energy as a function of temperature in Ag-Sn and Au- Availability. To experienced electron microscopists Contact: Dr. Bernard J. Hockey, Physical Properties Section, Materials Building, Room A355, Phone 301921-2901. ENVIRONMENTAL SULFUR DIOXIDE POLLUTION MONITOR. PRECISION HUMIDITY MEASUREMENT This facility comprises two precision humidity generators and a gravimetric hygrometer that can be used separately or in combination for calibration, testing, and development of instruments, sensors and devices and for research on the properties of moist gases. The generators produce continuous gas flows of constant moisture content whereas the hygrometer makes accurate humidity measurements. percent. Limited capability for response time test Data acquisition system available. Applications: Calibration of dew-point hygrometer psychrometers, electric hygrometers, infra-redgrometers, dewcels, coulometric hygrometers; eva tion and testing of such sensors as carbon film, a. minum oxide, crystal array, lithium chloride, bar floride; enhancement of water vapor in air w pressure. Availability: Facility available for use on tests. search or programs of NBS divisions, other Gover ment agencies, and industrial or scientific laborat ies. Literature: [1] J. Res. NBS 40, 479 (1948) [2] NBS Monograph 73 (1964) [3] ISA Trans. 7 (No. 4), 356-362 (1969) Contact: Arnold Wexler, Chief, Humidity Section SULFUR DIOXIDE Sulfur dioxide, released in air by burning sulfur-con taining coal and oil, is one of the most common a pollutants. This detector, based on measuring the tensity of the fluorescence excited by a Zn or C: light source, is capable of continuously monitor sulfur dioxide in air over a wide range of concentra tion. The procedure is rapid, simple in operation and is specific to sulfur dioxide. Capability: The device developed at NBS can meas ure SO., in air from 1500 parts per million down to a few parts per billion. The response is linear over th wide range of concentration. The detector responds specifically to sulfur dioxide and is free from inter ference with water and other common gases presen in air. In the ppm range the photoelectron signa can be amplified and displayed on a recorder. In the ppb range, however, a few minutes integration of the photoelectron flux from the photomultiplier tube necessary. Applications: The measurement of SO, in smokestack effluent and in ambient air. Quick calibration of cylinders containing standard mixtures of SO, and air Availability: To any qualified NBS research worker Capability: Gas flows up to 150 cubic decimetres per minute. Ambient temperatures from +65 to -75°C. Mixing ratios from about 150 to 1 x 50 g/kg (1.5 10 to 0.01 ppm). Dew point of +65°C to frost point of 100°C. Ambient pressures from atmos- after an initial training period with Dr. Frederick P pheric to 50 mb. Generated moisture contents known to 0.5 percent or better over most of range and to 2 percent at extremes. Measurement accuracy 0.1 Schwarz. In appropriate instances individual research workers from other Federal organizations can gain access to the facility. 4 A special laboratory building for large scale fire experiments has just been completed. Capability: A major feature of the building is a 60 ft X 120 ft test floor with a 32 ft ceiling height. The test floor is equipped with smoke abatement equipment to meet air pollution regulations, water supplies and floor drains, making it suitable for a variety of fire experiments. A shop for the fabrication of test structures, a conditioning room for the storage of materials and test structures prior to test, an instrument room, and office and service areas complete the building. The only permanent experimental facility on the test floor is the Fire Research Test Furnace described in detail below. Other test structures and apparatus are erected as needed for specific programs, providing maximum flexibility in space utilization. The facilities are: A room and corridor facility. This consists of a corridor approximately 50 ft long with two 8 ft by 8 ft rooms opening onto the side wall. Provisions are made for varying the wall and ceiling spacings and controlling draft conditions. The facility can be used for study of the spread of fire through corridors, the movement of smoke and gas through room-corridor systems, the effect of surface finishing materials on fire spread, and related purposes. A burn room and smoke movement facility. This is a two story masonry structure with controlled ventilation and communication between floors. It can be used to conduct studies of the burning of room furnishings or to study the spread of smoke, gas, and fire through a multi-compartment structure. A rate of heat release calorimeter. This instrument measures the rate of heat release and the total heat release from a large sample of material when exposed