Audible and visible signals reduce risk of dangerous, costly accidents.
Settings where crane hoists are employed pose significant dangers to technicians, operators, and other workers on the floor. Because of these safety risks, everyone on the floor must be alert to the crane and its load when nearby.
Audible and visible signals help protect workers by providing clear indications when there is a moving load nearby so they can take necessary precautions and avoid harm. Proper signaling is critical; inaudible and insufficiently visible signals on the shop floor can lead to dangerous and costly accidents.
When looking to maximize safety in environments with overhead cranes, dual sounder and strobe combination signaling devices are especially recommended. There is little cost difference between combination and individual signaling devices, however, the added benefit to the user is immense. Oftentimes, workshop conditions prevent workers from either hearing or seeing a signal, but rarely prevent both. Utilizing a combination of alert technologies can therefore be beneficial in maximizing safety, without additional cost.
Advantages of audible and visual signaling in overhead crane use
In overhead crane applications, combination signaling devices can offer cost savings through two different avenues: reduced risk of harm to personnel and increased throughput of the factory floor. Signaling devices reduce risk to personnel by warning of impending danger so that the risk of deaths and injuries are mitigated with no lost time. This reduced risk, however, depends on the efficacy of a signaling device, based on its decibel and joules output.
Photos courtesy of Pfannenberg
When looking to maximize safety in environments with overhead cranes, dual sounder and strobe combination signaling devices are especially recommended.
Additionally, signals increase throughput by reducing the likelihood of crane downtime. If a crane is down, there is a high likelihood of significant revenue loss. Signaling a need to change conditions or perform maintenance reduces the risk of that revenue loss. State-of-the-art combination signaling devices not only warn personnel of a moving load but also use varying tones and lights to warn operators of specific conditions that can cause downtime. Signaling devices can emit specific alerts for collision avoidance, over-speed alarms, hoist brake failure alarms, overload alarms, and over-temp VHD alarms. Businesses that rely on crane use to facilitate production can use integrated alert systems to minimize downtime, maximize worker safety, and effectively save their bottom line.
Selecting and installing the correct audible signal
When selecting an audible signal for an overhead crane application, it is important to ensure that the signal is the correct decibel level for the given application. Factors such as machinery noise output should be taken into consideration. Determining the correct audible signal decibel level is based on the application and area in which the device will be used. Signals should be set at no less than +5dB above the application’s maximum sound pressure level; however, the ideal set point is +10dB above this sound pressure level for added safety.
For example, a steel mill might have hundreds of overhead cranes used for the production and throughput of raw steel. However, it would not make sense to use the same signal on a crane in the blast furnace as the one that is used in a coil stacking yard. The latter setting would require a lower decibel level compared to the blast furnace, and using such in a blast furnace environment would augment risk in an already dangerous area. Companies that specialize in audible and visual signaling technology, like Pfannenberg, analyze years of extensive data to help determine appropriate volume levels for signaling sounders in a wide range of applications.
Once the decibel level of a sounder is determined, the next concern is the installation location. Most often, signaling devices are mounted on the moving trolley or the bridge of the crane. Additionally, it is important to mount the cone of the sounder in the same direction as the crane load, so the sound effectively reaches those within the risk path.
Selecting and installing the correct visible signal
The next step is to determine the joules needed for a combination signaling device’s visual signal. Sound decreases significantly over distance, and significantly louder-than-necessary audible signals can be startling and even dangerous to workers. Light-based alerts, on the other hand, maintain their intensity over distance, providing safe and effective messaging. Visible signaling devices are thus rated by the distance they effectively reach. But unlike increasing decibel output, adding joule power (increasing intensity and brightness) can only add to the signal’s safety factor and reduce personnel risk.
As with the audible signal, once the brightness level of a visible signal is determined, where to install the signal is the next important choice. Like audible signals, visible signaling devices are usually mounted on the moving trolley or the bridge of the crane. The pyramid shape of the strobe light should also be mounted in the direction of the load the crane is carrying to minimize risk.
Extreme environments demand specialized signaling equipment
Applications with extreme environments demand specialized signaling technology. Some signaling products, like the PATROL and PYRA series signaling devices from Pfannenberg, are designed for extreme high and low temperatures. These devices feature electronic board, digital sound capsule, and polycarbonate housing designs that enable them to be rated for use in -40°F to +131°F environments. Meanwhile, the company’s DS series sounders feature aluminum die-cast housings for use in areas up to +160°F. In loud environments, these same PATROL and DS series devices offer exceptionally high sound pressure outputs of and the capacity to be volume controlled up to -12dB to fit each exact application. RF
