journals. In the past, NIST has published such information in a variety of ways. This 

series will make this type of information more readily available to the user. 

This document, SP250-65 (2004), NIST Measurement Services: Heat-Flux Sensor 

Calibrations is a new publication. It covers the calibration of heat-flux sensors (test 

number 35101C in SP250, NIST Calibration Services Users Guide). Inquiries 

concerning the technical content of this document or the specifications for these services 

should be directed to the author or to one of the technical contacts cited in SP250. 

NIST welcomes suggestions on how publications such as this might be made more 

useful. Suggestions are also welcome concerning the need for new calibrations services, 

special tests, and measurement assurance programs. 

John R. Rumble, Jr. Katharine B. Gebbie 

Director Director 

Measurement Services Physics Laboratory 
 

 iv

ABSTRACT 

The Optical Technology Division at NIST is developing techniques to calibrate heat-flux 

sensors to meet the current calibration needs of U.S. science and industry. An outcome 

of this effort is a calibration service offered now through NIST Calibration Services to 

calibrate heat-flux sensors up to 50 kW/m2

. The calibration, performed using the 25 mm 

Variable-Temperature Blackbody as a broadband radiant source, transfers calibration 

from a primary electrical substitution radiometer standard to the heat-flux sensor. In 

contrast to other calibration methods using temperature traceability, the objective of this 

calibration is to provide heat-flux traceability to NIST primary standards. This report 

gives the calibration principle, the associated laboratory procedure, safety, and typical 

calibration results of a Schmidt-Boelter type heat-flux sensor. 

KEY WORDS: Blackbody, heat flux, sensor 
 

 v

TABLE OF CONTENTS 

Abstract iv 

1. Introduction 1 

2. Measurement principle 1 

3. Traceability 2 

4. Calibration technique 3 

 4.1 25 mm Variable-Temperature Blackbody 3 

 4.2 Transfer Standard Radiometer 4 

 4.3 Radiometer Calibration 5 

 4.4 Reference Calibration Sensor 5 

5. Calibration Procedures 8 

 5.1 Pre-Calibration inspection 8 

 5.2 Additional test equipment 8 

 5.3 Calibration 9 

 5.4 Post-Calibration inspection 9 

 5.5 Data reduction 10 

 5.6 Calibration report 10 

6. Measurement uncertainty 10 

 6.1 Transfer standard 10 

 6.2 Blackbody temperature (VTBB) 10 

 6.3 Blackbody emissivity 11 

 6.4 Blackbody radiation - aperture uniformity 11 

 6.5 Alignment error (distance) 11 

 6.6 Alignment error (angular) 11 

 6.7 Radiometer aperture size 11 

 6.8 Radiometer/Sensor reading 13 

 6.9 Other sources 13 

 6.10 Combined uncertainty 14 

References 15 

Appendix A: Heat-flux sensor: Laboratory procedure manuals 16 

Appendix B: Sample calibration report 22 

Appendix C: Blackbody operation: Laboratory procedure manuals 32 

Appendix D: How to request calibration services 38 
 

 vi

LIST OF FIGURES 

Figure 1 Transfer calibration and traceability 2 

Figure 2 Schematic layout of the 25 mm Variable-Temperature Blackbody 3 

Figure 3 Transfer standard Kendall radiometer layout 4 

Figure 4 Schematic representation of a Schmidt-Boelter sensor 6 

Figure 5 Typical calibration results on reference sensor in VTBB 7

Figure 6 Incremental change in configuration factor with distance 12 

Figure 7 Ratio of peak to average irradiance at sensor/radiometer location 12 

Figure 8 Standard deviation of the mean output for two sensor locations 13 

Figure A1 ESR control unit front panel 17 

Figure A2 ESR calibration [1] 21

LIST OF TABLES 

Table 1a Radiometer specification 4 

Table 1b Radiometer control unit specification 5 

Table 2 Reference Schmidt-Boelter sensor specification 6 

Table 3 Summary of linear regression results on reference sensor 8 

Table 4 Heat-flux at sensor location for different blackbody temperatures 9 

Table 5 Estimate of uncertainty in heat-flux sensor calibration [%] 14 
 

 1

1. Introduction

 The National Institute of Standards and Technology initiated a competence 

program in the year 1995 to develop techniques for calibration of high heat-flux sensors. 

An outcome of the competence program is the capability to calibrate heat-flux sensors 

with traceability to the High Accuracy Cryogenic Radiometer. The current range of 

calibration, performed with a 25 mm Variable-Temperature Blackbody (VTBB), is up to 

50 kW/m2. The calibration technique [1] uses an electrical substitution radiometer (ESR) 

as the transfer standard. 

 The calibration is now available to the user community through the NIST 

Calibration Services. Several sensors calibrated so far show good repeatability of the 

technique with an expanded uncertainty of 2 %, corresponding to a coverage factor of 

k = 2 or 95 % confidence level. This report gives a description of the equipment used in 

the calibration, laboratory procedure currently in practice, and an evaluation of the 

uncertainties in the measurement process. 

2. Measurement principle 

 Radiant heat flux is essentially a radiometric quantity representing the broadband 

irradiance or flux received per unit area by a surface. For a radiometer placed in front of 

a radiant source, the governing measurement equation for the radiometer signal output 

(V) is 

∫∫ ∫∫ ∫ V = G ⋅ dxdy cosθdθdφ dλ L(x, y,θ,φ,λ)⋅ R(x, y,θ,φ,λ) , (1) 

where x and y specify the location on the radiometer on which radiant flux is incident, θ

and φ specify the direction from which radiant flux is incident on the radiometer, λ is the 

wavelength, L is the radiance of the incident radiant flux, R is the responsivity of the 

radiometer, and G is the amplifier gain. The integrals are performed over the entire area 

of the radiometer upon which radiant flux is incident, over all directions from which 

radiant flux is emitted by the source and received by the radiometer, and over all 

wavelengths to which the radiometer is sensitive. Any temporal dependence is excluded 

in Eq. (1) since heat flux measurements are typically performed under steady-state 

conditions. 

 For a given range of directions for the source and radiometer, integration of Eq. 

(1) over the angles yields 

∫∫ ∫ V = G ⋅ dxdy dλ E(x, y,λ)⋅ R(x, y,λ) , (2) 

where E is the irradiance. Note that the integral over angles to obtain Eq. (2) depends on 

both the size of the source and the field-of-view of the radiometer. Also, the incident 

radiant flux at the reference plane of the radiometer is measured, not the absorbed flux. 

