Safeguarding workers from mixer hazards.
By Mindi Zissman
Whether it’s removing machine guarding, opening the hood during a batch run or cleaning without disabling the motor, mixer safety remains one of the biggest hazards in a precast concrete plant.
Just ask Mike Mueller of Teka North America, a mixer manufacturer.
“I went on a concrete plant visit recently and the mixer’s hood had been totally removed,” Mueller said. “There was equipment, including a walkway, over the mixer. If you fell over the rail, through the walkway, there would be nothing to stop you from falling into the mixer.
“The risks that plants are taking are very real and scary, and the dangers may even be unknown to workers themselves.”
An issue for large and small plants alike, mixer safety is outlined in a company’s safety rules and enforced by regulatory bodies like the Occupational Safety and Health Administration during inspections as well as the plant’s insurance company at policy renewal. Consider the following best practices for ensuring mixer safety.
Precast concrete manufacturers must ensure that mixer guards are in place to protect workers.
SAFETY REDUNDANCIES
There are a number of mixers in the U.S. market and any of them can include additional safety redundancies. For example, some manufacturers outfit mixers with an inspection window that has a protective steel grate, allowing a safe view of the concrete mix, and an opening through which small amounts of the raw materials can be added in, but nothing else.
Many precasters choose to purchase a lockout/tagout system for their mixer, providing an extra layer of security for mixer cleaning and maintenance by having a single lock and key added to the electrical panel that governs the mixer’s on/off switch. Before performing maintenance and entering the mixer, the operator puts the key in the lock position and then takes it into the mixer when performing the maintenance. With a lockout/tagout system, there is no way for anyone else to accidentally start the mixer since the only override key is with the operator.
A lockout/tagout system provides an extra layer of security for mixer cleaning and maintenance.
Additionally, more businesses are opting for mixers outfitted with automatic pressure washout systems. This is an automated system that uses water to clean the inside of the mixer. While these systems may still require an operator to clean parts of the mixer, it will reduce the amount of time spent inside the mixer.
Multiple safety features on a single mixer allow for redundancies. If one precaution fails, the second will prevail and so on.
CLEAR, OBLIGATORY SAFETY POLICIES
Enforce wearing safety gear and maintaining machine guarding. Create a system of safety inspections that occur daily, weekly, monthly and quarterly. A company’s safety policy should include mixer cleaning, maintenance, guarding and access rules. Finally, it’s never too late to establish and enforce a safety policy.
SITE-SPECIFIC TRAINING
Conduct site-specific training and point out the safety features of each mixer. To initially run the mixer, safety features must be enabled. Ensure workers do not disable them in order to make their daily work easier.
“A lot of producers like to have visual access to the inside of the mixer,” Mueller said. “To gain that, you have to open the mixer hood. We see it all too often that the safety features are purposely disconnected so the hood can be opened and they can see inside.”
According to Søren Pederson, vice president and director of sales at Haarup North America, this problem can be solved with training. When workers are trained to wear the proper safety gear, they can also be instructed on how to do their job efficiently and effectively while working with protective guarding.
“This has to be a policy you strictly enforce, otherwise workers will take the guarding off because it’s easier,” Pederson said. “Be strict about this. Have safety coordinators come in and verify that workers are doing their lockout/tagout at all times and that they’re not taking off machine guarding.”
During new hire onboarding, conduct the same training every time and convey the same safety message to show new hires that your plant is serious about safety. Consider biannual or quarterly site-specific training instead of just an annual mixer safety class.
The responsibility for safety lies with everyone. The plant’s owner/operator and all levels of workers need to be constantly retrained on the equipment’s safety features, rules of the plant and proper procedures to ensure they are complying with the company’s policies.
DON’T OVERLOOK DAILY CLEANING
Cleaning and maintenance are the most common causes of mixer accidents and personnel injury. Ideally, the operator who knows the mixer best should be the one charged with its daily maintenance and cleaning. Schedule a specific time for daily cleaning and allot the proper amount of time to clean the mixer effectively. Too many plants minimize cleaning time to be more productive, but this challenges the plant operator to do as much as possible in too little time.
SCHEDULE REGULAR MAINTENANCE
Like a car, a mixer will run its best when regularly maintained per manufacturer specifications.
“Companies that allow for cleaning and maintenance can actually schedule their down time,” Pederson said. “Those that don’t, yes, they may be more productive for months of the year, but then are going to be putting out fires. Scheduled maintenance is basically free.
“Unscheduled maintenance is costly. You could shut down production or, worse, someone could get seriously injured.”
With regular cleaning and maintenance, Pederson said even an old mixer can continue working and operating efficiently.
COMMON SENSE IS NECESSARY
It’s possible to drive without a seatbelt and not get hurt, although the driver is still unsafe. Similarly, it’s possible to use a precast mixer without the hood on, or without the protective guarding. But, that’s a risk responsible plant owners and operators don’t want to take. Beside the potential for employee injury, it also could be considered a safety violation within an OSHA inspection, which will add to the citation fine. Train plant staff to ask themselves, “Is this safe?” before performing each new or unprecedented action in the heat of the moment. If the answer is, “no,” then a broader safety conversation needs to take place with all parties involved.
Mindi Zissman is a Chicago, Ill.-based freelance writer who has covered the AEC industry, commercial liability and health care for more than 15 years.
I like that you mention how some newer mixers have automatic pressure washout systems but they still require someone to handle certain parts. When getting them cleaned, it would probably be a good idea to find a local company that offers concrete washout services. Working with a professional could ensure that the right parts are cleaned correctly so that the system will be kept in good condition and won’t have problems.