Every day, workers are exposed to a variety of hazards from equipment, industrial machines and processes. Although each worker is responsible to ensure he or she follows safety procedures at all times, companies are still obligated to ensure energy control procedures are in place and in compliance to applicable standards.

Companies are responsible for developing procedures to ensure a zero energy state and prevent inadvertent start-up of equipment, machines or processes to protect workers. Every company using equipment, industrial machines and processes that could potentially expose workers to hazards should have an energy control policy or similar plan in place that describes all safety procedures for each job function. This policy must be made available to new workers during orientation, and must explain all safety procedure types, including when and how to use them. The policy should describe all company and worker requirements, and include the frequency of worker retraining or skills demonstration.

Depending on the type of manufacturing environment, the energy control policy may need to describe methods of energy control that go far beyond the traditional lockout method, keeping in mind that lockout is not the only method of energy control. When special circumstances exist, you can use other methods in accordance with CSA’s Z460 standard, making matters more complicated for energy control policy developers.

In spite of all the efforts made by companies to implement energy control programs, we continue to hear about workplace accidents regularly, begging the question why?  In my opinion, there is a great deal of misunderstanding when it comes to energy control policies. Workers don’t understand the difference between an energy control policy, a safety device and a safety procedure. Recently, a worker was arguing with me during class. Why do we need safety procedures when safety switches are installed to protect us? But safety protection devices and a procedure on how to perform a task safely are two different things.

Yes, we need safety protection devices to ensure energy is interrupted under certain operating conditions, but hazards are all around workers when multiple energy sources are present. The only way to ensure a task is performed safely is to follow the steps outlined in a safety procedure after all risks have been assessed.

In my opinion, the most common causes of work-related accidents are: human error, outdated safety procedures and/or lack of training and improper risk assessments.

• Human error: Some workers continue to believe that just because they have performed a task several times, they have memorized the steps and are convinced they could perform the task safely every time. This is definitely a fallacy, and the cause of numerous workplace injuries. During one of my classes, I had an individual tell me that “if I can’t perform this task without the piece of paper, then I should not be called a tradesman and definitely should not be here doing what I’m doing.” I was very sympathetic with the individual and knew where he was coming from; still, I stressed, once again, the reason for writing procedures is so that we read them every time we perform a task to ensure the task is performed consistently, without forgetting a step, to minimize risks. By not following written procedures, we accept higher risk, which may lead to worker injury.

• Outdated safety procedures: Safety procedures must be maintained and current at all times. Safety procedures should be reviewed when equipment, machines or process modifications are made, because workers rely on safety procedures to gain safe access to equipment, machines or processes. Making modifications on interlocks, operation and/or safety devices demands a complete review of all relevant safety procedures and a PSR to be conducted, to ensure risk assessment is complete and all energy sources are isolated or controlled. It is also very important to train and/or re-train workers on how to use safety procedures. It is wise to involve workers from different departments during the assessment, escalating the importance of safety, creating meaningful dialogue and raising the awareness level.
 
• Improper risk assessments: Safety procedures in general must be developed by qualified people and must always be based on the results of a risk assessment. Conducting a risk assessment plays a key role in any safety procedure implementation in that it identifies all energy sources, hazards and equipment/process interactions or interlocks that may cause inadvertent start-up of equipment. The result of a risk assessment identifies all hazards and the steps required to eliminate them, which may include specific controlled actions by the worker. I witnessed one situation where the worker performed a task, inside the hazardous envelope, without a written procedure and all energy sources present. Someone had told the worker it was okay to do this on the machine when no one was looking. I believe you can figure out on your own how much risk the worker accepts by performing a task inside a hazardous envelope, without a written safety procedure.

An energy control policy should be the most critical element driving any safety program. It is like a business strategy plan; deserving much greater attention from both employers and workers.

