Permit-Required Confined
Space Entry
29 CFR 1910.146
Objectives
• Understand Legislation Developed by
Government Agencies
• Identify and Use Those Regulations
• Identify a Potentially Hazardous Confined Space
Organizations
• ANSI
•
– American National Standards Institute
– Consensus Standards for Atmospheric Hazards
NIOSH
– National Institute for Occupational Safety and Health
– Documents Incidents
– Develops Guidelines for Safe Work
Organizations
(continued)
• OSHA
– Occupational Safety and Health Administration
– Began Looking at Confined Spaces in 1975
– Cited Under General Duty Clause
– Proposed Standard Released June 1989
Permit-Required Confined Spaces
29 CFR 1910.146
• Became Law April 15, 1993
• Employers MUST
– Characterize the Confined Space
– Provide a Permit Allowing Entry
– Supply Personal Protective Equipment When
Required
• Excludes Agriculture, Construction, and
Shipyards
Permit-Required Confined Spaces
29 CFR 1910.146
A Confined Space is...
• Large Enough and Configured Such That an Employee
Can Enter and Perform Assigned Work
• Has Limited or Restricted Means for Entry or Exit (e.g.,
Tanks, Vessels, Silos, Storage Bins, Hoppers, Vaults, and Pits)
• Is Not Designated for Continuous Employee Occupancy
Permit-Required Confined Spaces
29 CFR 1910.146
A Permit-Required Confined Space...
•
•
•
Contains or Has Potential to Contain a Hazardous Atmosphere
Contains a Material That Has the Potential for Engulfment
Internal Configuration of Inwardly Converging Walls or Sloping
and Tapering Floor
•
Contains Any Other Recognized Serious Safety or Health Hazard
Permit-Required Confined Spaces
29 CFR 1910.146
Engulfment...
• Surrounding and Capture of a Person
• Liquid or Finely Divided (Flowable) Solid
• Can Cause Filling or Plugging of Respiratory
System Via Aspiration
• Can Exert Enough Force on Body to Cause Death
by Strangulation, Constriction, or Crushing
Permit-Required Confined Spaces
29 CFR 1910.146
Immediately Dangerous to Life or Health (IDLH)...
• Immediate or Delayed Threat to Life
• Causes Irreversible Adverse Health Effects
• Interferes With the Ability to Escape from a
Permit Space
Permit-Required Confined Spaces
29 CFR 1910.146
IDLH Conditions...
• Flammable Gas, Vapor, or Mist >10% of LFL
•
(LEL)
Airborne Combustible Dust > LFL
Dust Obscures Vision at a Distance of 5 ft. or less
• Oxygen < 19.5 % or > 23.5%
• Exposures in Excess of OSHA’s PELs
Employer’s Responsibilities
• Determines Whether Permit-Required Confined
Spaces Exist
(Appendix A - Flow Chart)
• Informs Employees and Posts Warning Signs
• Prevents Entry If Employees are Not to Work in
PRCS
Employer’s Responsibilities
(continued)
• Develop and Implement a Written Permit Entry
•
•
•
Program
May Use Alternate Procedures
If a Non-Permit Space is Reconfigured, Reevaluation of the Space is Required
Must Inform Contractors and Use Permitting
Program
DANGER
CONFINED SPACE
ENTER BY PERMIT
ONLY!
Permit-Required Confined Space
ELEMENTS OF THE PROGRAM
• Prevent Unauthorized Entry
• Identify and Evaluate the Hazards Prior to Entry
(Appendix B- Who Can Do This, & How)
• Develop Safe Entry Procedures
– Acceptable Entry Conditions
– Isolating the Permit Space
– Purging, Inerting, Flushing, or Ventilating
– Barriers to Protect from External Hazards
Permit-Required Confined Space
(PRCS)
Equipment
• Testing and Monitoring Equipment
• Ventilating Equipment
• Communications Equipment
• Personal Protective Equipment
Permit-Required Confined Space
(PRCS)
Equipment (continued)
• Lighting
• Barriers and Shields
• Ladders and Other Entry/Egress Equipment
• Rescue and Emergency Equipment
Permit-Required Confined Space
ELEMENTS OF THE PROGRAM
(continued)
• Evaluate Space Before and During Work
• Provide at Least One Attendant Outside for the
•
•
•
Duration of Entry Operations
Multiple Space Response Procedures
Designate Active Roles
Rescue and Emergency Response Procedures
Permit-Required Confined Space
ELEMENTS OF THE PROGRAM
(continued)
• System for Preparation, Issuance, Use and
•
•
•
•
Cancellation of Permits
Procedures for Multiple Employer Worksites
Procedures for Closing Space
Review of Entry Operations
Review of Program
Permit-Required Confined Space
(PRCS)
•
•
•
•
Permit System
Entry Permit
Training
Other Appendices
– Appendix C: Example Situations
– Appendix D: Example Check List & Permit
– Appendix E: Sewer System Entry
Permit-Required Confined Space
The Permit
1. DATE:____ TIME:____ A.M../P.M.
2. VESSEL #
3. JOB #
4. LOCATION:
5.DESCRIPTION OF WORK:
6.PHYSICAL HAZARD ASSESSMENT: Engulfment, Electrical, Steam, Augers, Chain Drives etc..
7. CORRECTIVE MEASURES: Physical Disconnects, Lockout / Tagout etc..
8. ATMOSPHERIC ASSESSMENT: Oxygen, LEL, CO, H2S (Other)
9. Instrument #
10. Calibration Date: 11. Name of Operator:
12. Substance
13. P.E.L.
14. Actual
15. Oxygen
16. < 19.5% or > 23.5%
17. Other
18. LEL > 10%
20.
