1. Calculate volume of gas released in worse case scenario

Calculation

Initial pressure of gas in cylinder [bar]
Cylinder vol. in m3[litres/1000]
Atmospheric pressure [bar]

 

Result

Volume of gas at atmospheric  [m3]

2. Calculate concentration of gas in room and compare with WEL where one has been assigned or flammablity/explosion limits [for flammable gases]

Calculation

Volume of gas at atmospheric pressure [m3]
Volume of room [m3]
 

Result

Concentration of gas in room %

Check the MSDS for the Gas - if 25% of flammability limit could be exceeded protective measures (monitoring, ? Of area, removing ignition sources, flashback arrestors) will be required - contact Safety Office.

NiIf a WEL has been assigned these can be converted to % by dividing by 10,000.

3. Calculate Oxygen concentration after release of gas

Calculation

Volume of room [m3] Vr
Vol gas at atmospheric [m3] Vg
Vr - Vg [m3]
Vo = 0.21 (Vr -Vg) [m3]
 

Result

% Oxygen after release
= 100 x Vo/Vr

Normal Conc. Oxygen is 21% - concentrations below 18% present serious risk of asphyxiation. BCGA recommend a minimum oxygen concentration of 19% and maximum concentration of 23.5%, and evacuation of area at 18%. In this example (1) monitoring is recommended as level is only just above 18%