| # | Company name | Role | # of projects |
|---|---|---|---|
| 601 | Omni Fireproofing Company. Inc. | Fire protection engineering | 2 |
| 602 | Optimal Fire Protection | Fire protection engineering | 1 |
| 603 | Oslo Brannsikring | Fire protection engineering | 3 |
| 604 | Ottawa Sprinkler Installations Ltd. | Fire protection engineering | 4 |
| 605 | Overhead Fire | Fire protection engineering | 1 |
| 606 | Ozik Systems Ltd. | Fire protection engineering | 3 |
| 607 | Øresund Safety Advisers AB | Fire protection engineering | 4 |
| 608 | P & L Fire Protection Inc | Fire protection engineering | 0 |
| 609 | P Nacey Sprinkler Co | Fire protection engineering | 1 |
| 610 | Pabst und Partner Ingenieure | Fire protection engineering | 3 |
| 611 | Pacific Fire Supression | Fire protection engineering | 0 |
| 612 | Palmetto Sprinkler | Fire protection engineering | 1 |
| 613 | Paloässät Oy | Fire protection engineering | 7 |
| 614 | Panhandle Fire Protection | Fire protection engineering | 1 |
| 615 | Parker Fire Protection | Fire protection engineering | 1 |
| 616 | Patriot Fire Protection | Fire protection engineering | 4 |
| 617 | Patriot Fire Protection | Fire protection engineering | 4 |
| 618 | Patriot Fire Protection Inc | Fire protection engineering | 0 |
| 619 | Patriot Mechanical Services | Fire protection engineering | 0 |
| 620 | Performance Fire Protection | Fire protection engineering | 1 |