Davis Hill

Sr. Extension Associate

Managing Agricultural Emergencies

PSU Ag Safety & Health

Farm Confined

Space Safety

Agricultural & Biological Engineering

Objectives

• Define confined space and ID farm spaces

• Talk about permits/checklists/best management practices

• Discuss specific hazards of more common farm spaces

• Discuss strategies farmers can use to safely manage

confined space issues

Typical Farm Confined Spaces

Determination of Confined Spaces

1. Large enough to enter

AND

2. Limited or restricted

means of entry and exit

AND

3. Not designed for

continuous human

occupancy.

Standards & Documents

• OSHA 29 CFR 1910.146

o Confined Space

o Permit required confined space

o Reclassification of confined space

• ANSI/ASSE Z117.1

o Consensus standard for non-permit confined space

• NFPA 350-Consensus standard

o Guide for Safe Confined Space Entry & Work

Permit required confined space

1. Contains or has potential to contain a hazardous atmosphere, OR

2. Contains a material that has the potential for engulfing an entrant,

OR

3. Has an internal configuration that might cause an entrant to be

trapped or asphyxiated by inwardly converging walls or by a floor

that slopes downward and tapers to a smaller cross section,

and/or

4. Contains any other recognized serious safety or health hazards.

To permit or not?

Permit depends on

• Work to be performed and the inherent, potential, or introduced hazards in the space at the time of entry.

• All confined spaces with identified hazards need permits.

• Permit is a documented checklist of important actions.

• Can hazards be eliminated????

Entry permit-checklist

Pre-entry evaluation

Non-permit confined space

• After pre-entry evaluation:

if no hazards are identified

and none will be introduced

then no permit is required.

Reclassified space

• A confined space with

hazards that have been

eliminated after the pre-

entry evaluation will not

need a permit.

Hazard identification

Inherent hazards

o Size & shape of portal

o Products stored

o Fixed equipment

o Physical location

Hazard identification

Introduced hazards

• Things brought into the

space that create a

hazardous environment• Electrical equipment

• Ladders, etc.

• Compressed gas, hot work

• Chemical hazards

E.g., hot water in bulk milk tank

Hazard identification

• Adjacent hazards

o Hazards from adjoining

areas may affect entered

space.

o E.g., silo gas can settle in

grain pit

Confined space is not safe

for entry until all hazards are

identified, evaluated and

eliminated or controlled.

Types of hazards

• Mechanical

• Electrical

• Physical

• Chemical

• Atmospheric

• Biological

• Psychological

Atmospheric Hazards

1. Oxygen Deficiency

2. Presence of

Combustible Gases

3. Presence of Toxic

Gases

None of these

conditions can be

seen.

Oxygen Deficiency

• High risk of asphyxiation

• Very common in confined spaces

• Caused by

o Combustion (welding/cutting torches)

o Decomposition of organic matter (manure) and/or plant material

(silage, grass clippings, etc.)

o Inerting (purging silo with nitrogen or carbon dioxide or steam

from hot water will purge oxygen from bulk milk tank)

Effect of hot water inerting on oxygen

Combustible Gas Hazards

3 components must be

present at once

1. Fuel (combustible gas)

• Methane

2. Air (oxygen)

3. Heat (some source of

ignition)

• Cutting torch, spark

from electric equipment

or cell phone, etc.

Toxic Gas Hazards on the Farm

• Hydrogen Sulfide

• Carbon Monoxide

• Carbon Dioxide

• Nitrogen Dioxide

• Ammonia

Silos

• Physical

• Mechanical

• Electrical

• Atmospheric

• Biological

• Psychological

Silos

• Silo gas

• Falls

• Entrapment in unloader

• Electrical shock

• Worker unable to descend

• Exposure to dust/mold

Silo gas

• Carbon Dioxide (CO2)

• Oxides of Nitrogeno Nitric oxide (NO)

o Nitrogen dioxide (NO2)-Most common

o Nitrogen tetroxide (N2O4)

• Exposure is called Silo Filler’s Disease

Created by the fermentation process. Production begins within four hours after the silo begins to fill. Concentrations reach a maximum in one or two days after filling. Production continues at a decreasing rate for two weeks after filling.

Properties

• Silo gas and CO2 produced

simultaneously

• Heavier than air

• Settle at silage surface and

down chute

• NO is colorless

• NO2 & N2O4 are red-brown

Levels of NO, NO2 & CO2 during early fermentation

Toxic Gases in Tower Silos, by B.T. Comings, F.J. Raveney and M.W. Jesson; National Institute of Agricultural Engineering, Wrest Park, Silsoe, Bedford

conducted in December 1970.

Effects of Various CO2 Levels

Effects of Various NO2 Levels

Grain bins

• Physical

• Mechanical

• Chemical

• Biological

• Psychological

Grain bin hazards

• Engulfment in flowing

material

• Entrapment in unloader

• Falls from heights

• Exposure to

dust/mold/fumigant

Entrapment speed and force

Bulk milk tank

• Mechanical

• Physical

• Chemical

• Atmospheric

• Psychological

Manure storage/pits

• Electrical

• Mechanical

• Atmospheric

• Physical

• Chemical

• Psychological

Manure storage/pits hazards

• Manure/sewer gas

• Explosive

• Mechanical/electrical

mechanism entrapments

• Slips/falls

Hydrogen Sulfide — Manure Gas

• Colorless gas

• Rotten egg odor

• Byproduct of decomposition

• Prolonged exposure deadens sense of

smell

• High concentrations can stop respiration

• Low concentrations will burn respiratory

tract

Effects of Hydrogen Sulfide Levels

Hazard evaluation

• Assess and evaluate risks

• Prioritize risks

• Determine control measures

o Eliminate

o Engineering controls

o Substitution

o Administrative

o PPE

• Establish SOP’s

• Implement and train

Hierarchy of controls

• Eliminate toxic atmosphere

by substituting fresh air

through ventilation.

• Train employees.

• Develop procedures to

follow.

• Provide PPE.

Hierarchy of controls

• Eliminate mechanical

hazards by employing lock

out/tag out.

• Train employees.

• Develop procedures to

follow.

Rescue — Is it needed?

• Recognition & Prevention

of existing and potential

hazards………NO!

• Train entrants to

understand and protect

themselves from potential

hazards.

o Exit the space when bad

happens

Summary

• Farms have spaces that meet the definition of confined

spaces

• Acknowledge and accept best practices

• Training of all involved

• IF ENTRY IS NEEDED

o ID and mitigate hazards

o 2 person job

o Lifeline with retrieval system