Panametrics XMO2 - Appendix A. Two typical applications; A.1 Blanketing gases in hydrocarbon liquid storage tanks

Appendix A. Two typical applications
A.1 Blanketing gases in hydrocarbon liquid storage tanks
The XMO2 transmitter and its associated sample system is often used to measure the concentration of oxygen (O
2
) in the
nitrogen (N
2
) or carbon dioxide (CO
2
) gases used to blanket hydrocarbon liquids during storage.
A.1.1 The problem
Air can leak into the vapor space above hydrocarbon liquids stored in tanks or process vessels, forming a potentially
explosive gas mixture. To solve this problem, inert gases such as N
2
or CO
2
are often used to purge the vapor space above the
stored liquid and dispel any O2 that may have leaked into that space. In such a system, one must constantly monitor the level
of O
2
in the vapor space to make sure that an explosive gas mixture does not form.
A.1.2 Equipment used
A typical instrumentation package for this application includes an XMO2 transmitter configured for a range of 0-21% O
2
in
N
2
or CO
2
and operating conditions of ambient temperature and atmospheric pressure. The XMO2 is mounted in a sample
system similar to the one shown in Figure 59 below (ref. dwg. #731-559).
Figure 59: Blanketing gas sample system
40