mkm0023's version from 2015-12-09 04:47


Question Answer
How toxicants enter biological organisms (list 4)1. Ingestion – enter through the mouth into the stomach and threat eliminated by enforcement of rules on eating, drinking, and smoking

2. Inhalation – enter through the mouth or nose into the lungs and threat eliminated by ventilation, respirators, hoods, and other PPE

3. Injection – enter through cuts into the skin and threat eliminated by proper protective clothing

4. Dermal absorption – enter through skin membrane and threat eliminated by proper protective clothing
How toxicants are eliminated from biological organisms (list 3)1. Excretion – through kidneys, liver, lungs, or other organs

2. Detoxification – by changing the chemical into something less harmful by biotransformation

3. Storage – in the fatty tissue
TLVThreshold limit value; below this does the body is able to detoxify the body and eliminate the agent without any detectable effects
TLV-CCeiling – The concentration that should not be exceeded during any part of the working exposure
PELPermissible exposure level – PEL values are OSHA’s threshold doses and follow the TLV-TWA very closely. However, the PEL values are not as numerous and are not updated as frequently. TLVs are often somewhat more conservative.
How many hours per day can workers be exposed to a toxin at its TLV-TWA? How many days per week?Eight hours a day, 5 days a week
A maintenance worker in a refinery was exposed to 600 ppm of gasoline vapor for 4 hours and 0 ppm for 4 hours, is that worker safe?No, the TLV-TWA is 300 and the TLV-STEL is 500


Question Answer
OSHA-PSM – Process Safety Management-On site, for workers
- Sets general requirements for the management of hazardous chemicals
-14 major sections: employee participation. process safety information, process hazard analysis, operating procedures, etc.
EPA-RMP - Risk Management Plan- Off site, for public

- Has the following elements: hazard assessment, prevention program, emergency response program, onsite documentation

- Updated when the process or chemistry changes or when an update is requested
MSDS - Material Safety Data Sheet (list 7)1. Hazardous ingredients/identity information

2. Physical/chemical characteristics

3. Fire and explosion hazard data

4. Reactivity Data

5. Health Hazard Data

6. Precautions for Safe Handling and Use

7. Control Measures
Personal Protective EquipmentThe last line of defense as a part of the chemical plant industrial hygiene methods

Prevents or reduces exposure by providing a barrier between the worker and the workplace environment.
What does bypassing mean in an enclosure?Bypass air is supplied through a grille at the top of the hood. This ensures the availability of fresh air to sweep out contaminants in the hood. The bypass air supply is reduced as the hood sash is opened.
Estimating worker exposure during vessel filling operations. Describe each of the two emission sources. What is the transport phenomena associated with each source (type of fluid, mass and heat transport)?Evaporation of the liquid (heat and mass)

Displacement of vapor in the vapor space by the liquid filling the vessel (mass and fluid)
Air-ventilation in an enclosure; is it needed on the inlet or the outlet or both? Show how it should be done.Air ventilation is need on the inlet and outlet of an enclosure. Air enters the workspace, closer to ground level, and is vented out through a higher point near the ceiling.

Fan should be placed on the exhaust end of the systems because fans create a tiny pressure drop and pulls air out of the system. This ensures that leaks in the system draw air in from the workplace rather than expel contaminated air from the ducts into the workplace.

Ch 4

Question Answer
What is meant by an orifice coefficient or a discharge coefficient?Co, A complicated function of the Reynolds number of the fluid escaping through the leak and the diameter of the hole.

The frictional losses in the leak are approximated by a constant discharge coefficeint

For flowing liquids the kinetic energy changes are frequently negligible and the physical properties are constant

for flowing gases and vapors these assumptions are valid only for small pressure changes (P1/P2 < 2) and low velocities (< 0.3 times the speed of sound in gas)
What is meant by sonic velocity?The velocity of a gas or vapor is the velocity of sound at the prevailing conditions
What is Pchoked? Where is it measured?Choked pressure

It is the maximum downstream pressure resulting in maximum flow through a hole/pipe

Measured at throat


Question Answer
What is a puff?A formation that results from a near instantaneous release of material; shaped a bit like a cloud the moves with the wind
Can you see a puff?You can only see it if the gas/vapor released is visible
Does the puff get more concentrated as it moves downstream?The maximum concentration is always found at the puff center
Where is the isopleth in a puff?The puff isopleth is close to circular as it moves downwind; the diameter of the isopleth increases initially as the puff travels downwind, reaches a maximum, and then decreases in diameter

atmospheric conditions

Question Answer
What combination gives the most mixing in atmospheric conditions?The most mixing occurs with low wind speed, high insolation, in the early hours of the day
Which combination gives the least mixing in atmospheric conditions?The least mixing occurs with high wind speed, low insolation, at night
atmospheric conditions - An example of combination is high wind speed, daytime, and low insolation... does it give the most mixing?No


Question Answer
How are atmospheric conditions quantified in a Pasquill-Gifford Case model?Classified according to 6 different stability classes, depend on wind speed and quantity of sunlight

Applies to only neutrally buoyant dispersion of gases

A = extremely unstable, F = moderately stable (two extremes)
What is the effect of buildings or plant structures on air mixing or the absence of buildings (urban vs. rural)?Trees and buildings increase mixing, whereas lakes and open areas decrease it
What are the advantages and consequences of higher elevation toxicant release (e.g. from flare stacks, vapor emissions from tall distillation columns, etc.)?The release height significantly affects ground-level concentrations

As the release height increases, ground-level concentrations are reduced because the plume must disperse a greater vertical distance

Buoyancy and momentum of the material released change the effective height of the release


Question Answer
What is Insolation?solar input energy
When is Insolation high?Strong insolation corresponds to a sunny midday in midsummer in England
When is Insolation low?Slight insolation corresponds to similar conditions in midwinter
What is meant by atmospheric stability? (Unstable/Stable Air)Atmospheric stability relates to vertical mixing of air

During the day, the air temperature decreases rapidly with height, encouraging vertical motions

At night the temperature decrease is less, resulting in less vertical motion
Unstable (atmospheric conditions)the sun heats the ground faster than the heat can be removed so that the air temperature near the ground is higher than the air temperature at higher elevations; results in instabilities because air of lower density is below air of greater density
Neutral (atmospheric conditions)the air above the ground warms and the wind speeds increases, reducing the effect of solar energy input; the air temperature difference does not influence atmospheric mechanical turbulence
Stable (atmospheric conditions)he sun cannot heat the ground as fast as the ground cools; therefore the temperature near the ground is lower than the air temperature at higher elevations; the influence of buoyancy suppresses mechanical turbulence


Question Answer
ERPGEmergency Response Planning Guidelines (ERPG) – for air contaminants issued by the American Industrial Hygiene Association (AIHA)
ERPG-2the maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing irreversible or other serious health effects or symptoms that could impair their abilities to take protective action
ERPG-3the maximum airborne concentration below which it is believed nearly all individuals could be exposed for up to one hour without experiencing or developing life threatening health effects