I&E Systems is one of Australia's leading instrument, electrical and safety system engineering companies. Based in Perth, Western Australia we are 100% Australian owned and have been operating since 1991.

MooN Safety Function Calculation Tool

The MoonSIF workbook can be used to evaluate performance of safety functions with any chosen ‘M out of N’ voting architecture with N up to and including 7.

MooN Safety Function Failure Probability Model

The purpose of this document is to explain the failure probability model used in the MoonSIF workbook.

High Demand vs Low Demand

What is the difference between low demand, high demand and continuous modes of operation in automated safety functions?

Safety Function Performance Comparison Spreadsheet

This spreadsheet has exercises that reveal the simple truth about what matters in safety function performance.

Practical Application of Bayes’ Theorem for Functional Safety

This paper reviews how Bayesian techniques might be applied in practice for functional safety and describes simple techniques that can be useful.





Dealing With Uncertainty

Typical levels of variability in safety function performance suggest that a factor of x3 should be applied as a design margin.

The Myth of Proof Testing and Mission Time

There’s a story going around that we can make up for limited proof test coverage of automated safety functions by reducing device mission time. It’s a convincing story, but is (almost) totally wrong.


Failure Rate Uncertainty

IEC 61511 §11.9.4 requires us to take into account uncertainty in reliability data. What is the uncertainty in the reliability data that we use? How should we take the uncertainty into account?


New Approach to SIL Verification

SIL verification calculations are meaningless if systematic failures are not actively and effectively controlled.


Prevent Preventable Failures

This paper discusses the reasons for the wide variability and uncertainty in measured failure rates. It draws conclusions on how failure rates and failure probability can be controlled in practice.


Reassessing Failure Rates

Failure probability calculations are based on the assumption that failure rates are fixed and constant. That assumption is completely invalid, but the calculations are still useful.


SIM in Practice: Automation in Construction

Design and engineering is only effective when it serves its intended purpose and is constructible within desired budget, time, quality and safety objectives.


Failure Probability of Composite SIFs

In a safety instrumented system how should we calculate risk reduction for a set of safety functions that shares a common final element?


Avoiding Hazardous Areas by Design

The extent of the hazardous areas should be reduced as far as practicable by applying principles of safety-by-design.


Functional Safety – The Next Edition of IEC61511

What can we expect to see in the new revised edition of IEC 61511? The new edition is expected to be released by the end of 2015.


Duty of Care

The main driver for functional safety is the need to demonstrate duty of care in managing risks.


Competence for Functional Safety

How can we make better use of competency based assessment in functional safety?


Functional Safety Management

Managing the risk of systematic failures is not difficult; the principles are essentially the same as in quality management and risk management.


Lessons Learnt from FSA

Independent audits and assessments reveal the commonly recurring and widespread problems.


Towards Systematic Integrity

This paper is on the topic of avoiding errors and failures due to the design, implementation and operation of the systems.


Achieving Compliance in Hardware Fault Tolerance

Many users in the process sector have not been able to comply fully with the requirements for hardware fault tolerance – but there are practical ways of achieving compliance.


Derivation of the Simplified Equations

Even the ‘simplified’ equations for probability of failure can seem to be a bit mysterious. Here is an explanation in plain language.


Assessing the impact of RFIs in Electrical and Instrumentation
Engineering Contracts – Research Paper

The cost of managing RFIs in todays complex E&I projects is much higher then generally expected.


Data Flow & Business Process Modelling
for Manufacturing Operations Management – White Paper

A typical MES or MOM System adheres or adopts the principles of a 3 – tier architecture.


Documentation Errors in E&I Systems – Research Paper

Poor design and documentation has been identified as a major factor contributing to poor performance and productivity in the construction industry.