21. Carbon Monoxide (CO)
22. 50 ppm
23. Other
24. Hydrogen Sulphide (H2S)
25. 10 ppm
26. Other
27. PPE
28. Respirators
29.Rescue Equipment
30. Other
31. Other
32. Other
33. Names of entrants, Attendants, and Entry Supervisors:
34. Time work / shift completed:
(35.) Problems / concerns
36. Emergency contact:
Other OSHA Regulations
Hazard Communication
– 29 CFR 1926.59
– MSDS
– Training
– Labeling
– Written Program
Control of Hazardous Energy
Sources
– 29 CFR 1926.417 & 1910.147
– “Lock Out/Tag Out”
– De-Energize ALL Sources of
Energy
– Written Program
Permit-Required Confined Spaces
Administrative Controls
Permit Space Entry Program
Learning Objectives
• Describe the Guidelines for a Permit-Required
•
Confined Space Program
Identify Conditions Which Allow the Use of
Alternate Procedures
General Requirements
•
•
•
•
A Written Permit Space Program
Authorized Personnel
Confined Space Evaluation Procedures
Acceptable Entry Conditions and Procedures
PRCS Program
The Entry Permit Shall Identify:
1) The Permit Space to be Entered.
2) The Purpose of the Entry.
3) The Date and Duration.
4) The Authorized Entrants.
5) The Attendants.
6) The Entry Supervisor.
7) The Hazards of the Space to be Entered.
8) Measures to Isolate and Eliminate the Hazards Before Entry.
9) The Acceptable Entry Conditions.
10) The results of Initial and Periodic Tests with Initials of
Testers.
PRCS Program
The Entry Permit Shall Identify:
11) The Rescue and Emergency Services That Can Be
Summoned.
12) The Communication Procedures Used By Entrants and
Attendants.
13) Equipment such as Testing, Communication and
Emergency Equipment.
14) Any Other Information Necessary, In Order To Ensure
Employee Safety.
15) Any Additional Permits Such As a Hot Work Permit.
Authorized Entrant Duties
•
•
•
•
Knows Hazards, Symptoms, and Consequences
Proper Use of Equipment
Communicate With Attendant
Exit Promptly From PRCS When Necessary
Attendant Duties
• Knows Hazards, Symptoms, and Consequences
• Awareness of Behavioral Effects of Exposure
• Continuously Identifies Number and Identity of
Entrants
• Remains Outside of PRCS
• Communicates With Entrants
Attendant Duties
•
•
•
•
•
Monitors Entrant & Surrounding Activity
Summons Rescue If Needed
Keeps Unauthorized Persons Away From PRCS
Performs Non-Entry Rescues
Performs Only Attendant Duties
Entry Supervisor Duties
• Knows Hazards, Symptoms, and
•
•
Consequences
Verifies Performance of Permit Testing,
Procedures and Equipment
Terminates PRCS Entry and Permit
Entry Supervisor Duties
• Verifies Availability and Communication
•
•
With Rescue Services
Removes Unauthorized Personnel
Determines Compliance With the Entry
Permit
Rescue and Emergency Services
Using Employer’s Personnel...
• Trained in PPE and Rescue Equipment
• Trained in Rescue and Authorized Entrant Duties
• Practice Rescues Once Every 12 Months
– Simulated With Mannequins or People
– In Actual PRCS
• Trained in CPR and Basic First Aid
– At Least 1 Member of Rescue Service Holding Current
Certification
Rescue and Emergency Services
Outside Rescue Service...
• Must Be Informed of Hazards Prior to
Arrival
• Must Have Access to All Spaces to Assess
and Allow for Practice of Rescues
Rescue and Emergency Services
Non-Entry Rescue...
“Retrieval Systems or Methods Shall Be Used Whenever
an Authorized Entrant Enters a PRCS”
–
–
Unless Equipment Increases Risk or Would Not Assist Rescue
–
–
Attached to Mechanical Device or Fixed Point Outside Space
Chest or Full Body Harness, Center of Back Near Shoulder or Above
Head; Wristlets ONLY if Harness is Infeasible or Greater Hazard
MSDS Must Be at Worksite and Furnished to Medical Facility Treating
Exposed Entrants
Testing and Monitoring
Appendix B
•
Evaluation Testing
– Any Hazards
– Prior to Entry
– Technically Qualified Professional
•
•
•
•
•
OSHA Consultation Service
CIH
Registered Safety Engineer
CSP
Verification Testing
Testing and Monitoring
Appendix B
• Duration of Testing
• Testing Stratified Atmospheres
– Atmospheric Envelope of 4 ft. in Direction of Travel
and to All Sides
– Rate of Progress of Entrant Slowed to Accommodate
Instrument Sampling Speed and Response Time
Hot Work Permits
Defined As: Written Authorization to Perform
Operations Capable of Providing a Source of
Ignition (Such As Welding, Cutting, or Brazing)
Required for: Hot Work in Grain Handling
Facilities and Any Other Combustible/ Explosive
Areas
Hot Work Permits
General Provisions
• Remove Fire Hazards & Combustibles
• Guard the Work
• Guard Openings to Other Areas
• Maintain Fire Extinguishers
Hot Work Permits
General Provisions
• Maintain Fire Watch
• Written Permit Authorization
• Protect Floors & Walls
• Protect Drains, Dusts, and Pipes
Alternate Procedures
Can be used if...
•
•
•
•
ONLY Hazard is an Actual or Potential Hazardous
Atmosphere
And
Can Demonstrate That Continuous Forced Air is
Sufficient to Maintain the Space as Safe
Data is Developed to Support the Above
A Permit Program is Followed During Data
Collection
Alternate Procedures
(continued)
• Hazard from Removing Entrance Cover is
•
•
Eliminated
Entrance is Made Safe to Prevent Accidental Falls
Atmospheric Testing for
– Oxygen
– Flammability
– Toxic Contaminants
Alternate Procedures
(continued)
• No Hazardous Atmospheres Develop While
•
Employee is In Space
Continuous Forced Air Ventilation is Used
– No Entry Until Safe
– Remains Until Everyone Has Left Space
– Air is From a Clean, Safe Source
• Periodic Testing
Alternate Procedures
(continued)
• If A Hazard Develops
– Evacuation of Space
– Evaluation as to the Source
– Protection of Employees Prior to Re-entry
• Documentation
– Date, Location, Signature of Person Certifying
– Certification Made Prior to Entry and Available to
each Employee
Alternate Procedures
(continued)
At Issue -“Elimination” of Hazards
•
•
If the Stated Conditions Are Met, the Employer Does Not Have to
Implement
–Personnel Duties
–PRCS Program
–Rescue
–Permit System
–Emergency Services
–Entry Permit
OSHA Compliance Letter (10/12/95) Interprets the Elimination
Provision: “… If the Non-Atmospheric Hazards Were
Permanently Eliminated, the Alternate Procedures Could
Subsequently Be Applied…”
Hazards are usually dictated by...
