| 7650901 |
Ball seat leveler |
— |
2010-01-26 |
| 7152615 |
Earthquake actuated horizontal valve with micro switch |
— |
2006-12-26 |
| 6917004 |
Earthquake actuated micro switch |
— |
2005-07-12 |
| RE38220 |
Earthquake actuated automatic gas shutoff valve |
— |
2003-08-19 |
| 6213142 |
Earthquake actuated automatic gas shutoff valve |
— |
2001-04-10 |
| 6112764 |
Automatic safety shutoff valve |
Roger P. Engdahl |
2000-09-05 |
| 5307699 |
Seismic initiator for earthquake shutoff valves and the like |
Roger P. Engdahl |
1994-05-03 |
| 5209454 |
Automatic safety shutoff valve |
Roger P. Engdahl |
1993-05-11 |
| 5144598 |
Intergrating, indicating, and controlling seismometer |
Roland S. McGee, Roger P. Engdahl |
1992-09-01 |
| 4694304 |
Earthquake displacement recorder |
— |
1987-09-15 |
| 4684958 |
Seismic displacement recorder for base-isolated structures |
Roger P. Engdahl |
1987-08-04 |
| 4630483 |
Peak accelerograph |
— |
1986-12-23 |
| 4223319 |
Passive multielement shock recorder |
— |
1980-09-16 |