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OSHA Confined Space Requirements

confined space requirements

OSHA defines a confined space as: a space large enough and so configured that an employee can bodily enter and perform assigned work, has limited or restricted means for entry or exit (e.g., tanks, tankers, silos, storage bins, vaults and pits), and is not designed for continuous employee occupancy.

Confined spaces can be dangerous. That's why the Occupational Safety and Health Administration (OSHA) has set standards that employers and employees must follow when working in confined spaces.


  1. What is confined space monitoring?
  2. What are the 3 criteria for something to be considered a confined space?
  3. Permit vs Non-Permit Confined Spaces
  4. Examples of Confined Spaces
  5. Confined Space Air Monitoring Requirements
  6. OSHA Confined Space Requirements
  7. What is the OSHA standard for a Confined Space?
  8. What should not be used in a confined space?
  9. What are OSHA Quick Cards?
  10. OSHA Regulatory and Recommended Limits
  11. Why are OSHA Confined Space Standards and Training Important?
  12. Atmospheric Monitoring in Confined Spaces
  13. What are the main hazards to agricultural workers in confined spaces?
  14. What are the main hazards to brewers or beverage workers in confined spaces?
  15. What should not be used in a confined space?
  16. OSHA Confined Space Fact Sheets
  17. Confined Space Monitoring Equipment

1. What is confined space monitoring?

Confined space monitoring provides rules for any confined space or enclosed space with limited entry or exit access. Because of the possibility of harmful gases, limited visibility, or the inability to quickly recover someone who is incapacitated, OSHA has created safety standards for workers who access confined spaces.

These safety standards are used as a means to monitor and identify high hazard areas with poor visibility that could result in dangers for those working around hazardous environments. By monitoring confined spaces, it helps mitigate risk and enhance the decision-making process during an emergency.

Gas detection monitors can also safeguard and are used to detect hazardous gases like carbon dioxide, carbon monoxide, or oxygen deficiency before or while the space is being used. This equipment uses a gas sensor to detect or sample for higher than normal gas concentrations, preventing workers from entering or remaining in a hazardous area.

2. What are the 3 criteria for something to be considered a confined space?

In the gas detection world we rely on the Occupational Safety and Health Administration (OSHA) when referencing required workplace safety standards, assessments, and guidelines. In the United States, OSHA ensures safe and healthy conditions for workers by setting and enforcing standards.

According to OSHA, the 3 criteria used to define a confined space is defined as:

  1. A space large enough to enter in and work
  2. A space which holds limited opening for entry and exit
  3. A space not designed for continual worker occupancy

A confined space must meet ANY or ALL of the above criteria to be designated as a confined space. Examples include freezers, keg coolers, beverage dispensing rooms, small grow spaces, underground pits, sewers or wells, tunnels, tanks, chimneys, grain silos, or commercial freezers.

For example, even if a worker enters and exits a keg cooler several times a day, because it only has one door to enter and exit it is defined as a confined space.

3. Permit vs Non-Permit Confined Spaces

OSHA also defines two different types of confined spaces:

  1. Non-permit confined spaces
  2. Permit-confined spaces

1. Non-Permit Confined Spaces

Non-permit confined spaces are defined as spaces that do not have a hazardous atmosphere, cannot engulf an individual or asphyxiate upon entry, does not hold internal configuration hazards, and does not contain any recognizable hazard. Using our example above, a beer cooler would be classified as a non-permit confined space.

2. Permit Confined Spaces

Permit-required confined spaces are defined as a confined space that has any of the following criteria:

  1. Contains, or has the potential to contain a hazardous atmosphere
  2. Contains material that can have the potential to engulf an individual/entrant
  3. Has walls that converge inward, or floors that slope downward and taper into a small restricted area that could asphyxiate or trap an entrant
  4. Contains any other recognized safety or health hazards
  5. Is large enough and configured that an employee can bodily enter and perform assigned work
  6. Has limited or restricted means for entry or exit
  7. Is not designed for continuous occupancy

The Code of Federal Regulations created 29 CFR 1910.146 for OSHA. This regulation was written to place an affirmative duty on employers to train their employees and staff who work in or around any confined space locations. The code also places a particular emphasis on employers and staff to be aware of the potential hazards, recognize the precautions to take, and be knowledgeable about protective equipment needed to safely perform tasks and duties

Ironically, although OSHA created and actively promotes these standards, many individuals throughout the beverage, brewery, agriculture, and safety industries are unaware of them and lack the knowledge needed to work in and around these hazardous spaces.

