Portable Silt Density Index Tester LSDI-A10 -Portable SDI Tester Labtron Portable Silt Density Index Tester measures SDI from 0 to 20 with selectable filtration time of 1 to 15 minutes. A DC 12 V rechargeable battery provides up to 25 hours operation, while a built in booster pump supports low inlet pressure. The unit suits field and water filtration testing.