Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4886114 | Electric surface controlled subsurface valve system | Donald H. Perkins, Phillip S. Sizer | 1989-12-12 |
| 4798247 | Solenoid operated safety valve and submersible pump system | Donald H. Perkins | 1989-01-17 |