• The material stored in the confined space.
• The activity carried out in the confined space. (a
particular chemical reaction)
• The external environment. (a tank located near
rising waters)
OSHA Estimates
• 224,000 establishments have permit required
confined space.
• 2.1 million workers enter these spaces annually.
• 60% of the deaths that occur in confined spaces
are the rescuers who go in after the victim.
Confined Space Hazards
• Chemical Hazards
• Physical Hazards
• Biological Hazards
• Ergonomic Hazards
Engulfment
• The surrounding or covering of a person by a
liquid or flowable solid. Death may result by
suffocation, strangulation, constriction, or
crushing.
– Concrete
– Asphalt
Primary Constituents of Normal Air
(Permanent Gases)
Constituent
Chemical
Formula
Molecular
Weight
Percent
by Volume
Nitrogen
N2
28
78.1
Oxygen
O2
32
20.9
Argon
Ar
40
0.9
Water vapor content varies, but is usually the third largest
constituent by volume in air.
Definitions of O2 Deficient Atmosphere
29 CFR 1910.146 (PRCS)
Source
42 CFR Part 84 (NIOSH Resp. Approval)
<19.5%
Oxygen <19.5%
Content
29 CFR 1910.134(g) (Resp. Std.)
16.0%1
29 CFR 1910.94 (Ventilation. Std.)
<19.5%
29 CFR 1915.11(b) (Shipyards)
<19.5%
ANSI Z117.1-1995 (Confined Spaces)
<19.5%
ANSI Z88.2-1992 (Respirator Practices)
16.0%2
ACGIH (TLV booklet)
18.0%
1
2
Letter of interpretation
Oxygen partial pressure <122 mmHg. Confined space with <20.9 % O2 is IDLH, unless
source of O2 reduction is understood and controlled.
Oxygen-Deficient Atmospheres
O2 Content
Effects and Symptoms (at patm)
15-19%
Decreased ability to work strenuously. May impair coordination and
induce early symptoms in persons with coronory, pulmonary, or
circulatory problems.
12-14%
Respiration increases in exertion, pulse up, impaired coordination,
perception, and judgment.
10-12%
Respiration further increases in rate and depth, poor judgment, lips
blue.
8-10%
Mental failure, fainting, unconsciousness, ashen face, blueness of lips,
nausea, and vomiting.
6-8%
8 min., 100% fatal; 6 min., 50% fatal; 4-5 min., recovery with treatment.
Coma in 40 sec., convulsions, respiration ceases, death.
4-6%
NOTE: Exposure to atmospheres containing 12% or less oxygen will bring about unconsciousness
without warning and so quickly that individuals cannot help or protect themselves.
How an Oxygen-Deficient Atmosphere Can
Occur in a Confined Space
1. Consumption
a)
b)
c)
2. Displacement
a)
b)
c)
3. Adsorption
a)
Nitrogen (N2)
• Colorless, odorless inert gas
• Slightly lighter than air
Argon (Ar)
• Colorless, odorless inert gas
• Heavier than air
Argon (Ar)
• Colorless, odorless inert gas
• Heavier than air
Methane (CH4)
•
•
•
•
•
Natural, marsh, swamp gas
Colorless, odorless flammable gas
Lighter than air
Toxic?
LEL = 5%; UEL = 15%
Carbon Dioxide (CO2)
•
•
•
•
•
•
•
Colorless, odorless noncombustible gas
Heavier than air
Common in solid and compressed liquid forms
Carbonation
Inerting
Organic decay (grain elevators, sewers, storage bins,
wells)
Fermentation (digestors, molasses pits, beer and wine
vats)
CO2 (cont’d)
•
•
•
•
PEL = 5,000 ppm - TWA (Table Z-1)
TLV/REL = 5,000 ppm - TWA; 30,000 ppm - STEL
IDLH = 50,000 ppm
LEL = none
Carbon Monoxide (CO)
•
•
•
•
•
Colorless, odorless gas
Slightly lighter than air
Chemical asphyxiant
Primary source: incomplete combustion of
organic material
Gasoline-fueled combustion engines
CO (cont’d)
•
•
•
•
•
•
PEL = 50 ppm - TWA
TLV = 25 ppm - TWA
BEI: <3.5% COHb; 20 ppm (end-exhaled air)
REL = 200 ppm - STEL; 35 ppm - TWA
IDLH = 1500 ppm
LEL = 12.5%; UEL = 74.2%
Concentration of CO
Necessary to Produce Symptoms
Percent ppm Effects
0.02
200
Possibly headache, mild frontal in 2-3 hrs.
0.04
400
Headache, frontal, and nausea after 1-2 hrs.; occipital after 2-1/2 to 3-1/2
hrs.
0.08
800
Headache, dizziness and nausea in 3/4 hour, collapse and possible
unconsciousness in 2 hrs.
0.16
1,600
Headache, dizziness and nausea in 20 min.; collapse, unconsciousness,
possibly death in 2 hr.
0.32
3,200
Headache and dizziness in 5 to 10 min., unconsciousness and danger of
death in 30 min.
0.64
6,400
Headache and dizziness in 1 to2 min., unconsciousness and danger of
death in 10 to 15 min.
1.28
12,800
Immediate effect; unconsciousness and danger of death in 1 to 3 min.
