Sub MkIIP Oxygen & Carbon Dioxide Monitor
User Manual - US Navy Version
Document Ref
: AS2-802-14 -
January 2016
Page 22
13 Appendix A
– %SEV explanation
The specification for the O2 readings for this product are reported on the display as percent
surface equivalent value (%SEV). %SEV is a partial pressure unit of measurement, indicating
the concentration of oxygen (% by volume) at the surface that yields the same partial
pressure of oxygen as that present in the current environment. %SEV on the Sub MkIIP uses
1000mbara as its surface pressure for a point of reference.
For example:
1) If the atmospheric pressure on the day of the test was 1003mbara
2) Assume the gas being used was 100% medical grade oxygen
3) Without any tolerance on the reading, the perfect reading on the display of this
instrument would be 100.3 %SEV.
4) Adding in the tolerance of ±1% of the reading would allow a maximum error of
±1.003%SEV.
5) Making the upper limit = 101.303 %SEV
6) Making the lower limit = 99.297 %SEV