How to develop an energy control program
You first need to ask yourself one question: Do we need an energy control program? If you operate equipment/machinery that needs to be cleaned, oiled, adjusted, repaired or have maintenance work performed on it, the answer is a resounding yes. According to section 75 of the Occupational Health & Safety Act, this type of work can only be performed when: motion that may endanger a worker has stopped; and any part that has been stopped and that may subsequently move and endanger a worker has been blocked to prevent its movement.

Employers are responsible for developing safe operating procedures that comply with all applicable federal and provincial laws and regulations, and workers must be trained on safety procedures to ensure these are followed at all times. So how do you go about doing this? You select all of the in-house expertise that you have, as well as outside professionals who are practitioners in this field, and develop a set of policies and procedures that address the needs. This comprehensive set of policies and procedures can be called an energy control program/policy, or whatever you like, as long as it establishes the rules of how workers must perform their duties in a safe manner and in compliance with all regulations.

Starting with a visual that is easy to understand, the energy control program becomes the “visual” blueprint that includes all of the elements required to satisfy your specific application; a blueprint that is used as a guide throughout the entire development process. Do not make the mistake of generating material that is dry and requires much reading to arrive at the intended result. Use as many visuals as possible. Visuals are very effective in conveying your message and always increase retention. Although not all blueprints will be the same, similarities do exist from one application to another. Let’s take a closer look at this energy control program blueprint.

Begin by developing or updating your current inventory of equipment/machinery, and then examining all issues of compliance for each piece of equipment or machine type. Keep in mind that the new energy control program needs to satisfy all applicable government health and safety regulations, as well as corporate regulations and standards if these exist. Section 75/76 of the Occupational Health & Safety Act and CSA – Canadian Standards Association Section 7, which relates to Pre-Start Health & Safety Reviews (PSR), is a good place to start before developing any procedure.

Procedures
Written procedures are required, starting with the most commonly practised lockout. Depending on the complexities of your specific equipment/machinery or process, the number of safety procedures will vary. In this particular example, four types of safety procedures are used: Lockout to isolate all energy sources; CAP (control access procedure) to guide the worker through the steps on how to bring a complex machine into a safe state; ASA (approved safety access) to guide the worker on how to gain safe access to a specific area of the machine; and finally the JES (job element sheet) to guide the worker on how to perform a specific task. No procedure can be written until a risk assessment is completed.

Energy maps
Energy maps are visuals that clearly identify all sources of energy for a particular piece of equipment/machine. Typically, the footprint of the equipment/machine is drawn in full colour, clearly highlighting all machine sections, material flow, safety devices (including guards), energy sources and isolation devices. Where multiple sources of energy are used, the sequence of energy source isolation is shown.

Training
Training is a very critical element to the successful implementation of any safety program, and embarking on a new energy control program is no exception. When all the work is completed, training helps to take the message to the workers and, in return, workers must demonstrate that they have the skills required to work with each safety procedure. Training should also provide a system for workers to be re-trained each year, and every company should maintain training records to ensure workers are competent in carrying out tasks safely.

Records
All safety procedures must be reviewed and updated periodically, or when equipment/machinery is relocated or modified. A central location must be identified and a record maintenance system be put in place that can be audited at any time. Document creation date, revision history, reviewer’s name, and the name or names of the approver are shown in records. In the case of PSRs, the name of the engineer who approved the PSR is shown. Records show when safety documents were issued, reviewed and revised, and they make your life easier during regulatory agency audits.

Review
Periodic reviews are a great way to share safety information with workers. They provide a great opportunity to discuss updates, procedure changes, results of risk assessment, PSR approvals and general safety information with workers, keeping them informed.

In summary, any energy control program implementation must address the issues of compliance, types of safety procedures, energy maps, periodic reviews, worker training and records maintenance. Although the detail and complexity of each topic and your energy control program will vary in each situation, the thought process and mechanics of getting there remain the same.

Bill Valedis is the president of Imperial Automation Technologies Inc. You can reach him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Muting, applied in numerous safety-related automation applications with light curtains, is the temporary suspension of the protective field for access guarding into a danger zone without the safety outputs turning off. Muting is always started by at least two independent sensor signals, typically with the use of retro-reflective sensors.

