FAQ'S/

Welcome to our Mining Frequently Asked Questions. Understanding Your Needs and Looking for Customized Solutions!

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What is a Refuge Chamber?

ON₂ builds, supplies, and services our mobile mine refuge chamber, the TommyKnocker. It is easy to move and can include a Refuge One Air Centre making it a complete Mine Refuge System. The ON₂ TommyKnocker Sales Brochure explains the function, sizes and uses of the TommyKnocker Refuge Chamber and outlines all of the standard and optional equipment.

When do you need a mine refuge chamber?

You need to install an ON₂ mine refuge chamber when:

There is no escape-way or secondary means of exit from the mine.
Miners are working in remote areas of the mine, away from the normal access route into the mine
Developing new levels
Developing a new mine
Re-entering an old mine

When initial mine development is underway, interim safety procedures are necessary until refuge chambers are established underground. The use of portable ON₂ refuge chambers or the provision of oxygen self-rescuers are alternatives if a permanent refuge chamber is not practical.

How many refuge chambers do you require?

The number of chambers and their size depend on the maximum number of workers expected to use the chamber at one time. Be prepared for contingencies, such as when additional individuals could be present at any location (e.g. geologists, visitors, inspectors, trainees, managers, etc.). Always have enough ON₂ Refuge One Air Centers on hand to provide breathable air for the maximum capacity of the chamber.

Where should refuge chambers be located?

Locate a refuge chamber at these point in your mine:

Main or normal travel routes
As close as possible to the greatest number of working places
A safe distance from hazardous areas

How long should it take to evacuate to a refuge chamber?

The chamber should be within a maximum 15-minute walk for any crew member.

How many miners will need to evacuate to and occupy the refuge chamber?

This will depend on the number of miners and other workers within a 15-minute walk of the chamber. Be prepared for contingencies, such as when there could be additional individuals at any location (e.g. geologists, visitors, inspectors, trainees, managers, etc.).

What is the maximum amount of time it could take rescuers to reach the refuge chamber?

A mine’s rescue plan should include the maximum time it will take to rescue trapped miners. This is the mining company’s responsibility to prepare and train for. ON₂ builds Air Centres and Refuge Chambers that provide up to 96 hours of breathable air.

What are your sources of breathable air?

There are 3 main sources of breathable air in a refuge chamber:

Dead air space within the refuge chamber
The Mine's compressed air pipelines
ON₂'s Refuge One Air Centre

Can compressed air cylinders, oxygen candles or high pressure oxygen cylinders be used as a source for breathable air?

No, these systems do not address the proper control of carbon dioxide, which can quickly build up and contaminate your occupants’ air supply.

What are safe levels of cabon dioxide and oxygen in a sealed refuge chamber?

In a sealed refuge chamber without ventilation, falling oxygen and rising carbon dioxide concentrations pose varying degrees of discomfort and potentially life threatening circumstances to the occupants. The size of the chamber and how long occupants will be contained will impact the air quality (see Performance Data Sheet). Safe values must be determined by your mine’s Industrial Hygienist.

What level of carbon dioxide is acceptable in a sealed refuge chamber?

350 ppm: Normal carbon dioxide concentrations
5000 ppm: The Time-Weighted Threshold Limit Value (TLV-TWA), where occupants would experience increased breathing rates.
10,000 ppm: Headaches occur
30,000 ppm: The Short-Term Exposure Limit (TLV-STEL); no more than 15 minutes at this level
50,000 ppm: Causes panting and discomfort; intoxication will occur within 30 minutes
100,000 ppm: Unconsciousness occurs
>100,000 ppm: Unconsciousness followed by death within 1 minute

What level of oxygen depletion is acceptable in a sealed refuge chamber?

20.9% Oxygen: The normal atmospheric oxygen concentration
19.5% Oxygen: The minimal acceptable level of oxygen
18% Oxygen: Occupants will require additional effort to breathe
16% Oxygen: Flames are extinguished and the occupants' pulse & breathing rate will increase
14% Oxygen: Occupants experience fatigue upon exertion, emotional upset, impaired judgement, and faulty coordination
12% Oxygen: Occupants' respiration is impaired, causing heart damage, poor judgement, discomfort, vomiting, and nausea
<10% Oxygen: Unconsciousness & death occur

How long would it take for these levels to become dangerous?

Depending on the size of the chamber and the number of occupants, studies have shown likely levels of 5000 ppm carbon dioxide, the Time-Weighted Threshold Limit Value (TLV-TWA), will be reached in less than one hour and dangerous levels (20,000 ppm) are reached within four hours.Furthermore, depletion to 18% oxygen, which causes increased breathing rate, could be reached in less than five hours and dangerous levels (less than 16% oxygen) in less than eight hours.

How do i determine occupancy times for a refuge chamber?

The maximum safe time within a refuge chamber depends on the size of the chamber, the number of occupants, the expected time of occupancy in a worst case scenario, the acceptable levels of CO₂ and O₂ and the source (if any) of breathable air.
ON₂ suggests designing and equipping your chamber to keep the occupants alive for at least 48 hours and ON₂ has redesigned their Refuge Systems to provide up to 96 Hours of breathable air.

Is the Refuge One CSA approved?

Our Refuge One Air Centre is manufactured to field-testing standards. There are currently no CSA standards for this type of unit, so the unit itself is not CSA approved. However, the 120-volt charger is CSA approved, as are all other components in the unit.

What kind of carbon dioxide absorbents can be used in the ON₂ Refuge One?

ON₂’s Refuge One Air Centre is designed to use a particular size of carbon dioxide absorbent to obtain maximum efficiency. Please CONTACT US for more information about the type of carbon dioxide absorbent we recommend.

How long will the batteries and sodalime supply last before they need replacement?

5 years, from the date of manufacture which is stamped on both the Battery case and the Sodalime Keg.

How many occupants fit in the ON₂ TommyKnocker?

The standard 14 ft. (4267mm) chamber accommodates 10 occupants; for every additional 2 ft in length, the chamber can hold another 2 people. The maximum number of people that an ON2 TommyKnocker can accommodate is 20.

What type of power does the ON₂ TommyKnocker use?

The TommyKnocker (and the Refuge One Air Centre) require 120V AC and 60 Hz charger inputs and 12V DC outputs. The optional Air Conditioning unit is wired for 230V AC, with inverted battery power as backup. We can also supply 220V and 50 Hz units (other voltages and frequencies are available).

What is a Refuge One Air Centre?

Refuge One Air Centre provides breathable air to both permanent refuge stations and mobile refuge chambers such as our ON₂ TommyKnocker. The Air Centre scrubs the carbon dioxide from the internal chamber air and replenishes oxygen at a metered rate from the high pressure oxygen cylinders. The ON₂ Refuge One Air Centre Sales Brochure explains the function, sizes and uses of the Air Centre and outlines all of the standard and optional equipment.

Does the Refuge One Air Centre require mine compressed air and / or electrical supply?

The Refuge One Air Centre works independently, regardless of the supply of external electricity and/or mine compressed air.

Is the ON2 Refuge One Air Centre included in the price of the TommyKnocker?

The TommyKnocker can be quoted with or without the Refuge One Air Centre.

What options are available for the TommyKnocker?

Contact ON2 for more information and prices on these additional features available for the TommyKnocker:

Compressed air system
Carbon monoxide scrubber
Communication Centre
Portable gas monitor
Air conditioner
Entertainment unit

MINING FAQ'S

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Welcome to our Mining Frequently Asked Questions. Understanding Your Needs and Looking for Customized Solutions!

Please do not hesitate to CONTACT US for additional information.

Please do not hesitate to CONTACT US for additional information.

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