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A centimetre of water [1] is a unit of pressure. It may be defined as the pressure exerted by a column of water of 1 cm in height at 4 °C (temperature of maximum density) at the standard acceleration of gravity, so that 1 cmH 2 O (4°C) = 999.9720 kg/m 3 × 9.80665 m/s 2 × 1 cm = 98.063754138 Pa ≈ 98.0638 Pa, but conventionally a nominal maximum water density of 1000 kg/m 3 is used, giving ...
The units are conventionally used for measurement of certain pressure differentials such as small pressure differences across an orifice, or in a pipeline or shaft, [1] or before and after a coil in an HVAC unit. It is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. At a temperature of 4 °C (39.2 ...
British thermal unit (60 °F) BTU 60 °F: ≈ 1.054 68 × 10 3 J: British thermal unit (63 °F) BTU 63 °F: ≈ 1.0546 × 10 3 J: calorie (International Table) cal IT: ≡ 4.1868 J = 4.1868 J: calorie (mean) cal mean: 1 ⁄ 100 of the energy required to warm one gram of air-free water from 0 °C to 100 °C at a pressure of 1 atm ≈ 4.190 02 J ...
Wine was measured with units based on the wine gallon of 231 cubic inches (3.785 L), beer was measured with units based on an ale gallon of 282 cubic inches (4.621 L) and grain was measured with the Winchester measure with a gallon of approximately 268.8 cubic inches (one eighth of a Winchester bushel or 4.405 L). In 1824, these units were ...
The miner’s inch measures the amount of water that would flow through a slot of a given area at a given pressure (for example, at a head of 6 inches of water, or 1.5 kPa.) In miner's inch the word inch refers to the area of the slot in square inches, while the pressure in inches of water refers to the height of water above the slot. A ...
The shed is a unit of area used in nuclear physics equal to 10 −24 barns (100 rm 2 = 10 −52 m 2). The outhouse is a unit of area used in nuclear physics equal to 10 −6 barns (100 am 2 = 10 −34 m 2). The barn (b) is a unit of area used in nuclear physics equal to one hundred femtometres squared (100 fm 2 = 10 −28 m 2).
In the European Union the gallon was removed from the list of legally defined primary units of measure catalogue in the EU directive 80/181/EEC for trading and official purposes, effective from 31 December 1994. Under the directive the gallon could still be used, but only as a supplementary or secondary unit.
A variant of the metric perm is used in DIN Standard 53122, where permeance is also expressed in grams per square meter per day, but at a fixed, "standard" vapor-pressure difference of 17.918 mmHg. This unit is thus 17.918 times smaller than a metric perm, corresponding to about 0.084683 of a U.S. perm.