Issued Patents All Time
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4856554 | Vacuum check valve and method of control | Donald L. Heffner, David A. Homan | 1989-08-15 |
| 4756333 | Vacuum check valve | Donald L. Heffner | 1988-07-12 |
| 4724867 | Vacuum check valve | William H. Gillespie, III, Donald L. Heffner, David A. Homan, James W. Miller, Donald L. Parker | 1988-02-16 |