Safety Engineering Group
ODH Cryogen Tool Instructions
This tool is designed to allow the user to analyze and document the Oxygen Deficiency Hazard of a room or area in compliance with the SBMS Subject Area: Oxygen Deficiency Hazards (ODH), System Classification and Controls.
- Enter the information requested in the units specified.
- The system complexity assigned a failure rate to use for the fatality factor calculation. If a specific system failure rate has been determined by an engineering evaluation, that rate may be used.
- The tool will calculate the lowest concentration of oxygen possible (assumes no ventilation available) and whether an ODH Classification may be exempt.
- If ventilation is available, the tool provides the minimum time after the leak has stopped that will allow oxygen concentration to reach to a level of 19.5% (Non-ODH Atmosphere level).
- If ventilation is assumed and required for the ODH classification, the ventilation performance must be verified by Safety Engineering.
| Cryogen: | Select a typically use cryogen from the pull down menu (if not listed, contact the SME) |
| System Complexity: | Select from the pull down menu the best description of the system. This is used to automatically fill in a system failure rate. |
| Failure Rate: | Generic of system failure rates will be filled based on system complexity. If "Other" is selected or the user has established a specific failure rate (i.e. from historical data or analysis), the user enters in the system failure rate in failures per hour. |
| Expansion Ratio: | From the Characteristics of Cryogenic and Low Temperature Fluids table, the appropriate liquid to gas expansion ratio will be filled in based on the cryogen selected. |
| Dewar Volume (liters): | Enter the system liquid volume in liters (typical dewar quantity). Note: 1 cubic foot = 28.31 liter |
| Free Room Volume (ft3) - V: | Enter the free space (air) volume of the room in cubic feet (a calculator is provided). Note: 1 meter = 35.3 cubic feet |
| Minimum Oxygen Concentration without Ventilation: | Calculates the Oxygen concentration if the cryogen freely expands in the room without any ventilation |
| Minimum Room Ventilation Rate (ft3/min) - Q: | Enter room ventilation rate in ft3/min (if known). |
| ODH fatality rate (per hour) - No Ventilation: | Calculate the ODH Fatality Rate based on Oxygen Concentration and Failure Rates provided (using formulas from subject area). |
| ODH Class - No Ventilation: | Provides ODH Class based on Fatality Fact with no ventilation (worst case). |
| Leak Rate (ft3/min) - R: | Input leak rate in ft3/min of the inert gas. Typically this will be either the boil-off rate of the experiment or the relief valve vent rate of the dewar (dewar vacuum jacket failure). Examples of relief valve rates are provided. |
| Maximum Leak Time (min): | Give time (in minutes) for the dewar to empty based on the given leak rate. |
| Ventilation Draws In Fresh Air: | Used to determine which ventilation formula is used. Yes - Ventilation system dilutes area with fresh air No - Ventilation system draws from room (such as a fume hood). |
| Oxygen Concentration at End of Leak: | Will calculate the minimum oxygen concentration with ventilation. |
| Safe Re-enter Time (min): | Calculates the time oxygen concentration will return to 19.5%. |
| ODH fatality rate (per hour) - With Ventilation: | Calculate the ODH Fatality Rate based on Oxygen Concentration and Failure Rates provided (using formulas from subject area). |
| ODH Class - With Ventilation: | Provides ODH Class based on Fatality Factor. |
| Calculate: | Tool performs ODH calculations when depressed. If any fields are changed, hit "Calculate" button again.. |
Last Modified: <% Response.Write (FileLastMod()) %>
Please forward all questions about this site to:
SEG Admin