Effects from a window or the absorptance of the detector are included in the responsivity. 

 Integrating Eq. (2) over the area of the radiometer, assuming the responsivity is 

uniform over the area, yields 

∫ V = G ⋅ A⋅ dλ E(λ)⋅ R(λ) , (3) 
 

 2

where A is the area of the radiometer over which radiant flux is incident and E is the 

average irradiance. The average irradiance is used in Eq. (3) because in nearly all 

measurement situations the irradiance has a spatial distribution that is a maximum at the 

center of the radiometer. Therefore, the average irradiance will depend upon the size of 

the radiometer. 

 Finally, a typical radiometer used as a heat-flux sensor has a responsivity that is 

independent of wavelength, so Eq. (4) reduces to 

∫ V = G ⋅ A⋅ R dλ E(λ) , (4) 

where R is the average responsivity over wavelength. The product of the amplifier gain, 

area, and the average responsivity is the quantity calibrated for heat-flux sensors. 

3. Traceability 

 Heat-flux sensor calibrations are traceable to the primary detector standard for 

radiometric measurements. However, because of the range of radiant powers between the 

primary standard and the heat-flux sensor (microwatts to watts), the traceability chain 

involves multiple steps, shown in Fig. 1. 

 The primary detector standard is the High Accuracy Cryogenic Radiometer 

(HACR) [2], which uses low-power lasers to calibrate the responsivity of primary trap 

detectors. These primary trap detectors are used in turn in the Spectral Comparator 

Facility (SCF) [3], a lamp-illuminated monochromator system, to calibrate the 

responsivity of quantum efficient detectors (QED). The maximum radiant power for a 

QED is about 2 mW, which precludes its use to calibrate heat-flux sensors, for which the 

radiant power is several orders of magnitude greater. 

Figure 1. Traceability of heat-flux sensor calibrations 

High Accuracy Cryogenic Radiometer (HACR)

Primary Trap Detectors

Quantum Efficient Detector (QED)

Electrical Substitution Radiometer (ESR)

Heat-Flux Sensors

(Gardon, Schmidt-Boelter)

Spectral Calibration Facility

High-Power Lasers

Variable-Temperature Blackbody

Low-Power Lasers

Detectors Sources
 

 3

 A cavity-type ESR operating at room temperature is the transfer standard for heatflux sensor calibrations. The QED is used to calibrate the radiant power of a high-power 

krypton laser, which is then used to calibrate the responsivity of the ESR. The final step 

in the traceability chain, described in detail in the following, transfers the calibration 

from the ESR to the heat-flux sensor using the VTBB. 

4 Heat-flux sensor calibration 

4.1 Variable-Temperature Blackbody 

 The VTBB is a thermally insulated graphite tube cavity heated electrically. 

Figure 2 shows a schematic layout of the blackbody and the test arrangement for 

calibrating a typical heat-flux sensor. Direct resistance heating of the tube using large 

AC currents at low voltages provides for quick heating and cooling. The heated tube 

cavity diameter is 25 mm, and the heated section is 28.2 cm long with a center partition, 

0.3 cm thick. 

 The water-cooled end caps of the heated tube connect directly to the heating 

electrodes. The design provides a sharp temperature gradient between the end cap and 

the graphite heater element, and a uniform temperature distribution along the cavitylength of the graphite tube. An optical pyrometer measures the blackbody temperature by 

sensing radiation from one end of the furnace. A Proportional-Integral-Derivative (PID) 

controller regulates the power supply to maintain the furnace temperature to within 

± 0.1 K of the set value. The maximum recommended operating temperature for the 

blackbody is 2973 K. 

 With the standard extension installed and the sensor located 1.25 cm from the 

exit, the distance between the sensor and the end of the heated section will be 17.4 cm. 

However, the maximum flux-level at this location is limited. With a shorter-extension 

installed, the sensor location can be closer to the blackbody radiating-cavity resulting in 

higher flux-levels. At a distance of 1.25 cm from the exit, the maximum flux-level is 

approximately 50 kW/m2

. Away from the aperture, the irradiance decreases rapidly, and 

is about 10 kW/m2

 at a distance of 62.5 mm. 

Figure 2. Schematic layout of the VTBB 

Graphite tube cavity

Heated section

Computer Power supply

Optical

pyrometer

Extension

(not cooled)

ESR

Heat-flux

sensor

Aperture: 25 mm dia.

Purge gas: Argon

Temperature: up to 2973 K

Heat-flux sensor: 50 kW/m2

Extension

(not cooled)

Water-cooled end caps
 

 4

4.2 Transfer Standard Radiometer 

 The ESR transfer standard is a water-cooled Kendall radiometer [4],1

 shown in 

Fig. 3. The ESR absorbs the incident radiant flux almost completely because of the 

blackened cavity walls and multiple reflections within the cavity. The equivalent 

electrical power, measured by the current through a precision resistor, required to 

produce the same cavity temperature rise as the radiant flux, is the power of the radiant 

flux. The maximum incident radiant power for the ESR is 4.2 W and the aperture area is 

1 cm2

. The time constant (1/e) for a step change in irradiance is 6 s. For large changes in 

irradiance, it is necessary to allow about 60 s for stabilization before taking 

measurements [5]. The manufacturer stated uncertainty of this radiometer is 0.5 %, as 

determined by an experimental measurement of the Stefan-Boltzmann constant. Tables 

1a and 1b give the radiometer and the control unit specification, respectively. 

Cooling water

Aperture

Cavity

Figure 3. Transfer standard Kendall radiometer layout. 

Table 1a. ESR transfer standard specifications 

Type Kendall MK-IV, S/N 47601 

Range 0.04 kW/m2 to 42 kW/m2

Accuracy ± 0.5 % of reading ± 0.2 mW/cm2

Time constant 6 s (1/e) 

Sensitivity > 10 mV/(W/cm2) 

View angle No view limiting aperture 

Calibration heater 230 W, 150 mA maximum 

Outer surface coating 0.005 mm pure gold plate 

Mounting 5 mm metric machine screw 

Cabling 4 m long, Bendix PT06A-14-19P 

Size 51 mm diameter, 76 mm long 

Weight 0.9 kg 

 

1

manufactured by Technical Measurements Inc., La Cañada, CA. Certain commercial equipment, instruments, or materials are 

identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National 

Institute of Standards and Technology, nor does it imply that the materials or equipment are necessarily the best available for the 

purpose. 

