Wendy Baker explains how mine operators can deploy innovative technical solutions to help them maintain best practice when it comes to worker safety
The risk of exposure to hazardous contaminants within the mining industry is high. From the excavation of the ore through to its marketable form, the raw materials and chemical processes involved pose a danger to worker safety.
Personal protective equipment (PPE) contributes to a safe workplace and is required by law to control substances that are hazardous to health. Specific site standards and detailed risk assessments help determine the steps that should be taken to protect the safety of employees. However, health and safety guidelines surrounding hazardous substances and decontamination can be difficult to decipher.
Guidelines often recommend the provision of ‘hygiene procedures’ or ‘washing facilities’ to ensure potentially harmful substances are removed before a worker moves on to another task or finishes work for the day. An ordinary shower or sink is not enough to achieve complete decontamination, especially in the event of an accidental chemical spill or splash. Where a substance can cause harm or severe irritation to skin or eyes, the first 10 seconds following exposure is critical to minimise serious injury. It’s imperative that a specifically designed safety shower or eye/face wash is provided to effectively decontaminate in the event of an accident or to clean PPE prior to removal.
Safety showers and eye washes are manufactured to operate according to International and European standards, ANSI Z358.1-2014 and EN 15154, which recommend performance requirements for this equipment to ensure effective decontamination.
Water temperature
According to ANSI, safety showers and eye wash equipment should deliver tepid water in the range of 16-38°C. The human body strives to maintain a steady internal temperature within a normal range of 32 to 38°C. When the body encounters water temperature significantly above or below its core temperature, it instinctively reacts.
A higher water temperature may scald the injured person, adding temperature burns to their chemical injury. Hotter water may also cause the skin to absorb more of the hazardous chemicals. The opposite reaction occurs when the body experiences extreme cold. Lower temperatures can lead to hypothermia or thermal shock. People are also less likely to remove contaminated clothing and PPE if the water is too cold. Clothes containing chemical residue will prolong exposure and exacerbate burns if not removed.
Whether the water is scalding or freezing, the natural human reaction is to withdraw from the extreme temperature to protect the body. Standards recommend at least 15 minutes of shower time to completely rinse away most hazardous chemicals. The only way to ensure this length of time is adhered to is to control the water temperature in the tepid range.
Flow Rate of safety showers
Safety showers deliver a water flow of at least 76 litres per minute for 15 minutes. This provides enough time to remove contaminated clothing and rinse thoroughly. If the flow rate is too low, hazardous substances may not be completely washed off the skin, leading to ongoing chemical burns. Water flow from safety showers is much greater than the standard home shower head, which averages 8-11 litres per minute of flow. The dangers vary by each chemical’s specific properties, but a deluge of water is generally required to wash them away. Eyewash equipment must deliver at least 12 litres per minute for 15 minutes to ensure complete decontamination.
Operation of safety equipment
Safety equipment must be accessible and easy to operate, even with impaired vision. Safety showers and eye wash valves are designed so the flushing flow remains on without the use of the operator’s hands. The control valve must go from ‘off’ to ‘on’ in one second or less.
The provision of safety showers that meet these standards can be challenging within the mining industry due to the often-remote nature of these sites, the lack of a reliable water supply or low water pressure. In these circumstances, a self-contained tank-fed safety shower is ideal, supplemented by mobile units to manoeuvre around the site as the location of the hazard changes.
The ANSI- and EN-compliant Hughes tank-fed safety shower features an overhead tank holding 1,500 litres of water. Upon activation, either via a push bar or hands-free foot panel, the shower will drench the casualty with 76 litres per minute of potable water for up to 15 minutes, ensuring thorough decontamination. An optional eye wash can also be included. The jacketed and insulated models suit ambient temperatures up to 40C, and with the addition of a chiller unit will operate in extremely hot climates up to 55C. The chiller unit is crucial to prevent water within the tank from reaching dangerous levels and potentially scalding a casualty upon activation. For cold climates, immersion heated models are essential to prevent water within the tank from freezing. In environments where temperatures can drop to -50C, the polar tank shower incorporates a double-skinned fibreglass insulated cubicle fitted with internal heaters to protect the user from the elements. With a wide selection of optional fittings, a tank shower can be customised to fit the site’s exact requirements.
On sites where the location of the hazard changes as a project progresses, it is wise to supplement fixed installations with a mobile unit. The Hughes 1,200-litre mobile safety shower with ABS closed bowl eye/face wash unit allows flexibility of location, being easily transported behind a suitable vehicle using the towing hitch provided.
Workforce safety in decontamination processes
The safety of the workforce is paramount. Whilst standard hygiene facilities have their place as part of workplace health and safety, in the case of hazardous substances, they cannot replace the efficiency and effectiveness of precisely designed emergency safety showers and eye wash equipment to provide a full decontamination process.
Wendy Baker is with Hughes Safety Showers
