Plant personnel working in process manufacturing facilities have to be aware of their surroundings and nearby dangers. Conscientious companies provide them with appropriate personal-protective equipment (PPE), and with safety shower and eyewash stations to minimize the impact from unfortunate encounters with irritating or otherwise harmful products. Plant personnel should know where the nearest emergency stations are and how to use them, but the question remains, does anyone else know when someone is in trouble?
As Alex Patterson and Marcio Donnangelo point out in a recent article in Plant Engineering, the only way operators may be aware of an emergency is if the affected person manages to make a distress call on the plant radio, or the incident is observed by a coworker. This isn’t a good situation.
Safety managers generally want an alarm system capable of informing operators when an incident is happening without the need for the victim to call in and report, or for another individual to witness the action and call in. The activation of a shower or eyewash station alone should be sufficient to alert operators, without requiring any further action by the victim, as well as to meet regulations and specifications. To meet OSHA’s good practices recommendations, such as no more than four minute first-aid response in the location where the operation is in distress and no more than 15 minutes for qualified assistance, everything starts with an efficient and effective alarming system.
A process plant or facility could have dozens or even hundreds of safety shower installations, and running cables to each would be extremely expensive, which is why many plants have never done it. Fortunately, as wireless instrumentation networks become more common, there is a very practical and far less expensive alternative.
The practicality of using a wireless network to support safety shower sensors has increased as more companies deploy WirelessHART networks for process instruments. Where such networks already exist, it is a simple matter to add safety shower sensors. Where no wireless networks have been deployed, the initial gateway and backhaul infrastructure will have to be added, but this can in turn support wireless instrumentation.
WirelessHART has been in use for many years now, and operates everyday in plants around the world in every imaginable application, so it can be counted on to do the job. Well-designed networks combined with the right devices can provide the highest level of reliability, and Emerson has the components to implement this and other wireless solutions.
Emerson uses an assembly consisting of a Rosemount 702 two-input discrete WirelessHART transmitter to outfit a typical safety shower and eyewash station and TopWorx magnetic proximity sensors. Each station needs its own assembly, and the WirelessHART transmitter communicates to the gateway serving as the collection point for the wireless transmitter data transmission.
Of course, the right components don’t constitute a complete solution, appropriate work practices and training for everyone in the plant is also needed.
Adding the hardware and setting up the transmitters on the WirelessHART network is only the beginning of creating a comprehensive program. To get to the point where activation of either the shower or eyewash activates an alarm in the control room or security room, where one or more people are on duty 24/7, requires the implementation of corresponding safety and work procedures. System status should be shown on a new human-machine interface (HMI) screen, added as part of the project. The new HMI typically shows a diagram of the plant and the locations of the shower/eyewash stations. If a shower or eyewash handle is pulled, an alarm should sound and screen graphics should supply a clear indication of the station’s location.
Most plants treat such an alarm as a high-priority process alarm since a worker may be in peril, and also because the situation responsible for the leak or vent may still be happening. Besides attending to the individual, additional steps may be necessary to solve the problem. These projects require the participation of many groups within the facility, with appropriate training for all involved.
You can find more information like this, and meet with other people looking at the same kinds of situations in the Emerson Exchange365 community. It’s a place where you can communicate and exchange information with experts and peers in all sorts of industries around the world. Look for the Wireless Group and other specialty areas for suggestions and answers.