ISSUE DATE: 12/09/2010 

PROGRAM INFORMATION BULLETIN NO. P10-21 

FROM: KEVIN G. STRICKLIN 

 Administrator for 

 Coal Mine Safety and Health 

 JEFFERY H. KRAVITZ 

 Acting Director of Technical Support 

SUBJECT: Breathable Air, Air-Monitoring and Harmful Gas Removal 

 Components for Use in Refuge Alternatives Consisting of 

 15-psi Stoppings 

Who needs this information? 

This Program Information Bulletin (PIB) applies to operators of underground coal 

mines, miners’ representatives, Mine Safety and Health Administration (MSHA) 

enforcement personnel, and other interested parties. 

What is the purpose of this bulletin?

This Program Information Bulletin (PIB) provides information to the mining 

community on breathable air, air-monitoring, and harmful gas removal components 

that may be used with refuge alternatives consisting of 15-psi stoppings. This 

information is being provided since refuge alternatives consisting of materials 

prepositioned for miners to deploy in a secure space with an isolated atmosphere that 

MSHA has accepted in approved Emergency Response Plans (ERP) that were in use 

prior to March 2, 2009 are permitted only until December 31, 2010, or until replaced, 

whichever comes first. 

Information

Until breathable air, air-monitoring, and harmful gas removal components approved by 

MSHA under Title 30 Code of Federal Regulations (C.F.R.) Part 7 are commercially 

available for use with refuge alternatives consisting of 15-psi stoppings, mine operators 

may comply with the Federal Mine Safety and Health Act (Mine Act) by: 
2 

1. Using breathable air, air-monitoring, and harmful gas removal components that 

are grandfathered for use until December 31, 2013 under 30 C.F.R. § 

75.1506(a)(3). These include breathable air, air-monitoring and harmful gas 

removal components that MSHA accepted in ERPs and that were in mines prior 

to March 2, 2009 for use with brattice cloth or other pre-positioned material for 

miners to deploy after an event to create a secure space with an isolated 

atmosphere. While brattice cloth or other pre-positioned material may not be 

used as the structural component of a refuge alternative after December 31, 2010, 

other components initially approved for use with brattice cloth or other prepositioned material may be used until December 31, 2013 if approved for use in a 

15-psi stopping refuge unit as part of a revised ERP. In reviewing the ERP, the 

District Manager will determine whether the components will maintain trapped 

individuals for a sustained period of time if used in conjunction with the 15-psi 

stopping unit specified in the revised ERP. The guidance document “Use of 

Non-Part 7 Approved Components with 15 psi Stoppings” is attached to this PIB 

to provide further information. 

2. Purchasing a packaged system designed for these applications from a 

manufacturer of State-approved prefabricated refuge alternatives having a rated 

capacity for persons that is equivalent to the capacity of the 15-psi stopping unit. 

While the breathable air, air-monitoring, and harmful gas removal components’ 

capacities should be at least equivalent to the capacities of corresponding 

components in the State-approved prefabricated units, purge air capacity should 

be sized to fit the dimensions of the 15-psi stopping unit, including the air lock 

system. The breathable air, air-monitoring and harmful gas removal components 

are subject to review and approval by the District Manager to assure that they 

are capable of maintaining individuals for a sustained period of time if used in 

conjunction with the 15-psi stopping unit specified in the revised ERP. 

3. Connecting a compressor or fan to an existing 15-psi stopping unit via a borehole 

or via horizontal, buried (or otherwise protected) line such that breathable air 

can be provided immediately after an event that may require miners to seek 

refuge. This system is subject to review and approval by the District Manager to 

assure that it is capable of maintaining individuals for a sustained period of time 

if used in conjunction with the 15-psi stopping unit specified in the revised ERP. 

While this option is available to any mine operator, MSHA recognizes that it may 

be most viable for new mines or existing mines establishing an additional 

working section. 
3 

What is the background for this PIB?