By allowing transported material faster access into or out of a danger area without interrupting material flow, muting provides productivity gains in the automation process and guarantees personnel protection at the same time.

The two most common types of muting solutions are two-sensor parallel and four-sensor sequential.

Figure 1 shows an example of four-sensor sequential muting at a robot station, accomplished with four inductive muting sensors (MS1 to MS4) that are activated in sequence by the carrier. This type of muting is used when each piece of transport material has the same dimensions and enough space is provided for entry and exit.

In this case, the muting controller checks only the sequence of the sensor activation/deactivation; the time interval between the sensor signals is not that important.

Two-sensor parallel muting, shown in Figure 2 in a palletizer system, is activated by two muting sensors, which cross over each other. Note that the crossover point in the “X” made by the sensors is located inside the “danger” zone. This is done to eliminate tampering and ensure valid muting signals during the transit. Both sensor signals (MS1 and MS2) must be activated within a prescribed time, basically instantaneously. This type of muting is frequently used when the dimensions of the transport material are not consistent or where space is at a premium.

As it stands, an AS-i (Actuator Sensor interface) system can easily incorporate safety components by adding an AS-i safety monitor to the system. However, adding the muting functionality to the safety monitor is the next step that will provide an especially flexible automation solution to the growing AS-i installed base.

The required sensor equipment is made up of muting and safety sensors, which are directly polled by the AS-i interface and then analyzed by an AS-i safety monitor. An example of a cost-effective Safety At Work AS-i solution would be to lay the yellow AS-i flat cable on one side of the system and the passive elements on the other, selecting retro-reflective light beam devices as muting sensors and a transceiver-type light beam safety device with a deflecting mirror.

Connecting the muting sensors, muting start/restart button and muting indicators would be done with standard AS-i input and output modules. The standard light beam safety device would be selected with an integrated AS-i interface and then connected to a safe AS-i input module.

To achieve safety Category 3 or 4 in accordance with EN ISO 13849-1, MS1 and MS2 muting signals with a two-sensor parallel muting solution would use separate standard AS-i input modules. An optional configuration could have a muting sensor via a standard AS-i input module and a second independent software signal via the AS-i master output bit.

With a four-sensor sequential muting system, the muting sensor signals (MS1 to MS4) would be integrated with two separate standard AS-i input modules (MS1/MS3, MS2/MS4). Optionally, two signals (MS2, MS3) can be transferred via a standard AS-i input module, and two independent software signals (MS1, MS4) can be transferred directly by the control unit via the AS-i master.

For the muting start function and the muting status indicator, the same AS-i slaves can be used where possible to reduce costs.

In the past, a separate muting controller had to be integrated into the system by an additional safe AS-i input module. This is no longer necessary. The safety monitor, with muting functionality built in, can now monitor and evaluate the muting equipment. One distinct system advantage, depending on the number of AS-i addresses, is that several muting areas can be configured and monitored by a single AS-i safety monitor. The configurable muting modes can be changed at any time with the safety monitor configuration software (ASIMON). This would reduce the number of components and result in a simpler and faster system to start up and maintain.

With muting functionality available in AS-i safety monitors, existing and potential users of AS-i now have a cost-effective way to add muting solutions while still maintaining personnel safety and increasing system productivity.

Mark Smokowicz is the lead product manager and safety products manager for Leuze electronic, which serves Canada, the U.S. and Mexico. Leuze is a long-standing AS-i SaW consortium member and will release a certified version of the AS-i safety monitor with muting functionality.

Five years ago, when the CSA Z142-02 power-press standard was first published, it was a major improvement on its predecessor. More stringent requirements for controls and safety devices were established, and it offered the first attempt at harmonization with other standards at the time, such as ANSI B11.1, RIA 1506 and EN693. Afterward, both the CSA Z434 for industrial robots and robot systems and CSA Z432 for machinery safeguarding adopted these same requirements.