 
 

 5

Table 1b. ESR transfer standard control unit specification 

Kendall MK-I Radiometer Control Unit (Serial No. 17601)

Accuracy Absolute measurement uncertainty < ± 0.5 % full scale 

Zero drift < ± 0.1 % per month of full scale 

Time constant < 2 s (1/e) 

Display ± 39 999 counts normal range 

Output: Analog ± 10V, ± 5 mA 

Output: Digital Buffered, stored, parallel BCD 

Size 43 cm wide, 14 cm high, 46 cm deep 

Weight 10 kg 

4.3 ESR Calibration

 The self-calibration feature of the ESR facilitates absolute measurements of the 

incident irradiance within the stated experimental uncertainties. However, other 

uncertainties related to cavity heating and long-term drift make it desirable to 

characterize the radiometer independently by comparison to a QED with a high-power 

krypton laser [1]. The calibrations from three different sets of measurements of the ESR 

showed a high degree of linearity with a regression factor of 0.999. The calibration 

constant agreed to within 1 % between two tests conducted a year apart. From these 

tests, the relation between the corrected (Ec) and the indicated (Ei) ESR readings is 

obtained as [Appendix A] 

c 9855 i E = 0. E , (5) 

 All of the calibrations performed with the VTBB use this relation to provide 

consistency and establish the long-term repeatability of the calibration technique. The 

uncertainty associated with the ESR calibration is of Type-B [7] in determining the total 

measurement uncertainty. 

4.4 Reference Sensor Calibration 

 The heat-flux sensor calibration procedure is repeatable as demonstrated from 

periodic calibrations of a reference sensor. This reference sensor calibration, performed 

before calibrating a customer-supplied sensor, ensures that the long-term stability of the 

calibration procedure is monitored. The Schmidt-Boelter type reference sensor, shown in 

Fig. 4, works on the principle of axial one-dimensional heat flow. It measures the 

temperature difference across a thin, thermally insulating layer to determine the incident 

heat flux. Due to the axial flow of heat, the temperature distribution across the sensing 

surface is uniform. The maximum body temperature is limited to about 200 o

C when the 

sensor is not water-cooled. For applications involving continuous use, the sensor body is 

water-cooled. Reference [6] gives a detailed description of Schmidt-Boelter sensor 

operation. 

 Table 2 lists the specifications of the Schmidt-Boelter reference sensor. The body 

diameter and length are 5 mm and 9 mm, respectively. The design heat-flux value of 

110 kW/m2

 is representative of the calibration range of interest. A number of calibrations 

of this sensor performed over a period of time cover different locations from the 
 

 6

blackbody aperture, and different blackbody temperature ranges. Figure 5 shows the 

results of the calibration for incident heat flux of up to 50 kW/m2

. 

Figure 4. Schematic representation of a Schmidt-Boelter sensor 

Table 2. Reference Schmidt-Boelter sensor specification 

Type Schmidt-Boelter 

Manufacturer Medtherm Corp.

Model 12-10-0.35-75-20841J

Serial Number #94761

Design flux 110 kW/m2

Body diameter 5 mm

Body length 9 mm

Thermocouple Shielded copper wires

Body not water-cooled

X = 12.5 mm (7/23/96)

X = 12.5 mm (5/30/97)

X = 12.5 mm (5/25/97)

X = 62.5 mm (7/31/96)

X = 12.5 mm (8/21/97)

X = 12.5 mm (8/19/97)

0 10 20 30 40 50

0

1

2

3

4

5

6

Heat flux [kW/m2]

Sensor output [mV]

x

Sensor

Blackbody

Figure 5. Typical calibration results on the reference sensor.

Black

paint

Heat sink

Wafer

Temperature

distribution

Copper

leads

Heat flux
 

 7

 All of the calibrations show a linear response of the sensor, with regression 

factors close to unity. Table 3 summarizes the results of the sensor responsivity 

calculations from linear regression analysis of the measured data. The responsivity 

values from several calibrations agree to within ± 0.7 % of the mean value. The good 

repeatability of the data supports the long-term stability of the transfer standard ESR, the 

reference sensor, and validates the VTBB transfer calibration technique. The standard 

deviation of responsivity determined from these measurements is an additional source of 

uncertainty when determining the total uncertainty of other calibrated heat-flux sensors. 

Table 3. Summary of linear regression results on the reference sensor 

Schmidt-Boelter Sensor (NIST): #94761, 12-10-0.35-75-20841J

 

Test Distance Intercept Responsivity 

No. Date x mm kW/m2 mV/(kW/m2) Deviation % 

1 23-Jul-96 12.5 0.0018 0.1189 -0.18 

2 31-Jul-96 62.5 -0.0687 0.1184 -0.59 

3 25-Apr-97 12.5 0.0608 0.1190 -0.04 

4 30-Apr-97 12.5 0.0186 0.1181 -0.83 

5 19-Aug-97 12.5 0.0077 0.1191 0.06 

6 21-Aug-97 12.5 0.0202 0.1197 0.50 

7 9-Nov-97 12.5 0.1003 0.1200 0.76 

8 11-Nov-97 140 -0.0186 0.1180 -0.92 

9 2-Jun-98 12.5 0.1348 0.1189 -0.16 

10 16-Jul-98 12.5 0.0318 0.1199 0.71 

11 17-Jul-98 62.5 0.0053 0.1187 -0.31 

12 27-May-98 12.5 0.1149 0.1188 -0.27 

13 29-May-98 12.5 0.2526 0.1183 -0.62 

14 9-Jul-00 12.5 -0.0644 0.1201 0.86 

18 22-Jul-01 12.5 0.0300 0.1186 -0.38 

19 16-Aug-01 12.5 0.0364 0.1183 -0.62 

20 5-Nov-01 12.5 0.0374 0.1211 1.70 

21 6-Nov-01 12.5 0.0472 0.1198 0.60 

22 18-Aug-02 12.5 -0.0006 0.1187 -0.27 

 

Arithmetic mean 0.0393 0.1191 0.00 

Standard Deviation 0.0732 0.0082 0.69 

Standard Error 0.0168 0.0019 0.16 

5. Calibration Procedures 

 The following specifies the stepwise procedure for calibrating heat-flux sensors 

with reference to the transfer standard radiometer using the VTBB. 
 

 8

5.1 Pre-Calibration inspection 

 The continuity of the sensor signal leads is checked and the value of the 

resistance, using a multi-meter, is recorded. The condition of the high absorptance 

coating on the sensor surface is inspected. If the conditions indicate the need for 

repainting, the customer is informed. The surface is not repainted at NIST. 

