Imperial units

Figure 1. Imperial unit hydrate chart for sour natural gas.

I have used units likely to be most familiar to the majority of my readers. Although I welcome the increasing use of SI units, many people still use imperial units—they are more familiar with a 1-in. pipe that a 25-mm pipe-... 

A graphical representation as shown in Figure 19.11. This is drawn in the logarithm-logarithm format and allows a rapid estimate of pressure loss to be expected. Note that this particular chart is in imperial units and is drawn for use with town gas. A correction for specific gravity would be needed for natural gas. 

SI units are widely used in the gas industry. Imperial units are also employed, particularly for measuring gas and for its calorific value. In some areas SI and Imperial units can co-exist, particularly thermal ratings, this can equally be expressed in kW and MW or in Btu/h and therm/h. 

American combustion equipment is frequently used. This tends to use Imperial units as well as degrees Fahrenheit and ounces per square inch pressure. 

Valve capacities can be compared by use of the Kv (or Cv when Imperial units are used) values. These factors are determined experimentally, and the Kv value is the number of cubic meters per hour of water that will flow through a valve with a pressure drop of one bar. The Cv value is the number of gallons per minute of water that will flow through the valve with a pressure drop of one-pound f. per square inch. As the gallon is a smaller unit in the USA, the number of gallons passed is greater, and the US Cv is 1.2 times the UK Cv. The Kv is about 0.97 of the UK Cv value. 

The unit of heat is the watt. However, the imperial unit should be understood, as it will still be met, particularly outside Europe. The ton of refrigeration is derived from an ability to remove sufficient heat from a short ton (2000 lbs) of water at 32°F to turn it to ice at the same temperature in the course of 24 hours. This amounts to a heat extraction rate of 3.517kW. 

Abbreviation for pounds per square inch although this abbreviation is very popular it has never had official approval, the correct imperial unit is lbf/in2. 

Convert the SI units to Imperial units and find the answer. 

See column 5 below. It is desirable to also include results in imperial units because many farmers, and possibly agricultural consultants, continue to think of manure use in imperial terms. Thus, 1 unit = 1% of one hundredweight = 1.12 lb (pounds), or 0.488 kg. 

Laboratories must use calibration standards that are metrological trace-ability to an embodiment of the unit in which they are expressed. This requires use of certified reference materials, usually to make up working standards that calibrate instruments in the laboratory. Implicit is that results will be expressed in common units, and while this is increasingly the case, the example of the Mars Climate Orbiter (chapter 1) should signal those still using versions of imperial units that it might be time to join the rest of the world and use SI units. 

There are two normally quoted formulas for the calculation of wheel parameters. The first is the classical formula, which is still quoted in imperial units ... 

At the time of writing, conversion from the Imperial (F.P.S) to metric system of units, especially in North America, is far from complete. Thus Imperial units have generally been used in the text with metric equivalents provided in brackets. In tables and figures, the system of units given in the original source (usually Imperial) has been retained. 

Conversion Factors for UK Imperial Units and Other Non-SI Units OF Measurement... 

Miscella Flux Rate The miscella flux rate is the maximum volumetric flow rate of miscella that can flow down through the bed of material per unit of material bed surface area. In SI units, it is commonly expressed as m /h per m, and in Imperial units, it is commonly expressed as gpm per ft. By simplification of units, the miscella flux rate can also be expressed as the maximum downward velocity of the miscella through the material bed (in m/min or ft/min). Miscella flux rates for various prepared oleaginous materials vary widely (see Table 1). 

The information below shows imperial to SI unit conversions for the units of measurement most commonly used in the Handbook. SI units are used throughout with, where appropriate, imperial units reported in parentheses. 

The intention of the Green Book ever since its appearance was not to present a list of recommendations as commandments, but rather its aim was and still is to help the user in what may be called a good practice of scientific language . Many well-established conventions are used in science and technology, but mixing conventions can lead to misunderstandings or even cause severe errors. One of those errors, caused by confusion of metric and imperial units, led to the loss of the NASA Mars Climate Orbiter (MCO) in 1999, worth about 200 Million USD of equipment and a non-quantified loss of scientific data and work. The reason for tlie loss of MCO was that Lockheed Martin Astronautics (LMA) software used imperial units (Ibf s) and Jet Propulsion Laboratory expected output from the LMA software... 

