Avalanche release by gas mixture ignition

Avalanche warning sign

When an avalanche is triggered by gas mixture ignition, pressure is built up on an unstable snow cover by igniting a gas-oxygen mixture in order to trigger an avalanche artificially and in a controlled manner (see: Artificial avalanche triggering ). Avalanches can be triggered by igniting a gas mixture using permanently installed equipment or mobile. The gas mixtures are ignited remotely throughout.

Trigger effect

The ignition of a gas mixture, depending on the gas volume and gas mixture, has similar effects on the snow cover as explosives - detonations (see: Avalanche release by explosives ). The additional pressure on the unstable snow cover is intended to create a chain reaction of a small avalanche before a large avalanche can develop through accumulation of snow, which then goes off in an uncontrolled manner and can cause great damage.

Trip point height

Explosion point height	Cargo type	Charge size	Radius / zone of action [m]
Over-snow blasting (approx. +3 to 3.5 meters)	explosive	4 - 5 kg	120 - 130 ^{note 1}
Over-snow blasting (approx. +1 meter)		1.5 - 2.5 kg	60-70
Surface cracking		4 - 5 kg	50-60
Surface cracking		1.5 - 2.5 kg	35-40
Release with 12 cm mine thrower (snow surface)		3 kg	40
Triggered with rocket tube 80 (RAK) 8.3 cm (snow surface)		0.7 kg	20-25
Blasting under the blanket of snow		1.5 - 3 kg	10
Over-snow ignition	Propane gas - oxygen mixture	0.8 m³	30th
		1.5 m³	40
		3.0 m³	50

^{Note 1} Similar to the triggering of an avalanche by explosives, the best effect is achieved when the triggering pressure is built up about 0.5 to 3 meters above the snow cover.

For the right time to trigger an avalanche, see: Artificial avalanche triggering - triggering time .

Systems

A basic distinction can be made between permanently installed and mobile systems for triggering avalanches by igniting gas mixtures. Examples of companies that are used in practice are also presented.

Permanently installed systems

Systems with permanently installed pipes

Ex-gas system in the Rosa Khutor ski area in Krasnaya Polyana, Sochi, Russia

Schindler Kar in Klösterle, Vorarlberg, Austria, with gas ex-systems

Gas central (container) type Gasex

Systems with pipes permanently installed on the mountain slope and remote-controlled release generate the release pressure on the snow cover by means of a propane / oxygen mixture (18%: 82%) in an open metal pipe (ignition pipe) facing downwards and away from the mountain slope. These ignition tubes are each connected to a gas center (also: container) with a separate gas and oxygen line, and the explosive gas-oxygen mixture is only mixed in the ignition tube when required and then ignited. Depending on the size of the gas center, up to ten ignition tubes can be connected. Up to 30 ignitions can take place per bottle set. The manufacturer is the company: Technologie Alpine de Sécurité TAS

Technical specifications

Ignition tube

The ignition tube installed on the slope is offered in several dimensions, e.g. B. for 0.8 m³, 1.5 m³ or 3 m³ propane gas / oxygen mixture. Old systems also with 4.5 m³. The ignition tubes can also be supplied in different colors.

Gas center

The gas center (container) located on the mountain near the ignition tubes contains the gas bottles and oxygen bottles, the electrical control and self-sufficient energy supply with photovoltaic modules , batteries, trigger control, system monitoring, seismometer, weather station, etc.

System advantages

The system has been offered under the trade names Gasex® and Gasflex® since 1988 and has been installed since 1989.

Simple gas storage,
no manipulation with explosives required,
Installation and use possible even in places that are extremely difficult to access,
Ignition above the snow cover, therefore pressure wave on the snow cover,
Vibration on the site,
no duds ,
Remote ignition (safety for operating personnel),
simple and inexpensive handling,
Triggering possible in any weather and no visual contact required,
Very short triggering consequences: 2 to 3 minutes follow-up time per ignition with several tubes, approx. 15 minutes waiting time, with ignition in the same tube.

Operation and release

The operation of the permanently installed system does not require any special additional training, only training.