5.2 Additional test equipment 

 Heat-flux sensors have a wide range of configurations. Standard mounting blocks 

and sensor holders are readily available for mounting the 25 mm diameter Gardon and 

5 mm diameter Schmidt-Boelter sensors. However, some sensors may require special 

mounting arrangement. If so, a suitable accessory is designed for fabrication in advance 

of the calibration. The cooling requirements for the sensor, and the need for any special 

instruments like amplifiers, thermometers etc., are checked. 

5.3 Calibration 

 Appendices A and B detail the heat-flux sensor calibration procedure. The 

reference standard radiometer (ESR) requires self-calibration prior to testing. Appendix 

A describes the self-calibration procedure. The self-calibration, at a radiant power of 

approximately 920 mW, is necessary to be consistent with the radiometer settings during 

calibration and use. Self-calibration at other radiant powers within the range of the 

radiometer is acceptable as long as the instrument settings during calibration and use are 

identical. Appendix B describes the heat-flux sensor calibration procedure at about 

8 to 10 heat flux levels covering the calibration range. Table 4 shows the required 

temperature settings of the VTBB and corresponding heat-flux level at the sensor, for 

different locations of the sensor from the blackbody aperture. 

Table 4. Heat-flux values at sensor location for different blackbody temperatures 

X = 12.5 mm X = 62.5 mm X = 140 mm 

Temperature Heat-flux Temperature Heat-flux Temperature Heat-flux 

[K] [kW/m2] [K] [kW/m2] [K] [kW/m2] 

1573 8.84 1823 5.09 1073 0.32 

1773 13.07 1963 7.43 1573 1.30 

1973 18.91 2108 9.72 1973 2.99 

2123 24.19 2233 11.91 2273 5.11 

2273 30.88 2373 14.94 2473 7.04 

2273 30.91 2573 20.38 2573 8.21 

2373 36.19 2773 27.08 2673 9.52 

2453 41.17 

2553 47.31 

2653 54.81 X: Distance from blackbody aperture to sensor location 

 The heat-flux values listed are approximate and are useful in deciding the 
 

 9

optimum sensor location from the blackbody aperture to cover a desired calibration 

range. The actual heat flux values may vary over the long term because of aging of the 

graphite heating element and other factors. However, this variation will have no effect on 

the actual calibration. The transfer standard radiometer measurements give the actual 

heat flux values. Prior to calibrating the test sensor, it is desirable to perform a 

calibration on the reference Schmidt-Boelter sensor described in Sec. 4.4. 

5.4 Post-Calibration inspection

 The heat-flux sensor is removed from the test installation after disconnecting the 

signal lead, thermocouple lead, and cooling water. The signal lead continuity and the 

resistance are checked, as well as the condition of the high absorptance coating to ensure 

that it did not changed during the calibration process. 

5.5 Data reduction 

 Appendix C gives the data reduction procedure. An EXCEL spreadsheet or other 

standard statistical software may be used. The measured heat flux is calculated from the 

measurement equation, 

S

V V E s d

c

− = , (6) 

where Vs is the measured sensor signal in V or mV, Vd is the measured dark signal of the 

sensor in V or mV, and S is the measured responsivity of the heat-flux sensor expressed 

in mV/(W/cm2

) or mV/(kW/m2). The regression curve fit for the data is generally linear 

with regression factors close to unity. In some cases, a small degree of non-linearity may 

appear at low heat flux levels, when calibrating with the sensor located close to the 

blackbody aperture. This non-linear effect is due to argon purge-gas flow effects, and 

reduces with increasing heat flux. The calculated responsivity depends largely on the 

readings at high heat flux levels. 

5.6 Calibration report 

 A calibration report is prepared as per the standard format, shown in Appendix D, 

including any special comments specific to the calibration and measurement 

uncertainties. 

6. Measurement uncertainty 

 The measurement uncertainty evaluation follows the procedure described in 

reference [7]. The individual uncertainty at each stage of the calibration is either of 

Type-A, evaluated using statistical methods, or Type-B, evaluated by other means2

. The 

combined uncertainty is the root-sum-square of the individual uncertainty values. In the 

transfer technique calibration of heat-flux sensors, the measurement uncertainties accrue 

at two different stages. First, the uncertainty associated with the calibration of the 

transfer standard radiometer; and secondly, the uncertainty arising while calibrating the 

heat-flux sensor with the VTBB. 

 

2

 Previous measurement data, experience, manufacturer’s specification, other sources of data 
 

 10

6.1 Transfer standard radiometer

 The uncertainty associated with the transfer standard radiometer calibration, 

discussed in Secs. 3 and 4.3, is a Type-B uncertainty and estimated to be 0.6 %. 

6.2 VTBB temperature 

 The absolute temperature of the VTBB has no influence on the transfer technique 

calibration because the heat flux is determined independently from the radiometer 

measurements. It is only necessary that the blackbody temperature be stable over the 

time interval of the radiometer and test sensor measurements. The VTBB has a longterm stability within ± 0.1 K of the set temperature. The corresponding uncertainty in the 

radiant heat flux is 0.01 % at 1000 K and 0.004 % at 2773 K. This is negligible compared 

to the other uncertainties and can be ignored. 

6.3 VTBB emissivity

 The estimated emissivity of the VTBB is 0.99. However, the blackbody 

emissivity has no influence on the transfer calibration. Higher emissivity values result in 

realizing higher heat flux levels at the sensor surface for a given operating temperature. 

6.4 VTBB radiation - aperture uniformity

 The uniformity of radiation from the VTBB aperture has no major influence on 

the calibration because of identical effects on both the transfer standard and the test 

sensor. However, even with a uniformly radiating aperture, the irradiance distribution at 

the sensor location may not be uniform. This non-uniform distribution may require a 

correction to the measured responsivity of the sensor, as detailed in Sec. 6.7. 

6.5 Alignment error (distance) 

 The location of the effective aperture of the VTBB is close to the heated end, 

about 8.5 cm inside the blackbody aperture with the short extension piece installed. The 

test sensor and the transfer standard radiometer are at a fixed distance from the blackbody 

aperture. Assuming a maximum error of about 0.2 mm in the location of the transfer 

standard radiometer and the sensor with respect to the reference plane, the corresponding 

uncertainty values will be 0.2 %, 0.14 % and 0.09 % at sensor locations corresponding to 

12.7 mm, 62.5 mm, and 140 mm from the blackbody aperture, respectively. The 

uncertainty in the longitudinal location of the sensor translates into a corresponding 

change in the configuration factor (Cfa) between the radiating aperture and the sensor. 

