Safety automation isn’t automatic
Creating a safety automation system is a step-by-step process. NFPA 79 is one place to start to understand U.S. standards.
Is there an Olympic event that made you say, “I can do that?” So filled with budding excitement you go out and try it. At first you struggle just to get up. But it’s OK since you know you’ll get the hang of it with just a little bit of practice. After a few weeks reality sets in. You realize how difficult it really is and want to give up. Of course, there are a few people who will stick with it and become the next generation of Olympic athletes.
Applying safety is a lot like an Olympic event. It looks like it should be simple to add a few safety devices, but it can be overwhelming when you dive straight into it. What standards to use, performance levels, applying it correctly, vendor selection, all of the complaints from people who don’t want it. It looks like it is just easier to give up.
Yes, it is easier to give up. But we are going to get you started with a plan that will lead to success. Your reward will be seeing your coworkers walking out of the factory every night with all of their limbs.
I am going to give you a plan to get you started with applying safety. These steps are just for emergency stops, something everyone should already have. Once you are done with these, simply apply the same thought process to the rest of your system in small steps. Soon you will realize that with a bit of effort, you really can find the tools you need to incorporate safety.
Learning the basics
When learning anything new, you have to understand the basics before you can go out and apply it. You can find the safety basics in standards. In the case of emergency stops used in the United States, the standard is NFPA 79, found at www.nfpa.org. Many industries and countries have different standards. These are developed by subject matter experts based on past lessons learned. For instance, you won’t find rocket scientists writing the standards for the industrial robot industry. The best way to understand which standards to use are to go to your industry sites, read articles, attend safety conferences, and talk to safety suppliers. Also, make sure you learn the standards for the country your equipment will be installed in.
Did you know emergency stops are not machine safe guarding devices? The purpose of an emergency stop is a conscious action to stop a hazard. And as the name states, they should only be used for an emergency. Some common misuses are using the emergency stop for everyday activities such as maintenance to pause the machine during break time or shift changes, and as part of the operating procedure.
Task #1: Find out how often the emergency stop buttons are being used. If they are being used a lot, find out why. Then work with the team to come up with other solutions.
Another common misuse is the placement. It won’t do anyone any good to have an emergency stop located smack dab in the middle of the hazardous work area. The location might have once made sense, but additions and changes to the system might now render it useless.
Emergency stops need to be conveniently located—and that means for everyone, not just the designer. I am only 5’1”. If I have to get a running start to try to jump up to activate the emergency stop, chances are it is not a good location. Where do operators spend most of their time? At the control panels/stations.
Task #2: Make a diagram of your emergency stop locations, making sure there is one on every control panel, and other necessary locations. Verify they are easy for everyone to access.
Did you ever drive in a foreign country and wonder what the sign you just passed was telling you? It leaves you wondering if it was something really important. Same is true with emergency stop devices. You want them to be easily recognizable, even for new employees or visitors.
Task #3: Make sure all of your emergency devices are red with a yellow background. If using pushbuttons, they also have to be mushroom-shaped.
Many years from now, someone may ask you why you made the decision you did. You will do this with a machine safeguard assessment / risk assessment. This will list all of the possible hazards, how some were changed through design, the reduced risks by the implication of safety devices, training, procedures, and validation. You will also want to add the references to the standards used. If someone does get hurt, it will be your way of demonstrating that you did your due diligence to reduce the risk.
Task #4: Document all of your risks and possible injuries, levels of risk, how applying emergency stops reduced the risk, and what standard was used. Verify the format and wording complies with your company’s legal department.
Task #5: This might sound silly, but make sure they actually work, and as intended for its purpose.
Safety doesn’t stop once the initial installation and validation are complete. You need to maintain it. Here are some topics commonly overlooked.
- If machinery is moved or changed, the safety needs to be upgraded to meet the current standard.
- Password protect software and verify measures are in place so safety devices cannot be bypassed or altered.
- Use safety rated devices and controllers.
- Correct wiring and application is just as important as selecting the safety devices.
- Have a plan to test safety devices on regular basis and/or a safety control in place to continuously monitor.
- Don’t leave your team with a false sense of safety. If a safety device is not active, remove it. If it cannot be removed, put a big sign on it and define the back-up procedure.
- Make it a team effort.
- Stay involved and sympathetic. Use team member’s frustration as an opportunity to look for new solutions. Many times they also increase production.
Tina Hull is a safety product engineer for OMRON Automation and Safety. Their Website is www.sti.com.