Confined Space Entry and Ventilation Rates
Confined Space Entry
Learning Objectives:
Define a confined space.
Able to understand differences between Permit-Required Confined Spaces and non-Permit Confined Spaces.
Understand the hazards associated with Confined Spaces.
Understand responsibilities related to confined space entry.
Have basic understanding of emergency rescue.
Definition of Confined Space:
It is the workspace which has restricted means of entry or exit that is not designed for continuous human occupancy.
Grain Silos, trenches or Manholes going into sewers are some of the examples of Permit Required Confined Spaces. Motor control cabinets and Drop ceiling are some of the examples of non-Permit Required Confined Spaces.
Confined spaces are dangerous because the air in those confined space may not be suitable for humans, a physical entrapment can occur denying the person breathable air, water and food for several hours. Sharp objects can cause bleeding resulting in loss of blood and thereby causing death.
Joe Mabel, CC BY-SA 3.0, via Wikimedia Commons
Isolation/Lockout/Tagout:
- Separating piping from a confined space
- May include blanking, binding and double block and bleed
Hazards in Confined Space:
- Oxygen deficiency
- Toxic gases above PEL
- Potential for engulfment
- Flammable gas above 10% of LEL
- Potential for IDLH atmospheres
Low Oxygen Symptoms:
- 16% - Rapid breathing, drowsiness
- 14% - Faulty judgement, raapid fatigue
- 12%- Unconciousness
- 6%- Death
Solved Example: 9942-01
The main aim of Lockout/Tag out is to:
A. Maintain workplace coordination
B. De-energize equipment or material
C. Prepare data sheets
D. Organize the workplace
Correct Answer: B
Solved Example: 9942-01
What is the correct order of lockout tagout procedure?
A. Isolate, De-energize, Dissipation, Prepare for shut down
B. De-energize, Isolate, Dissipation, Prepare for shut down
C. Prepare for shut down, Isolate, De-energize, Dissipation
D. None of the above
Correct Answer: A
Ventilation Rates
Natural Ventilation:
A habitable room:- Requires one or more ventilation openings,
- The total area of which must not be less than $\dfrac{1}{20}^{th}$ of the floor area
- Some part of the opening must be more than 1.7 meters above floor level
Ventilation by Mechanical Means:
- One change per hour (1 ACH) must be provided to habitable rooms
- Three air changes per hour (3 ACH) to bathrooms and kitchens
- 30-40 ACH for catering and commercial kitchens
- 4-6 ACH for office areas
- 10 ACH for meeting rooms
- 10-15 ACH for hotel
- 6-15 ACH laboratories
- 0.5-1 ACH for high rise buildings
- 6-10 ACH for broadcasting studios
- 4-6 ACH for call centers
- 45-60 ACH for Horticulture
Solved Example: 9941-01
What is the purpose of local exhaust system?
A. Controls radiation of heat
B. Provides local cooling
C. Removes contaminants from work
D. Provides air supply
Correct Answer: C