4. Examples of Confined Spaces

  • Oxygen-deficient atmospheres
  • Vaults
  • Condenser Pits
  • Fermenters, Mash Tuns, Silos
  • Indoor Greenhouse 
  • Cultivation Rooms
  • Grain Silos
  • Keg Coolers (Cold Box)
  • Manholes
  • Pipe assemblies
  • Ventilation Ducts
  • Chemical/Water Tanks
  • Sumps
  • Containment Cavities
  • Heat Sinks
  • Electrical Transformers

5. Confined Space Air Monitoring Requirements

Prior to entering a confined space, the air must be monitored. What you're typically looking for includes: the proper levels of oxygen and that no combustible gases are present. 

In order to monitor the air in a confined space the space must be continuously monitored and the employer must be able to demonstrate that the equipment for continuous monitoring is periodic and sufficient to safeguard potential hazards.

Is continuous monitoring required in a confined space?

Yes, continuous monitoring is required in a confined space. Enclosed spaces with potentially hazardous atmospheres should always be monitored prior to entry and continuously during entry to mitigate potential hazards from occurring.

Additional information on confined space monitoring can be found at OSHA

6. OSHA Confined Space Requirements

OSHA provides a few requirements that employees should know when it comes to highlighting the hazards associated with any confined space:

You should understand the following hazards that could be present such as:

  • Toxic atmospheres that cause various acute health effects
  • Oxygen deficiency environments that displace air by another gas
  • Oxygen enrichment environments that can result in an increased risk of fire or explosion
  • Flammable atmospheres that can present a risk of explosion or a suspension of combustible dust in air
  • Flowing liquid that can cause drowning, suffocation, burns, or injury
  • Excessive heat that can increase the risk of heat stroke or cause an employee to heat collapse from heat stress

7. What is the OSHA standard for a Confined Space?

OSHA's standard for confined spaces (29 CFR 1910.146) contains the requirements for practices and procedures to protect employees in general industries from the hazards of entering permit spaces. Employers in general industries must also evaluate their workplaces to determine if spaces are permit spaces.

The OSHA standard also states that the standard defines confined spaces as hazard atmospheres, meaning an atmosphere may expose employees to the risk of death, incapacitation, impairment of ability to self-rescue, injury, or illness from one or more of the following causes:

  1. Flammable gas, vapor, or mist in excess of 10% of its lower flammable limit (LFL).
  2. Airborne combustible dust at a concentration that meets or exceeds its LFL; Note: This concentration may be approximated as a condition in which the dust obscures vision at a distance of 5 feet (1.52 m) or less.
  3. Atmospheric oxygen concentrations below 19.5% or above 23.5%
  4. Atmospheric concentration of any substance for which a dose or a permissible exposure limit is published in subpart G, Occupational Health and Environmental Control, or in subpart Z, Toxic and Hazardous Substances, of this part and which could result in employee exposure in excess of its dose or permissible exposure limit.
  5. Any other atmospheric condition that is immediately dangerous to life or health.

8. OSHA Confined Space Air Monitoring Requirements

For those individuals, team members, and staff that are required to enter confined spaces, OSHA has established a list of criteria that must be met in order to meet standards and procedures.

  • A written program must be developed addressing potential hazards and precautions
  • Inform those employees who have not been trained in the standard to keep away during the entry activities
  • Each employee who is involved or has the potential to be involved in confined-space entries must be trained before entering any space
  • Use appropriate signs and barricades to prevent entry from others
  • Identify and evaluate hazards in the permit space, before entry
  • Specification of acceptable entry procedures. This includes having an oxygen content between 19.5 percent and 23.5 percent, LFL of substances below 10 percent and below established PELs, TWAs, and TLVs. – Isolation of the permit space
  • Lockout/Tagout procedures will be followed on all applicable equipment.
  • Indication of specific locking and tagging equipment to prohibit use while the entry is taking place. (Ex: Control or elimination of atmospheric hazards through purging, inerting, flushing or ventilating)
  • Maintenance of appropriate gas detection/ventilation equipment

9. What are OSHA Quick Cards?

OSHA Quick Cards are small cards that offer individuals an overview of important safety topics as well as tips to help staff raise awareness of common workplace hazards. Typically, these cards can be stored in a familiar work space and used as a handy tool to increase productivity and training opportunities.

