Fire Extinguishers and LPG: What Employers Need to Know

The Counterintuitive Truth About LPG Fires

When a fire breaks out in most workplaces, the instinctive response is clear: grab an extinguisher and put it out. This response is so deeply ingrained that it forms the basis of most fire safety training. However, when LPG is involved, this instinct can transform a dangerous situation into a catastrophic one.

The Safety Data Sheet for LPG contains guidance that surprises many employers when they first encounter it: “Do not extinguish an LPG fire – allow gas to burn out.” This seemingly counterintuitive instruction reflects the unique physics of gas fires and carries profound implications for how workplaces should approach fire safety training when LPG-powered equipment is present.

Why You Shouldn’t Extinguish an LPG Fire

Understanding the rationale behind this guidance requires thinking about what happens when LPG escapes from a cylinder or fitting. Unlike a liquid fuel that pools in a fixed location, LPG vapour spreads and accumulates, often in unexpected places. Because LPG is heavier than air (approximately 1.7 times denser) it sinks into low-lying areas, depressions, and enclosed spaces.

When escaping LPG ignites, the fire acts as a visible warning system. The flame indicates exactly where the gas is and, crucially, it’s consuming the fuel as it burns. If someone extinguishes the flame without first stopping the gas supply, the leak continues but now there’s no visible indicator of where the gas is going. The gas continues to accumulate, potentially filling enclosed spaces, flowing into drains, or pooling around ignition sources elsewhere. When this accumulated gas eventually finds another ignition source (and in an industrial environment, it almost certainly will) the resulting explosion can be far more devastating than the original controlled flame.

This is why the first priority in any LPG fire is always to cut off the gas supply if it’s safe to do so. Only once the fuel source is eliminated does the fire naturally extinguish itself as the remaining gas burns off.

When Fire Extinguishers Are Appropriate

The Safety Data Sheet does acknowledge one exception: “If it is essential to extinguish the fire then use only dry chemical powder extinguishers.” This applies to situations where there’s an immediate threat to life and evacuation isn’t possible, or where the fire is preventing access to the gas shut-off valve.

However, this exception comes with an important caveat. Extinguishing the flame without stopping the gas flow creates an immediate and urgent need to eliminate all potential ignition sources in the affected area. This includes not just obvious sources like electrical switches but also the hot surfaces of recently running equipment, mobile phones, and even static discharge. In practice, achieving this level of ignition source elimination in an active workplace is extraordinarily difficult.

The Real Danger: Cylinder Rupture

When an LPG cylinder is exposed to fire, the situation escalates along a dangerous trajectory. The heat causes the liquid LPG inside the cylinder to expand and vaporise more rapidly, increasing the internal pressure. Modern cylinders are fitted with pressure relief devices designed to vent gas before catastrophic failure, but sustained heating can overwhelm these safety mechanisms.

The Safety Data Sheet warns that “temperatures in a fire may cause the tank or cylinder pressure relief devices to open and release gas, or eventually rupture.” It also notes that “if water is not available or can’t be sprayed on the tank or cylinder safely, the metal may weaken from the heat and explode.” This type of failure, sometimes called a BLEVE (boiling liquid expanding vapour explosion), releases the entire contents of the cylinder almost instantaneously, creating a massive fireball and launching cylinder fragments at lethal velocities.

This is why the correct response to an LPG fire involving a cylinder is to drench and cool the tank or cylinder with water spray from a safe distance, whilst waiting for emergency services. The water absorbs heat and slows the pressure build-up inside the cylinder, buying time for either the fire to burn itself out or for professional firefighters to take control.

Your Legal Obligations as a PCBU

Under New Zealand’s Health and Safety at Work Act, persons conducting a business or undertaking (PCBUs) have specific duties regarding fire safety and emergency preparedness. These obligations extend beyond simply having fire extinguishers on the premises.

PCBUs must ensure that workers receive information, training, and instruction about what to do in emergencies involving the hazardous substances present in their workplace.

