Q.1 Define H2S and its characteristics and allowable limit.
Ans. H2S- It is a highly poisonous gas produced by decaying of organic substances. A common hazard in oil&gas industry, which got a characteristic to deaden the sense of smell, if exposed to a high concentration for prolonged time.
Characteristics of H2S:-
* odor of rotten egg even at very low concentration below 1ppm (parts per million).
* Colorless gas.
* Extremely corrosive .
* Soluble in water, crude oil or oil fraction (while the liquid turbulate, H2S will get released)
* Burns with blue flame releasing another toxic gas- Sulphur di Oxide (SO2).
Effects- 0-5ppm – eye complaints, irritations, rotten egg smell, bronchial constriction for asthma patients.
10 ppm- decreased Oxygen intake, increased blood lactate concentration(feeling tired),
20 pm- fatigue, loss of appetite, head ache, irritability, poor memory, dizziness.
>100 ppm (more than) – olfactory paralysis (smelling system).
>400 ppm (more than)- respiratory distress (difficulty in breathing)
> 500 ppm- Death.
STEL – short term exposure limit
TWA – Time weighted average
Q.2. Define IFR and Severity Rate.
Ans. Injury Frequency Rate (IFR) – Number of Injuries divided by Total Manhours worked per One Million (1,000,000). (No of Injuries/Total manhours worked) x 1000,000.
Incident Severity Rate (ISR) – Number of Lost Time Injuries (LTI) divided by Total Manhours worked per One Million. (No of LTI/ Total Manhours worked) x 1000,000.
Q3: Define arrestors:
Arrestor is a device that prevents or stops a specified thing.
Spark arrestor keeps the sparks from escaping outside.
Lightning arrestor is a protective device for electrical equipment that reduces excessive voltage from lightning to a safe level by grounding.
Q4.Explain Confined space and different types of gases in confined space.
Ans. Confined Space is a space which is large enough for a person to enter and perform...