(Source: Hamilton & Hardy)
Symptoms of CO Exposure
Percent*
Symptoms
0-10
Shortness of breath on exertion
10-20
Tightness across forehead, slight headache
20-30
Throbbing headache
30-40
Severe headache, nausea, vomiting, collapse on exertion
40-50
All symptoms increased, pulse rate and breathing increased
50-70
Coma, interrupted breathing (Cheyne-Stokes), death
* Percent saturation of Hemoglobin with CO [Blood Levels]
Hydrogen Sulfide (H2S)
•
•
•
•
Sewer gas, stink gas (rotten eggs)
Odor threshold: 0.02 - 0.2 ppm
Colorless, flammable gas
Heavier than air
•
•
•
•
•
PEL = 20 ppm - C; 50 ppm - Peak (10 min. once)
TLV = 15 ppm - STEL; 10 ppm - TWA
REL = 10 ppm - C (10 min.)
IDLH = 300 ppm
LEL = 4.3%; UEL = 46%
H2S (cont’d)
•
•
•
•
•
PEL = 20 ppm - C; 50 ppm - Peak (10 min. once)
TLV = 15 ppm - STEL; 10 ppm - TWA
REL = 10 ppm - C (10 min.)
IDLH = 300 ppm
LEL = 4.3%; UEL = 46%
Effects of H2S Concentration
ppm*
Local
Systemic
20
50
Irritant of conjunctival and
corneal epithelium
50-100
Eye and respiratory tract
irritation in 1 hr.
100-150
Slight systemic symptoms after several hrs.
150
Olfactory nerve paralysis
Fatal in 8-48 hrs.
200
Pulmonary irritation and pulmonary
Nervous system depression
edema after prolonged exposure
* Concentration by Volume
Effects of H2S Concentration (cont’d)
ppm*
Local
Systemic
250-350
Fatal in 4-8 hrs.
350-450
Fatal in 1-4 hrs.
500-600
Excitement, headache, dizziness and
unconsciousness, death in 30-60 min.
600-700
Rapid collapse, death in 2-15 min.
700-2,000
Cessation of respiration, rapidly fatal
* Concentration by Volume
Other Toxics
May arise from the:
1. Product(s) stored
2. Manufacturing processes
3. Work being performed
4. Adjacent areas
Definitions
• Vapor Pressure- Pressure exerted by a vapor.
If a
vapor is kept in confinement over its liquid so that the
vapor can accumulate above the liquid, the vapor
pressure approaches a fixed limit called the maximum
vapor pressure. (How much the liquid wants to become a
gas)
•
Flash Point- The minimum temperature at which a liquid
gives off vapor within a test vessel in sufficient
concentration to form an ignitable mixture with air near
the surface of the liquid.
Combustible is >100 F
Flammable is <100 F
0
0
BOILING POINT
IA
IB
100 F
0
IC
II
IIIA
IIIB (NFPA)
(29 CFR 1910.106)
Flammable/Combustible Liquid Classification
Flammable (Explosive) Limits
• When vapors of a flammable or combustible liquid are mixed with air in the
proper proportions in the presence of a source of ignition, rapid combustion or
an explosion can occur. The proper proportion is called the flammable range
and is also often referred to as the explosive range. The flammable range
includes all concentrations of flammable vapor or gas in air, in which a flash
will occur or a flame will travel if the mixture is ignited. There is a minimum
concentration of vapor or gas in air below which propagation of flame does not
occur on contact with a source of ignition. There is also a maximum proportion
of vapor in air above which propagation of flame does not occur. These
boundary-line mixtures of vapor with air are known as the lower and upper
flammable or explosive limits (LFL or UFL) respectively, and they are usually
expressed in terms of percentage by volume of vapor in air.
Atmospheric Pressure
• Atmospheric pressure is 760 mmHg a
substance with a vapor pressure of 760 mmHg
is a gas at room temperature.
– Water vapor pressure= 25 mmHg
– Fuel oil vapor pressure= 2 mmHg
– Vinyl chloride vapor pressure= (760 mmHg)(3.4)
• “1300 rule”
– 1300*VP= concentration just above the surface of the
liquid
MSDS Exercise
• What color is this substance?
• What type of odor does it have?
• What PEL or TLV is set for this substance?
• What are some of the synonyms for this substance?
• What products are incompatible with this product?
• What type of PPE should be worn while handling this product?
• What are some of the symptoms of overexposure?
• If a co-worker was overexposed to this product what information should be
•
•
give to medical personnel?
Is this substance designated as a hazardous waste by the EPA?
Who might you call for more information about this product?
Air Monitoring
Permit-Required Confined Spaces
Objectives
• Describe Why the Work Environment Needs to
•
•
Be Monitored
Understand the Value of Personal, Area, and
Perimeter Monitoring
Identify Several Types of Monitoring Equipment
Why Do Monitoring?
• To Detect if Potential Hazardous Conditions
Exist
• To Measure Concentrations of Hazardous
Substances
Detection of Hazards
• To Determine Whether Hazardous Materials Are
•
•
•
Present Under Normal Conditions
Whether the Environment is IDLH
Measure Releases During Work to Ensure Proper
PPE and Work Practices
Ensure That No Hazardous Materials Remain
After a Release
Hazards In The Air
•
•
•
•
•
Oxygen Deficiency/Enrichment
Explosive Atmospheres
Toxic Chemicals
Radioactivity
Biological Hazards
Oxygen
Oxygen Enriched
23.5%
Oxygen Deficient
19.5%
16.0%
14.0%
6.0%
Minimum for Safe Entry
Impaired Judgment
& Breathing
Faulty Judgment
Rapid Fatigue
Difficulty in Breathing
Death in Minutes
Explosive Limits
Too Rich
UEL
Combustible
LEL
Too Lean
10% of LEL
Personal Air Monitoring
•
•
•
•
PRO
Accurate Measure of
Actual Exposure
Compares to OSHA PEL,
STEL
Documents Exposure
Allows Appropriate PPE
Selection
•
•
•
•
CON
Lab Analysis 1 to 14
Days
No Peak or Ceiling
Measures
Need to Know What
Exposures are Possible
Preparation and
Calibration Needed Prior
and Following
Personal Monitoring Equipment
• Battery Operated Sampling Pumps
– Filters - Fumes/Particles/Mists
– Charcoal Tubes - Gases/Vapors
– Silica Gel Tubes - Gases/Vapors
• Passive Badge Dosimeters
Gases and Vapors
Real-Time Measurements
•
•
•
•
•
PRO
Immediate Measures
Measures Variety of
Exposures
Measures IDLH
Situations
Detects Peak Toxic and
Flammable Levels
Determines Ability to
Enter PRCS
•
•
•
•
•
CON
May Not Detect “Low”
Levels
Not Specific
May False Alarm
Interferences and Cross
Sensitivity
May Require Factory
Calibration
Direct Reading Instruments
•
•
•
•
•
Oxygen Meter
Explosive Gas Meter/Combustible Gas Indicator
Detector Tubes
Personal Alarm Monitors
Multi-Gas Analyzer/Meters
Examples of Direct Reading
Instruments
Review
•
•
•
•
Where Are Measurements Taken?
