What Is Safety Mat

21^st February, 2024.

In this post, we will see the concept of a safety mat.

When you are working in an industrial environment, it is necessary that the safety of the nearby environment be maintained. Whether the machine be critical or non-critical, any system can be harmful if it's safety criteria is overridden. For example, just simply consider a metal cutting machine. It works in a very high speed and also produces sparks during operation. So, if a worker accidentally goes near it during running condition, then it may cause damage to him. So, it is required that a safety system be employed near the machine for a safe and hazardless operation. One such system is a safety mat. It is the most used ones in every critical system very safety is a must. In this post, we will see the concept of a safety mat.

How do safety pressure mats work?

A safety pressure mat is a pressure sensitive device which is used to detect the change in pressure and create an electrical signal output for control. This signal is fed to a mat controller, which in turn generates an external signal for stopping the machine. Let us extend the example discussed earlier. We have a metal cutting machine and suppose we have laid a safety mat around the machine. Now, when someone accidentally is walking and he touched the mat, then the mat will feel the change in pressure applied and trigger an electrical signal, which will be used to stop the machine operation immediately. So, safety matting a critical device prevents the users and nearby environment from any untoward incident.

The working of the mat is pretty simple. A single mat mostly is not enough for a machine; for this, a series of mats are laid around the machine. Each mat has two conduction plates mounted upon each other and separated via a separator which is non-conductive. When the mat is pressed, the plates touch each other and make a contact. This allows for a conducting path to be made, since the resistance decreases. Due to this, the mat controller will detect it and generate an external signal for the machine to stop. This mat is so sensitive that it detects even a light weight immediately and stops the system. The system will become healthy for operation only when the operator has released his foot and there is no pressure in any part of the mat. Then, the system can be restored for operation by either pressing reset button to the controller or the controller will reset automatically after a certain time of healthiness. This stops the command given to the external controller and brings the machine back into operation.

Safety Distance Calculation:

Now, the main question comes as to how to lay the mat near the machine. This makes safety distance calculation a very and the most important parameter. For that, you must know what's the safest distance from the machine which will not cause any harm. At that point, the mat laying starts. For example, a metal cutting machine is at a distance of 10 feet from the operator. It has a moving arm which is not moving right now, but when moved, it comes closer to 5 feet. So, you should not consider these 5 feet as the distance, but should consider 10 feet as the distance. This ensures that even if the arm is extended fully, the operator will be safe from any touching. For this, the standard used is EN999 formula. These standards give you a minimum distance after which the machine is unsafe for touching. When a machine is bought, it is written in it's specifications with the distances. The formula for calculating distance is S=(K*T) +C. Here, S is the safety distance, K is the approach speed (in mm/secs), T is the stopping timing of the system and C is additional distance which is dependent on design and installation. Approach speed means how fast the operator can come in a second. Timing is an addition of stopping time required by the system and response time of the mat. So, consider an example now. K is 1400 mm/secs, time 1 is 45msecs, time 2 is 23 msecs, C is 1100 mm. So, S = (1400*(0.045+0.023)) +1100. The answer comes to 1195 mm. This means that the mat should be started to lay before 1195 mm till 0 mm of machine position. After 1195 mm, the operator is safe to stand.

Safety Mat Maintenance:

Below are some general steps given for safety mat maintenance:

1. It is highly resistant to water, alkalis, salts and acids; but poor resistance to benzene, acetone, ketones and other esters. So, care must be taken that harmful ones be not be allowed to enter the restricted zone for safety purpose. It should also be tried to keep free from oil, grease or other sticky substances. Prolonged use can damage the mat layers and make it useless.
2. The floor on which the mat is laid must be flat, free of nails or other sharp substances, smooth and firm to hold. Soft ends or pores will result in unintentional operation of the mat as it will become more sensitive and the machine will stop irregularly.
3. Regularly check the mat surface for any damage and test whether it is functioning properly by taking a proper shutdown and allowing a person to stand on it. This will ensure that the safety mat does not malfunction when in actual use.
4. Check electrical and mechanical connections as per standards on a regular frequency and see whether there are no loose ends or short circuits or any other kind of interruption from the machine which it is protecting.

I have covered a general theory related to safety pressure mats used in industries. I have also not attempted to cover all the methods, as it can vary from systems to systems. Once you are familiar with this engineering, you can easily tackle all types of problems in it.

Thank you for reading the post. I hope you liked it and will find a new way in this type of technology.