Building construction classes

The discussion of laboratory facihties has been limited to the building occupancy class in order to avoid having to go into all the parameters which would be needed if this discussion were to be extended to high hazard, or educational classes, the next most likely possibilities. However, laboratory facilities do represent a degree of risk greater than many other uses which would also be considered appropriate to the same classification so extra care is needed to ensure that construction practices and materials used in the interior finish do not add to the risks or defeat the intended level of protection. 

Thermoplastic rubber is a relatively new class of polymer. It has the solubility and thermoplasticity of polystyrene, while at ambient temperatures it has the toughness and resilience of vulcanized natural rubber or polybutadiene. These rubbers are actually block copolymers. The simplest form consists of a rubbery mid-block with two plastic end blocks (A-B-A), as shown in Figure 5.7. Examples of commercial products are Kraton and Solprene . These materials are often compounded with plasticizers to decrease hardness and modulus, eliminate drawing, enhance pressure-sensitive tack, improve low-temperature flexibility, reduce melt and solution viscosity, decrease cohesive strength or increase plasticity if desired, and substantially lower material costs. Low levels of thermoplastic rubbers are sometimes added to other rubber adhesives. These materials are used as components in the following applications PSAs, hot-melt adhesives, heat-activated-assembly adhesives, contact adhesives, reactive contact adhesives, building construction adhesives, sealants, and binders. Two common varieties of thermoplastic rubber adhesives are styrene-butadiene-styrene (S-B-S) and styrene-isoprene-styrene (S-I-S). ... 

A low viscosity, preaccelerated, thixotropic flame retardant polyester (ASTM E-84, <25 flame spread - Class 1 - with 3% antimony trioxide or pentoxide, or <75 - Class 2 - without either addition), offering excellent wet-out and low drainage for use in hand-lay, spray/projection and filament winding in the manufacture of articles for the transportation, mining, electrical and building-construction industries. 

The seismic loss estimation of buildings is dependent on the lateral load resistance characteristics of buildings. Since building codes are being improved over the years, load resistance is dependent on the age of buildings. In addition, the resistance also depends on (1) construction class (e.g., steel moment-resisting frame),... 

The metallic impurities present in an impure metal can be broadly divided into two groups those nobler (less electronegative) and those less noble or baser (more electronegative) as compared to the metal to be purified. Purification with respect to these two classes of impurities occurs due to the chemical and the electrochemical reactions that take place at the anode and at the cathode. At the anode, the impurities which are baser than the metal to be purified would go into solution by chemical displacement and by electrochemical reactions whereas the nobler impurities would remain behind as sludges. At the cathode, the baser impurities would not get electrolytically deposited because of the unfavorable electrode potential and the concentration of these impurities would build up in the electrolyte. If, however, the baser impurities enter the cell via the electrolyte or from the construction materials of the cell, there would be no accumulation or build up because these would readily co-deposit at the cathode and contaminate the metal. It is for this reason that it is extremely important to select the electrolyte and the construction materials of the cell carefully. In actual practice, some of the baser impurities do get transferred to the cathode due to chemical reactions. As an example, let the case of the electrorefining of vanadium in a molten electrolyte composed of sodium chloride-potassium chloride-vanadium dichloride be considered. Aluminum and iron are typically considered as baser and nobler impurities in the metal. When the impure metal is brought into contact with the molten electrolyte, the following reaction occurs... 

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