Standards frequently used

The luminometer index (ASTM D 1740) is a characteristic that is becoming less frequently used. It is determined using the standard lamp mentioned above, except that the lamp is equipped with thermocouples allowing measurement of temperatures corresponding to different flame heights, and a photo-electric cell to evaluate the luminosity. The jet fuel under test is compared to two pure hydrocarbons tetraline and iso-octane to which are attributed the indices 0 and 100, respectively. The values often observed in commercial products usually vary between 40 and 70 the official specification is around 45 for TRO. 

In vinyls, the aryl phosphates are frequently used in combinations with phthalate plastici2ers. The proportion of the more expensive phosphate is usually chosen so as to permit the product to reflably pass the flammability specifications. In plastici2ed vinyls used in automotive interiors, these phosphates are used to pass the Federal Motor Vehicle Safety Standard 302. 

The volumes of heads must be calculated separately and added to the volume of the cylindrical portion of the tank. The four types of heads most frequently used are the standard dished head, torispherical or ASME head, ellipsoidal head, and hemispherical head. Dimensions and volumes for all four of these types are given in Luken.s Spun Heads, Lnkens Inc., Coatesville, Pennsylvania. Approximate volumes can also be calculated by the formulas in Table 10-65. Consistent units must be used in these formulas. 

This discussion of pressure vessels is intended as an overview of the codes most frequently used for the design and construction of pressure vessels. Cnemical engineers who design or specify pressure vessels should determine the federal and local laws relevant to the problem and then refer to the most recent issue of the pertinent code or standard before proceeding. Laws, codes, and standards are frequently changed. 

The U-tube exchanger with copper tubes, cast-iron header, and other parts of carbon steel is used for water and steam services in office buildings, schools, hospitals, hotels, etc. Nonferrous tube sheets and admiralty or 90-10 copper-nickel tubes are the most frequently used substitute materials. These standard exchangers are available from a number of manufacturers at costs far below those of custom-built process-industry equipment. 

Temperature Measurement This is usually simple, and standard temperature-sensing elements are adequate for continuous use. Because of the high abrasion wear on horizontal protection tubes, vertical installations are frequently used. In highly corrosive atmospheres in which metallic protection tubes cannot be used, short, heavy ceramic tubes have been used successfully. 

Rutherford back-scattering spectroscopy (RBS) is one of the most frequently used techniques for quantitative analysis of composition, thickness, and depth profiles of thin solid films or solid samples near the surface region. It has been in use since the nineteen-sixties and has since evolved into a major materials-characterization technique. The number and range of applications are enormous. Because of its quantitative feature, RBS often serves as a standard for other techniques. 

The API standards describe the method used in rating engines and the recommended practice for engine installation, maintenance, and operation [2,3]. In oil field operations the API rating standards are most frequently used. 

The word concentration is frequently used as a general term referring to a quantity of substance in a defined volume of solution. But for quantitative titrimetric analysis use is made of standard solutions in which the base unit of quantity employed is the mole. This follows the definition given by the International Union of Pure and Applied Chemistry1 in which ... 

The most frequently used standard state is the pure liquid (x = 1) at the system temperature and pressure. When this standard state is used for all components in the mixture, the activity coefficients are said to be symmetrically normalized, because in this case, for every component /,... 

This pump is the same in principle as the piston type but differs in that the gland is at one end of the cylinder making its replacement easier than with the standard piston type. The sealing of piston and ram pumps has been much improved but, because of the nature of the fluids frequently used, care in selecting and maintaining the seal is very important. The piston or ram pump may be used for injections of small quantities of inhibitors to polymerisation units or of corrosion inhibitors to high pressure systems, and also for boiler feed water applications. 

The relative standard deviation RSD (also known as the coefficient of variation, c.o.v., or CV), which is frequently used to compare reproducibilities, is calculated as... 

Recently a new method was developed for the complete liquid chromatographic separation and diode array detection of standard mixtures of the 14 most frequently used synthetic colorants. Protocols for RP-HPLC - " and IP-HPLC techniques have been extensively described and the techniques were compared with micellar electrokinetic capillary chromatography, - which has been shown to be suitable for the analysis of synthetic colorants. 

Ampicillin is the standard penicillin that has broad-spectrum activity, and is the drug of choice for enterococci sensitive to penicillin. Amoxicillin is frequently used as well. Increasing E. coli resistance has limited amoxicillin use in acute cystitis. Amoxicillin-clavulanate is empirically preferred due to resistance. 

To assure consistency and speed in multidisciplinary structure analysis of low-MW compounds involving various techniques (IR, NMR, MS, etc.) most industrial laboratories use a Standard Operating Procedure (SOP). In such schemes IR analysis is frequently used as a cheap filter for a quick starting control and as a means for verification. As IR detects only structural units identification of an unknown compound on the basis of IR is difficult. Mass spectrometry is used as the prime identification tool and is especially important in the determination of the exact mass and gross formulae. While structural prognostication on the basis of MS is difficult for the non-expert, a posteriori interpretation is quite feasible. H NMR is both easy and cheap, however requires greater sample quantities than either... 

Chemical ionisation is the most frequently used ionisation technique in SFC-MS. It provides better sensitivity compared with charge exchange. All standard Cl reagent gases can be used in SFC-MS. In the absence of a modifier, CO2 can act as reagent gas giving real molecular ion spectra (eq. 7.2) ... 

HPLC log P techniques, first described by Mirrlees et al. [374] and Unger et al., [375], are probably the most frequently used methods for determining log/1. The directly measured retention parameters are hydrophobicity indices, and need to be converted to a log P scale through the use of standards. The newest variants, breadths of scope, and limitations have been described in the literature [292-298]. A commercial automated HPLC system based on an extension of the approach described by Slater et al. [150] has just introduced by Sirius (www. sirius-analytical. com). 

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