To Heat or Not to Heat? That Is the Question
Improvements in health and safety awareness, duty of care to employees, and increasingly extreme environmental conditions mean more thought than ever has to go into safety shower purchasing decisions.
- By Janet Dickinson
- May 01, 2016
With the worldwide search for oil, gas, and other natural resources ever widening, global contractors are turning their attention to increasingly inhospitable environments. The extraction of such resources, which in the past focused on open water areas such as the Gulf of Mexico and the North Sea, have more recently encompassed countries with extremes of temperature such as in Africa, Kazakhstan, and Alaska.
Today's drilling techniques enable operations to take place in temperatures dropping to minus 40 degrees centigrade and right up to 50 degrees centigrade. The goal posts are therefore moving all the time with regard to coping with potential hazards. Fortunately for the welfare of workers, previously less stringent rules governing safety in plants have long gone. Even in the emerging markets, health and safety requirements surrounding quick, effective decontamination are getting tougher, with companies having to meet strict specifications and compliance with standards such as the ANSI Z358.1-2014 international standard and OSHA. Such requirements are encouraging operators and specifiers to look at the quality of the units, their operational needs, and length of service. And going for cheap is not necessarily going to be economical in the long term.
The argument over the pros and cons of whether or not to install heated water safety showers has possibly run its course, with ANSI standards for some time now recommending 15 minutes tepid water drench time for all emergency showers, "tepid" being defined to be between 60° F (16° C) and 100° F (38° C). Safety officers and purchasing/facility managers now have to be mindful of the fact that it is no longer an option to give their workforce cold water safety showers direct from the mains. The right decision can therefore be difficult to make about what safety equipment they actually need for the purpose.
A safety shower is a piece of equipment that business and industry have seen, until recently, as an afterthought. It may stand unused for weeks, months, or even years (apart from a weekly test), which hardly makes it the most vital piece of equipment; that is, until there's an emergency, and then it becomes invaluable. If you are the person who has just been sprayed with concentrated acid, you will want to know that the emergency shower is going to do its job perfectly—first time, every time—without exacerbating the problem further.
Improvements in health and safety awareness, duty of care to employees, and increasingly extreme environmental conditions in which an operative has to work mean that more thought than ever before has to go into safety shower purchasing decisions.
Many COSHH sheets state that a casualty has to shower for at least 15 minutes in order for the satisfactory removal of hard-to-shift chemical contaminants, such as caustic soda. The necessity for 15 minutes or more of tepid water is absolutely vital, so as to avoid minimizing the premature cessation of decontamination due to thermal shock. So when specifying a safety shower, areas including water access/storage, available space, the costs of heating large volumes of water, the cost of installing and running inline instantaneous water heaters, and the environment are all points for consideration for what will be the purchase of the most effective piece of equipment.
Emergency Shower Types for All Environments
A "tank" shower is possibly the most effective solution to guarantee tepid water because, by the very nature of being able to store water, operationally it is not affected by water or power failures. Regardless of ambient or incoming water temperatures, the shower will deliver a guaranteed 15 minutes of tepid water at 76 liters per minute as recommended by ANSI because of the effective management of the stored water.
If there is access to suitable mains water providing the correct flow rates, then it is possible to install a “mains-fed” safety shower. However, this sort of equipment will not deliver tepid water (a common misconception) and therefore must be connected to a tepid water supply. Add to this that, with a safety shower system that does not store water in the pipework and is completely self-draining, you have a piece of equipment that is more energy-efficient and resistant to corrosion. And if it does not hold any water at all, then it cannot ever freeze or overheat.
You then need to look at the environment. In very hot countries where the water supply feed is exposed to extreme heat, the water would be heated naturally by the sun to a dangerously high temperature. If the water was to remain at this temperature, it could cause or increase injury to the user. So how can industry get it right for the right environment?
As a starting point, you need to look at your water supply. If you can't connect directly into a reliable mains water supply, then gravity-fed tank showers are the ideal solution providing a guaranteed supply and instant tepid water. Operationally, these are some of the most efficient and cost-effective safety showers on the global market. Units should be built entirely of GRP and stainless steel, which ensures they are corrosion resistant and avoids costly maintenance issues normally associated with using galvanized steel and wood-based materials.
In situations where the contaminant is a burn-inducing chemical, the hot water would intensify the burns and cause the substance to be absorbed further into the skins pores. At the other end of the environmental scale, to suddenly douse someone with freezing cold water would not only shock them but at the very least, give them hypothermia. The pores would close immediately, trapping the contaminant and therefore hampering attempts to wash it off.
More sophisticated methods are available that heat the tank so that it is operable in temperatures down to minus 40 degrees centigrade. Equally, the method of applying a "chiller" to the tank enables safe use in temperatures up to plus 40 degrees centigrade. Effective water cooling and heating methods that go beyond the 15-minute tepid water drench time are also available to give you up to 30 minutes' drench time for when working with or near potentially harmful substances.
In hot climates, the provision of a chiller unit coupled to a tank shower reduces the water to the recommended 20° C. The chiller activates only when the incoming water exceeds this temperature; when the water has been cooled to the correct temperature, the unit deactivates. Chiller units can be fitted to any tank shower.
In cold climates, where temperatures reach down to minus 40 degrees C, the water supply needs to be heated to 20 degrees C. Tank showers that have the capacity and capability to provide tepid water instantly for durations in excess of the recommended 15 minutes allow for more difficult chemical substances to be washed off while ensuring affected workers don’t leave the safety shower too soon due to the water temperature becoming uncomfortable. Water is heated by means of a thermostatically controlled immersion heater, which keeps the water to a constant tepid temperature. This energy-efficient system will use a 3kw immersion heater, so it is economical in terms of running costs, installation, and gives immediate first aid.
Showers for Offshore Use
Tankless systems can take vital seconds for the water to become tepid, resulting in the initial delivery of water being cold and causing the worker to suffer thermal shock also. Due to the flow rate of 76 liters per minute being required, the amount of power needed to heat such a flow instantaneously can be expensive to run and very costly to install due to power supplies required of up to 110 kw. This can also be said for simply testing the system weekly for maintenance purposes.
Moving away from dry land to the sea, safety showers on oil and chemical tankers have to meet different design specifications than those on oil and gas fields. The units need to soak up huge wave momentum while also delivering an uninterrupted flow of water to wash away hazardous spills and materials.
The water tank of a safety shower can hold in excess of 1.1 tons of liquid 3 meters up in the air. When static on land, this tremendous weight is not a problem. Out on the high seas, however, a shower is put under extreme stresses and strains. This will twist a solid stainless steel water tank because the constant shifting of its load exerts a huge strain on the tank. By using a flexible plastic tank and 316 external reinforced stainless steel framework, the forces involved can be absorbed, as well as withstanding the salty atmosphere. An additional special GRP internal baffle de-compartmentalizes the load, thus reducing momentum.
So while it may look daunting to have to make the right choices, it no longer becomes a "heated" issue. Simply by first looking at your environment, potential hazard, and water supply, the right purchasing decision to ensure you are compliant becomes easier, remembering of course that a safety shower is for life, not for luxury.
This article originally appeared in the May 2016 issue of Occupational Health & Safety.