Gauge pressure psig

Gauge pressure is the pressure indieated on a simple pressure gauge. Simple pressure gauges establish an artificial zero reference at atmo,spheric pressure. The formula is psig = psia - ATM. 

The term vacuum is used to e.xpress pressures less than atmospheric pressure (sometimes represented as a negative psi on pressure gauges). Another scale frec]uently used is inches of mercury . The conversion is 14.7 psia = 29.92 Hg. Another scale gaining in popularity is the kilopascal (Kp) scale. 14.7 psia = 100 Kp 

Note that there are many ways to express vacuum. Simple gauges record vacuum negative psig. Compound gauges record vacuum as a positive psia. The v-t h.-uses inches of mercury in the daily forecast, and millibars ( GOO i  

Pump manufacturers express vacuum in aspirated feet of water in a ver r -i (0 psia = -33.9 feet of water). The pharmaceutical and chemical indue r Pascals (100,000 Pascals = atmospheric pressure) and the term TO C. conglomeration of values and conversion n, causes confusion. In (  

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Absolute pressure (psia) = boiler gauge pressure (psig) + atmospheric pressure (psiatm)... 

Gauge Pressure (psig). The gauge pressure is the pressure above atmospheric (or below in a vacuum). 

Measured with respect to zero (absolute) vacuum in a vacuum system, absolute pressure (psia) is equal to the negative gauge pressure (psig) subtracted from the atmospheric pressure. 

Another example a mixture of a solid and water had to be heated to 300°C at a gauge pressure of 1,000 psig (70 bar) before the... 

Pressures are quoted in pounds force per square inch (psi) and also in bars. As it is not usual to refer to bar gauge, I have, for example, referred to a gauge pressure of 90 psi (6 bar), rather than a pressure of 90 psig. ... 

Puv = maximum pressure developed in an unvented vessel, bar (gauge) or psig... 

Free Air q m Cubic Feet Per Minute at 60 F and 14.7 psia Compressed Air Cubic Feet Pci Minute at 60 F and 100 psig Pressure Drop of Air In Pounds per Square Inch Per 100 Feet of Schedule 40 Pipe For Air at 100 Pounds per Square Inch Gauge Pressure and 60 F Temperature ... 

Pressure. Pressure, defined as force per unit area, can be expressed as an absolute or relative value. Although atmospheric pressure constantly fluctuates, a standard value of 101.3 kPa (14.7 psia) has been assigned as the accepted value at sea level. The MaM in the psia stands for absolute, ie, the pressure is 14.7 psi (101.3 kPa) above zero pressure or a vacuum. Most ordinary pressure-measuring instruments do not measure true pressure, but rather a pressure relative to the barometric or atmospheric pressure. This relative pressure is called gauge pressure. The atmospheric pressure is defined to be 1 psig, in which the "g" indicates that it is relative to atmospheric pressure. Vacuum is the pressure below atmospheric pressure and is, therefore, a relative pressure measurement as well. The relationship between absolute and relative pressure is shown in Figure 3 (see Pressure measurement, Vacuum technology). 

The inlet pressures listed in the table are gauge pressures the pressures used in the calculations of j and f are absolute pressures. Thus, atmospheric pressure had already been accounted for in the inlet pressure. The outlet pressure is taken as standard atmospheric pressure. As an example, for a measured gauge pressure of 137.9 kPa (20 psig), the ratio Pjabs/P0 is 2.361. The actual value of the atmospheric pressure will vary day to day, and with altitude thus if an exact value for j or f is desired, local pressure measurements must be made. 

Vacuum and pressure measurements were all originally made compared to atmospheric pressure, or gauge pressure. The term psig (pounds per square inch-gauge) refers to this comparison. Absolute pressure includes atmospheric pressure (14.7 psi) and is called psia (pounds per square inch-absolute). For example, your tire pressure is 35 psig or 49.7 psia. Generally, unless otherwise identified, the lone identification psi refers to gauge pressure. 

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