What Types of Measurements Can Be Made?
How Are These Measurements Used?
What Are Some of the Limitations of Air
Sampling?
Instrumentation
• O2 Meters
– Use O2 Meters
• Flammable Gases and Vapors
– Use Combustible Gas Indicator
• Toxic Air Contaminants
– Use Colorimeteric Detector Tubes
Combustible Gas Indicators
• Used to sample vapor concentrations near and in
permit spaces
• Reads LEL
• A reading above 10% should be considered a
potentially explosive atmosphere
Combustible Gas Indicators
Precautions
• The equipment may not respond the same to all
vapors
• O2 MUST BE MEASURED FIRST!
Oxygen Meters
• Used to sample oxygen concentrations in and near
•
•
•
confined spaces.
Reads between 0-25% or 0-100%
At greater than 23.5% O2, the explosion hazard
increases.
At less than 19.5% the space cannot be entered
without a SCBA or SAR with escape pack.
Oxygen Meter Precautions
• Very sensitive to temperature and pressure
changes.
• At high concentrations of carbon monoxide, the
meter may give improper readings.
• Must be calibrated before every use!
Colorimeteric Detector Tubes
• Used to sample gas or vapor concentration in any
work space.
• Reads percent of the concentration in PPM.
• Concentration indicated by color change or length
of color stain.
Detector Tube Precautions
• They are not very accurate-- within 25% of the
•
•
•
real value at best.
The tubes are very sensitive to temperature and
humidity.
Different tubes must be used for different
chemicals.
They are breakable.
Tips To Help In Monitoring
•
•
•
•
Check the accuracy of the instruments you are going to
use.
– Have they been recently calibrated?
Always test in this order: Oxygen,
Flammability/Combustibility, and Toxic Gases.
Test the air from the top to bottom including all corners
and spaces!
Test the atmosphere frequently!
Ventilation of Permit-Required
Confined Spaces
Comfort - General/Dilution
Ventilation
• Temperature and humidity regulations
ASHRAE 55-1992
– Winter: 68 - 74oF
– Summer: 73 - 79oF
– RH: 30 - 60 %
Comfort - General/Dilution
Ventilation (cont’d)
• Odor removal - outside air movement
ASHRAE 62 - 1989
– Public bathrooms: 50 CFM/wc or 2 CFM/ft2
– Office: 15 CFM/person
– Smoking lounges: 20 - 60 CFM/person
Safety - General/Dilution Ventilation
Fire and explosion control
(1) Volume of air required to dilute the vapor from 1
gallon of solvent to 25% LEL. [1910.94(c)(6)(ii)]
Dilution volume =
4(100-LEL)VV
LEL
VV = cubic feet of vapor per gallon of solvent
(vapor volume)
Safety - General/Dilution Ventilation
(cont’d)
Example: acetone
Dilution volume =
4(100-2.5)44.0
2.5
= 6,864 ft3 air / gal acetone (70oF)
Safety - General/Dilution Ventilation
(cont’d)
(2) Volume of air required to dilute the vapor from 1
gallon of solvent to 10% LEL. [1910.146(b)]
Dilution volume =
10(100 - LEL)VV
LEL
Safety - General/Dilution Ventilation
(cont’d)
Example: acetone
Dilution volume =
10(100 - 2.5)44.0
2.5
= 17,160 ft3 air / gal acetone (70oF)
Ventilation Volume Calculation
Ventilation volume = Dilution volume x Gallons of
solvent evaporated per minute
CFM =
ft3 air
gal solvent
x
gal solvent
min
Ventilation Volume Calculation (cont’d)
Example: Acetone-thinned paint applied at rate of
one gallon per minute. Paint is 40% solvent.
Ventilation volume (for 25% LEL)
6,864 ft3 air
gal solvent
x
1 gal paint
min
x
0.4 gal solvent
gal paint
= 2,746 CFM
Ventilation volume (for 10% LEL)
17,160 ft3 air 1 gal paint 0.4 gal solvent
x
x
gal solvent
min
gal paint
= 6,864 CFM
Dilution Ventilation
for Fire and Explosion
• Reduce the concentration of vapors within an
•
enclosure to below the LEL.
This concept is never applied in cases where
workers are exposed to the vapor. Dilution rates
for health hazard control are always applied in
these instances, since the PEL is a much lower
concentration than the LEL.
Safety - Dilution Ventilation
Q=
403(SG)(100)(C)(w)
(MW)(LEL)(B)
where,
Q = air flow rate (CFM) required to dilute vapor
concentration to safe condition
403 = conversion factor
SG = specific gravity of liquid (water = 1)
Safety - Dilution Ventilation (cont’d)
100 = constant to convert LEL to decimal fraction
C = dimensionless safety factor which depends on % LEL
necessary for safe conditions (10% LEL: C = 10, 25% LEL: C = 4
w = pints of liquid evaporated in one minute
MW = molecular weight of vapor
LEL = lower explosive limit (%)
B = constant reflecting fact that LEL decreases at elevated
temperatures (£ 250oF: B = 1, > 250oF: B = 0.7)
Flammable Liquid Storage Rooms
Ventilation must provide for a complete change of air
within the room at least six times per hour (6 A.C. / hr).