A number of mine operators have expressed an interest in using refuge alternatives 

consisting of 15-psi stoppings constructed prior to an event. These units must be used 

in conjunction with breathable air, air-monitoring and harmful gas removal 

components that have been approved for use pursuant to 30 C.F.R. Part 7 or that have 

been grandfathered for use until December 31, 2013. However, Part 7-approved 

breathable air, air-monitoring, and harmful gas removal components presently are not 

commercially available, and not every mine operator has access to grandfathered 

components. 

An operator who wants to use 15-psi stoppings to provide refuge may design a plan for 

construction of the stoppings for a District Manager to consider during the ERP review 

process. See MSHA Program Policy Letter No. P09-V-14, 15 psi Stoppings as Structural 

Components for Refuge Alternatives (12/18/09). This PIB provides guidance for the use of 

15-psi stopping refuge alternatives until December 31, 2013 and prior to the commercial 

availability of Part 7-approved components. 

What is MSHA’s authority for this PIB?

Section 316 of the Federal Mine Safety and Health Act of 1977, as amended, 30 U.S.C. 

§ 876; 30 C.F.R. §§ 75.1506 and 75.1507. 

Is this PIB on the Internet?

This PIB may be viewed on the Internet by accessing the MSHA home page 

(www.msha.gov ) then choosing “Compliance Info” and “Program Information 

Bulletins.” 

Who is the MSHA contact person for this PIB?

Coal Mine Safety and Health, Division of Safety 

Erik Sherer, (202) 693-9523 

E-mail: sherer.hubert@dol.gov

Technical Support, Approval and Certification Center 

Howard Epperly, (304) 547-2034 

E-mail: epperly.howard@dol.gov

Who will receive this PIB?

MSHA Program Policy Manual Holders 

Underground Coal Mine Operators 

Coal Special Interest Groups 

Attachment 
 1

Use of Non-Part 7 Approved Components with 15 psi Stoppings 

This supplement is intended to provide guidance for underground coal mine operators 

and other interested parties with respect to refuge alternatives utilizing 15 psi stoppings. 

This guidance is being provided as per PIB No. 10-21 for non-MSHA Part 7 approved 

components placed behind a 15 psi stopping after March 2, 2009. This guidance will 

apply on an interim basis and expire on 12-31-2013. After December 31, 2013, all 

components for use inside 15 psi stoppings will have to be MSHA Part 7 Approved. This 

guidance does not supersede or replace any provisions of the Final Rule for Refuge 

Alternatives. 

General 

The illustration below depicts an example that consists of a skid located between two 15 

psi stoppings with an inner wall that is constructed to provide for the airlock. The inner 

wall is not required to be rated for 15 psi. The skid contains all of the components and 

provisions required to sustain trapped miners for the period of time designated in the 

ERP. The refuge alternative must have the ability to be pre-shifted as defined by §75.360 

(d). 

The stoppings should be inset in the crosscut as much as possible and still allow the 

required area for the number of intended occupants. A flush location is less desirable 

since this would expose stoppings to higher pressure and debris from an explosion. 

Refuge alternatives must provide at least 15 square feet of floor space per person and at 

least 30 to 60 cubic feet of volume per person as outlined in the Final Rule 

§75.1506(b)(1). The airlock measurements can be used to meet the space and volume 

requirement if waste is disposed outside the refuge alternative and airlock areas. 
 2

Among other things, the ERP must include the rated capacity of each refuge alternative, 

the number of persons expected to use each refuge alternative, and the duration of 

breathable air provided per person by the approved breathable air component of each 

refuge alternative. The actual dimensions of the airlock and internal space (location of 

skid) should be provided in the ERP. A district manager may refuse to approve an ERP if 

the operator does not demonstrate that the maximum apparent temperature inside the 

refuge will not exceed 95 degrees F when the refuge is used at its maximum capacity 

throughout the entire period of time that it may be used. 

