A purpose-built Ex01–04 preparation system

Walk into your Ex01–04 assessment completely ready.

POSISYS™ is purpose-built for instrument, electrical and E&I engineers preparing for Ex01–04 Gas & Vapours — created by a Senior Instrument Engineer and Technical Authority with over 40 years of hazardous-area experience.

Get POSISYS™ — £89 See what's inside
Built by a field practitioner — not a training company
iOS · Android · Web — £89 one-time, no subscription
Independent of all assessment centres
Darren Emery M.Sc.
Darren Emery M.Sc.
Senior Instrument Engineer
& Technical Authority
40+ Years hazardous-area experience
DSEAR · ATEX · IECEx authority
B.Sc. & M.Sc. — Teesside University
Early Access Price
£89
One-time · Lifetime access · No subscription
Register for Early Access
40+
Years of field
experience built in
4
Units covered
Ex01 · Ex02 · Ex03 · Ex04
60+
Practice questions
with worked answers
£89
One-time payment
No subscription
The real problem

Engineers fail Ex01–04 not because they lack knowledge — but because they lack preparation.

Ex01–04 is the gateway qualification for hazardous-area work — refineries, offshore platforms, COMAH-regulated chemical plants. Without it, you cannot be signed off as competent in the environments your career is built around.

Five days. A written paper you must pass to 70% per unit. A practical assessment you must pass. Most candidates underestimate what is actually required until they are already in the room — and by then it is too late to fix it.

A failed assessment is not just embarrassing. It is operationally damaging, professionally costly, and personally demoralising. POSISYS™ exists to make sure that never happens to you.

Read the full Ex01–04 guide →

Financial Cost

Assessment fees, travel and accommodation — repeated. For self-funded candidates, a direct personal hit twice over.

Operational Cost

Without the qualification you cannot be deployed. Roles redistribute. Site responsibilities shift. Contracts cannot be accepted.

Professional Cost

Assessment outcomes rarely stay private in the engineering world. A failed attempt carries weight — especially for 5-year returners.

Personal Cost

A failed assessment damages confidence. Engineers start doubting knowledge they previously relied on. Recovery takes time.

What we are

Exactly what you need.
Nothing you don't.

01

Structured by assessment unit

  • Ex01 — Explosive atmosphere fundamentals
  • Ex02 — Equipment selection and installation
  • Ex03 — Intrinsic safety systems
  • Ex04 — Inspection and maintenance
02

Written exam preparation

  • 60+ practice questions with worked answers
  • Spaced-repetition question bank (SM-2)
  • Timed mock exam mode with scoring
  • Weak-area identification and targeted review
03

Practical assessment readiness

  • What the practical assessment demands
  • Common failure points — and how to avoid each
  • Inspection procedure walkthroughs
  • Documentation requirements covered
Darren Emery M.Sc.
Who built this

Built by the engineer who has been where you are.

This is not preparation built by a training company. It is built by someone who started as an Instrument Apprentice at 16, spent over 40 years across ICI, offshore platforms, steelworks, refineries and petrochemical sites, and understands what the qualification means in practice — not just on paper.

Senior Instrument Engineer & Technical Authority
Offshore, refinery, COMAH Tier 1 & chemical plant background
Deep operational knowledge of DSEAR, ATEX & IECEx
B.Sc. and M.Sc. — Teesside University
Time-served Instrument Artificer
"I built POSISYS™ because I have seen engineers fail assessments they were more than capable of passing — not because they lacked the knowledge, but because nobody properly prepared them for what was coming."
— Darren Emery M.Sc., Founder, The Engineering University
Read Darren's full story →
The product

POSISYS™ — complete Ex01–04 preparation.

Ex01

Zone classification & fundamentals

ATEX and IECEx zone classification, gas groups, temperature classes, LEL/UEL, ignition sources — all of Ex01 covered the way the written paper tests it.

Ex02

Equipment selection & ATEX marking

Protection concepts, EPLs, equipment categories, cable glands, and the full ATEX marking decode. Be able to read any marking string accurately under time pressure.

Ex03

Intrinsic safety systems

Entity parameters, Zener barriers, galvanic isolators, IS loop design. The unit most candidates find hardest — with worked calculation examples throughout.

Ex04

Inspection & maintenance

All four inspection grades, IP rating codes, inspection forms, defect grading. Know exactly what each grade requires and when to apply it.

Mock Exam

Timed mock exam with scoring

60+ questions under realistic timed conditions. Score tracking across sessions. Identifies the gaps before the assessor does.

Calm & Focus

Assessment-day stress toolkit

Stress is a measurable risk factor in Ex01–04 failure. POSISYS™ includes daily practices for the preparation period and a structured assessment-morning routine.

Early Access — Open Now
£89
One-time · Lifetime access · No subscription
  • Full question bank — all four units
  • Spaced repetition (SM-2 algorithm)
  • Full mock exam with worked answers
  • ATEX marking Ready Reckoner
  • Assessment countdown timer
  • Calm & Focus stress toolkit
  • Pre-Study Guide (PDF)
  • All future updates included
Register for Early Access

Price increases at full launch

Early access locks in £89. General release will be higher. Register now to secure the early-access price before the app goes live.

Unit by unit

What the five-day assessment actually covers.

Ex01

Explosive Atmosphere Fundamentals

Gases, vapours, ignition sources, zone classification (Zone 0, 1, 2), gas groups, temperature classes, DSEAR, ATEX Directive, area classification documents.

Ex02

Equipment Selection and Installation

Full ATEX marking decode, EPLs, all protection concepts (Ex d, Ex e, Ex i, Ex n, Ex p, Ex m), cable glands, conduit sealing, IEC 60079-14 installation requirements.