Figure 6 shows the relative change in the configuration factor with respect to location of 

the sensor from the aperture [8]. At large distances, the irradiance varies inversely as the 

square of the distance from the aperture. Hence, the uncertainty in irradiance at the 

sensor will be approximately two times that due to positioning uncertainty. The 

corresponding uncertainty values for the irradiance are 0.4 %, 0.3 % and 0.2 % at sensor 

locations of 12.7 mm, 62.5 mm, and 140 mm, respectively. 

6.6 Alignment error (angular)

 The errors due to angular misalignment vary as the cosine of the angle. Assuming 

a maximum misalignment of about 2°, the corresponding uncertainty will be 0.06 %. 
 

 11

Figure 6. Incremental change in configuration factor with distance [8] 

6.7 Radiometer aperture size

 The areas on which radiant flux is incident on the transfer standard radiometer 

and the test sensor are different, and the heat-flux distribution in the test plane is not 

uniform. The distribution is a maximum at the center, and decreases away from the 

center. The sensitive area of the heat-flux sensor is generally small, and responds to the 

peak of the distribution. However, the aperture size of the transfer standard radiometer is 

much larger. Hence, the response of the transfer standard radiometer will be proportional 

to the average irradiance over the distribution. 

 Due to the averaging of the distribution over the aperture area, a correction to 

the radiometer measurement is necessary to determine the peak value of the distribution 

from the average reading. This peak value corresponds to the radiation incident on the 

sensor surface. The correction is a function of the sensor location from the blackbody 

aperture [8]. Figure 7 shows the calculated correction for different sensor dimensions as 

a function of sensor location from the blackbody aperture. 

 The correction factor is unity when the sensor is located at the aperture plane 

because of the uniform distribution. The correction peaks at a distance approximately 

equal to the radius of the aperture, and decreases asymptotically to unity at large 

distances. The correction is a strong function of the ratio of the sensor to the aperture 

radii. For the VTBB transfer calibration setup, a conservative value of the radiometeraperture to sensor diameter ratio is about 0.44. The corresponding correction is less than 

0.3 % of the measured radiometer reading. The correction increases rapidly when 

moving closer to the blackbody aperture. The uncertainty involved in evaluating this 

correction arises mainly from the difficulty of defining the exact position of the effective 

blackbody aperture. However, even with an uncertainty of about 5 % in the effective 

0 2 4 6 8 10

0

-0.5

-1.0

-1.5

-2.0

d/b

= 0.5

= 0.1

dCfa/Cfa

dh/h

dCfa/Cfa

dh/h

h/b

b: Blackbody aperture radius

d: Sensing surface radius

h: Distance blackbody to sensor
 

 12

location, the corresponding uncertainty in the correction will be less than 0.05 %. 

 

Figure 7. Ratio of peak to average irradiance at sensor location [8] 

6.8 Radiometer/Sensor reading 

 The averaging times for the sensor and the radiometer measurements varies from 

10 s to 60 s depending on the heat-flux level. If the sensors are water-cooled, longer 

averaging times are feasible. Figure 8 shows a typical variation of standard deviation of 

the mean (standard error) of the sensor output at two locations from the blackbody. The 

uncertainty will be a maximum of about 0.2 %, and will be much less at heat-flux levels 

greater than 10 kW/m2

.

0.0

0.2

0.4

0.6

0 20 40 60

Gage

25 mm VTBB

X X = 62.5 mm

X = 12.5 mm

Heat flux kW/m2

Standard error [% of mean]

Sensor

0 2 4 6 8 10

b: Blackbody aperture radius

d: Sensing surface radius

h: Distance 0.3

h/b

d/b =

0.5

0.1

1.00

1.02

1.04

1.06

1.08

Blackbody

Flux distribution

h

Transfer standard

Sensor

Flux ratio peak to average
 

 13

Figure 8. Standard deviation of the mean output for two sensor locations [1] 

6.9 Other sources

 The VTBB uses low-velocity argon gas flow to purge the cavity continuously 

during operation. The average exit-flow velocity is about 0.08 m/s. When the sensor is 

close to the cavity-exit, the low velocity jet impinging the sensor surface causes changes 

in the local heat transfer. This influence becomes smaller away from the exit because of 

jet spreading effects. The good agreement in calibrations obtained for different sensor 

distances from the blackbody suggests that the purge gas effect is not significant, and is 

within other experimental uncertainties. The agreement also suggests that the sensor’s 

high-absorptance is gray because of different blackbody temperature ranges used to 

obtain the same heat flux level at the sensor. 

 The calibration of a heat-flux sensor over a period of time will show statistical 

variations because of experimental conditions that are difficult to control. Therefore, an 

uncertainty that indirectly accounts for purge-gas as well as other effects, based on longterm repeatability, is necessary. Several repeat measurements on the same reference 

sensor give a standard uncertainty value of 0.7 % for repeatability. 

6.10 Combined uncertainty 

 Table 6 lists the individual uncertainties for different sources. The root-sumsquare of individual uncertainties gives the combined uncertainty value uc. The relative 

expanded uncertainty U, corresponding to a coverage factor of k =2, is about 2.1 %. 

Table 5. Estimate of uncertainties in heat-flux sensor calibration [%] 

(Heat-flux range 10 kW/m2

 to 50 kW/m2) 

Uncertainty Source Type Uncertainty

1. Transfer standard ESR (previous calibration) B 0.60 

2. Blackbody temperature B 0.01 

3. Blackbody emissivity B < 0.001 

4. Blackbody aperture - radiation uniformity B < 0.001 

5. Alignment (distance) B 0.40 

6. Alignment (angular) B 0.06 

7. Radiometer aperture size B 0.05 

8. Signal output: Radiometer A 0.20 

 Sensor A 0.20 

9. Other sources: purge-gas, repeat tests A 0.70 

10.Relative expanded uncertainty (U = kuc) k = 2 2.1
 

 14

References

1. A. V. Murthy and B. K. Tsai, “Transfer calibration of heat flux sensors at NIST,” 

HTD-Vol. 345, ASME proceedings of the National Heat Transfer Conference, Edited 

by D. Kaminski, A. M. Smith and T. F. Smith, 7, 81-88 (1997). 

2. T. T. Gentile, J. M. Houston, J. E. Hardis, C. L. Cromer, and A. C. Parr, “The NIST 

high accuracy cryogenic radiometer,” Appl. Optics 35, 1056-1068 (1996). 