While OSHA Quick Cards have been made for confined spaces, additional quick card topics include:

  • Aerial Lift Fall Protection
  • Vehicles and Equipment Safety
  • Medical Surveillance for Workers
  • Cold Stress 
  • Combustibles and Dust Explosions
  • Workers Slips, Trips, and Falls
  • Electrical Safety
  • Forklift Safety
  • Hazard Communication
  • Safe Work Practices
  • and More

See OSHA's full publications and quick cards by type here.

10.OSHA Regulatory and Recommended Limits

OSHA provided regulatory and recommended limits for dozens of different gases and chemicals. For example, the limits for CO2 are below:

OSHA Regulatory



OSHA Regulatory


9000 ppm

California Regulatory

TWA 5000 ppm
(ST) 30,000 ppm

OSHA Recommended Short term exposure Limit

30,000 ppm

OSHA Recommended 8-hour TWA

5000 ppm

* PEL - personal exposure limit
* TWA - Time Weighted Average
* ST - Short term

See a complete list of all OSHA limits here.

11. Why are OSHA Confined Space Standards and Training Important?

There are several safety precautions that individuals need to be aware of in their daily work environments. Confined spaces requirements are recognized as critical due to the number of deaths and fatalities around confined space and hazardous gas exposure each year.

According to OSHA, there were 1,030 confined space occupational injuries between 2011 and 2018. Of these, 94 were fatal injuries as the result of inhalation of a harmful gas.

For further reference of OSHA confined space fact sheets, read more here.

12. Atmospheric Monitoring in Confined Spaces

Because confined spaces exist and are potentially dangerous there are certain atmospheric monitors and gas detection solutions that have been designed specifically for detecting gas concentrations in hazardous environments. Although individuals working in and around confined spaces often believe they can detect if a hazardous gas is present by smell, there is no other tool that can sense gas concentrations more effectively, quickly, and accurately than a  professionally designed and manufactured gas monitor, detector, or analyzer.

Without proper fixed or portable monitoring in place, individuals can quickly experience overexposure to hazardous gases. Symptoms can include fatigue, headaches, nausea, asphyxiation, and even death from overexposure.

OSHA additionally specifies that "In order to enter any confined space without the use of special types of personal protective equipment or monitoring, such as a self-contained breathing apparatus - atmospheric conditions must have these characteristics:"

  • Oxygen: 19.5 percent to 23.5 percent 
  • Flammability: below 10 percent of the lower flammable limit (LFL) for gases, vapors, mists or combustible dust
  • Toxic gases: below the permissible exposure limit (PEL)/threshold limit value (TLV) or time-weighted average (TWA) of a substance

Should a hazardous space contain higher than allowable gas concentrations, utilizing a proper gas detection monitor is a must and will instantly alert the users that higher concentrations are present by audible and visual indicators.

13. What are the main hazards to agricultural workers in confined spaces?

Agricultural workers and indoor farmers can be overcome by gases like nitrogen dioxide and carbon dioxide when entering a grow room that does not have proper ventilation. Gases that build in grow rooms, manure pits, or silos can quickly kill an unsuspecting worker if gas detection safety monitors are not present.

Employers also have the primary responsibility for protecting the safety and health of their workers. Employees are responsible for following a safe work practice in order to adhere to the proper confined space requirements.

Confined Space Safety Solutions in Agriculture:

  • Be aware that there is always a danger of gases or an oxygen deficiency risk in confined spaces and make sure you are trained to use all necessary safety equipment.

  • Never enter a confined space without:

    • Confirming the space has sufficient oxygen and is not an oxygen deficient atmosphere.

    • Verifying it has been ventilated and CO2 levels are within limit

    • Posting a second person outside the grow space that you can communicate with by sight, sound, or signal.

Are grain silos confined spaces?

Entry into storage areas such as grain silos may be necessary for many reasons such as inspection, maintenance, or cleaning. However, entry into a space that was not designated or intended for regular work and one that has limited means of entry/exit contains physical hazards and is considered a confined space.

