The hydrogen Lyman lines provide important diagnostic information about the solar chromosphere during flares, but until recently we have had no
systematic measurements. The Multiple EUV Grating Spectrograph B (MEGS-B) detector on the Solar Dynamics Observatory observes the Sun continuously for 3 hours per day.
Operating in the 37-105nm wavelength range with a resolution of 0.1nm, MEGS-B covers the hydrogen Lyman lines (from Lyman-beta upwards) and
continuum. We use the hydrogen Lyman lines to investigate the flows during solar flares, presenting two methods for the detection of Doppler-shifts in the spectral lines during 18 flares from the current
solar cycle. The first method performs Gaussian fits to the lines to obtain their positions, and compares the quiet-Sun centroids with the flaring ones to obtain
the Doppler shifts. The second method uses cross-correlation to detect wavelength shifts between quiet-Sun and flaring spectra. Both methods allow a precision of 10kms^-1, although the cross-correlation
method allows for greater time-resolution as it does not attempt to time-average the spectra. We find
that most Doppler velocities are on order of tens of kms^-1, and that the Doppler velocities increase as the flare intensity increases.
In addition, around 70% of the flares exhibit redshift in the Lyman lines during their progress, with the remainder exhibiting blueshifts.