3. T. C. Larason, S. S. Bruce, and A. C. Parr, “NIST Measurement Services: 

Spectroradiometric Detector Measurements: Part I – Ultraviolet Detectors and Part II 

– Visible and Near-Infrared Detectors,” NIST Special Publication 250-41 (1998). 

4. J. M. Kendall, Sr., and C. M. Berdahl, “Two blackbody radiometers of high 

accuracy,” Appl. Optics 9, 1082-1091 (1970). 

5. Instruction Manual for Kendall Radiometer System - Radiometer Model No. MK-IV, 

Serial No. 47601; Control Unit Model No. MK-I, Serial No. 17601; by Technical 

Measurements Inc., La Cañada, CA 91011. 

6. Kidd, C. T., and Nelson, C. G., “How the Schmidt-Boelter gage really works,” 

Proceedings of the 41st International Instrumentation Symposium, pp. 347-368 

(1995). 

7. B. N. Taylor, and C. E. Kuyatt, “Guidelines for evaluating and expressing uncertainty 

on NIST measurement results,” NIST Technical Note, 1297 (1994). 

8. A. V. Murthy, B. K. Tsai, and R. D. Saunders, “Aperture proximity effects in high 

heat flux sensors calibration,” J. Res. Natl. Inst. Stand. Technol, 103 (6), 621-624 

(1998). 
 

 15

Appendix A 

Heat-flux sensor: Laboratory procedure manual 

 HFMLP1: Kendall Radiometer Operating Procedure 

 HFMLP2: Heat-Flux Sensor Calibration Procedure 

 HFMLP3: Data reduction procedure
 

 16

Kendall Radiometer Operating Procedure

Figure A1. ESR control unit front panel 

1. Radiometer/Controller set-up 

a. Radiometer controller power-switch in off-position 

b. Connect radiometer Bendix cable to controller, & controller power cable to mains 

c. Cover the radiometer front end with the cap 

d. Connect the cooling water-pump outlet to the radiometer inlet 

e. Connect cooling water-pump inlet & the radiometer outlet to the coolant reservoir 

f. Adjust the dial on the pump flow-controller to a flow-rate of 0.5 L/m or higher 

g. Switch-on radiometer controller power 

h. Allow about 20 min for stabilization 

2. Digital voltmeter check-out (as and when needed) 

a. Set switch “S1” to “OPERATE” 

b. Connect a Standard voltage source to the BNC input connector 

c. Set switch “S2” to “ZERO” position 

d. Turn DVM’s “ZERO” adjust potentiometer to set the read-out to zero 

e. Set switch “S2” to “SCALE” position 

f. Adjust DVM’s “SCALE” potentiometer to read the standard voltage source value. 

continued 

Optical Technology Division (844) 

Heat-flux Measurements Laboratory Procedure 

Kendall Radiometer Operating Procedure 

Page 1 of 2 

Written by: Murthy Annageri Procedure: HFMLP1 

Approved by: ................... Date: ................... 

Revised by: ................... Date: ................... 
 

 17

3. Dark signal 

a. Set both the switches “S1” and “S2” to “OPERATE” 

b. Allow the unit to stabilize for about 20 min 

c. The steady read-out gives the dark-signal value 

d. Turn the “TARE(R17)” adjustment potentiometer to set the read-out to 0.000 

4. Radiometer self-calibration & Operation (See note) 

a. Set switch “S1” to “SCALE” position, and set switch “S2” to “VOLTS” position 

b. Turn potentiometer “HEATER-R16” to adjust to the desired voltage 

c. Set switch “S2” to “VOLTS” position: Note the voltage “V” on the meter 

d. Set switch “S2” to “CURRENT” position: Note the heater current (I) in mA 

e. Calculate electrical power (Pc) = V (Volts) x I (mA) x Cf (=0.9925) 

 [Cf is the radiometer aperture area (cm2

). For the radiometer in use Cf = 0.9925] 

f. Set switch “S2” to “OPERATE” position 

g. Allow the read-out to stabilize: Note the indicated power Pi on the meter 

h. If Pi ≠ Pc, adjust potentiometer “SCALE(R18)” to set read-out Pi, to Pc

i. Set both the switches “S1” and “S2” to “OPERATE” position. 

Note: The radiometer self-calibration is at a power level ≈ 920 mW corresponding to the calibration 

power level used in the laser facility. The radiometer calibration gives the actual heat flux value. 

Optical Technology Division (844) 

Heat-flux Measurements Laboratory Procedure 

Kendall Radiometer Operating Procedure 

Page 2 of 2 

Written by: Murthy Annageri Procedure: HFMLP1 

Approved by: ................... Date: ................... 

Revised by: ................... Date: ................... 
 

 18

Heat-flux Sensor Calibration Procedure

 

COLLISION

1. Calibration set-up 

a. Remove the standard graphite tube extension on the viewing end of the VTBB 

and replace it with the short extension. 

b. Locate/align the reference ESR and the test-sensor at a fixed distance from the 

VTBB exit using standard gage blocks3

c. Note down position values for the Aerotech-stage corresponding to the ESR 

(Station-1) and the test sensor (Station-2) location when aligned with VTBB axis 

d. Identify another position (Station-3) away from the ESR and the sensor, to station 

VTBB while being heated or cooled 

e. Connect cooling water pump to the ESR and set the flow-rate to 0.5 L/m or higher 

f. If the test-sensor is water-cooled, make appropriate cooling arrangements as per 

manufacturer’s specification 

g. If the test-sensor has body-temperature thermocouple, connect the leads to Fluke 

thermometer to monitor body temperature during testing 

h. Connect analog output of the control unit to Channel-1 of the HP multi-meter 

3457A 

i. Connect the sensor signal leads (or the amplifier output) to Channel-2 of the HP 

multi-meter 3457A 

j. Check connections, signal-polarity and instrument-cooling for proper functioning 

k. Record dark signals for the ESR and test sensor for about 60 s. 

 

 continued

 

3 Recommended location of the sensor from the blackbody exit is 12.5 mm, 62.5 mm and 140 mm for 

calibration up to about 50 kW/m2

, 25 kW/m2 and 10.0 kW/m2, respectively. 

Optical Technology Division (844) 

Heat-flux Measurements Laboratory Procedure 

Heat-flux Sensor Calibration Procedure 

Page 1 of 2 

Written by: Murthy Annageri Procedure: HFMLP2 

Approved by: ................... Date: ................... 

Revised by: ................... Date: ................... 
 

