Also known as the moisture content or specific humidity. Humidity Ratio, W: The mass of water vapor present per unit mass of dry air. When reading a psychrometric chart, the specific enthalpy is the diagonal line intersecting the leftmost straight line. It takes into account both the sensible and latent heat components. Specific Enthalpy, h: The total energy content per unit mass of moist air. When reading a psychrometric chart, the relative humidity lines are the curved lines that span the chart. Specific Volume: The volume occupied by a unit mass of moist air. P s = saturation water vapor partial pressure at the pressure, p, and the dry-bulb temperature, Temperature, db P w = water vapor partial pressure at the total pressure, p, and dew-point temperature, Temperature, d p

The equation to calculate relative humidity is: Relative Humidity, RH%: The ratio of water vapor in the air to the maximum amount of water vapor the air can hold at a given temperature. The dewpoint temperature is the temperature at which the humidity ratio is equal to the humidity ratio at saturation: When reading a psychrometric chart, it is the horizontal line that intersects the curved leftmost line. Dew Point Temperature is also referred to as the condensation point because it is the temperature at which the water turns to liquid from vapor in the airstream. When reading a psychrometric chart, it is the diagonal line that intersects the curved leftmost line.ĭew-point Temperature, T dp:The measure of the dry-bulb temperature at the point that water vapor starts to condense to liquid or be removed from the air. It is used to determine the humidity and adiabatic saturation properties of air. Wet-bulb Temperature, T wb: The temperature measured by a thermometer with its bulb covered in a wet wick exposed to moving air. When reading a psychrometric chart, it is the horizontal axis at the bottom of the chart. It represents the sensible heat component of the air. Please pardon the dust while we complete this work :)ĭry-bulb Temperature, T db: The temperature of the air as measured by a standard thermometer. ** CONSTRUCTION ZONE ** We are actively updating the information below. Be aware that various brands and conditons will cause variations.The following psychrometric chart equations and terms have been adapted from the ASHRAE Fundamentals Handbook (I-P Edition), Chapter 1, Psychrometrics. Below the calculator is an approximate chart relationship of temperature to pressure. Now that I have indicated that, it relieves a lot of pressure. Psia is absolute pressure, which means it is gauge pressure + 14.7 psi. Psig (inches of mercury) is equal to psia â€“ 14.7 at sea level. Psig is equal to psis at sea level (14.7 psi). The term gauge signifies that the pressure has been read from a gauge that actually measures the difference between the pressure of the fluid or gas and the pressure of the atmosphere. Enter the temperature in either F or C degrees and the returned result is the alternate temperature and determined pressure in Barg and psig. It is the common phase 'environment friendly' replacement for R12 but does require system retrofit modifications. It is used in both automotive and commercial air conditioning applications. This refrigerant takes a significant step forward in environmental protection by achieving an ozone depletion factor of zero. Refrigerant R134a or HFC-134a is a commercially available hydrofluorocarbon (HFC) refrigerant for use as a long-term replacement for R-12 in new equipment and for retrofitting medium temperature CFC-12 systems. Refrigerant R134a or HFC-134a was developed to meet these needs.

Environmentally acceptable replacement compounds are therefore needed for use in existing medium and low temperature refrigeration applications. Production of chlorofluorocarbons (CFCs) has been phased out. This script determines the gas pressure based on temperature of R134a refrigerant. This calculator requires the use of Javascript enabled and capable browsers. R134a Refrigerant Pressure Temperature Calculator

Pressure enthalpy chart calculator