OCHS2420 Mod7 Hydrogen Sulphide Flashcards
(27 cards)
Describe the health effects of inhalation of hydrogen sulphide.
Odor.
Irritation - eyes, nose, mouth, throat, lung. Loss of appetite.
Loss of smell
Headache, dizziness, ataxia, collapse.
Respiratory paralysis, cardiac arrhythmia, death.
How H2S is formed?
1, organic material
2, anaerobic conditions
3, sulphate-reducing bacteria
= H2S
Explain the role of OHS regulators and energy boards in regulating worker exposure to hydrogen sulphide
H2S is covered by broad hazardous material OHS laws, and a few specific H2S regulations in known high-risk industrial activities (oil & gas).
National and provincial energy board regulators, in their activities to protect public safety, indirectly improve worker safety.
Note:
- BC Oil and Gas Commission
- Canada Energy Regulator
What is hydrogen sulphide?
H2S
Usually a gas (unless under high pressure or extreme cold)
Highly toxic
In tiny amounts, has a rotten egg/sulphur smell
H2S is typically a by-product of other processes
H2S is created by anaerobic decomposition of organic material
Rapidly dissolves in water (or mucus membranes) to produce sulphuric acid.
What is sour gas?
Natural gas mixed with H2S.
The natural gas industry processes sour gas to remove H2S.
What is the usual H2S ceiling?
The ceiling limit for hydrogen sulphide is 10 parts per million.
C 10 ppm
No worker, at any time, for any duration, may be exposed to more than 10 ppm.
What is the H2S IDLH?
The Immediately Dangerous to Life or Health limit for hydrogen sulphide is ~100 ppm
What are the health effects of hydrogen sulphide?
Inhalation:
Airway irritation, pulmonary edema, headache, respiratory paralysis, unconsciousness, death.
Long term effects may cause asthma, RADS (reactive airway dysfunction syndrome), nervous system dysfunction.
Skin contact:
Cold effects from liquid form.
Eye contact:
Irritant. Cold effects from liquid form.
Not known to be carcinogenic, teratogenic, embryotoxic, reproductive toxin, mutagenic.
What is the rule of thumb for H2S concentrations?
1-10-100-1000ppm
1= Smell 10= Irritation (Regulatory limit) 100= Severe nose/throat/lung irritation, loss of appetite (severe enough to prevent self-rescue) 1000= Respiratory paralysis, arrhythmia, death
(around 150ppm, sense of smell stops working)
What workplaces may have H2S? (Name 4/7)
Gas plants, refinaries, petro-chemical plants, sulphur recovery plants.
Underground mines
Tank cars (railway), tank trucks (road)
Commercial laboratories
Septic tanks, sewers, manure handling areas
Pulp & paper mills
Pipelines
What is the LEL? (context, fire risk)
LEL = Lower Explosive Limit
The lowest concentration (%) of a gas or vapour in air capable of producing a flash of fire in presence of an ignition source (arc, flame, heat).
Sometimes called the Lower Flammable Limit.
Percentage vs ppm
1% = 10,000 ppm
What is the UEL? (context fire risk)
UEL = Upper Explosive Limit
The concentration (%) above which a gas will not burn.
What is the flammable range? Specifically for H2S.
The flammable range, is the range between the LEL and the UEL.
H2S has a range of 4 - 44.
(4% to 44%)
What H2S-specific sections are in the BC OHS Regulation?
The only H2S-specific regulations are under part 23, Oil and Gas.
What H2S-specific sections are in the BC OHS Regulation?
The only H2S-specific regulations are under part 23, Oil and Gas.
Why do most OHS regulations in Canada not have specific H2S sections in industries where H2S is a known hazard?
While there are not specific H2S sections/requirements, the general requirements for chemical hazards and confined space hazards provide sufficient regulation that would include H2S hazards.
List 5 areas of regulation (OHS & public safety) that apply to H2S, anhydrous ammonia, and chlorine gas.
- Design standards for equipment used in processes.
- Design standards for process facilities.
- Mandatory or highly recommended qualifications for workers who operate processes.
- Requirement for safe work procedures for normal work and emergency response.
- Exposure control plans.
Why might management of a H2S OHS program be potentially more challenging than for ammonia or chlorine?
There are uncertainties about the presence and quantity of H2S in a given situation.
Emergency scenario’s involving release and exposure of H2S can be sudden and with severe consequences.
How should an OHS program for H2S be started/approached?
1, Read the regulations and the ‘nearly law’ best practices carefully/completely.
2, Read the guidance documents from OHS and energy board regulators carefully/completely.
What is the maximum recommended short term exposures to H2S in a given day per the ACGIH?
5.
The ACGIH recommends no more than 5 short term exposures to H2S in a day.
American Conference of Governmental Industrial Hygienists.
How many breaths of high H2S concentrations are necessary to kill a worker?
1.
Name three broad areas of regulation for H2S.
1, General OHS regulations for hazardous materials.
2, Specific OHS regulations for activities where H2S is a known hazard.
3, Public safety laws, such as those administered by energy boards.
Why would a worker remain in an area of high H2S concentrations when there is a distinct/nauseating odor?
At high levels, H2S dissolves into the blood and paralyses the olfactory part of the brain, eliminating the sense of smell. Workers may be unaware of the high levels.