 19

 

2. Calibration Measurements 

 

BRIGHT SOURCE 

BURN 

ELECTROCUTION

IMPORTANT 

Prior to calibration of test-sensor, perform a check out calibration on the reference sensor 

a. Record laboratory temperature and humidity 

b. Locate the VTBB at Station-3

c. Turn on the VTBB as per procedure in manual RTMLP11.1 

d. Set the desired temperature(Table 4) and allow the VTBB to stabilize

e. Move the VTBB in front of the ESR located at Station-1 

f. Allow about 60 seconds for the ESR readings to stabilize

g. Record ESR output for about 20 s to 60 s depending on the heat-flux level4,5

h. Move the VTBB to Station-2 in front of the test sensor

i. If the sensors are not water-cooled, go to Step (l) 

j. Water-cooled sensors: Record output signal for about the same duration as ESR 

k. Go to Step (m) 

l. Data taking duration: Limited by the sensor body-temperature increase with time. 

Monitor body-temperature-rise when exposing to radiant heat flux. Limit 

exposure time to about 10 s or less at high heat flux levels. 

m. Move the VTBB to Station-3

n. Set VTBB temperature to the next value of heat flux and wait till stabilization 

o. Follow Steps (e) to (m) till completion of calibration range 

p. At the end of calibration, move the VTBB to Station-3

q. Shut down blackbody following standard procedure in the Laboratory 

r. Remove the radiometer and the test sensor from the setup. Inspect to ensure the 

instruments are in good condition 

 

4

 > 60 s at heat-flux of 10 kW/m2, 20 s or lower at 50 kW/m2 when the distance between the blackbody and 

the sensor is 12.5 mm. About 10 s to 20 s when the distance is 62.5 mm or higher 

5 Note: Use a suitable file name to store the radiometer and sensor output data for later analysis 

Optical Technology Division (844) 

Heat-flux Measurements Laboratory Procedure 

Heat-flux Sensor Calibration Procedure 

Page 2 of 2 

Written by: Murthy Annageri Procedure: HFMLP2 

Approved by: ................... Date: ................... 

Revised by: ................... Date: ................... 
 

 20

Data reduction procedure

1. Calculate the mean value of the radiometer output (Ei) in W/cm2, and the test-sensor 

output (V) from the data for each temperature setting of the blackbody. 

2. Subtract the dark signals from the mean values calculated in Step-1. For calibration 

at high heat flux levels, the dark signals are small compared to the signal levels. 

3. Calculate statistical quantities of interest such as standard deviation of the mean, from 

the radiometer and sensor output readings to calculate measurement uncertainty. 

4. Convert the indicated radiometer mean value (Ei) to corrected radiometer power (Ec)

by using the relation by Ec = 0.9855 x Ei [See Fig. A2] 

5. Express sensor output in mV

6. Perform a linear regression analysis for the heat-flux (Ec) and the sensor output (mV)

The slope of the linear regression gives the responsivity of the sensor in mV/(W/cm2

) 

7. Plot the calibration data as shown in Fig. 5 for the reference Schmidt-Boelter sensor. 

8. Calculate measurement uncertainty in the calibration as listed in Table-5

Note: For calculation of mean value, standard deviation, and standard error, use a spreadsheet or other 

statistical software. 

Figure A2. ESR calibration [1]

0 0.5 1.0 1.5 2.0 2.5

0

0.5

1.0

1.5

2.0

2.5

Indicated power Ei [W]

Corrected power 

Ec [W]

Optical Technology Division (844) 

Heat-flux Measurements Laboratory Procedure 

Heat-flux Sensor Calibration Data Reduction Procedure 

Page 1 of 1 

Written by: Murthy Annageri Procedure: HFMLP3 

Approved by: ................... Date: ................... 

Revised by: ................... Date: ................... 
 

 21

Appendix B 

Heat-flux sensor - Sample Calibration Report 
 

 22
 

 23
 

 24
 

 25
 

 26
 

 27
 

 28
 

 29
 

 30
 

 31

Appendix C 

VTBB operation: Laboratory procedure manual 

 RTMLP Safety.1 Safety Issues 

 RTMLP1 Running General Data Taking Program 

 RTMLP11: VTBB Operation 
 

 32

Safety Issues

Safety glasses are required in the laboratory at all times. 

The following hazards have been identified in this laboratory. Safety measures are in 

place to reduce the risk of injury from the hazards below. 

BRIGHT SOURCE

Avoid staring at the source 

Can cause eye damage 

Use the correct neutral density filter when viewing is required 

BURN

Keep body and clothes away 

COLLISION

Keep the boxcar path clear 

Do not hang cables from boxcar 

ELECTROCUTION

High voltage connections present 

Do not touch electrical parts 

LASER

Avoid staring into a laser 

Can cause eye damage 

Block laser or turn off when not in use 

Displays, similar to the one below, are used throughout this document to alert the 

operator to potential hazards. 

LASER

Optical Technology Division (844) 

Radiance Temperature Measurements Laboratory Procedure 

Safety Issues 

Written by: Charles Gibson Procedure: RTMLP1 

Approved by: ................... Date: ...................

Revised by: ................... Date: ...................

RTMLP Safety.1 Page 1 of 1
 

 33

Running the General Data Taking Program 

1. Turn on the computer 

2. Enter the password to work online, or click on the Cancel button to work offline 

3. Load the Visual Basic program: c:\programs\datatakn\pyro.mak (do one of the 

following) 

a. Click on the Pyro.mak shortcut icon 

b. Double click on the folder c:\programs\datatakn\pyro.mak using Windows 

Explorer 

4. Run the program (do one of the following) 

a. Press F5 

b. Click on the _ tool bar icon 

c. Click on the menu item “Run” then on “Start” 

5. The Hardware.frm is used to set up the equipment with settings used by other 

programs 

6. The Software.frm is used to input data used by other programs 

7. All other programs can be run from these forms

Optical Technology Division (844) 

Radiance Temperature Measurements Laboratory Procedure 

Running General Data Taking Program 

Written by: Charles Gibson Procedure: RTMLP1 

Approved by: ................... Date: ...................

Revised by: ................... Date: ...................

