Retrieve data from changed rows records

I'm working in Microsoft SQL Server 2005 Management Studio. I'm new to T-SQL and i have to make the following report:

I have a table (H2O) that contains a records of timestamp, pumpstatus, tankVolume.

The data is inserted into H2O every 1 minute.

I have to make a report (based on timestamp between date1 and date2) on the emptying tank.

The indicator when the emptying process is started is the pumpstatus chages from 2 to 3

The indicator when the emptying process is finished is the pumpstatus chages from 3 to 2

Thanks for any help!