The Health and Safety at Work (Hazardous Substances) Regulations 2017 specify that emergency response plans must cover all reasonably foreseeable emergencies arising from the hazardous substances in the workplace. For any workplace using LPG-powered forklifts, this means having a plan that addresses LPG-specific fire scenarios and ensuring workers understand the different response required.

Fire Extinguisher Requirements

For workplaces storing or using LPG, specific fire extinguisher requirements apply. When the quantity of Class 2.1.1A flammable gas (which includes LPG) exceeds 50 kg of non-permanent gas or 30 cubic metres of permanent gas, at least one fire extinguisher must be provided. These thresholds are easily exceeded in workplaces with multiple LPG forklifts and cylinder storage areas.

The regulations specify that fire extinguishers must be clearly visible and readily accessible. Readily accessible typically means positioning extinguishers along normal thoroughfares, near exits, or near (but at a safe distance from) specific hazards. The maximum travel distance to any fire extinguisher should not exceed 30 metres from the flammable gases.

Fire extinguishers must also meet specific capability requirements; they need to be usable by one person and meet Class C performance test requirements for gas fires. The minimum rating specified in the regulations is 30B.

However, simply having the correct extinguishers installed is only part of the obligation. Workers need to understand when and how to use them and, equally importantly, when not to use them.

What Training Should Cover

Effective fire safety training for workplaces using LPG must address several key areas that differ from standard fire training.

First, workers need to understand why LPG fires are handled differently. Without understanding the physics of gas fires and the dangers of extinguishing a flame while gas continues to flow, workers may default to their general fire training instincts. Comprehension, not just compliance, is the goal.

Second, workers must know the location of gas shut-off points and how to use them safely. The primary response to any LPG fire is stopping the fuel supply, so this knowledge is critical. Workers should practice locating and operating shut-offs during drills, not discover them for the first time during an emergency.

Third, training should cover the use of water to cool cylinders. Workers need to understand why cooling is prioritised over extinguishing, and they need to know how to apply water from a safe distance and position. They should also understand when cooling is not safe. For instance, if the cylinder has been exposed to flames for an extended period and may already be at risk of rupture.

Fourth, workers need clear guidance on evacuation procedures. The Safety Data Sheet advises moving people from the potential affected area and keeping upwind. Workers should know the designated evacuation routes, assembly points, and the importance of staying upwind of any gas release.

Finally, training should address when to call emergency services and what information to provide. Fire and Emergency New Zealand can review emergency response plans to ensure they align with operational realities, and their personnel have specialist training and equipment for dealing with LPG incidents.

The Cost of Getting It Wrong

An untrained worker who extinguishes an LPG fire without first stopping the gas supply doesn’t just create an immediate explosion risk; they potentially set up a delayed catastrophe. The gas continues accumulating in hidden spaces, in floor drains, under equipment. Minutes later, when an unaware colleague switches on a piece of equipment or a vehicle engine turns over, the ignition occurs far from the original fire, catching everyone off guard.

Proper training doesn’t just protect the individual worker; it protects everyone in the workplace and potentially in surrounding buildings. It also protects you as an employer from the regulatory consequences of an incident investigation that reveals inadequate training.

Building a Fire-Safe LPG Workplace

Creating a genuinely fire-safe workplace where LPG is used requires integrating several elements. Emergency response plans must specifically address LPG fire scenarios and must be tested at least annually. The regulations require that test results be documented and retained for at least two years.

Fire extinguishers must be appropriate for gas fires, correctly positioned, and regularly maintained. But beyond compliance with equipment requirements, the human element matters most. Workers need training that covers not just how to respond but why specific responses are required. They need supervised practice, not just theoretical instruction. And they need regular refresher training to ensure that correct responses remain instinctive.

Taking the Next Step

If your workplace uses LPG-powered forklifts or other equipment, your workers’ fire safety training needs to specifically address the unique characteristics of LPG fires.