The ability of the Haz Mat Tech to predict vapor concentrations in an atmosphere with a known contaminant is valuable for an accurate hazard/risk assessment. In this section we will show the math as a continuation of the "Understanding Meter Readings" section. In the 1300 Rule Calculations section of this App it describes the method [...]
The formula: Meter Reading x C.F. = actual concentraions in PPM is used to determine actual PID readings. To predict a PID meter Reading for a known chemical use the following method: Predicted concentration in PPM using the 1300 Rule divided by the C.F. equalls the meter reading.
Predicting PID readings: Meter readings scenario: Your team is reading a known spill of xylene. Entry reports readings of 19,782 PPM on PID. Using the CF for xylene of 0.46 the actual concentration in air is 9,100 PPM. You are the science officer on this incident: You know that xylene has a vapor pressure of [...]
Predicting PID readings: Predict the following PID meter reading for a known chemical at S.T.P. Vapor Pressure (VP) of 33 mmHg, CF of 6.
Predicting PID readings: Predict the following PID meter reading for a known chemical at S.T.P. Vapor Pressure (VP) of 17 mmHg, CF of 2.4.
Predicting PID readings: Predict the following PID meter reading for a known chemical at S.T.P. Vapor Pressure (VP) of 15 mmHg, CF of 5.
Predicting PID readings: Predict the following PID meter reading for a known chemical at S.T.P. Vapor Pressure (VP) of 10 mmHg, CF of 1.8.
Oxygen meter drop conversion to PPM Review: O2 detector reports in percent (%). Oxygen represents approximately 1/5 of the air. The other 4/5 is primarily composed of Nitrogen (N2). When a oxygen sensor is indicating a drop in oxygen content, it is reflecting only 1/5 of the actual drop in the atmosphere. Therefore, we must [...]
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 [...]