API unit

The steel housing rarely exceeds 0.5 in. (12 mm) and a calibration is done in terms of API units, arbitrary units defined in a standard calibration pit located at the University of Houston. 

The MWD total gamma ray tools cannot be calibrated in the standard pit, since they are too large. Their calibration in API units is difficult because it varies with the spectral content of the radiation. By spectral matching the MWD logs can be made to closely resemble the wireline logs. The logs which were recorded by the MWD companies in counts per second (cps) are now recorded in API units. 

From P. tenuifolia, a plant which has been used in traditional Chinese medicine for thousands of years as an expectorant, tonic, tranquilizer, and to treat dementia, amnesia, and neurastenia, 11 saponins (7-17) were isolated. They share the same common sequence cited above (3-0-Glc-presenegenin-28-0-Fuc -Rha -Xyl) with additional substitutions at Fuc-3 either by a Rha (7,13-16) [12-15] or a Gal moiety (11) [13] or a (Z)-trimethoxycinnamoyl unit in the case of 9,10, and 17 [13,16], In the compounds 7,8,11-14, and 16, an acylation was observed at Fuc-4 by either an ( )- or (Z)-4-methoxy- or an ( )-trimethoxycinnamoyl group [12,13]. The originality of some compounds was observed by an unusual substitution at C-3 of Rha [13]. Namely, the presence of a jS-o-apiofuranosyl (Api) unit which is acylated at C-5 by a glutaroyl moiety (9-12) is very rare in the family of Polygalaceae. Finally, the Xyl of the trisaccharide sequence at C-28 is free or substituted by a monosaccharide at C-3 or C-. ... 

The measurement scale of the gammalog is the American Petroleum Institute (API) unit. This reference standard allows consistent comparisons between different gamma-ray counting devices. The API standard is a calibration test pit at the University of Houston. The American Petroleum (API) facility is constructed of concrete with an admixture of radium to provide uranium decay series, monazite ore as a source of thorium and mica as a source of potassium. The facility has 4.07% K, 24.2 ppm Th and 13.1 ppm U (Ellis, 1987). The API standard gives 200 API, equal to twice the mean of an average shale. Table 5.8 gives mean API values for some rock-forming minerals. 

Starches, used first in the late 1930s for filtration control (71), are stiU in use in the 1990s. Com starch is most commonly used in the United States. Potato starch is also used in the United States but primarily in Europe and elsewhere. Both com and potato starches are pregelatinized before dispersion in water (72). The API specifications for drilling fluid starch are listed in Table 8 (73). 

The basicities of indazole (1.31), 1-methyl (0.42) and 2-methyl (2.02) derivatives and of eight other substituted indazoles have been measured (67BSF261 The effect of substituents in the 3-position is similar in pyrazoles and indazoles with Api values as follows Me, 0.80 and 0.86 Cl, -3.01 and -2.98 Br, -2.85 and -2.82, respectively. A nitro group in the homocycle has an expected base-weakening effect of -2 pK units, whether it is at the 5- or the 6-position. 

The incremental pressure drop for wet mesh is not available for all operating conditions or for mesh of different styles. The data of York and Poppele for wet-mesh incremental pressure drop, APi in cm of water, are shown in Fig. 14-122 or parameters of liquid velocity L/A, defined as liquid volumetric flowrate, cmVmin per unit of mesh cross-sectional area in cm" liqiiid density Pl is in g/cm. ... 

Pressure-Vacuum Relief Valves For apphcations involving atmospheric and low-pressure storage tanks, pressure-vacuum relief valves (PVRVs) are used to provide pressure relief. These units combine both a pressure and a vacuum relief valve into a single assembly that mounts on a nozzle on top of the tank and are usually sized to handle the normal in-breathing and out-breathing requirements. For emergency pressure rehef situations (e.g., fire), ERVs are used. API RP 520 and API STD 2000 can be used as references for sizing. 

Relative density is usually determined at ambient temperature with speciahzed hydrometers. In the United States these hydrometers commonly are graduated in an arbitraiy scale termed degrees API. This scale relates inversely to relative density s (at 60°F) as follows (see also the abscissa scale of Fig. 27-3) ... 

For practical engineering purposes, relative density at 15°C (288 K), widely used in countries outside the United States, is considered equivalent to specific gravity at 60°F (288.6 K). With the adoption of SI units, the American Petroleum Institute favors absolute density at 288 K instead of degrees API. 

Lube oil units are typieally available in two versions the manu-faeturer s standard or in aeeordanee with API Standard 614. The major eomponents of a unit are the oil tank, auxiliary oil pump, double filter and, seleetively, one or two oil eoolers. All eomponents of the smaller units are mounted on a eommon bedplate, separated from the other eomponents. The oil ean be heated by an eleetrieal or steam-powered heating unit. The neeessary instrumentation is a standard supply item and, if requested, the switehes and motors ean be prewired. The main and auxiliary oil pumps are driven by different types of drivers (e.g., one by an eleetrie motor and the other by either a small steam turbine or by direet eonneetion to the shaft end of a major maehine easing in the turbotrain). 

API Std 613 Speeial-Purpose Gear Units for Refinery Serviees... 

All vibration equipment shall eonform to API 670. The probes shall be properly loeked to prevent movement during operation. Conneetions from oseillator/demodulators to the Purehaser s wiring shall terminate at suitable terminal bloeks loeated within junetion boxes mounted at the edge of the unit or baseplate. The probes shall be externally removable and adjustable without unit shutdown. 

API Std 613 Special Purpose Gear Units for Petroleum, Chemical, and Gas Industry Services, 4th Edition, June 1995... 

The lubrication system for the turbine is designed to provide both lubrication and cooling. It is not unusual that in the case of many gas turbines the maximum temperatures reached in the bearing section is about 10-15 minutes after the unit has been shutdown. This means that the lubrication system should continue to operate for a minimum of 20 minutes after the turbine has been shutdown. This system closely follows the outline in API Standard 614, which is discussed in detail in Chapter 15. Separate lubrication systems for various sections of the turbine and driven equipment may be supplied. Many vendors and some manufacturers provide two separate lubrication systems One for hot bearings in the gas turbines and another for the cool bearings of the driven compressor. These and other lubrication systems should be detailed in the specifications. 

This standard API Standard 613 covers special purpose gears. They are defined as gears, which have either or both actual pinion speeds of more than 2900 rpm and pitchline velocities of more than 5000ft/min (27 meters/sec). The standard applies to helical gears employed in speed-reducer or speed-increaser units. 

API 613, Special Purpose Gear Units for Refinery Services, 2nd edition, Washington, D.C., 1977. 

The internals of the reservoir should be coated unless the reservoir is constructed of 300 series stainless steel. API 614 mandates the use of 304L, 321, or 347 stainless steel processed to ASTM A 240. For the critical equipment units, the stainless steel reservoir is a good idea. A decision must be made by the user relative to the general purpose units. A good coating can keep the internals clean and free of corrosion if applied properly. When the idea of stainless steel reservoirs was introduced, it met with immediate resistance, but as the alternatives were considered, it began to gain acceptance. 

The special purpose gear unit should have a specified API 613 service factor of 1.4 as a minimum. The service factor used in the gear design should be selected to meet the requirements of API for the application. 

The low speed gear shaft and the housing must be designed to permit installation of a stub shaft for a torsiograph unit if an operational problem occurs. API 613 gives the details of the shaft end requirements for attaching a torsiograph. This should be done on all synchronous motor compressors and on multiple driver or multiple compressor case trains. 

If the gear unit application must have its own oil supply, such as with some retrofits, the intent of the API 614 should be employed. 

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