Every month, over 4 million LPG cylinders (12.5 kg capacity) are refilled in Nigeria; this number will jump to over 10 million by year 2020. Based on the world bank estimates, as far back as 2004, Nigeria’s LPG consumption potential stood at about 3.2 million tons/year, implying that the current LPG consumption of about 600,000 tons/year is far less than the actual demand. This is how vast the Nigerian LPG market is. The market is picking up rapidly and showing signs of explosive expansion. However, this is not without some serious safety implications as evidenced by the exponential increase in LPG related accidents in Nigeria. These challenges beg for more concerted efforts from the stakeholders such as the Department of Petroleum Resources (DPR), Standards Organisation of Nigeria (SON), Nigerian National Petroleum Corporation (NNPC), Federal Fire Service, Nigeria Liquefied Petroleum Gas Association (NLPGA) and the academic community where safety cultures could be hatched out and embedded into curricula. Below are a few random health and safety notes on domestic LPG utilization. and embedded into curricula. Below are a few random health and safety notes on domestic LPG utilization.
LPG for Nigeria’s domestic utilization is basically composed of Butane (70-75%) and Propane (25-30%). Pure LPG is colourless, odourless, flammable, heavier than air and stored under high pressure. Handling a gas with such properties in our homes presents high risks since leakages of a colourless and odourless gas can easily go undetected. Consequently, from safety point of view, the gas is normally mixed with an odorant (a smelly chemical called Ethyl Mercaptan or Ethanethiol) to aid detection in case of leakage.
The expiry date of a gas cylinder is given as an alphanumeric code, in the form: LetterDigits, e.g.: A12, B13, C20, D25. The letters A, B, C and D correspond to the four quarters in a year (ending in March, June, September and December). The digits corresponds to the expiry year, 18 refers to 2018, 20 refers to 2020, etc. So, a D18 cylinder (image shown above) would have expired by December, 2018. Alas, a number of cylinder brands are out there bearing only the test date rather than the expiry date, so be careful.
In Nigeria, the regulation prescribes a maximum of 15 years as the lifespan of LPG cylinders, (maximum of 40 years for pressure vessels such as LPG trailers and 25 years for smaller LPG tanks).
Pressure within the cylinder is very sensitive to surrounding temperature. For instance, when the temperature jumps from 20℃ to 35℃, the pressure within the cylinder could be doubled, depending on gas composition. The free space left at the top, i.e. the ullage (15-20%), is meant to accommodate the changing vapour pressure within the cylinder; So, don’t overfill your cylinder.
Major causes of LPG accidents/precautions:
- Substandard Facilities: Using cylinders with substandard design, poor material of construction especially around weld seams and valve, inadequate labelling, substandard regulator, etc..
- Improper Installation: Poor installation and/or maintenance culture – leaks often results from poorly installed components, e.g.: broken/torn supply hose.
- Poor Ventilation: Mounting the cylinder in a poorly ventilated space (confined kitchen) or close to exits and passages.
- Expired Cylinders: Usage beyond expiry date.
- Poor Regulatory Regime: Relevant regulatory and enforcement agencies need to be on top of the situation – roll out or adopt essential regulatory instruments, ensure regular inspections, public enlightenment, etc.
- Size of Storage: Avoid holding large amounts of LPG indoor, the smaller the amount, the less the hazard in your kitchen (of course the more the frequency of refill, your home safety is worth the refill trouble).
- Cylinder in Car Trunk: When going for refill or returning the refilled cylinders, make sure the gas is not leaking in your car trunk/boot; also with cylinder in the boot, avoid parking the car under the sun for long periods of time.
Summary: Avoid leakages, avoid confined/poorly ventilated spaces and eliminate all sources of ignition.
Dr. Usman Abubakar Zaria, Safety, Health and Environmental Research & Training (SHERT) Group, Department of Chemical Engineering, Ahmadu Bello University (ABU), Zaria, Nigeria.