# Howl-Mann Equation

 L : equivalent standard leak rate
V : internal volume of the device package cavity
Po : atmospheric pressure absolute
Pe : pressure of exposure absolute
t1 : time of exposure to Pₑ
t2 : dwell time between release of pressure and leak detection

### Tracer gas

Krypton 85

Tank Specific Activity µCi/atm/cc (Kr85 concentration : {{ Kr85_ppmv.toFixed(0) }} ppmv)
Conversion : µCi = c/m (counts per minute)
Conversion : K factor = (c/m)/µCi

Tracer gas is used for pressurization and detection. It is assumed not to be part of cavity initial content.

Partial pressure of {{ Pe_gas }} forced in during pressurization = {{ D(Pt1) }} {{ Pe_unit }}

Partial pressure of {{ Pe_gas }} remaining after dwell time = {{ D(Pt2) }} {{ Pe_unit }}

R1 : measured leak rate of {{ Pe_gas }} = {{ R1 }}

Rad : measured radiation of {{ Pe_gas }} = {{ D(Kr85_RadAfterDwell) }} µCi ({{ D2(curieToCounts(Kr85_RadAfterDwell)) }} c/m)

Warning – Measured Radiation is below 500 c/m

## Reverse Calculations

If the Partial Pressure of {{ Pe_gas }} forced in is {{ Pe_unit }} then L = {{ LFromPt1 }} {{ L_unit }} of {{ L_gas }} and R1 = {{ RFromPt1 }} {{ R_unit }} of {{ Pe_gas }}

If R is measured at {{ R_unit }} of {{ Pe_gas }} then L = {{ LFromR }} {{ L_unit }} of {{ L_gas }}
If Rad is measured at c/m, equivalent to {{ D(countsToCurie(kr85_counts)) }} µCi then L = {{ D(LFromCounts) }} {{ L_unit }} of {{ L_gas }}

DISCLAIMER : Please contact Oneida Research Services, Inc. at (315) 736-5480 or Daniel Rossiter by email at djrossiter@orslabs.com for technical discussions regarding the application of the Howl-Mann equation.
28-nov-2018 v3.4