Manufacturing systems, system safety integration

Specified SIL rating. The safety integrity level of the component is calculated and certified by the component manufacturer (the proper authority to do the determination). Brake system designers are not required to determine the SIL rating at the component level—they can put their efforts at determining the SIL rating at the safety system level. 

Industrial Automation Systems. Safety of Integrated Manufacturing Systems, Basic Requirements (CD 11161), TC 184AVG4, Geneva, Switzerland ISO. 

At the other end of the spectrum, are standards which address the processes of development and manufacture - non-safety examples range from the very broadly based ISO 9000 series to the more specific ED-78A (Guidelines for the Approval of the Provision and Use of ATS Supported by Data Communications) and ED-109 ( Guidelines for CNS/ATM System Software Integrity Assurance). In none of these cases would it be appropriate to certify a product against them, from a safety viewpoint however, compliance with such standards, especially the more specific ones, could provide excellent Backing Evidence for safety requirements... 

The standard applicable for application software, has limited variability or fixed programmed but not for manufacturers, safety instrumented systems designers, integrators, and users that develop embedded software. 

To implement safety systems through the certified organization These are stated here to understand by the manufacturers and system integrators how to get the accredited certificates. 

For any safety loop comprising several components, the safety integrity level (SIL) achievement is a joint responsibility of end-user and supplier, as will be clear from Table IX/1.0-1. Why discussing this here These are discussed here to show that equipment manufacturer/system integrator or end-user is not only responsible for the same in isolation. In a safety life cycle, there are several phases involving several activities. So, at various stages there will be involvement of either end-user or sup-plier/manufacturers. The same issue has been elaborated in Clause 1.0.1 refer to Fig. IX/1.0-1 also. 

The following are the general features in safety integrated systems. The features given here is extracted parts from a practical factory automation system from a manufacturer... 

The main duty on manufacturers or suppliers is to ensure that equipment destined for use in potentially explosive atmospheres satisfies relevant Essential Health and Safety Requirements, which are listed in Schedule 3 of the Regulations. The Requirements relate to three groups common requirements, supplementary requirements for equipment, and supplementary requirements for protective systems. Protective systems are defined as design units which are intended to halve incipient explosions immediately and/or to limit the effective range of explosion flames and explosion pressures. Protective systems may be integrated into equipment or separately placed on the market for use as autonomous systems. 

Interface). The former tends to be used where high levels of functionality and data rates are needed whereas the latter, which is based on the controller area network (CAN) protocol, is used in applications where there are lower functionality and simple input/output requirements. The manufacturers of these fieldbus systems have worked on developing them for use in safety applications, mainly to incorporate appropriate levels of fault tolerance or safety integrity. This has led to the availability of the Profisafe and AS-Isafe fieldbuses. In addition, PILZ has developed the SafetyBUS fieldbus for safety applications, which is again based on the CAN protocol, and the Open Devicenet Vendors Association has developed a safety version of the DeviceNet fieldbus called DeviceNet Safety. 

ANSI R15.06-1999, Industrial Robots and Robot Systems, Safety Requirements—provides requirements for industrial robot manufacture, remanufacture and rebuild, and robot system integration/installation and methods of safeguarding to enhance the safety of personnel associated with the use of robots and robot systems. 

Systemic failures are due to human errors (e.g. mistakes, misconceptions, miscommunications, omissions) in the specification, design, build, operation and/or maintenance of the system. Errors in this case are taken to include both mistakes and omissions. Errors can be introduced during any part of the lifecycle and errors are caused by failures in design, manufacture, installation or maintenance. Systematic failures occur whenever a set of particular conditions is met and are therefore repeatable (i.e. items subjected to the same set of conditions will fail consistently) and thus apply to both hardware and software. It is difficult to quantify the rate at which systemic failures will occur and a qualitative figure based on the robustness of the development/build process is normally used. The probability of systemic failures is often evaluated by means of safety integrity (or development assurance) levels. 

Robots will become an essential component of Integrated automated manufacturing systems In the future The development of a reliable sensor system for detecting the Intrusion of humans Into robotic work areas will greatly Improve the safety conditions Many types of systems are possible candidates, but the capacitive system Is the most promising one at the present time ... 

---