| # | Company name | Role | # of projects |
|---|---|---|---|
| 21 | Davis Ulmer Sprinkler Co Inc | Fire protection engineering | 2 |
| 22 | Davis Ulmer Sprinkler Company. Inc. | Fire protection engineering | 2 |
| 23 | Davy Fire Sprinklers | Fire protection engineering | 1 |
| 24 | Debis Risk Consult GmbH | Fire protection engineering | 1 |
| 25 | Defire | Fire protection engineering | 2 |
| 26 | Dehart Alarm Systems Inc | Fire protection engineering | 1 |
| 27 | Delco Fireplaces Ltd. | Fire protection engineering | 1 |
| 28 | Delta Automatic Systems | Fire protection engineering | 0 |
| 29 | Delta Fire Inc. | Fire protection engineering | 1 |
| 30 | Dependable Fire Protection | Fire protection engineering | 0 |
| 31 | Desert Fire Protection | Fire protection engineering | 0 |
| 32 | Desert Fire Protection Inc | Fire protection engineering | 0 |
| 33 | Desert Security Fire Protection | Fire protection engineering | 0 |
| 34 | Design Build Fire Protection | Fire protection engineering | 3 |
| 35 | Devcon Security Services Corporation | Fire protection engineering | 6 |
| 36 | Dipl-Ing. Dr. Sesselmann + Kollegen | Fire protection engineering | 7 |
| 37 | Dipl.-Ing Paul Corall | Fire protection engineering | 4 |
| 38 | Dipl.-Ing. Elmar Püschel | Fire protection engineering | 4 |
| 39 | Dipl.Ing.Franz Schächer Ingenieurbüro für Baustatik und Baulichen Brandschutz | Fire protection engineering | 3 |
| 40 | Diplom-Ingenieure Endreß GbR | Fire protection engineering | 12 |