Search results
Results from the WOW.Com Content Network
It can be measured with a dissolved oxygen probe such as an oxygen sensor or an optode in liquid media, usually water. [1] The standard unit of oxygen saturation is percent (%). Oxygen saturation can be measured regionally and noninvasively. Arterial oxygen saturation (SaO 2) is commonly measured using pulse oximetry.
It is measured as a unit of energy per unit mass or volume of substance. The HHV is determined by bringing all the products of combustion back to the original pre-combustion temperature, including condensing any vapor produced. Such measurements often use a standard temperature of 25 °C (77 °F; 298 K) [citation needed].
The concentration of oxygen in the air (mmols O 2 per liter of air) therefore decreases at the same rate as the atmospheric pressure. [26] At sea level, where the ambient pressure is about 100 kPa , oxygen constitutes 21% of the atmosphere and the partial pressure of oxygen ( P O 2 ) is 21 kPa (i.e. 21% of 100 kPa).
Under these conditions, p 1 V 1 γ = p 2 V 2 γ, where γ is defined as the heat capacity ratio, which is constant for a calorifically perfect gas. The value used for γ is typically 1.4 for diatomic gases like nitrogen (N 2) and oxygen (O 2), (and air, which is 99% diatomic).
The latent heat with respect to volume is the heat required for unit increment in volume at constant temperature. It can be said to be 'measured along an isotherm', and the pressure the material exerts is allowed to vary freely, according to its constitutive law p = p ( V , T ) {\displaystyle p=p(V,T)\ } .
Air changes per hour, abbreviated ACPH or ACH, or air change rate is the number of times that the total air volume in a room or space is completely removed and replaced in an hour. If the air in the space is either uniform or perfectly mixed, air changes per hour is a measure of how many times the air within a defined space is replaced each hour.
2 is usually obtained by the fractional distillation of liquefied air. [53] Liquid oxygen may also be condensed from air using liquid nitrogen as a coolant. [54] Liquid oxygen is a highly reactive substance and must be segregated from combustible materials. [54]
Assuming initial atmospheric conditions (1 bar and 20 °C), the following table [1] lists the flame temperature for various fuels under constant pressure conditions. The temperatures mentioned here are for a stoichiometric fuel-oxidizer mixture (i.e. equivalence ratio φ = 1).