It is usually triggered by a radio connection or a GSM network or GPRS connection and our own software from the valley. The software enables secure access, permanent monitoring of the system, ignition and triggering of an avalanche, recorded with a seismometer and documented by the software.

lifespan

The lifespan of the systems has not yet been adequately investigated, but should in any case be more than 40 years. All of the systems installed since 1989 are still in operation.

Installed systems

Around 2150 ignition tubes are expected to be installed worldwide in 2013. Selection of installation locations (as of January 2010): Andorra : 42; Argentina : 8; Austria : 284; Canada : 28; Chile : 49; France : 973; Germany : 11; Italy : 146; Japan : 11; Russia : 24; Slovenia : 3; Spain : 46; Switzerland : 74; Turkey : 3; USA : 72.

O'Bellx

O'Bellx® is a stationary system for generating the gas pressure required to trigger an avalanche, in which the gas center and ignition unit are combined in one device. The device in the form of a metal cone including gas supply bottles is placed on a 4 m high mast with a helicopter, which is permanently installed in the area, whereby no ground staff is required (similar to some avalanche detonators ).

The energy supply is self-sufficient via photovoltaic modules. Operation, monitoring and ignition are controlled fully automatically via radio or GSM.

In contrast to systems with pipes, this system can be operated without external supply containers and lines. A device should be able to trigger around 40 times before it has to be replaced. Refilling and maintenance take place in the valley.

The mobile version of the same system is marketed as Daisybell® (see below).

AVALHEX

AVALHEX is a stationary established system for the generation of the required gas pressure for triggering avalanches, are summarized in the gas unit and the ignition unit and the gas mixture-filled natural rubber - balloons are brought to ignition.

The gas mixture consists of hydrogen and oxygen ( oxyhydrogen ) in a ratio of 31:69.

In France, Savoy , 20 AVALHEX Exploders were installed.

Mobile systems

Mobile avalanche triggering systems are used where a permanently installed system is not economically viable or where special weather conditions require rapid response. The mobile systems described here are flown to their destination with helicopters and the system is ignited while hanging on the helicopter during a hover (see: Avalanche release with a helicopter ).

The advantages of the permanently installed devices for triggering avalanches by igniting gas mixtures are also largely present in mobile devices.

Daisybell

Daisybell® is a mobile system for triggering an avalanche, in which a bell-shaped device weighing around 600 kg with gas bottles on a 20 to 25 meter long rope is located under the helicopter and the ignition of the hydrogen / oxygen gas mixture is as close as possible above the snow cover takes place (ideally 0.5 to 5 meters). The distance between the bell-shaped device and the snow cover is recorded by laser distance measurement and the correct trigger position is determined and reported to the helicopter. The ignition bell is filled with hydrogen and oxygen before it is immediately used on site and is automatically ignited immediately after readiness for operation is displayed. The resulting pressure wave can trigger an avalanche.

All work processes are controlled from the helicopter. There are less than 10 seconds between release and ignition. 50 to 55 releases can be made with one unit, with no waiting time between two successive shots. The resulting compressive force is comparable to a 0.8 m³ Gazex ignition tube.

Avalanche Blast

Avalanche Blast is a mobile system for triggering avalanches, in which a 550 kg device with gas bottles is attached to a rope below the helicopter. In this facility, a latex balloon with a diameter of about 1.2 to 1.6 meters is inflated and ignited by a hydrogen / oxygen mixture. The hydrogen / oxygen gas mixture is ignited as close as possible above the snow cover (0.5 to 3 meters). The resulting pressure wave after the ignition of the gas mixture can trigger an avalanche. Up to eleven ignitions can be carried out one after the other.

The system was made ready for series production by Werner Greipl as a prototype and by Elikos in Val Gardena in winter 2003/2004.

commitment

All permanently installed systems can also be used in poor visibility and in the dark. A license to use the devices is not required in Austria. Mobile systems can usually only be used when visibility is good.

Detection

In the case of permanently installed devices, a geophone or microphone built into the device measures and displays whether the ignition and the success of the triggering of the avalanche occurred . With mobile systems, a visual check is carried out to determine whether an avalanche has occurred or not.