The methods for operation of the refuge alternative components (breathable air, airmonitoring and harmful gas removal) should be included in the ERP. These methods 

also must be made readily accessible at the refuge alternative, and they should provide 

the necessary level of detail to allow the miners to operate the refuge alternative as 

intended and be formatted to be easily read and understood by miners while subjected to 

the stress of an emergency. This material should be used in quarterly and annual 

expectations training. Additionally, information should be provided for pre-shift 

examinations, maintenance, and maintenance training. Maintenance procedures or 

methods should include scheduled refuge alternative examinations and checks for expired 

components and provisions. 

The refuge alternative must have a two-way communication facility that is a part of the 

mine communication system, which can be used from inside the refuge alternative; and 

accommodations for an additional communication system and other requirements as 

defined in the communications portion of the operator’s approved ERP. 

The refuge alternative needs to be stocked with the following provisions: 

 Lighting sufficient for persons to perform tasks. 

 A means to contain human waste effectively and minimize objectionable odors. 

 First aid supplies. 

 Materials, parts, and tools for repair of components. 

 A fire extinguisher that meets the requirements for portable fire extinguishers 

used in underground coal mines under part 75. 

 Food and water. 

Containers used for storage of refuge alternative components or provisions should be 

 Airtight, waterproof, corrosion resistant and rodent proof; 

 Easy to open and close without the use of tools; and 

 Conspicuously marked with the expiration date of the corresponding contents and 

instructions for use. 

Components should not liberate harmful or irritating gases or particulates into the 

structure. Some nonmetallic materials liberate “off-gas.” Vapors, aerosols or particulates 

should not be released into the refuge alternative. Materials used in a refuge alternative 

or component should be evaluated to verify that they do not release harmful or irritating 

gases. Materials that have a potential to ignite should not be used or should be stored in a 

sealed noncombustible container. 
 3

All miners should be trained on the safe use and potential hazards of oxygen and 

compressed gases, and they must be trained on the operation of the components. 

Additionally, the transportation (including placement) of the skid and use of its contents 

and components should be covered during all training sessions including new miner and 

all training required by the final rule. 

For miners who will be constructing the 15 psi stoppings prior to an event, the guidance 

given in Program Policy Letter P09-V-14 should be followed. 

A statement should be included stating that the components or parts are compatible with 

other components and, upon replacement, are equivalent to the original components or 

parts. The intent is to assure that components or parts must be interchangeable or must 

integrate with the other components or parts in the refuge alternative so that the refuge 

alternative will continue to operate as intended 

The information submitted should include the components’ make and model number, if 

applicable. Documentation should include features of each component and contain 

sufficient information to document the technical specifications. The information should 

include the dimensions and layout of the refuge alternative components, controls, and 

materials necessary for proper operation. 

Each component’s or part’s in-mine shelf life, service life, and recommended 

replacement schedule should be included. 

Spare regulators and tools to make repairs should be provided in the event of failure of 

the primary regulator on the compressed breathable air and oxygen system. 

All electrical components located inside the refuge alternative must be either MSHA 

approved as intrinsically safe or permissible. 

Breathable Air 

The methods for providing breathable air with sufficient detail of the component’s 

capability to provide breathable air over the duration stated in the ERP must be provided. 

Breathable air should be supplied by compressed air cylinders and / or compressed 

breathable-oxygen cylinders or from boreholes with fans or compressors installed on the 

surface. Only uncontaminated breathable air should be supplied to the refuge alternative. 

As referenced in the final rule, MSHA recommends using Grade D compressed air. 

Grade D air specifications: 

 O2 = 19.5 to 23.5 % 

 CO = 10 PPM max 

 CO2 = 1000 PPM max 

 Oil = 5 mg/m3 max 

 Odor = lack of noticeable odor 
 4

When using refuge alternatives designed for 5 or fewer miners, operators should consider 

using only compressed air due to the increased risk of fire associated with compressed 

oxygen systems. Compressed air in lieu of an oxygen system uses 5 times the number of 

cylinders, however, with fewer people, the number of cylinders needed to provide 

breathable air is still practical. The use of compressed air cylinders that deliver 6.6 cubic 

feet of air per hour per person would still require CO2 scrubbing. 