to a controlled energy flux. It is used to measure the energy contribution of materials involved in a building fire. A research test furnace. This is a medium-sized unit providing conformity with the temperature-time exposure specification of ASTM E119, plus extension to 150%. It will accommodate 30-ton walls or partitions 10 feet long by 8 feet high, 20-ton columns 8 feet high, or 20-ton floor-ceiling assemblies 8 feet by 10 feet. Furnace pressure is controllable between -0.05 and +0.15 in. water to permit study of the effect on fire performance. The furnace can be used for fire endurance tests on structural components such as ducts, dampers, doors, and plumbing systems, on innovative constructions such as double modular walls, and on joints in wall-floor assemblies. Applications: The Fire Research Laboratory provides. a location where large scale fire experiments can be carried out under controlled conditions. Space is available for the construction of a variety of experimental installations. Availability: Available upon request for research experiments for other Government agencies and industrial groups. Available for research programs of industrial Research Associates. Availability of specific facilities is dependent on workload. Application: System I has been used for ultrasond measurements on solids and liquids, for electrica resistance measurements, for measurements of crack propagation in glasses and for the study of pha transition. Apparatus requiring electrical leads can be plugged into a receptacle at the inside bottom of the pressure vessel. A total of four leads are available. System II has been used for ultrasonic measurement: in liquids and in solids under either hydrostatic or non-hydrostatic conditions. Transducers to detec shear or longitudinal mode properties are mounted on the outside; they use a back plate as acoust buffer. A back plate with one electrical lead is als available. Availability: The equipment is available to qualife researchers after an initial training period or with assistance from Section personnel. Literature: D. L. Decker et al, High-Pressure Calibration, A Critical Review, J. Phys. & Chem. Ref. Data 1, no. 3, pp. 173-836, 1972. Contact: Dr. Peter L. M. Heydemann, Chief, Pressure and Vacuum Section, Metrology Building, Room A149, phone 301-921-2121. HIGH PRESSURE FLUORESCENCE SYSTEM The optical system measures the pressure-depender shift of the sharp fluorescent R,-line of ruby whic has been calibrated against the compression of NaC as the primary standard. The system was developed to measure pressure in the diamond-anvil high pressure cell, but with minor modification can be used in am pressure vessel which has optical access. Capability: Quantitative pressure determinations are made to 200 kbar with an accuracy in the range of 5 percent. Temperature capability to 300°C is also available, but the accuracy in the pressure measurement is significantly reduced at this temperature. Applications: Characterization of phenomena induced by pressure-such as phase transitions in solids freezing pressures of liquids, glass transition pressures in vitrified materials, compressibility measurements (in conjunction with x-ray measurement), and pres I sure distribution in various pressure transmitting media. Availability: On a selective basis when not required for Crystallography Section programs. The system must be operated by Section personnel and only work of mutual interest can be undertaken. This PVT (pressure-volume-temperature) apparatus is used to measure the density of liquids and solids (including polymers) with varying temperature and pressure. The method employs pressurized dilatometry in which a dilatometer is placed in a pressure chamber with glass windows. This chamber is, in turn, placed in a liquid thermostat with glass windows which is controlled by a refrigerator and electric heaters. The pressure is generated by a hand pump and may be determined by a bourdon or dead weight piston gage. The sample volume is determined in terms of the relative height of the mercury column of the dilatometer, using a cathetometer. Capability: Temperature range, -40 to 200°C. Constant heating and cooling rates may be selected as low as .05/hr; pressure range, 800 bar. (This range may be extended to 2 kbar by using a suitable pressure chamber.) A dead weight piston gage is available to maintain constant pressure during, for example, isobaric heating and cooling, and volume creep measurements. Applications: Ordinary equilibrium PVT measurements, including phase changes. Non-equilibrium measurements may include influence of temperature and pressure on glass transition and crystal growth mechanisms, glasses formed at constant volume, and volume creep and stress (pressure) relaxation. The densification of polymer glasses at elevated formation pressures gives a higher refractive index which suggests their use as optical lenses. Availability: By research workers on problems of mutual interest with those of the Rheology and Mechanical Properties Section. Initial instruction will be given by the Section staff. Literature: [1] J. E. McKinney and R. W. Penn, Rev. Sci. Instr. 