Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5567327 | Air-assist discharge of filter press cake | Joel D. De Haan, Daniel De Haan, Gregory De Haan, David J. Spyker, Wesley G. Koops +1 more | 1996-10-22 |
| 5456022 | Batch-type sludge drier | David J. Spyker, Daniel De Haan, Greg De Haan, Wesley G. Koops, James E. Roelofs | 1995-10-10 |
| 5275740 | Filter press with adaptive automated control arrangement | David J. Spyker, Victor A. Van't Hof | 1994-01-04 |