Mechanisms generally should be provided and procedures included so that the refuge 

alternatives sustain each person for at least 96 hours. Mechanisms include gauges, valves, 

manifolds, adjustable flow-rate control and associated charts for required flow-rate based 

on occupancy. 

Oxygen should be delivered at a rate of 1.32 cubic feet per hour per person. 

The oxygen concentration should be maintained at levels between 18.5 and 23 percent, 

and the average carbon dioxide concentration maintained at 1.0 percent or less, with 

excursions not to exceed 2.5 percent. 

The following table is used to determine the minimum number of oxygen cylinders 

needed for maintaining breathable air for 96 hours within the refuge. The table is based 

on an oxygen consumption rate of 1.32 cubic feet per hour per person. 

Total Quantities of Oxygen for 96 Hours 

Persons 

 O2 

(Ft3) 

4500 psi

cylinders Persons

 O2 

(Ft3) 

4500 psi 

cylinders 

1 127 1 19 2,408 5 

2 253 1 20 2,534 6 

3 380 1 21 2,661 6 

4 507 2 22 2,788 6 

*5 634 *2 23 2,915 6 

6 760 2 24 3,041 7 

7 887 2 25 3,168 7 

8 1,014 3 26 3,295 7 

9 1,140 3 27 3,421 8 

10 1,267 3 28 3,548 8 

11 1,394 3 29 3,675 8 

12 1,521 4 30 3,802 8 

13 1,647 4 31 3,928 9 

14 1,774 4 32 4,055 9 

15 1,901 4 33 4,182 9 

16 2,028 5 34 4,308 9 

17 2,154 5 35 4,435 10 

18 2,281 5 36 4,562 10 
 5

* From the paragraph above the table related to using refuge alternatives with 5 or less 

persons, the number of compressed air cylinders (4500 psi) required for 5 persons would 

be 5 times the quantity of Oxygen cylinders or 10 cylinders of compressed air required 

for breathable air. Other compressed air cylinders are required for purging requirements 

and would be in addition to the 10 in this situation. 

Oxygen Hazard Identification and Prevention

An analysis or study should evaluate the potential fire and ignition risks of compressed 

oxygen systems. The results of this analysis or study should be included in the ERP. 

Oxygen fire hazards can be avoided by plumbing the oxygen cylinders into a manifolded 

system in a certified oxygen clean facility. The term “certified” means that 

manufacturers, suppliers, and rebuilders of oxygen systems and components ascertain and 

confirm that a part or system is (a) clean, (b) suitable for use with oxygen in accordance 

with industry standards, and (c) able to withstand (i.e., compatible with) the 

corresponding pressures given industry recognized safety factors. The reference cited in 

the Refuge Alternatives Final Rule preamble was: Safe Use of Oxygen and Oxygen 

Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, 

Storage, and Transportation, ASTM Stock No.: MNL 36 

. 

Picture showing secured cylinders with manifold 

Oxygen systems should not be assembled or maintained underground to minimize the 

contaminant ignition hazard. Plumbing of these systems should incorporate flow valves 

that prevent a leaking cylinder from evacuating the entire system. Individual gauges 

should be used for each cylinder valve to facilitate pre-shift inspection. 

Sharp angled bends and fittings should be avoided to prevent particle ignition inside of 

the system. This can be accomplished 

by the use of smooth radius bends, as 

shown in the illustration. Use only 

commercially available parts that have 

been tested as suitable for oxygen use, 
 6

including ‘no oil’ gages. The system should be designed such that flow velocities will be 

below 100 ft. per second to alleviate the possibility of particle ignition. As a reminder, 

velocity in ft/second is not to be confused with flow in cubic ft/second as shown on flow 

gauges. Please see the relationship between velocity and flow rate in the chart below: 

Relationship Between Velocity and Flow Rate 

Nominal Diameter 

(inches) 

Inside Diameter

(inches) 

Velocity (ft/sec) Flow Rate 

(cfm) 

Flow Rate

(lpm) 

1/8 0.125 100 0.6 14.4 

1/4 0.25 100 1.8 58.2 

3/8 0.375 100 4.8 130.2 

1/2 0.5 100 8.4 231.6 

5/8 0.625 100 12.6 361.8 

3/4 0.75 100 18.6 521.4 

7/8 0.875 100 25.2 709.2 

1 1 100 33 926.4 

Maintain a minimum distance of pipe length to 10 times the pipe diameter downstream of 

a potential high velocity component, such as valves, tees, or at any location where the 

flow changes directions. Particle ignition can occur with velocities greater than 150 ft 

per second. Do not use non-metallic hoses in the oxygen system. 