BS 5295 was first published in 1976 its room classification standards were strictly comparable to those of FS 209B except for approximations needed to convert imperial units (FS 209B) to metric units (BS 5295). 

The American specifications differ only in number of dimensional details and are based essentially on Imperial units. In case of rigid polymer blends (such as engineering blends), the specimen can be molded, machined on a lathe, or simply cut out from thin, flat sheets. 

Finally, the world literature on energy production and consumption is plagued by a proliferation of measurement units. Variously, data are presented in terms of the International System of Units (SI, e.g., metres, pascals, joules), traditional industry-based units e.g., barrels of oil, kilowatt hours of electricity, million tonnes of oil equivalent) and, especially in the USA, Imperial units e.g., miles, British thermal units of heat, quads of energy, cubic feet of natural gas, bars of pressure). For the expression of time, however, units of days and years are generally more appropriate than the SI unit (seconds) in this field. In order to assist readers in translating units into those with which they are familiar, a set of conversion factors has been included. 

Dimension name Imperial unit Imperial abbreviation ... 

ASME SECTION VII APPENDIX - Consists of conversion factors for converting Imperial units to SI Units. 

The ASTM test follows the same principles but differs in certain details. The standard test specimen is based on imperial units, so that the preferred test piece is 127 mm long by 12.7 mm wide by a thickness of 12.7. 6.4, or 3.2 mm. The details of the apparatus used are the same as for the Izod test, which is covered in the nc.xi section but the form of expressing the result is different, being based on the energy normalized with respect to the length of the notch only, and not on the area behind the notch. This only serves to add to the difficulty in making comparisons between data obtained by the ASTM standard, with its dilTcrcnt test piece sizes and impact conditions, to that of the ISO standard. 

A variety of units are used in the literature for thermal properties, and this can be a nuisance when different sets of results have to be compared, or when values from an older publication are being used for ealculations. Prior to the adoption of the SI system, the two most eommon units for thermal conductivity were the cal. cm s C and the BTU in ft h F. There are two units of length in the imperial unit, because area is measured in square feet and thickness in inches, and this inconsistency is a potential pitfall for the unw ary. A self-consistent conductivity unit, the BTU ft h F, is obtained if the temperature gradient is measured in F ft instead of F in. but this is not as common. For diffusivity the e.g.s, unit is the cm s and the imperial unit is the ft h. The SI unit for conductivity is the W niK. and the unit for diffusivity is the m" s. For polymers it is more convenient to use a submultiple of the diffusivity unit, the mm" s. because this eliminates a factor of 10 Conversion factors arc given in Table 1. 

Note original values in Imperial units, converted to SI. Source SPI 48th Annual Conference... 

A rate of penetration, that is, the thickness of metal lost. This may be expressed in imperial units, mils per year (mpy), a mil being a thousandth of an inch, or in metric units, millimeters per year (mm/y). 

H-x charts in SI units for aqueous solutions of sodium carbonate and sodium sulphate (both recalculated from original data) are given in Figures 4.9 and 4.10, respectively, and a chart for magnesium sulphate, retained in its original Imperial units, is given in Figure 4.11. 

Table 10.4 shows the effect of two heat sources on various types of fabric. Woven and nonwoven fabrics of different area densities made from aramid and FBI fibre have been compared in terms of their respective thermal protective performance (TPP) indices and the results are shown in Table 10.5. TPP values are the times for a temperature gradient of 25 °C to be generated across the fabric thickness when exposed to a heat source as defined in ASTM D4108. The higher the TPP value, the better the thermal protective property. The original fabric constructional data were published in imperial units and they have been converted to SI units for consistency. Woven fabrics were designed as the outer shell material in firefighters turnout coats, and the needlefelt, nonwoven fabrics could be considered for use as a backing or thermal liner in thermally protective apparel. This work shows that nonwoven fabrics provide...

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