Web links

Commons : Avalanche Safety and Precautions - Collection of Pictures, Videos and Audio Files

GAZEX
Function of a Gaz-Ex system , youtube.
National Avalanche Center of the United States Forest Service
GAZEX® The most powerful avalanche triggering system , website: Federal Forest Research Center ( Austrian Federal Forest Office ). As of January 2010, last accessed on December 28, 2018.

Individual proof

↑ The effective zone is the circular area around the detonation point within which the additional pollution generated has a certain minimum size. Effective zones are used for assessing negative explosions (“Which area was tested by the explosion?”) And for developing safety concepts (Lukas Stoffel [1] ).

↑ The percussion fuse must be fine-tuned accordingly so that it is triggered as far as possible on the surface of the snow.

↑ According to Lukas Stoffel: Davos Artificial Avalanche Release: Blasting Effect , Methods, Benefits, Problems , WSL Institute for Snow and Avalanche Research SLF, Innsbruck 2010, the mixture of the company Gasex: Propane: Oxygen = 18%: 82%.

↑ Lukas Stoffel: P Artificial Avalanche Release , Tec 21, Volume 131, 9/2005, p. 6.

↑ Lukas Stoffel: Comparison of blasting methods: Gazex, Avalanche Guard / Mast Inauen-Schätti, Wyssen Sprengmast, Avalancheur , Comparison of methods for artificial avalanche release, WSL Institute for Snow and Avalanche Research SLF, January 24, 2013, p. 4.

↑ According to LAVINRÖJNING: GAZEX VID KOOTENAY PASS, CANADA , the Gas.Ex system was invented in 1988 by Jacob Schippers ( Netherlands ) from Technologie Alpine de Sécurité ( France ).

↑ ^a ^b ^c Anja Brucker: Artificial release of avalanches to secure traffic routes in Austria - status quo and assessment from the perspective of experts.

↑ Mag. Josef Six: New ways of triggering avalanches , website: Tiroler Forstverein.

↑ Lukas Stoffel: Comparison of the blasting methods: Gazex, Avalanche Guard / Mast Inauen-Schätti, Wyssen Sprengmast, Avalancheur , Comparison of methods for artificial avalanche release, WSL Institute for Snow and Avalanche Research SLF, January 24, 2013, p. 3.

↑ Lukas Stoffel: Comparison of the blasting methods: Gazex, Avalanche Guard / Mast Inauen-Schätti, Wyssen Sprengmast, Avalancheur , Comparison of methods for artificial avalanche release, WSL Institute for Snow and Avalanche Research SLF, January 24, 2013, p. 2.

↑ GAZEX® The most powerful avalanche release system , website: Federal Research Center for Forests., P. 32.

^ ^A ^b Alain Duclos, Pierre Senabre: AVALHEX: New Gas-Mix-Explosive System for Avalance Triggering - Statement After Two Seasons of Use in Savoie, France .

↑ Lukas Stoffel: Davos Artificial Avalanche Release: Blasting Effect, Methods, Use, Problems , WSL Institute for Snow and Avalanche Research SLF, Innsbruck 2010.

↑ Philippe Berthet-Rambaud, Louis Noel, Bruno Farizy, Jean-Marc Neuville, Stéphane Constant, Pascal Roux: DEVELOPMENT OF AN HELICOPTER-BORNE GAS DEVICE FOR AVALANCHE PREVENTIVE RELEASE , International Snow Science Workshop 2008.

↑ MAK: Daisy Bell - safe release of avalanches by helicopter in Mountain Manager 8/2008, p. 74 f.

↑ Manufacturer: Gummiwerk Czermak & Feger.

↑ THE LATEX BALLOON in its diverse uses, here on avalanche excitement, website: ballonpoint.com.

[1] The effective zone is the circular area around the detonation point within which the additional pollution generated has a certain minimum size. Effective zones are used for assessing negative explosions (“Which area was tested by the explosion?”) And for developing safety concepts (Lukas Stoffel [1] ).

[2] The percussion fuse must be fine-tuned accordingly so that it is triggered as far as possible on the surface of the snow.