Possible grain silo confined space hazards include but are not limited to:

  • Engulfment from grain, dirt, or liquid
  • Explosion from combustible dust created
  • Configuration of the space such as sloping walls and floors
  • Entanglement in moving parts such as shafts, couplings, or gears
  • Energy hazards such as heat, electricity, or stored (lockout tagout is required for all energy sources)
  • Thermal conditions such as extreme heat or cold

14. What are the main hazards to brewers or beverage workers in confined spaces?

Entering confined spaces in a brewery can be very hazardous, and it's crucial to prioritize safety to protect the health and well-being of workers. Some of the main hazards that brewers may encounter when entering confined spaces include fermentation tanks, mash tuns, brew kettles, walk-in keg coolers, cellars, or tanks and vessels. 

Employers also have the primary responsibility for protecting the safety and health of their workers. Employees are responsible for following a safe work practice in order to adhere to the proper confined space requirements.

It's important to assess and classify these confined spaces, implement safety measures, and provide proper training and gas detection equipment to workers who may need to enter them.

Proper ventilation, gas monitoring, confined space permits, and rescue plans should be in place to ensure the safety of brewery personnel when working in these confined spaces.

Confined Space Safety Solutions in Brewery and Beverage:

  • Conducting thorough risk assessments when entering confined spaces or limited entry or exit paths.
  • Providing appropriate PPE equipment and installing or using gas detection safety monitors, like the Remote CO2 Storage Safety 3 Alarm.
  • Having a rescue plan and continual gas safety trainings to ensure all personnel know what to do in the evident of a potential hazard.

15. What should not be used in a confined space?

When a CO2 extinguisher is used in a confined space there is danger that he user may become overwhelmed by the sudden increase in carbon dioxide emissions. This occurs because carbon dioxide is a known asphyxiant and the confined space means oxygen can quickly be replaced by the CO2 much faster.

In addition, any individual working in or around confined spaces that they have never entered before, one should test for oxygen, combustible gases, and then for toxic gas and vapors.

16. OSHA Confined Space Fact Sheets

In order to help maximize safety for workers and individuals in confined spaces, there are a number of resources out there such as fact sheets to follow prior to any hazardous entry. As a reminder, OSHA requires a signed permit for entry into any confined space with hazards. Below we highlight a few additional resources and fact sheets you an utilize in your own establishment.

In addition, in order to educate you and your employees on proper confined space guidelines, precautions, and standards the best place to start is the OSHA website. OSHA compliant consultants and training sessions are available online as well.

For an example of a confined space written program template, view this free template by the Brewer's Association Safety Committee.

17. Confined Space Monitoring Equipment

In addition to portable safety monitors or wall-mounted safety monitors  confined space equipment includes:

  • Gas-detection equipment
  • Ventilating equipment
  • Proper warning signage
  • Communication equipment (if necessary)
  • PPE to be used when engineering controls such as ventilation equipment is not practical
  • Lighting equipment
  • Barricades to prevent unauthorized entry (Ladders to provide safe access to and egress from the permit space)
  • Rescue and emergency equipment

CO2 Safety Devices

1. Personal Safety Monitors for Confined Spaces

confined space monitor

Portable safety monitors and alarms like the SAN-10 Personal 5% CO2 Safety Monitor or the SAN-20 Personal Low Oxygen Safety Monitor are designed for employees who work in enclosed areas where carbon dioxide or other gas buildup may cause personal harm. In addition, the device also features audible/visual alarm indication, exclusive data logging capabilities, and a man down alarm that can be triggered when an employee fall occurs.

For those looking to detect multiple gas concentrations, we recommend a device like the CM-1000 - Multi-Gas Sampling Data Logger

2. Enclosed Area Safety Monitors

enclosed area safety monitor

A common gas detection monitoring system that is used throughout beverage, brewing, agriculture, restaurant, and safety industries is the Remote CO2 Storage Safety 3 Alarm. It is designed to detect and alarm for high carbon dioxide concentrations in confined spaces such as fermentation cellars, keg coolers, indoor greenhouses, and mechanical rooms. The device also allows the user to trigger an exhaust fan or send an alert to the fire control panel.

For other enclosed area applications where there is a danger of inert gases displacing oxygen the RAD-0002-ZR Oxygen Deficiency Alarm is recommended.

See more products to help you meet OSHA Confined Space Requirements.

For more information on confined space and OSHA procedures or additional training, contact us today.

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