RTMLP1 Page 1 of 1
 

 34

VTBB Operation 

 

BRIGHT SOURCE 

BURN 

ELECTROCUTION

1. Turn On Procedure

a. Open tap water valve 1/8 turn 

b. Check that the blue box flow rate is about 2 GPM 

c. Open chilled water valves 

i. open supply valve 1/4 turn 

ii. fully open return valve 

d. Press the reset button on the blue water switch box to select chilled water 

e. Check that the blue box flow rate is about 5 GPM 

f. Fully open the argon cylinder valve 

g. Turn on the argon alarm and check that it trips at 10 CFH 

h. Purge the BB using a argon flow rate of 70 CFH 

i. Cover both BB openings for 5 s with your hands 

ii. Uncover one end and wait 5 s 

iii. Cover both BB openings for 5 s with your hands 

iv. Uncover the other end and wait 5 s 

i. Repeat step h 5 times 

j. Reduce the argon flow rate to 10 CFH 

k. Check that the BB housing is cool and that the argon is flowing 

l. Insert correct detector filter for the initial set point 

i. Filter 0, 700 to 1300 °C, Low with insulation (LIN) 

ii. Filter 1, 1300 to 1800 °C, Medium (MED) 

iii. Filter 2, 1800 to 2500 °C, High (HI) 

iv. Filter 3, 2500 to 3100 °C, Extra High(XH) 

m. Switch control mode to [MANUAL] 

n. Turn the potentiometer to 0 

o. Press the [START], [WATER ON], and [RUN] buttons 

i. Note: The BB does not control the chilled water flow the automatic 

BB shut off switch has been disabled 

p. Turn the potentiometer slowly until the voltmeter reads between 150 VAC 

and 200 VAC (sets BB below 1300 °C) 

RTMLP11 Page 1 of 3

Optical Technology Division (844) 

Radiance Temperature Measurements Laboratory Procedure 

Variable-Temperature Blackbody Operation 

Written by: Charles Gibson Procedure: RTMLP11

Approved by: ................... Date: ...................

Revised by: ................... Date: ...................
 

 35

2. Operating Procedure

a. Run the BB control program 

i. Program is BBPROG.PRG in BetterBasic 

ii. Enter BB at the DOS prompt 

iii. Enter measurement direction 

(1) ‘0' to run high to low 

(2) ‘1' to run low to high 

iv. Enter set point unit 

(1) ‘C’ for ° C 

(2) ‘F’ for ° F 

v. Enter temperature range 

(1) LOW 

(2) LIN 

(3) MED 

(4) HI 

(5) XH 

vi. Insert the correct filter and press [Enter] 

b. Press [Shift S] to enter the initial set point 

c. Adjust the potentiometer until the temperature is 20 °C above the set point 

d. Switch the control mode to [PC] to maintain the set point 

WARNING! 

DO NOT INCREASE THE SET POINT BY STEPS LARGER THAN 

20 °C TO REDUCE DAMAGE TO THE BB 

e. Select a new set point (the set point is in °C or °F depending on set point 

unit selected) 

i. Press [Shift S] to enter the set point 

ii. Use the numeric keypad to increment the set point 

(1) Press the increment key 

(a) 100 °C ('7' key) 

(b) 10 ('4' key) 

(c) 1 ('1' key) 

(d) 0.1 ('0' key) 

(2) Press the Arrow key to set the new set point 

(a) ↑, to increase the set point ('8' key) 

(b) ↓, to decrease the set point ('2' key) 

Optical Technology Division (844) 

Radiance Temperature Measurements Laboratory Procedure 

Variable-Temperature Blackbody Operation 

Written by: Charles Gibson Procedure: RTMLP11

Approved by: ................... Date: ...................

Revised by: ................... Date: ...................

RTMLP11 Page 2 of 3
 

 36

f. If the new set point is not in the current range then the program will pause 

(suspending BB control) 

i. Depending on the measurement direction the default set points are 

(1) High to low default set points 

(a) XH 2500 °C 

(b) HI 2300 °C 

(c) MED 1800 °C 

(d) LOW 1300 °C 

(2) Low to high default set points 

(a) LOW 800 °C 

(b) MED 1300 °C 

(c) HI 1800 °C 

(d) XH 2500 °C 

ii. If the new set point is not the default value, then switch the control 

mode to [MANUAL] 

iii. The program will loop to step 2.a.v. (see )) 

3. EMERGENCY TURN OFF Procedure

a. Press the [EMERGENCY STOP] button on the power supply (the chilled 

water and argon will continue flowing) 

b. Continue with steps 4.b. to 4.j. 

4. Turn Off Procedure

a. Switch the control mode to [MANUAL] 

b. Turn to potentiometer to 0 

c. Press the [EMERGENCY STOP] button on the power supply (the chilled 

water and argon will continue flowing) 

d. Switch off the main breaker on the wall 

e. Wait until the furnace has stopped glowing 

f. Close the chilled water supply valve 

g. Close the chilled water return valve 

h. Close the cold water supply valve 

i. Close the argon cylinder valve 

j. Close the argon flow meter valve 

Optical Technology Division (844) 

Radiance Temperature Measurements Laboratory Procedure 

Safety Issues 

Written by: Charles Gibson Procedure: RTMLP11

Approved by: ................... Date: ...................

Revised by: ................... Date: ...................

RTMLP11 Page 3 of 3
 

 37

Appendix D: How to Request Heat-Flux Sensor Calibrations 

1. Prepare a purchase order with the following: 

 a. Company name and address 

 b. Contact person's name and phone number 

 c. Billing address 

 d. Service ID number requested (include range and points) 

 e. Test fee 

 f. Address to ship test item 

 g. Return shipping instructions (prepay and add, COD, charge to account with shipper) 

 i. the test fee does not include shipping costs 

 ii. customers are responsible for all shipping costs 

iii. If no instructions are given, NIST will return the test item by common carrier, 

 collect, and uninsured. 

2. Send the purchase order to: 

 Calibration Services 

 National Institute of Standards and Technology 

 100 Bureau Drive, Stop 2330 

 Gaithersburg, MD 20899-2330 

 

Tel.: (301) 975-2002 

FAX: (301) 869-3548 

E-mail: 

calibrations@nist.gov 

3. Send the test item(s) to: 

Charles Gibson 

National Institute of Standards and Technology 

100 Bureau Drive, Stop 8441 

Gaithersburg, MD 20899-8441 

Tel.: (301) 975-2329 

FAX: (301) 869-5700 

E-mail: cgibson@nist.gov

 WWW: http://physics.nist.gov/Divisions/Div844/staff/Gp3/gibson.html 

Heat-flux sensor calibrations are performed in February, May, August, and November. 

Requests for calibration services are scheduled after the receipt of a purchase order. 

NIST policy requires prepayment of all calibration services performed for non-U.S. 

organizations. Please contact the Calibration Program office to arrange payment.