Cylinder valves should remain in either the on or off position depending on the circuit 

design. Turning cylinder valves on and off should not be part of the pre-shift inspection 

procedure. Turning oxygen valves on and off is a potential source of particle impact, 

frictional flow, and/or adiabatic compression ignition. The proper procedure is to open 

the valves on oxygen cylinders slowly to prevent potential impingement induced fires or 

explosions in the systems. The ERP should include instructions for use that includes 

language about the importance of proper deployment. Additionally, a label detailing this 

procedure should be affixed in the area of the manifold. 

Oxygen systems should be housed so as to prevent corrosion to the system, and the 

housing should be ventilated to avoid oxygen enrichment of the enclosure. Firefighting 

accessibility should be taken into consideration when approving the system. 

A compressed breathable oxygen system should not be used with a previously used 

compressed air system because a fire or explosion could occur when pure oxygen 

contacts oil and grease from the previously used compressed air system. 

Harmful Gas Removal 

Airlock / Purging

Each refuge alternative should include means for removing harmful gases. Purging or 

other effective procedures should be provided for the airlock to dilute the carbon 

monoxide concentration to 25 ppm or less and the methane concentration to 1.0 percent 
 7

or less as persons enter, within 20 minutes of persons deploying the refuge alternative. A 

minimum of four purge cycles would be required. 

The airlock should have a volume of compressed air designed for repeat purging to allow 

multiple uses of the airlock by persons entering to accommodate the structure’s 

maximum occupancy. The sum of these purging volumes will determine the total amount 

of compressed air needed for purging. 

The procedures for monitoring and maintaining breathable air in the airlock, before and 

after purging should be specified. The instructions for determining the quality of the 

atmosphere in the airlock and refuge alternative interior and a means to maintain 

breathable air in the airlock should be specified. 

The air that is used to purge the airlock must be in addition to the breathable air needed to 

sustain persons for 96 hours. 

 

The airlock should be configured to accommodate a stretcher that allows the doors to be 

closed with the stretcher in the airlock. 

Without an airlock, the interior volume must be purged to bring the harmful gas 

concentrations to an acceptable level prior to persons removing breathing apparatus after 

entry and within 20 minutes of persons deploying the refuge alternative. 

Chemical Scrubbing

Carbon dioxide removal components should be designed and sized to have the capability 

to remove carbon dioxide at a rate of 1.08 cubic feet per person per hour for the stated 

duration of breathable air based on the maximum designed occupancy of the refuge. 

Mechanisms (controls and monitoring) should be provided so that the average carbon 

dioxide concentration is 1.0 percent or less, and excursions do not exceed 2.5 percent 

within the refuge alternative. The oxygen concentration should be maintained at levels 

between 18.5 and 23 percent. Procedures describing these controls should be provided 

and kept for ready reference inside the refuge alternative. These procedures for the 

chemical scrubbing should include deployment, operation and temporary disposal of 

spent scrubbing material. 

The ERP should include information from the manufacturers of chemical scrubbing 

material that is relevant to the specific refuge alternative design. This information should 

include calculations demonstrating that their product meets the 1.08 cubic feet per hour of 

CO2 per person basis for an approval consideration. As an example, the ERP should 

indicate the calculations and number of curtains or quantity (if a powered system is used) 

of scrubbing material required on a per person/per hour basis. 
 8

Harmful gas removal components should meet the following: 

 Chemicals should be contained such that when stored they cannot come in contact 

with persons, the mine atmosphere, moisture, and they cannot release airborne 

particles. When the product is used, it should not come in contact with persons or 

release airborne particles. 

