- The exam is ASME's written Combustion Examination for municipal solid waste facilities without heat recovery.
- Weights are 30% waste management, 30% theory, 40% facility operation.
- Passing needs at least 70% overall and at least 50% in each of the three parts.
- Format: 75-130 multiple-choice questions, three hours, closed book, non-programmable calculator allowed.
Scope Check: Which Exam This Sheet Covers
This cheat sheet covers one credential only: the Combustion System Operator certification offered by the American Society of Mechanical Engineers (ASME) under its QRO program for municipal solid waste combustion facilities. The exam is the written Combustion Examination, and its scope is municipal solid waste facilities without heat recovery.
Two scope boundaries matter before you memorize anything:
- The certification is not facility-specific. It does not test the quirks of one particular plant.
- It is neither a prerequisite for nor a substitute for Provisional or Site-Specific Shift Supervisor/Chief Facility Operator certification. The separate two-hour oral Site-Specific examination is outside this scope entirely.
If you are still orienting yourself to the acronym and the program, start with What Is QRO Certification? and then return here for the one-page review. For a broader look at how the credential fits into plant careers, see QRO Jobs.
Format and Scoring Numbers at a Glance
Keep this table on your wall. Every figure comes from ASME's published applicant information.
| Item | What to Know |
|---|---|
| Exam type | Written Combustion Examination, multiple choice |
| Question count | 75-130 questions (a range, not one fixed number) |
| Time allowed | Three hours |
| Reference materials | Closed book |
| Calculator | Non-programmable calculator permitted |
| Overall passing standard | At least 70% |
| Per-part floor | At least 50% in each of the three parts |
| Attempt limit | No more than two attempts in a six-month period |
| Certification term | Five years |
For more on how the scoring thresholds play out, see QRO Passing Score 2026: Exactly What You Need to Pass.
The Three Subject Areas and Their Weights
ASME's brochure labels the written-examination subject areas Part 1, Part 2, and Part 3. They total 100%. These are exam objectives, not recommendations for how to split your preparation hours.
| Part | Subject Area | Weight |
|---|---|---|
| Part 1 | Solid waste collection, transfer, and management topics | 30% |
| Part 2 | Theory | 30% |
| Part 3 | Operation of a solid waste combustion facility | 40% |
The operations area is the single largest at 40%, but it is not a majority. Two 30% areas together carry 60% of the exam, which is why ignoring collection, transfer, and theory is a poor strategy. A detailed breakdown lives in QRO Exam Domains 2026: Complete Guide to All 3 Content Areas.
Eligibility and Application Mechanics
Who qualifies
The brochure sets two entry requirements:
- A high school diploma or equivalent
- Two years of industrial-process or machinery-operation experience
The fuller walkthrough is in QRO Requirements 2026: Eligibility, Prerequisites & How to Qualify.
How the current workflow runs
- The current Combustion application is request-only through ASME. You ask ASME for it rather than downloading a form.
- Applications and renewals are handled in ASME-PC Connect.
- Accepted applicants are directed to Prometric test centers.
- Acceptance starts a 180-day examination-eligibility period.
Scheduling windows and deadlines are covered in QRO Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Fees, Retests, and Renewal
Published fee figures (dated)
The pricing document currently linked by ASME is the FY20 QRO Pricing Structure. Its Combustion figures are:
| Item | FY20 Published Amount |
|---|---|
| New application | USD 713 |
| Retest | USD 265 |
| Renewal | USD 396 |
Renewal rules
- Certification lasts five years.
- Renewal requires evidence of qualifying employment for three of the preceding five years.
- That employment must involve MSW-feed control, combustion-process control, and industrial-process or machinery-operation experience.
- Renew before expiration. The current application page states zero tolerance for expired certificates.
Put your expiration date in a calendar the day you are certified, and keep employment records organized throughout the five years so the renewal evidence is easy to assemble.
Topic Checklist by Subject Area
The brochure gives the three subject names and weights; the topic lists below are the working areas a combustion operator should be fluent in for each heading. Use them as a self-audit rather than as an official syllabus.
Part 1: Solid Waste Collection, Transfer, and Management Topics (30%)
This area is about what happens to waste before it reaches the furnace and how it is managed as a material stream.
