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What could be more important than making provision for your employees for when things go wrong? Although PPE covers most eventualities and easily prevents most incidents requiring medical treatment there are occasions when these defences are breached. This article, split into three parts, aims to provide you with food for thought and solutions to potential problems.
What could be more important than making provision for your employees for when things go wrong? Although PPE covers most eventualities and easily prevents most incidents requiring medical treatment there are occasions when these defences are breached. This article, split into three parts, aims to provide you with food for thought and solutions to potential problems.
Apologies to Sir Isaac Newton!
Gravity-fed emergency showers do have their drawbacks…
In its simplest terms, an emergency shower is a fairly basic apparatus, which drenches industrial accident victims with substantial quantities of water. The problem is that the equipment is rarely used in its “simplest terms”!
Standard products or catalogue items generally work well for many applications, but often times they are used in circumstances outside of their specific design parameters. Industrial accident victims are often exposed to hazardous chemicals such as corrosives (acids and bases), oxidisers, and solvents. The object is to both remove the hazardous materials to halt further injury, and to mitigate the effects of the exposure to that point.
Since contact with most hazardous materials requires at least 15 minutes of immediate and constant flushing, having the correct volume of water and a minimum water pressure available are critical. There are three emergency shower system variations to consider: (1) Plumbed-in assets, where there is access to municipal water, (2) Air-Charged systems offering a stable, low-mounted water supply that is pressure fed for use, via bottled compressed air and (3) Gravity-fed systems that have a supply of water suspended over the emergency equipment until needed. Each of the three variations can be configured as a shower, eyewash or combination system.
It’s obvious that the best solution is to have a plumbed-in system available in the closest proximity to potential use. That’s because plumbed-in equipment offers the ability to temper the water and can most easily treat multiple victims. Tempering supply water minimises the possibility of hypothermia, which can occur when a victim is exposed to the temperatures of many areas’ tap water for 15 continuous minutes. And, since plumbed-in systems have the shortest recovery time, their ability to treat multiple victims is readily apparent.
In areas where the water supply is either unstable or not available at all, the best choice is air-charged shower/eyewash systems. In these products, a sufficient volume of water is held for use at the system, in a pressurised state, and is consistently fed through the emergency equipment at the proper pressure (up to 50 psi) for the entire 15 minute shower cycle.
When you contrast air-charged systems to gravity-fed equipment, several things jump out immediately: (1) Many gravity-fed systems do not hold sufficient volumes of water. Basic calculations of volume and pressure indicate that a 1,200 litre holding tank, for example, cannot supply the ANSI required minimum of 20 gpm over a full 15 minute use cycle. Some gravity-fed systems have the ability to re-fill the holding tank while in operation. But that refill process (at a typical 10 psi) will not keep pace with the outflow, which results in the level in the tank constantly diminishing throughout the use cycle. (2) The design of gravityfed equipment uses the water pressure created by elevating the tank above the system, as well as the physical pressure of the weight of the water in the tank pressing downward. As indicated above, the water level drops throughout the use cycle. There is a danger, then, that the pressure will also decrease, most likely to below the ANSI required 20 gpm minimum flow rate. Sorry, Sir Isaac, but gravity alone simply can’t supply water volume, at the proper pressure, to assure adequate rinsing and/or irrigation.
More and more we are asked to assess our customers’ operations and assist them in developing an Engineered Solution for their specific circumstances. And, more and more we find ourselves gaining insight into customers’ businesses, so we can more effectively advise them and adjust our standard products to an everchanging norm. The “state-of-the-art” in emergency equipment continues to advance, fueled by this collaborative effort.
Casey Hayes is the Engineering Manager at Haws Corporation, located in Sparks, Nevada. He can be reached at +1 (775) 353-8320 or [email protected]
You can also call Niklaus Wittwer at the European office on +41 34 423 2300 or email him at [email protected] Haws Corporation designs, manufactures and distributes drinking fountains and emergency equipment.
Published: 10th Oct 2003 in Health and Safety International
