What is a PSIS Pressure Gauge?

[spanishfly25]

does anyone knows what the second S stand for on a presure gauge label PSIS  Pound square inch ?

[USMCPMEL]

From what I can find that means it is a sealed gauge.

http://www.definiteanswers.com/q/What-are-PSIA-absolute-PSIG-gauge-and-PSIS-sealed-gauge-pressure-sensors-and-how-do-they-dif-4d6308499d0a4

[jimmyc]

http://www.dynisco.com/stuff/contentmgr/files/1/162fe0347e667528bd874845e66a40ef/pdf/gageabspress.pdf 

[darkness63]

Here is a good link for answers: http://bit.ly/PrtZe3

[spanishfly25]

Thanks everyone, I got it now. PSIG is reference to ambient atmospheric pressure, PSIA is reference to true 0 pressure and PSIS is reference to 14.7 PSI......interesting