Oxygen drop conversion to PPM review: A short cut method that can be used to quickly determine oxygen sensor drop to PPM: For each 1/10th of a percent (the smallest the oxygen sensor can read) there is a 5,000 PPM corresponding drop. Summary: 0.1% O2 drop = 5,000 PPM 0.2% O2 drop = 10,000 PPM [...]
Predicting O2 meter reading: Multiply vapor pressure (of known material) times 1300 to find maximum achievable PPM. Divide PPM by 50,000 to get predicted drop. [The reverse of multiplying times 5, and then multiplying times 10,000 (O2 is 1/5 of air) used in the "Understanding Meter Readings" section to get PPM] Subtract the predicted drop [...]
Predicting O2 meter reading: Known material has vp of 31 mmHg. Which of the following is the correct predicted O2 meter reading?
Predicting O2 readings: vp 15 mmHg Which of the following is the correct predicted O2 meter reading for this vapor pressure?
Predicting O2 readings: vp of 300 mmHg Which of the following is the correct predicted O2 meter reading for this vapor pressure?
LEL conversions to PPM review: LEL reading % times CF times PLEL% = ? ÷ 100 = ?% times 10,000 = ? PPM LEL % x CF x PLEL% = ? ÷ 100 = ?% x 10,000 = ? PPM 10% x 3.4x 4% = 136 ÷ 100 = 1.36% x 10,000 = 13,600 PPM
Suggested Monitoring Order: 1. Radiation 2. Corrosive 3. Oxygen 4. Flammable 5. Toxic
Suggested action for explosive atmospheres: <10% LEL continue investigation 10% - 25% LEL continue with extreme caution >25% LEL withdraw immediately (implement engineering controls such as ventilation etc.)
Lower Explosive Limits Formulas: Simple: LEL Reading x CF = Actual % LEL Entry Team Turn Back: Desired % LEL Reading (i.e. 25%) ÷ CF = Actual LEL meter Reading Obtain 10% LEL: PLEL x 10,000 ÷ 10 = 10% LEL in PPM Convert meter % to PPM: LEL Reading % x CF x PLEL% [...]
Oxygen: Meter % Drop to PPM: 20.9% - Actual Reading% x 5 x 10,000 = PPM Drop Predicted O2 Reading: 1300 Rule PPM for Known Chemical ÷ 50,000 = Predicted drop Subtract Predicted Drop from 20.9% = Predicted % O2 Meter Reading