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Signaling Technology Critical for Maintaining Safety in Crane Hoist Applications

Audible and visible signals reduce risk of dangerous, costly accidents

By Jacob Vernon, Signaling Specialist Audible & Visual Signaling, Pfannenberg

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. Utilizing a combination of alert technologies can 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 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.

Additionally, signals increase throughput by reducing the likelihood of crane downtime. Signaling a need to change conditions or perform maintenance reduces the risk of 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.

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. 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.

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 -40ºF to +131ºF environments. Meanwhile, the company’s DS series sounders feature aluminum die-cast housings for use in areas up to +160ºF. 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.

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