Exploding Gas Appliances in Sri Lanka
Posted on December 3rd, 2021

Sarath Bulathsinghala

4 Dec 2021

The ‘experts’ – the politicians, the administrators, and the businessmen are trying to ‘rediscover the wheel’! A few days ago, we witnessed parliamentarians, administrators, and perhaps businessmen with vested interests in the ‘gas saga’ sitting together to find solutions for the gas explosions happening throughout Sri Lanka.

Is this the best coterie of ‘wise men’ who can come up with solutions for what is happening? The country would have expected the Institution of Engineers investigating almost now a month of Guy Fawkes ‘fire works’ happening throughout the island.

Why not follow the best practices from the rest of the world without ‘pussy footing’ around the problem? The ‘experts’ look like an assembly of beggars trying to make porridge around a campfire, only a few having anything worthwhile to contribute in terms of real experience!

From what has happened already the evidence for gas fires and explosions point to the following:

  • Loss making Gas companies resorting dubious business practices
  • Recently an abundance of leaking gas bottles released to the users
  • Absence or near absence of added smelling agent
  • Collection of leaked gas confined spaces in houses or other places of gas use – gas being heavier than air!
  • Presence of gas igniting mediums eg: unsafe electrical wiring, electrical switches, mobile phones, simply match sticks used for initiating gas ring fire for cooking or even hot surfaces left after cooking initiating fires or explosions

All this is happening while the rest of the world is using gas safely and happily without concern or untoward incident. Gas has been in use for lighting, heating, transportation and power generating purposes for nearly two centuries. Over the years the world has mastered how to obtain gas from natural sources – ground based natural gas (methane) , or from petroleum manufacturing – LPG (Propane, Butane etc) . They have also mastered how to store, transport (over land, sea and air) and use gas safely in widely different places and climes – in business, transportation, industry and in households.

Liquefied petroleum gas (LPG or LP gas) is also referred to by its constituent names – propane or butane. LPG are hydrocarbon fuel gases used for heating, cooking, hot water and vehicles. Most countries have either 100% propane (Australia & USA), an LPG gas mixture of 60:40 propane:butane (NZ & Belgium) or percentage of propane and butane in LPG around 35:65 propane:butane LPG gas mixture (India, Spain & Hungary). Thus, the much talked about ‘doctoring’ of the mixtures now in vogue among the ‘frogs of the Diyawanna Oya doesn’t seem to have much traction in the science of gas mixtures technologically speaking!  PROBLEMS LIE ELSEWHERE TO BE FOUND OUT BY REAL EXPERTS AND NOT BY THE PRETEND TO BE QUALIFIED, THE BARELY QUALIFIED, THE RARELY QUALIFIED AND THE NOT QUALIFIED!

The safe and best practices have been used and are working well elsewhere in the world with little danger to users. It is worthwhile to note that behind every safety practise now in use, there are many of victims, some still among the living with horrid tales to tell and others as dearly departed, leaving only sad memories for those left behind to suffer not only their personal loss but also the loss of entire livelihoods.  

For safe practises, it is not only the dead and the injured that are counted – ALSO THE ‘NEAR MISSES’! Every ‘NEAR MISS’ IS CONSIDERED ALMOST AS A REAL INCIDENT FOR IT COULD HAVE GONE ONE WAY OR THE OTHER – MAIMED, DEAD OR ‘ESCAPED WITHOUT INCIDENT’! So far in Sri Lanka the reported incidents discounting fake news are only ‘near misses’! This is no cause to celebrate for death was only inches away for those who escaped grave injury or death! Also in Sri Lanka, it is not readily apparent that near misses are taken seriously enough to give due recognition and consideration. This is unfortunate! Most left in the category of God’s will, Good Luck or Good Karma!

In industry, it is usual when untoward incidents take place for engineers to come together an analyse the cause of the incident and come up with solutions to completely eradicate or if not find ways to mitigate the possibility of such incident happening again. One such investigative method is called a HAZOP ( Hazard and Operability)  study. During this investigation, simple questions are asked and answered leading to intelligent insights and methodologies to improve the process or mitigate danger to acceptable level where entire elimination of the problem is not cost effective.

In the case of the above incidents, carrying out a simple HAZOP involving the gas bottle, its accessories and the gas burning device study would suffice. Each of the components should be studied asking relevant questions.

Hazops

Can it happen? – leaks, fires, explosions

How do you know? – smell; gas hose connections damaged, substandard; hissing noise or soap bubble test;

Does it matter? – If matters, can the leaks if any be stopped, what regulatory measures should be implemented by law and by the vendors? Role of the governmental safety watchdogs?

For the gas bottle: The design specifications of the gas bottle – holding capacity litres, weight, maximum and all pressure limits of the bottle, storage and handling methodologies;

LPG cylinder can blast if it is continuously kept exposed to immense heat or fire. In houses, LPG cylinder will not just get blasted on its own. first there will be a LPG leak from the O ring/ faulty regulator or leaky cylinder (rare). then the gas will mix with air, form a combustible mixture and when it comes in contact with a spark or naked flames, the gas explodes. But then also LPG cylinder itself will not get blasted.” – Gautam Das, Indian Oil Corporation.