43, 1212; [2] J. E. McKinney and M. Goldstein, J. Res., Nat. Bur. Stand. (U.S.) 78A, no. 3, 331-353 (May-June 1974). Contact: John E. McKinney, Rheology Section, Polymer Building, Room B330, Phone 301-921-2116. HIGH TEMPERATURE FACILITIES Levitation vacuum melting equipment for preparation of high-purity materials in the ALLOY PREPARATION LABORATORY. ALLOY PREPARATION Research grade samples of metals and alloys are prepared when such samples are not readily available commercially, or when accurate details are required concerning the purity of the constituents and the melting and fabricating history. Capability: Vacuum-induction melting and casting; arc furnace; levitation melting furnace; electron-beam zone refiner; electron-beam button melter; electronbeam evaporator; induction and resistance melting and casting furnaces; heat-treating furnaces; coldworking equipment for rolling, swaging, and drawing. Applications: High purity iron ingot with 1.194 ± 0.004% carbon; homogeneous ingot of magnesiumzinc; 200-mesh lead-indium powders. Literature: NBS Tech. News Bull. Vol. 56 No. 8, p. 182-183 (Aug. 1972). Contact: H. C. Burnett, Scientific Assistant, Metallurgy Division, Materials Building, Room B260, Phone 301921-2813. MICROCALORIMETRY Capability: The facility provides the capability for measuring small thermal power (uncertainty within ±10μW) associated with (a) energies of reaction in aqueous solution at 300 K; (b) energies of transition. over the range 300 to 470 K; and (c) energies of vaporization from 300 to 470 K. A commercial Calvettype microcalorimeter and NBS-designed microcalorimeters are available, utilizing the basic principles of heat conduction microcalorimetry. A thermopile is used to measure the temperature difference between the reaction vessel and a heat sink maintained at constant temperature. Measurement of the emf of the thermoelement as a function of time yields a measure of the rate of heat exchange. Resolution of the thermoelement voltage to within a few nV corresponds to a temperature sensitivity of a few tenths of a microdegree. Data are recorded both in analog and in digital form. For calibration purposes, electrical energy may be introduced with a precision better than 0.01%. Applications: Many applications are found in the biological sciences where heat, as a totally non-specific entity, has been found to be a useful tool for studies involving enzyme catalyzed reaction, bacterial metabolism, cellular phenomena, and immunological processes. Since nearly all reactions of biological substances are accompanied by heat effects, microcalorimetry also possesses substantial potential for analytical purposes. Availability: Because of the complexity of the instrumentation and the procedures of operation, use of the facility is limited to qualified members of the NBS staff or other scientists, after specific training of perhaps two months. The facility may be used indirectly through cooperative or contractual research agreements. Literature: [1] E. Calvet and H. Prat, "Recent Progress in Microcalorimetry," translated from the French by H. A. Skinner, The MacMillan Company, New York, 1963. [2] "Biochemical Microcalorimetry," H. D. Brown, editor, Academic Press, New York, 1969. [3] R. N. Goldberg, R. L. Nuttall, E. J. Prosen, and Typical specific data for different standard reference materials of polyethylene, using the LOW TEMPERATUR ADIABATIC CALORIMETER. The second-order glass tran tion is evident for the sample with the largest C, around 240 K. PLATINIUM-LINED Capability: Liquid or crystalline samples up to 2" cm in volume are dissolved in 300±15 cm2 of any solution reactant that does not attack platinum. Minc modifications permit the introduction of gaseou samples in a flow system. For exothermic or endothermic reactions of 200 J or more, enthalpies solution may be measured between 293 and 363 for both rapid and slow reactions, with a precision of 0.02%. Calorimeter temperatures are measured with a quartz oscillator sensor with digital printout. The adiaba Ishield temperature is controlled automatically! eliminate heat transfer to the calorimeter from A. P. Brunetti, NBS Report No. 10 437 (1971). environment. The data are processed by a time-shared computer. The calorimeter is calibrated by supplying Contact: Dr. G. T. Armstrong, Chief, Thermochemistry a known amount of electrical energy to the calor Section, Chemistry Building, Room B350, Phone 301 921-2131. meter resistance heater before and after the chemica reaction measurements. |