GAS PRESSURE

ANEROID BAROMETER

• a device for measuring atmospheric pressure, often specially calibrated for use as an altimeter, consisting of a box or chamber partially exhausted of air, having an elastic top and a pointer to indicate the degree of compression of the top caused by the external air.

UNITS OF PRESSURE

• The unit of pressure in the SI system is the pascal (Pa), defined as a force of one Newton per square meter.

MEASURING GAS PRESSURE

• Gas Pressure is measured in mmHg (millimeters of mercury) with a barometer, which gives the barometric pressure. The standard atmospheric pressure is "the pressure exerted by a mercury column of exactly 760 mm in height when the density of mercury= 13.5951 g/cm3 (0 degrees C) and the acceleration due to gravity."

BAROMETER

• an instrument measuring atmospheric pressure, used especially in forecasting the weather and determining altitude.

TORR

• is a unit of pressure based on an absolute scale, now defined as exactly 1760 of a standard atmosphere. Thus one torr is exactly 101325760 pascals (~133.3 Pa). Historically, one torr was intended to be the same as one "millimetre of mercury".

STANDARD PRESSURE

• Standard temperature is defined as zero degrees Celsius (0 0C), which translates to 32 degrees Fahrenheit (32 0F) or 273.15 degrees kelvin (273.15 0K). This is essentially the freezing point of pure water at sea level, in air at standard pressure.

STANDARD ATOMSPHERE

• The International Standard Atmosphere (ISA) is an atmospheric model of how the pressure, temperature, density, and viscosity of the Earth's atmosphere change over a wide range of altitudes or elevations.

MANOMETERS

• is an instrument that uses a column of liquid to measure pressure, although the term is currently often used to mean any pressure measuring instrument.