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Frequently asked questions

Our clients have trusted our industry knowledge and expertise for over 100 years. Below are some of the most commonly asked questions we hear in our work with machine safety and process training.
What should be considered before starting safety implementation in a machine?
Without a doubt, the first step in the safety implementation process is the machine safety risk assessment. There are a few methodologies available to help you achieve this first step. At Wieland, we strongly recommended following the international standard ISO 12100. To learn more, visit our standards and regulations page.
Do safety-related ISO standards meet the national legislation requirements?
It depends on the country or region where you are operating. Most of the specifications in similar standards within different organizations, institutes, commissions, etc., are quite similar, but some variations could exist. For example, EN ISO standards are harmonized to guarantee compliance with European legislation. In Mexico, national legislation and standards follow the basis of international laws and standards. Our team would be happy to advise you on your specific needs; reach out to us today to learn more.
What speed is considered safe for manual mode?
It depends on the type of machine or process involved. A risk assessment can better determine the most suitable speed for manual and safe operation modes. Some Type-C standards also specify speed limits based on the most common operating conditions on certain kinds of machines. For more information, contact our technical support department.
Should a reset function come from a standard PLC or a Safety PLC?
A reset function can come from either of them. Other measures can also be taken to prevent an unexpected reset, such as a manual monitored reset (from 1 to 0), in case the contact remains closed due to a failure.
What are the benefits of safety devices in comparison with standard devices?
Safety devices are manufactured under the strict recommendation of safety-related standards such as Performance Levels in ISO 13849-1. Installing such safety devices allows you to achieve machine safety more reliably, easily, and without the need for additional modifications.
Can I stop the machine safety system and safely inspect the process closely with the guards open?
A risk assessment will help to determine if this is possible. If yes, a manual operating mode can be considered. If no, we recommend working with an expert to inspect and adjust your machine.
What is the difference between machine safety and process safety?
One of the primary differences is the end goal: with machine safety, the goal is to bring the machine to a safe state as soon as possible without causing damage to any person, while the goal of process safety is to ensure the reliability of the full process itself.
What is the correct distance I should install my Light Curtain?
The safest distance calculation is based on the formula S = KT + C .
Where:
S = Safe Distance
K= (1.6 – 2 m/s)
T= Time for machine to come to a complete stop
C= Deep Penetration Factor also known as DPF

However, depending on the specific Light Curtain mounting, this formula could have some variations. As a result, we recommend reviewing ISO 13855 for further details. Once implemented, you will be required to measure the stop time with a certified device and validate the safety distance.

How many E-stop devices should I consider?
The number of E-stop devices you will need is determined by the unique risk assessment of your project. If you develop a proper risk assessment, you will have the right number and ideal locations for E-stops. For more information, please review the current ISO 13850 requirements, or contact one of our experts for assistance.
Is it possible to achieve a safety level in a system without using certified safety components?
It is nearly impossible to achieve this without the proper safety components in place. The electro-magnetic compatibility (EMC) level for safety devices is much higher than that of standard components. Safety devices are designed, manufactured, and certified based on basic tried-and-true safety principles and the norms for a given device. Choosing a standard device at random could pose potentially fatal safety gaps.
How can I check that a new machine purchased from another country meets all the necessary safety requirements in my country of operation?
The only way to confirm this is by asking for the technical file. This will include all the documents related to the machine’s safety lifecycle in the country of manufacture/sale, as well as how it measures up to the safety standards in your country.