Ex03

Intrinsic Safety

IS theory, entity parameters (Ui/Uo, Ii/Io, Ci/Co, Li/Lo), the four entity checks, Zener barriers, galvanic isolators, IS loop documentation, IEC 60079-11.

Ex04

Inspection and Maintenance

Initial, periodic, continuous and sample inspection grades, IP rating codes, inspection forms, defect grading (acceptable / monitor / investigate / danger), IEC 60079-17.

Full Ex01–04 guide — unit by unit →
The environments

Built for real hazardous-area work.

Offshore

Offshore Installations

Oil & gas platforms, FPSOs, wellhead facilities — where Ex qualification is operationally mandatory and errors are safety-critical.

Onshore

Refineries & Petrochemical

COMAH-regulated sites where equipment selection, inspection and maintenance carry direct safety and legal consequence.

Chemical

Chemical & Process Plants

DSEAR-regulated environments where zone documentation and Ex equipment compliance are live operational requirements.

Radical honesty

No fake testimonials. Ever.

POSISYS™ is pre-launch. We haven't had real candidates sit their assessment using it yet — because the app isn't fully released. We will not fabricate testimonials or invent names.

When real engineers use POSISYS™ and tell us it helped them pass, those are the stories we'll share. Until then, you have Darren's credentials, his 40+ years of field experience, and the honesty of this statement.

In the engineering world, your reputation is everything. Ours is built on the same principle as a good Technical Authority sign-off: we only put our name on what we can stand behind.

Read our Independence Statement →
"I built POSISYS™ because I have sat across from engineers who failed assessments they were more than capable of passing — not because they lacked the knowledge, but because nobody properly prepared them for what was coming. That is the problem this fixes."
— Darren Emery M.Sc., Senior Instrument Engineer & Technical Authority, 40+ years
Free resources

Start preparing today — for free.

5-Day Assessment Survival Guide

What each day covers, what each session demands, and where candidates typically lose marks. Know the shape of the week before you arrive.

Hazardous-Area Ready Reckoner

Zone classifications, ATEX marking codes, equipment categories, temperature classes, IP ratings — a reference card built for the assessment format.

Practical Assessment Checklist

Every documentation and certification check the practical assessment requires. What the assessor looks for. What catches candidates out. Print and work through it.

Pricing

One investment. Walk in ready.

No subscription. No ongoing fees. Pay once, prepare properly, pass your assessment.

Essential
£59

Core preparation for first-time candidates with a focused timeline.

  • All four unit content modules (Ex01–Ex04)
  • 30 practice questions with worked answers
  • Pre-Study Guide
  • iOS, Android & web access
Register interest
Early Access Open
Pro
£89

Complete preparation for new entrants and 5-year returners.

  • Everything in Essential
  • 60+ questions with full worked answers
  • Full timed mock exam with scoring
  • ATEX Ready Reckoner
  • Calm & Focus stress toolkit
  • All future content updates
Register for Early Access — £89

Both tiers include lifetime access on all devices. No subscription. Price increases at full launch.

For employers

Preparing your workforce for Ex01–04.

If your organisation regularly sends engineers through the Ex01–04 assessment, POSISYS™ can be part of your pre-course preparation process.

1

Reduce assessment failure rates

Candidates who understand what the assessment demands before they arrive perform measurably better on both the written and practical components.

2

Protect your training investment

A failed assessment repeats the full course cost, loses productive days, and creates a competency gap. POSISYS™ at £89 is the cheapest insurance against that outcome.

3

Group licensing available

Volume pricing for organisations sending multiple candidates through each year. Contact us to discuss your requirements.

Employer enquiries

If you are responsible for Ex qualification preparation within your organisation, get in touch to discuss how POSISYS™ can be integrated into your pre-course workflow.

hello@theengineeringuniversity.com
Make an employer enquiry
Questions answered

Straight answers — no marketing.

Ex01–04 is a five-day residential competence assessment for instrument, electrical and E&I engineers working in hazardous areas where gas or vapour explosive atmospheres may be present. It covers zone classification, ATEX and IECEx equipment, protection concepts, intrinsic safety, cable glands, inspection grades, and both written and practical assessments. It is the benchmark hazardous area qualification across the UK oil, gas, petrochemical, chemical, and process industries. See our full Ex01–04 guide.
POSISYS™ is built for instrument, electrical and E&I engineers preparing for Ex01–04 — both new entrants attending for the first time, and 5-year returners who need to revalidate. Both groups face the same written and practical assessment standards. Field experience alone does not guarantee a pass. POSISYS™ prepares both properly.
No — and we won't claim it does, because that would not be honest. What POSISYS™ does is ensure you arrive with a clear understanding of what each unit tests, what the written papers look for, and what the practical assessment requires. Candidates who have practised the question style under timed conditions and know where marks are lost are measurably better positioned than those who arrive cold.
Both tiers include lifetime access on all devices. No subscription, no renewal fee, no expiry. All future content updates are included at no additional cost. If you sit your 5-year revalidation in 2030, your POSISYS™ access still works.
No. The Engineering University and POSISYS™ are entirely independent. We have no commercial, operational, or contractual relationship with any licensed Ex assessment centre, certification body, or regulatory authority. POSISYS™ questions are original works written against the current IEC 60079 standard series — not sourced from assessment papers. See our Independence Statement.
iOS (iPhone and iPad), Android (phone and tablet), and web — accessible in any modern browser. Progress syncs across devices automatically. Study on your phone on site, continue from where you left off on a laptop at home.

Don't walk into your assessment unprepared.

The engineers who pass Ex01–04 first time are not more intelligent than those who don't. They arrived knowing what was coming. POSISYS™ makes sure you do too.

Get POSISYS™ Pro — £89 Start free first