- Collection and transfer operations and how they affect the waste delivered to a facility
- Characteristics of municipal solid waste as a feed material, including variability in composition
- Waste management approaches that sit alongside combustion
- Handling, receiving, and storage concepts at the facility tipping and pit stage
- Recognizing unacceptable or hazardous items in the incoming stream
Part 2: Theory (30%)
Theory questions test whether you understand why combustion behaves the way it does, so that operating decisions are grounded in principles.
- Fundamentals of combustion, including the relationship between fuel, air, and temperature
- Heat, energy, and basic thermodynamic ideas applied to a furnace
- Properties of waste as a fuel: moisture, heating value, and ash content
- Air supply concepts such as under-fire and over-fire air and what they accomplish
- Basic math and unit handling you can do with a non-programmable calculator
Part 3: Operation of a Solid Waste Combustion Facility (40%)
The heaviest-weighted area is hands-on and procedural. Expect scenario-style multiple-choice items about running the system.
- Feed control: how waste is charged and how feed rate affects combustion
- Combustion-process control, including recognizing and responding to upset conditions
- Start-up, normal operation, and shutdown concepts for the combustion system
- Monitoring instruments and interpreting what readings suggest about process state
- Safe operating practices, maintenance awareness, and residue handling
These operational themes also line up with the renewal language about MSW-feed control and combustion-process control, which tells you what ASME considers core to the role.
A Domain-Ordered Review Plan
Here is the one place this sheet addresses study sequencing, and it is tied to the weights. Because the closed-book format rewards recall and the per-part floor punishes neglect, order your review so no part is left thin, then finish on the 40% operations area while it is freshest.
Part 1 first
- Cover collection, transfer, and waste-as-feed topics, since they are the least familiar to many plant-floor candidates
- Protect your 50% floor early by getting this unfamiliar material in place
Part 2 theory and calculations
- Work combustion principles and practice calculator problems under timed conditions
- Remember the calculator must be non-programmable
Part 3 operations, then mixed review
- Drill feed control and process-control scenarios, the largest slice at 40%
- Finish with full-length mixed practice that mimics the three-hour, closed-book setting
For a longer-form plan, see QRO Study Guide 2026: How to Pass on Your First Attempt, and for formal instruction options, QRO Training. You can also pressure-test your recall with the QRO practice tests before you commit to an exam slot.
Common Traps and Source Caveats
Know the age of your source
The applicant brochure is a legacy, undated publication (its PDF title metadata reads QRO2006), not a newly issued 2026 exam guide. The three-part structure and weights come from it, so treat them as the published scope while confirming logistics through ASME's current application pages.
The standard reference is not a new blueprint
The program cites QRO-1-2005. ASME's catalog lists it as QRO-1-2005 (R2024), which is a reaffirmation and does not establish a new examination blueprint. The paid standard was not retrieved for this sheet, and regulatory references to an earlier reaffirmation should not be substituted for the issuer's selected exam scope.
Retake discipline
With no more than two attempts in a six-month period, a rushed first sitting is expensive in both time and money. Use practice results to find your weakest part before you sit, because a sub-50% result in any one part keeps you below the passing standard regardless of strength elsewhere.
Key Takeaway
Verify three things before you book: you are registering for the Combustion examination specifically, your fee numbers are current rather than FY20, and your 180-day eligibility window leaves you enough runway to complete your review.
If you are weighing the credential against your career plans, QRO Salary Guide 2026: Complete Earnings Analysis and Is the QRO Certification Worth It? Complete ROI Analysis 2026 help frame the decision, and How Hard Is the QRO Exam? Complete Difficulty Guide 2026 sets realistic expectations about difficulty.
Frequently Asked Questions
You need at least 70% overall and at least 50% in each of the three parts. Both conditions apply, so a strong overall score does not rescue a part that falls below 50%.
ASME's published format is 75 to 130 multiple-choice questions in a three-hour, closed-book written examination. The brochure gives a range rather than one exact count, so do not rely on any single fixed number.
No. This certification is not facility-specific and is neither a prerequisite for nor a substitute for Provisional or Site-Specific Shift Supervisor/Chief Facility Operator certification. The separate two-hour oral Site-Specific examination is outside its scope.
The Combustion application is request-only through ASME, and applications and renewals use ASME-PC Connect. Accepted applicants are directed to Prometric test centers, and acceptance starts a 180-day examination-eligibility period.
Certification lasts five years. Renewal requires evidence of qualifying employment for three of the preceding five years involving MSW-feed control, combustion-process control, and industrial-process or machinery-operation experience. Renew before expiration, as ASME states zero tolerance for expired certificates.