Exchanging all the air in the room is equivalent to 1
A.C. [i.e., Room volume (L x W x H) = 1 A.C.]
6 A.C. / hr = (6 x Room volume) / hr
CFM = [6 x Room volume (ft3)] x 1 hr / 60 min
CFM = Room volume (ft3) / 10
Health - Dilution Ventilation
403(SG)(106)(w)(K)
Q=
(MW)(PEL)
where,
Q = air flow rate (CFM) required to dilute vapor
concentration to the PEL.
K = dimensionless safety factor (varies from 3-10) to
maintain concentration well below PEL. Higher value for
high toxicity, high evolution rate, poor ventilation, and large
number of exposed workers.
Considerations for PRCS Ventilation
•
•
•
•
•
•
•
•
Space configuration
Ventilation mode (exhaust/supply)
Ventilation flow rate
Availability of make-up air
Obstacles for ducting
Availability of power sources
Location of employee within space
Characteristics of contaminant
Achievement of Accceptable
Atmospheres
• Dilution - use general/forced air ventilation to
•
•
dilute the contaminant
Exhaust - use local exhaust ventilation to remove
the contaminant
Dilution/Exhaust - use a combination of both
methods to remove the contaminant
Dilution Ventilation
• Introduces fresh air to space
• Best when toxicity levels
•
•
and concentrations are low
Best when contaminants
well distributed
Requires larger air volume
when contaminants generated
at a point
Local (Source) Ventilation
• Exhausts from a localized area
• Removes high concentrations
•
of contaminants from space
Requires smaller volume
of air
Solutions
• Inerting
• Purging
• Ventilation
Inerting
• Displacement of the atmosphere by a nonreactive gas (such as nitrogen) to such an
extent that the resulting atmosphere is
noncumbustible.
Purging
• The method by which gases, vapors, or other airborne
•
impurities are displaced from a confined space.
Purpose is to do a complete air exchange in a confined space
prior to entry. Normally, a purge is considered complete
when atmospheric tests indicate the air is of suitable quality
to sustain life.
Inerting
• Displacement of the atmosphere by a non-reactive gas
(such as nitrogen) to such an extent that the resulting
atmosphere is noncumbustible.
Ventilation
•
At opening of blower
100% capacity
•
Blower plus 25’ of hose
78% capacity
•
25’ of hose plus one 90 degree bend
67% capacity
•
25’ of hose plus two 90 degree bend
56% capacity
Electricity
• Electricity Doesn’t Spring Into Action Until
•
•
Current Flows
Current Doesn’t Flow Until there is a Loop to and
from the Transformer
Current Always Returns to the Transformer that
created it
Electricity
• Voltage  Water Pressure
• Ohms  Resistance / Size of Water Pipe
• Current  Flow Rate of Water
Electrical Shock
• Contact with a normally energized conductor
•
•
•
•
(wire).
Contact with an energized conductor on which the
insulation has lost it’s protective value
Equipment failure, causing an open or short circuit
Static Electricity Discharge
Lightning Strike
Cords & Corded Equipment
• Do not remove ground plug
• Flexible cords must Not be:
Used instead of fixed wiring
Run through holes in ceilings, walls, or floors
Run through doorways, windows, or openings
Concealed in walls, ceilings, or floors
• Flexible cords may be used for:
Pendants
Fixture wiring
Portable lamps or appliances
Cranes and hoists
Frequently Moved equipment
Lockout/Tagout
29 CFR 1910.147
Control of Hazardous Energy Sources
(Lockout/Tagout)
Scope
1910.147 (a)(1)(i)
• Covers servicing and maintenance of machines
when unexpected startup or release of stored
energy could cause injury.
Application
1910.147 (a)(2)(i)
• Standard applies to control of energy during
•
servicing and/or maintenance.
Note: Servicing / maintenance during normal
production operations is covered if:
an employee is required to remove or bypass a guard,
or
an employee must place his / her body into danger
zone
Does not cover:
1910.147 (a)(1)(ii)
• Construction, agriculture, maritime
• Installations under control of electric utilities
• Exposure to electrical hazards from work on,
•
near, or with conductors or equipment in electrical
utilization installations (see Subpart S)
Oil and gas drilling, and servicing
Also Excluded
1910.147 (a)(2)(ii) & (iii)
• Normal production operations (see Subpart O)
• Work on cord and plug connected equipment
• Hot tap operations, under special conditions
Definitions
1910.147 (b) & (c)(7)(i)(C)
*While not defined in 1910.147 (b), “other employees” are discussed in 1910.147 (c)(7)(i)(C).
• Authorized Employee: Person who locks or tags
•
•
machines / equipment to perform servicing.
Affected Employee: One who is required to use
machines / equipment on which servicing is
performed under lockout / tagout or who must
work in such an area.
Other Employees: * All employees whose work
operations are or may be in an area where energy
control procedures may be utilized.
Definitions (continued)
1910.147 (b)
“Capable of being locked out”
• Designed with hasp or attachment to which lock
can be affixed; or,
• Has locking mechanism built in; or,
• Lockout can be achieved without need to
dismantle, rebuild, replace or permanently alter.
Definitions (continued)
1910.147 (b)
• Normal Production Operations: Utilization of a
•
machine or equipment to perform its intended
function.
Servicing and/or Maintenance: Includes
lubrication, cleaning or unjamming, making
adjustments and tool changes, where employees
may be exposed to UNEXPECTED energization,
startup or release of hazardous energy.
Energy Control Program
1910.147 (c)(1)
• The employer shall establish a program consisting
of an energy control procedure and employee
training... in accordance with paragraph (c)(4) of
this section.
Lockout vs. Tagout
• Lockout system is preferred method and shall be
used when equipment can be locked out -- unless
employer can show that tagout system provides
full employee protection.
Full Employee Protection
1910.147 (c)(3)(i)
• When tagout is used on equipment which is
capable of being locked out:
Tags shall be attached where lockout devices
would be; and,
Employer must demonstrate that tagout will
provide safety equivalent to lockout.
