When it comes to mechanical safety, the safety level is definitely an inescapable topic. Both the former EN954-1 and the current ISO 13849-1 describe in detail the definition of different security levels.

When designing the safety control loop of a device, the motor control part can achieve the corresponding safety level by cutting off the power supply of the motor or the STO end of the controller (safe torque off).

Do you know how the pneumatic control part can achieve different safety levels?

The main reference standard for pneumatic circuits

The main standard involved in pneumatic circuits is ISO 4414 (GB/T 7932-2017) – “Pneumatic General rules and safety requirements for systems and their components”, The part related to the safety level should refer to the relevant content of ISO 13489-1 (GB/T 16855.1-2018) – “Safety related components of Mechanical Safety control systems Part 1: Design General Principles”.

Architecture of the security control system

The architecture of the security control system can be divided into five categories, which are category B, category 1, category 2, category 3 and category 4, and the architecture of the security control system is one of the important factors to determine its performance level.

PFVI401

Category B is the basic level, and all levels must meet the requirements of Category B; The resistance to common cause failure of class 1 is higher than that of class B; Class 2 In addition to using reliable components, must be designed so that the safety functions of the system can be tested automatically at suitable intervals by mechanical control; Class 3 control systems need to be designed so that a single failure does not result in loss of safety functions; Category 4 In addition to achieving a single failure that does not result in the loss of the safety function, a single fault needs to be detected before the next safety function can be performed.

Select the right product to easily achieve pneumatic circuits of different safety levels

The PNOZ multi series programmable safety controllers from Pielmagnet incorporate a certified safety valve output function block to connect signals such as safety valve and spool position monitoring to the safety controller. The certified software function block helps users quickly implement pneumatic circuits with different safety levels.

Realization method of different safety levels of pneumatic control loop

Category B/1, security level PL a to c
The movement of the cylinder is achieved by a circularly operated reversing valve (1VA/1VB)

The pressure is detected by the PS_OP pressure switch, and when insufficient pressure is detected, the start is prevented

There are two ways to implement Cat.B /1:

Shut off the air source and prevent accidental starting through the main valve 0V1
By 1VA and 1VB turn off the cylinder air supply to prevent accidental starting