ISO 13849: Determining PLr with the Risk Graph — S, F, P Decisions That Hold Up

Date
2026-10-26
Location
Online
Host
Zach L

About this event

A live 30-minute expert session on Determining PLr with the Risk Graph — S, F, P Decisions That Hold Up (ISO 13849 — Machinery Safety). What We'll Cover: What PLr determination is and where the risk graph sits between risk assessment and safety function design The S/F/P decision process step by step, with the 2023 edition's quantified thresholds for exposure frequency and avoidance How risk graph outputs map to Annex A and the per-function PLr rationale sheet added to the risk assessment Common mistakes: cherry-picking F1 to hit PL c, ignoring foreseeable misuse in P, and re-using PLr across dissimilar hazards The parameter justification narrative an auditor reads before accepting any PLr lower than PL d Related topics: plr determination · risk graph · annex a · severity parameter · freque

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About Functional Safety Foundations

This online session delivers expert-led instruction on the regulatory landscape and implementation approach for Functional Safety Foundations.

The cross-sector fundamentals underlying every functional safety standard: risk as severity × likelihood, the safety function concept, integrity levels, the safety lifecycle, and the split between random and systematic failures.

What it regulates

Shared vocabulary and reasoning: hazard → risk → risk reduction allocation → safety requirement → verified implementation → maintained integrity in operation.

Who must comply

Everyone entering the field — the conceptual base of the entire catalog.

Key requirements of Functional Safety Foundations

  • Hazard and risk fundamentals
  • Safety function anatomy: sensor-logic-actuator with defined safe state
  • Integrity ladders (SIL/PL/ASIL/DAL) as risk-reduction currencies
  • Random vs systematic failure treatment
  • Lifecycle and management of functional safety incl. competence

Key concepts: Functional Safety Foundations

Risk reduction allocation
Distributing required risk reduction among mechanical design, safeguards, control functions and procedures.
Functional safety management
Planning, competence, documentation and assessment wrapped around technical work.
Random vs systematic
Hardware wear-out/chance failures quantified statistically versus design/process errors controlled by rigor.
Safe state
The defined condition a function drives the equipment to on demand or fault.

Frequently asked questions: Functional Safety Foundations

Why can't testing alone prove safety?

Rare-event targets (like 1e-7/h) are unverifiable by test duration, and systematic errors evade random testing — hence the standards' dual machinery of quantified hardware analysis plus process rigor and independent assessment.

Standard information based on the published text of Functional Safety Foundations. Event content is provided by the host. For authoritative guidance, consult the official standard body.