As part of the CSA Standard process, standards are always being reviewed. During the five-year review process, a technical committee was assembled to determine if the current edition was still relevant and to assess whether there were any new technologies that would necessitate amending the document. It was then decided the standard would be updated to recognize new issues and maintain the existing technical requirements.

One of the first issues the committee faced was a coroner’s inquest into the death of an employee in Kitchener, Ont., during the maintenance of a power press. The inquest’s recommendation was for the CSA Technical Committee on Power Press Operation to develop maintenance safety requirements for the proper and safe removal of hydraulic tie rod nuts, because if the pressure on these nuts is released incorrectly, maintenance personnel can be placed at risk — and in this particular case, the error caused the death of a worker. Therefore, an additional technical requirement was added to the new standard: anyone attempting to use hydraulic tie rod nuts to release a press must use the equipment and procedures laid out in the standard.

The second issue the committee dealt with was the introduction of servo or direct-drive presses. Servo presses have been in the metal-forming industry for more than 20 years, but it’s only in the past several years that they have become more common in North America. Not only that, but they are common today in a large portion of new presses being sold, in part because of their flexibility, accuracy and efficiency. Unfortunately, these types of presses use direct and servo-drive technology that is not fully covered in the existing standard. Unlike conventional presses, starting and stopping is directly controlled by the press controllers. There are no valve actuators, so there is a prescriptive requirement on the safety performance level of the controllers. There is also a new requirement for holding brakes to ensure the slide is locked in position when power is removed from the drive controller.

Additionally, the committee looked at laser AOPD guarding devices, which have been commonplace on European press brakes for years but have not been widely used in Canada until the past few years. These laser safeguarding-systems are very flexible and allow the operator to be more productive than light curtains allowed. Unfortunately, under the existing edition of Z142, laser systems are not acceptable primarily because of the safe-distance requirements. The advantages these devices offer operators, and their flexibility in complex forming, make it very important that they be included in order to help Canadians compete in the global marketplace. Not allowing them places Canadian manufacturers at a disadvantage. The challenge facing the technical committee was to keep the intent of the existing ISO Standards for these devices intact while adapting Z142 to meet the needs of Canadian stakeholders. In the end, the committee decided to allow the use of 10-mm-per-second “slow speed” from Europe’s prEN 12622:2006 hydraulic press-brake standard as an acceptable condition for overriding these particular safety devices.

In developing the new standard, Z142 needed to be harmonized with other standards. During this time, the United States’ ANSI B11.1 was also in development, so it was important to ensure consistency with our largest trading partner.

Some items that were added to harmonize with the ANSI B11.1 included the addition of slide-lock requirements and references to issues with large presses previously not addressed. Other changes included the removal of brake monitors as a requirement when not used with safeguarding devices to signal a stop and the removal of RF devices as acceptable electronic safeguarding devices.

A final task by the committee was to try harmonizing with other standards for control performance level. In the previous edition of Z142, the term “control reliable” replaced the previous term “fail safe” as a performance requirement for all safety circuits, devices and safety-related control functions. The committee looked toward the recent ISO 10218 standard for industrial robots for assistance. It was decided the new term would be “safety circuit performance level” and allowed for the use of other standards that have equivalent levels to control reliability. It was not the committee’s intention to increase the performance levels but to allow equipment from other countries to meet requirements in Canada.

The updated version of CSA Z142 has finished the public review stage. The technical committee will be reconvened after the public review period and all comments submitted from industry will be reviewed. Assuming no major issues ensue, the new edition should be published by the end of 2009.

Cory Newton is the president and owner of Tekpress Solutions Ltd., a company specializing in power-press and machine guarding. He is the chair of the Z142 Code for Power Press Operations, the vice-chair of the CSA Z432 Safeguarding of Machinery Standard and a technical committee member of the CSA Z434 Industrial Robots and Robot Systems Standard.