Energy Control Procedure
1910.147 (c)(4)(i)
• Procedures shall be developed, documented
and utilized for the control of potentially
hazardous energy when employees are
engaged in servicing and maintenance.
Energy Control Procedures must be written,
unless all of the following exist: 1910.147 (c)(4)(i) exception
• Equipment has no potential for stored / residual energy.
• Equipment has a single energy source.
• Isolation and lockout of one energy source completely
•
•
•
•
deactivates equipment.
Equipment is isolated from energy source & locked out.
Lockout device is under exclusive control of authorized
employee performing maintenance.
No other hazards are created.
Employer has had no related accidents.
Procedures must contain:
• Scope
• Purpose
• Authorization
• Rules
• Techniques to be utilized
• Means to enforce compliance
1910.147 (c)(4)(ii)
Materials / Hardware
1910.147 (c)(5)
• Provided by employer
• Singularly identified
• Only devices used
• Not used for other purposes
• Durable
• Standardized
• Substantial
Periodic Inspection
•
•
•
•
•
•
1910.147 (c)(6)(i)
At least annually
Performed by authorized employee (other than the one(s) using
procedure being inspected).
Designed to correct deficiencies.
Lockout: Must review each authorized employee’s
responsibilities.
Tagout: Must review each authorized and affected employee’s
responsibilities and additional training requirements of 1910.147
(c)(7)(ii).
Employer certification required.
Training
1910.147 (c)(7)(i)
• Authorized Employee
– Recognition of hazardous energy sources
– Type & magnitude of energy in workplace
– Methods for energy isolation / control
• Affected Employee
– Purpose / use of energy control procedure
• Other Employee
– Procedure
– Prohibition on restarting machines or equipment
Additional Training - Tagout System
1910.147 (c)(7)(ii)
• Employees shall be trained in the limitations of
tags, as follows:
–
–
–
–
–
–
Warning devices only
Must not be removed / bypassed / ignored
Must be legible
Must withstand environmental conditions
May (will) evoke false sense of security
Must be securely attached
Employee Retraining
1910.147 (c)(7)(iii)
• Provided when:
– Change in job assignments
– Change in machines, equipment or processes
that present new hazards
– Change in energy control procedures
– Periodic inspection reveals, or employer has
reason to believe, there are deviations in
employee knowledge of procedures
Specific Procedures
1910.147 (d)(1) - (6)
• Lockout / Tagout procedures shall cover the
following elements in the following sequence:
– Preparation for shutdown
– Shutdown
– Isolation
– Lockout / tagout device application
– Release of stored energy
– Verification of isolation
Release from Lockout / Tagout
1910.147 (e)(1) - (3)
• Prior to restoring energy, the following
procedures are required:
– Inspect machine and equipment
– Safe positioning and notification of
employees
– Removal of lockout / tagout device
Testing of Machines
1910.147 (f)(1)
• When lockout / tagout devices must
temporarily be removed for testing /
positioning:
– Clear machine of tools / equipment
– Remove employees
– Remove lockout / tagout device
– Energize and test
– De-energize and reapply energy control measures
Outside Personnel (Contractors) 1910.147(f)(2)
• On-site employer and outside employer shall
•
inform each other of their respective
procedures.
On-site employer shall ensure that his / her
employees understand and comply with
contractor’s procedures.
Group Lockout / Tagout
1910.147 (f)(3)
• Additional Requirements
– Primary responsibility is vested in an authorized
employee for a set number of employees.
– Authorized employee must ascertain exposure status of
group members.
– If more than one crew is involved, coordinator needed.
– Each authorized employee shall use a personal lockout
/ tagout device and remove it when finished.
Shift / Personnel Changes
1910.147 (f)(4)
• Specific procedures needed to ensure
continuity of lockout / tagout protection.
Lockout/Tagout
Purpose - 1910.147(a)(3)
This section requires employers to establish a program and
utilize procedures for affixing appropriate lockout devices or
tagout devices to energy isolating devices, and to otherwise
disable machines or equipment to prevent unexpected
energization, start-up or release of stored energy in order to
prevent injury to employees.
Lockout/Tagout
Definitions - 1910.147(b)
Affected employee:
An employee whose job requires him/her to operate
or use a machine or equipment on which servicing or maintenance is being
performed under lockout or tagout, or whose job requires him/her to work in
an area in which such servicing or maintenance is being performed.
Authorized employee:
A person who locks out or tags out machines or
equipment in order to perform servicing or maintenance on that machine or
equipment. An affected employee becomes an authorized employee when
that employee’s duties include performing servicing or maintenance covered
under this section.
Energy isolating device:
A mechanical device that physically prevents
the transmission or release of energy.
Lockout/Tagout
Employer Responsibilities
Education
– Documentation: a written statement of company’s Energy
Control Plan.
– Employee training: to help employees in the use of the Energy
Control Plan.
Enforcement
– Inspection: to make sure energy control procedures are being
carried out.
– Self-audit: a periodic review of the procedures and the
program.
Lockout/Tagout
General - 1910.147(c)
The employer shall establish a program consisting of energy
control procedures, employee training and periodic inspections
to ensure that before any employee performs any servicing or
maintenance on a machine or equipment where the unexpected
energizing, start up or release of stored energy could occur and
cause injury, the machine or equipment shall be isolated from
the energy source, and rendered inoperative.
Lockout/Tagout
Applying Energy Controls
•
Energy isolation and lockout/tagout are to be applied
only by trained employees authorized to perform service
or maintenance.
•
Before lockout/tagout is applied, all employees who
work in the affected area must be notified.
•
The OSHA regulation requires that control of hazardous
energy be done according to a six-step procedure.
Lockout/Tagout
Preparation for Shutdown - 1910.147(d)(1)
Before you turn off any equipment in order
to lock or tag it out, you must know:
• The types and amounts of energy that power it
• The hazards of that energy
• How the energy can be controlled
Lockout/Tagout
Equipment Shutdown - 1910.147(d)(2)
• Shut the system down by using its operating
•
•
controls.
