List each enclosure and the prevention method the basis of safety names for it, then confirm the detectors, isolation devices, suppression, and interlocks are drawn and specified consistently across process, electrical, and controls documents. AI can flag conflicts; the specialist and the authority decide compliance.
What does NFPA 69 cover?
NFPA 69 is the Standard on Explosion Prevention Systems. NFPA describes it as providing requirements for installing systems for the prevention and control of explosions in enclosures that contain flammable concentrations of flammable gases, vapors, mists, dusts, or hybrid mixtures, and as intended for design engineers, operating personnel, and authorities having jurisdiction.
NFPA’s official NFPA 69 page identifies the 2024 edition as current when checked on October 3, 2026. Confirm the edition, local amendments, and project scope that actually govern the work. The publisher’s newest edition does not establish local adoption.
Where an enclosure is protected by venting instead, use the NFPA 68 deflagration venting guide. Record which method the basis of safety names for each enclosure; a project that switches methods late often leaves the old method on some drawings.
Collect the basis of safety and the control documents
Bring the basis of safety, the process and instrumentation diagrams, the equipment layout, the isolation valve and suppression product data, the electrical and controls drawings, the sequence of operations, and the specifications for the prevention system.
The specialist’s design calculations are outside a document comparison. Note which enclosures have stated design data and which are shown only by symbol.
Trace each prevention system
| Review question | Sources to compare | Decision to record |
|---|---|---|
| Method per enclosure | Basis of safety, P&IDs, equipment list | Reconcile which method protects each enclosure. |
| Detection | P&IDs, controls drawings, device schedule | Match detectors and their locations across sources. |
| Isolation devices | P&IDs, duct and piping drawings, product data | Confirm each isolation device shown on the P&ID is drawn on the physical layout. |
| Suppression | Equipment drawings, suppression schedule, specifications | Check that suppression containers and discharge points agree. |
| Interlocks | Sequence of operations, controls drawings | Identify shutdowns described in the sequence but missing from the controls drawings. |
| Power and signals | Electrical plans, fire alarm drawings | Confirm circuits and alarm signals for the system appear on both. |
Carry control interfaces into the electrical drawing checklist and alarm signals into the NFPA 72 guide.
Example: an isolation valve on only one drawing
Hypothetical example. The P&ID shows a chemical isolation device on the duct between a dryer and its dust collector. The mechanical duct layout and the controls drawings show no device or wiring at that location.
The P&ID shows an isolation device on the duct between the dryer and the dust collector, but the duct layout and controls drawings do not include it. Please confirm the isolation method and coordinate its location and controls.
The process engineer confirms the method and the mechanical and controls drawings are revised. Whether the system is adequate is the specialist’s and authority’s decision.
Review explosion prevention documents with Groundbook
Upload the current project PDFs and relevant specifications to Groundbook. Identify the governing issues and add the applicable NFPA 69 reference from a copy you are licensed to use, where the license permits uploading it. State the edition, amendments, review area, and known exclusions in your instructions.
Compare the basis of safety and P&IDs with the duct, piping, equipment, electrical, controls, and fire alarm drawings and the sequence of operations. Flag prevention methods, detectors, isolation devices, suppression, and interlocks that differ between sources. Use the supplied NFPA 69 edition where applicable and cite both sources.
Groundbook links each potential finding to the documents behind it. Keep missing design data separate from drawings that contradict each other.
Document review does not design, size, or verify an explosion prevention system. Those decisions remain with the specialist engineer and the authority having jurisdiction.