Ceiling

Ceiling exposure. This is the concentration that should not be exceeded, even instantaneously. 

However, in practice the octane number has a ceiling imposed by refining industry constraints such as composition, lead reduction or elimination, cost, and demand volume and distribution. 

BE.3038 Compact wall and ceiling climbing robotic vehicle with dexterous manipulator arm for low cost remote nondestructive insoection In hazardous environments Mr Bryan Bridge Univ. South Bank London... 

Knickelbein M B and Menezes W J C 1992 Optical response of small niobium clusters Rhys. Rev. Lett. 69 1046 Ceilings B A, Athanassenas K, Lacombe D, Rayner D M and Hackett P A 1994 Optical absorption spectra of AUy,... 

Ceilings P J 1990 Liquid Crystals. Nature s Delicate Phase of Maffe/ (Princeton Princeton University Press)... 

Exposure to manganese dusts, fume, and compounds should not exceed the ceiling value of 5 mg/ms for even short periods because of the element s toxicity level. 

Having brought home from Berlin Fischer s traditions and an overriding interest in natural products, particularly carbohydrate and glycoside chemistry, Zemplen established and ran his laboratory very much in the Fischer style, adding, however, his personal touches. The laboratories had tall ceilings and large windows (not unlike the Fischer... 

Calculations of the interaction energy in very fine pores are based on one or other of the standard expressions for the pair-wise interaction between atoms, already dealt with in Chapter 1. Anderson and Horlock, for example, used the Kirkwood-Miiller formulation in their calculations for argon adsorbed in slit-shaped pores of active magnesium oxide. They found that maximum enhancement of potential occurred in a pore of width 4-4 A, where its numerical value was 3-2kcalmol , as compared with 1-12, 1-0 and 1-07 kcal mol for positions over a cation, an anion and the centre of a lattice ceil, respectively, on a freely exposed (100) surface of magnesium oxide. 

Secondary Treatments and Uses. Insulation boards normally have few secondary treatments. Some boards may receive a coating of primer and others may be laminated into panels of several thicknesses. Insulation boards are used for economical, insulative wall paneling, ceiling tiles, bulletin boards, and similar uses. Laminated panels are used for insulative panels, usually as roof decking or insulation under built-up roofing. 

The thermodynamic ceiling temperature (26) T for a polymerization is computed by dividing the AfTp by the standard entropy of polymerization, The T is the temperature at which monomer and polymer are in equHibrium in their standard states at 25°C (298.15 K) and 101.3... 

Tunnel Test. The tunnel test is widely used to test the flame spread potential of building products such as electrical cable (15) and wall coverings (16). The test apparatus consists of a tunnel 7.62 x 0.445 m x 0.305 m ia cross section, one end of which contains two gas burners. The total heat suppHed by the burners is 5.3 MJ/min. The test specimen (7.62 m x 50.8 cm), attached to the ceiling, is exposed to the gas flames for 10 minutes while the maximum flame spread, temperature, and smoke evolved are measured. The use of this and other flame spread test methods has been reviewed (17). 

Factory Mutual Corner Test. This is a large-scale comer test used to test building products (18—20). The test rig consists of three sides of a cube. The two walls are 15.24 and 11.58 m by 7.62 m tall. The ceiling is 9.14 x 15.24 m. The product to be tested is mounted on the walls and ceilings ia a manner consistent with the iatended use. The fire source is a 340 kg stack of wood pallets located ia the corner. In order to pass the test, no flame can propagate to any extremity of the walls or ceiling. The Factory Mutual flammabiHty apparatus is proposed to replace this test for certain appHcations (21). 

Residential Construction. Owing to rising energy costs, the cost and low thermal conductivity are of prime importance in wall and ceiling insulation of residential buildings. The combination of insulation efficiency, desirable stmctural properties, ease of appHcation, abiHty to reduce air infiltration, and moisture resistance has led to use of extmded polymeric foam in residential constmction as sheathing, as perimeter and floor insulation under concrete, and as a combined plaster base and insulation for walls. 

These reactions are usehil for the preparation of homogeneous difunctional initiators from a-methylstyrene in polar solvents such as tetrahydrofuran. Because of the low ceiling temperature of a-methylstyrene (T = 61° C) (26), dimers or tetramers can be formed depending on the alkaU metal system, temperature, and concentration. Thus the reduction of a-methylstyrene by sodium potassium alloy produces the dimeric dianionic initiators in THF (27), while the reduction with sodium metal forms the tetrameric dianions as the main products (28). The stmctures of the dimer and tetramer correspond to initial tail-to-tail addition to form the most stable dianion as shown in equations 6 and 7 (28). 

The stoichiometric reaction of y -diisopropenylbenzene [3748-13-8] with two moles of j -butyUithium in the presence of triethylamine has been reported to produce a useful, hydrocarbon-soluble dilithium initiator because of the low ceiling temperature of the monomer (78,79) which is analogous in stmcture to a-methylstyrene however, other studies suggest that oligomerization occurs to form initiators with functionahties higher than two (80). 

The sound-absorbing properties of acoustical materials also are influenced by the manner in which the materials are mounted. Standard mounting methods for use in laboratory testing are specified in ASTM E795-92 (2). Unless noted otherwise, pubflshed data for acoustic ceiling materials are for Mounting Type E-400, for which the material being tested is suspended 400 mm below a hard surface. 

Products. There is a large number of commercially available sound-absorbing products for use on ceilings, walls, and for other special appbcations. Sound absorption coefficients and NRC values for some sound-absorbing products and treatments ate indicated in Table 2. 

Metal Pan Assemblies. These units consist of tiles and panels formed from perforated aluminum or steel with pads of fiber glass or mineral wool inserted into the pans to provide the sound absorption. They are used primarily for ceilings in a similar manner to acoustical tiles and panels. The pads are sometimes sealed in plastic film to prevent absorption of moisture, dirt, and odors. The perforated metal is relatively sound transparent and functions as the finished ceiling and the support for the sound-absorbing material. The perforated metal by itself has no acoustical value. 

Table 6. Acoustical Performance of Floor/Ceiling Constructions ...

Standard Test Methodfor Laboratory Measurement of Impact Sound Transmission Through Thor—Ceiling Assemblies Using the Tapping Machine, ASTM E492-90, ASTM, Philadelphia, Pa., 1990. 

Catalog of STC andllC Ratings for Wall andEloorj Ceiling Assemblies, Office of Noise Control, California Department of Health Services, Berkeley, Calif., 1984. R. S. Jones, Noise and Vibration Control in Buildings, McGraw-HiU Book Co., Inc., New York, 1984. 

The U.S. Occupational Safety and Health Administration (OSHA) has set a ceiling level for iodine of 0.1 ppm in air. The American Conference of Government and Industrial Hygienists (ACGIH) estabUshed 0.1 ppm as the TLV (TWA) for iodine. The maximum allowable concentration in air (MAK value) is also 0.1 ppm (104—106). 

Value is a PEL C, ie, permissible exposure limit ceiling exposure limit. 

Pipe StiU furnaces vary greatly and, in contrast to the early units where capacity was usuaUy 31.8—79.5 m /d (200—500 bbl//d), can now accommodate 3975 m (25,000 bbl) or more of cmde oU per day. The waUs and ceiling are insulated with firebrick and the interior of the furnace is partiaUy divided into two sections a smaller convection section where the oU first enters the furnace and a larger section fitted with heaters where the oU reaches its highest temperature. 

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