Follow whatever procedure is right for the
equipment, so that you don’t endanger anyone during
shutdown.
An orderly shutdown must be utilized to avoid any
additional or increased hazard(s) to employees as a
result of the equipment stoppage.
Lockout/Tagout
Equipment Isolation - 1910.147(d)(3)
• Operate all energy-isolating devices so that the
•
•
•
equipment is isolated from its energy sources.
Be sure to isolate all energy sources-secondary
power supplies as well as the main one.
Never pull an electrical switch while it is under
load.
Never remove a fuse instead of disconnecting.
Lockout/Tagout
Application of LOTO Devices - 1910.147(d)(4)
• All energy-isolating devices are to be locked, tagged or both according to company’s
•
•
•
•
•
•
•
Energy Control Plan.
Only the standardized devices supplied by your employer are to be used for
lockout/tagout, and they are not to be used for anything else.
Use a lockout device if you lock cannot be placed directly on the energy control.
When lockout is used, every employee in the work crew must attack his/her personal lock.
More than one employee can lock out a single energy-isolating device by using a multiplelock hasp.
For big jobs, a lockout box can be used to maintain control over a large number of keys.
If tags are used instead of locks, attack them at the same point as you would a lock, or as
closed to it as possible.
Fill tags out completely and correctly.
Lockout/Tagout
Control of Stored Energy - 1910.147(d)(5)
•
•
•
•
•
•
Inspect the system to make sure all parts have stopped moving.
Install ground wires.
Relieve trapped pressure.
Release the tension on springs, or block the movement of
spring-driven parts.
Block or brace parts that could fall because of gravity.
Block parts in hydraulic and pneumatic systems that could
move from loss of pressure.
Lockout/Tagout
Control of Stored Energy (con’t.)
- 1910.147(d)(5)
•
•
•
•
•
•
Bleed the lines and leave vent valves open.
Drain process piping systems and close valves to prevent the
flow of hazardous materials.
If a line must be blocked where there is no valve, use a blank
flange.
Purge reactor tanks and process lines.
Dissipate extreme cold or heat, or wear protective clothing.
If stored energy can reaccumulate, monitor it to make sure it
stays below hazardous levels.
Lockout/Tagout
Equipment-Isolation Verification - 1910.147(d)(6)
Take any of the following steps that fit your
company’s equipment and energy control program.
•
•
•
•
•
Make sure all danger areas are clear of personnel.
Verify that the main disconnect switch or circuit breaker can’t be
moved to the on position.
Use a voltmeter or other equipment to check the switch.
Press all start buttons and other activating controls on the equipment
itself.
Shut off all machine controls when the testing is finished.
Lockout/Tagout
Removing Energy Controls
•
Make sure the equipment is safe to operate.
– Remove all tools from the work area.
– Be sure the system is fully assembled.
•
Safeguard all employees.
– Conduct a head count to make sure everyone is clear of the equipment.
– Notify everyone who works in the area that lockout/tagout is being
removed.
•
Remove the lockout/tagout devices. Except in emergencies, each
device must be removed by the person who put it on.
Lockout/Tagout
Removing Energy Controls (con’t.)
• In some workplaces, the last person to remove
•
his/her lock may have extra duties.
– He/she may have to remove the hasp and
lockout device.
– Tags should be removed, signed, and turned in.
– In some companies, the supervisor always
removes his lock last.
Follow a checklist of required steps to re-energize
the system.
Limitations of Tags
1910.147(c)(7)(ii)
• Tags are essentially warning devices affixed to energy isolating devices, and do not provide the
•
•
•
•
•
physical restraint on those devices that is provided by a lock.
When a tag is attached to an energy isolation means, it is not to be removed without
authorization of the authorized person responsible for it, and it is never to be bypassed, ignored,
or otherwise defeated.
Tags must be legible and understandable by all authorized employees, affected employees, and
all other employees whose work operations are or may be in the area, in order to be effective.
Tags and their means of attachment must be made of materials which will withstand the
environmental conditions encountered in the workplace.
Tags may evoke a false sense of security, and their meaning needs to be understood as part of
the overall energy control program.
Tags must be securely attached to energy isolating devices so that they cannot be inadvertently
or accidentally detached during use.
Respiratory Protection
•
•
The basic function of a respirator is to reduce the risk of respiratory injury due
to breathing airborne contaminants. A respirator provides protection by
removing the contaminants from ambient air or by supplying the wearer with an
alternate source of clean breathing air.
All respiratory apparatus are composed of two main parts:
– the device which supplies or purifies air,
– the facepiece which covers the nose and mouth and seals out the
contaminants.
– The first component defines what class of respirator the device is; the
second determines the relative measure of protection afforded by that
respirator.
Respirator Program Elements
1.
2.
3.
4.
5.
6.
7.
8.
Selection
Medical evaluation
Fit testing
Use
Maintenance and care
Breathing air quality and use
Training
Program evaluation
Respiratory Protection
Classifications of respirators:
– Air purifying respirators (APRs)
• Particulate- mechanical filter
• Gas and vapor- chemical cartridge
• Requires knowledge of ambient concentration and
Maximum Use Limit (MUL) of the respirator
• APRs only clean the air, the ambient concentration of
oxygen must be sufficient (19.5%) for the user
Air-Purifying Respirator (APR)
• An air-purifying respirator that uses a blower to force the
ambient air through air-purifying elements to the inlet
covering.
Respiratory Protection
Classifications of respirators:
• Air supplying respirators (ASRs)
– Provide a substitute source of clean breathing air.
– The respirable air is supplied to the worker from either
a stationary source through a long hose, or from a
portable container.
• The first type are called supplied-air respirators.
• The second type are known as self-contained breathing
apparatus.
Supplied Air Respirator (SAR)
• An atmosphere-supplying respirator for which the source
of breathing air is not designed to be carried by the user.
Also called airline respirator.
Self-Contained Breathing Apparatus
(SCBA)
•
An atmosphere-supplying respirator for which the
breathing air source is designed to be carried by the
user.
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