The graph above shows how the bottle pressure varies according to the ambient temperature, (the pressure within being simply a function of the ambient temperature).  All bottles are normally designed to withstand 5 times or more pressure than what these gasses in any combination of can generate within, 100% Propane being the highest. They are normally equipped with a pressure relief valve in case the pressure goes high due to temperature hikes.

For the gas mixture: what gases were used and their properties, individually and in mixture. The effects of usage at different proportions – the experiences worldwide. Most countries have either 100% propane (Australia & USA), an LPG gas mixture of 60:40 propane:butane (NZ & Belgium) or percentage of propane and butane in LPG around 35:65 propane:butane LPG gas mixture (India, Spain & Hungary).

From high pressure to low pressure at the user’s end:  the accessories used – pressure relief valve and pressure regulators etc, when replaced last, whether within the warranty period?

For the gas utensil: domestic cooker mostly : what make, all connectors including gas hose from the pressure regulator to the gas ring; how old, within any warranty or not? whether maintained well?

However, in Sri Lanka they have to contend with dubious business and political interests too in arriving at ‘solutions’! The situation in Sri Lanka in regard to the ‘leaking gas bottles and blowing gas appliances’ should be understood in this context. Are we in Sri Lanka following the best practices followed elsewhere in the world? If not where have we gone wrong? Do we have to ‘rediscover’ the wheel in Sri Lanka or follow already well established safety protocols in use elsewhere in the world without wasting much needed capital?

https://www.elgas.co.nz/resources/elgas-blog/252-how-much-pressure-is-in-lpg-propane-cylinders-in-what-state/

https://www.elgas.co.nz/resources/elgas-blog/245-how-lpg-works-gas-bottles-regulators-appliances-vaporizers

3 Responses to “Exploding Gas Appliances in Sri Lanka”

  1. NeelaMahaYoda Says:

    It is funny that Sri Lankan engineers are spending days and days to find the reason and solution to this problem. I sincerely think that they should have asked any housewife in Europe or in Australia the reason behind gas cylinders exploding and they would have given the answer in two seconds.

    By the way, I wrote a comment to a newspaper report when the president decided to appoint a committee to investigate this unusual domestic gas explosion giving exactly the same reasons what you have given in your article. But they never published it

  2. Ratanapala Says:

    Very high temperatures and their effects are noticed at places of gas explosions. The following study carried out using a residential situation explains the effects of such explosions. At most places, shattered glasses and injuries show the effects of very high temperatures.

    Dynamic Characteristics of Gas Explosion and Its Mitigation Measures inside Residential Buildings
    https://static-01.hindawi.com/articles/mpe/volume-2019/2068958/figures/2068958.fig.0017.svgz

    Conclusions:

    The numerical model of gas explosion inside a residential building is developed based on the CFD code FLACS. The numerical simulations are performed for different gas filling schemes to identify the initial scenario. Meanwhile, the simulation results are compared with the explosion consequences associated with a real accident. In addition, the dynamic characteristics of explosion overpressure and indoor temperature are analyzed. Furthermore, the effects of vent area ratio and the activation pressure of vent panels in the kitchen are investigated to propose effective mitigation measures for gas explosions inside residential buildings. The conclusions are mainly provided as follows.

    (1) The initial scenario prior to ignition is identified as that the entire fuel region is filled with flammable gas cloud of a volume of 9.7 m × 7.5 m × 3 m and a gas concentration of 8.6%.

    (2) All the overpressure peaks simulated for initial scenario are within the overpressure peaks estimated for the actual accident scene. It indicates that the simulation results are in good agreement with the real accident consequences. Thus, it is feasible and reliable to investigate indoor gas explosion accidents based on the CFD model.

    (3) The overpressure distribution in a room is almost uniform at the same moment and there exists little spatial difference.

    (4) The maximum flame speed is in the range of 34.3 m/s and 230.9 m/s, which means that the gas explosion inside residential buildings is a typical deflagration process. Thus, the explosive products would not deposit and leave black smoke traces on interior walls.

    (5) The maximum temperature can reach up to 1953°C in each room, which can cause secondary fire accidents easily inside residential buildings. In this accident, the cotton and cloth in the master bedroom were ignited by the instantaneous high temperature, which led to incomplete combustion. Thus, a significant amount of black smoke traces was left on the walls and ground in the master bedroom.

    (6) The overpressure peak decreases rapidly with the increase of vent area ratio when , while it is almost independent on vent area ratio when . There is a proportional relationship between the overpressure peaks and the activation pressure of vent panels.

    (7) Natural gas should not be used in places with poor ventilation conditions, such as a basement or a room without windows. If natural gas must be used in these places, the forced ventilation facilities need to be equipped. The single glazed windows or doors are usually installed in the kitchen to mitigate gas explosions.

  3. Cerberus Says:

    We thank Mr.Bulathsinghala for this article. I would like to make a suggestion which I hope the authorities will pick up on. The idea is to add a tamper-proof band on the gas cylinder outlet valve. This has several benefits.
    1. It will prevent the gas from being stolen from cylinders before sale to customers. Currently, the customer has no way of knowing if they are getting a full tank or not.
    2. It will prevent anyone from tampering with the contents of the cylinder. Tampering with a cylinder by outside persons can have negative results for the company. Therefore it should be prevented.
    3. The cost of a tamper-proof band on the cylinder would not increase the cost that much and would have many benefits.
    If you can, please bring this idea to the attention of the authorities as soon as possible.
    Thank you again for writing in your concerns.

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