 Provided with all materials, parts (such as hangers, racks, and clips), equipment, 

temporary disposal containers, and instructions necessary for deployment and use. 

 Stored in an approved container that is conspicuously marked with the 

manufacturer’s instructions for disposal of used chemical. 

 Chemicals used for removal of carbon dioxide and its associated packaging 

should be evaluated for potential ignition and fire hazard. 

 A powered scrubber should not produce continuous noise levels in excess of 85 

dBA in the structure’s interior. Continuous noise above 85 dBA can interfere with 

communication and could adversely affect hearing. 

 Carbon dioxide removal components should be used when breathable air 

cylinders or oxygen cylinders are necessary for breathable air. 

Air-monitoring 

The air-monitoring component provides occupants with the ability to determine the 

concentrations of carbon dioxide, carbon monoxide, oxygen, and methane both 

immediately outside and inside the refuge alternative structure, including the airlock. 

Occupants need to be able to measure gas concentrations outside the refuge alternative 

without exiting the structure or allowing exterior gases to enter the breathable air space of 

the structure. 

The operating range, type of sensor, gas or gases measured, and environmental 

limitations, including the cross-sensitivity to other gases, of each detector or device in the 

air-monitoring component should be specified in the ERP. 

The following chart provides guidance on methods of gas detection, and the associated 

sensors, recommended for various gases: 

Gas to be monitored 

Recommended Primary 

Method of Detection Type of Sensor 

Oxygen Electronic gas detector electrochemical 

Carbon Dioxide 

Electronic gas detector (stain tube as 

secondary means) Infrared 

Carbon Monoxide 

Electronic gas detector (stain tube 

acceptable as secondary means for 

sampling outside of refuge alternative) electrochemical 

Methane Electronic gas detector catalytic or infrared 
 9

While not recommended as a primary means to measure gas concentrations in a refuge 

alternative, stain tubes provide a supplemental method for measuring carbon dioxide and 

for measuring carbon monoxide outside of the refuge alternative. 

In all cases, the methods for monitoring gas concentrations, including charging and 

calibration of devices, must be described in the ERP. The procedure for operation of the 

individual devices should be included in the ERP to demonstrate the instruments’ 

capability to function as necessary to test gas concentrations as appropriate over the 

period specified in the ERP for providing breathable air. The use of multiple detectors is 

preferred. Detectors that will be turned on and off to conserve the battery must be 

approved for use in this manner. 

Structural 

The refuge alternative skid should secure and protect the components including 

compressed gas cylinders during transportation. The skid also should be protected from 

falling roof and rib during storage and transportation. The enclosure should permit ready 

access to components for pre-shift and maintenance examinations. Electronic devices 

should be arranged so that they can be readily checked for battery charge and function. 

Valves, regulators, and piping should be protected against damage from handling and 

roof and rib falls by guarding, metal enclosures or other appropriate protective methods. 

A procedure should be described for keeping the internal area of the skid free from 

contamination of dust and debris, and a regular schedule should be provided for periodic 

housekeeping of the internal contents of the skid, including the cleaning of coal dust and 

other material. 

The skid should be provided with a means to indicate unauthorized entry or tampering. 

The skid generally is not subject to 15 psi overpressure or flash fire requirements if the 15 

psi stopping door remains closed. If the District Manager requires the doors to be left 

open (for example to ventilate the interior to prevent gas accumulations) the skid should 

meet overpressure and flash fire requirements in the final rule. 

The cleanliness of oxygen systems is critical for their safe operation. Small combustible 

particles and oils could provide a fuel source for a fire and explosion if they enter a 

compressed oxygen system. 

Tow bars or other appropriate devices should be used to transport the skid. 

Inadequate rigging and towing devices could result in hazards to miners. As shown 

below, the skid should be designed with proper connections for tow bars to eliminate the 

need for chains, ropes, or slings. 
 10

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