discarded having a sample only large enough for testing with no extra amount to dispose of means the sample is easier to discard with less pollution of the environment purging timer 19 fig1 controls the main supply and exhaust line 20 from the well 21 which supplies oil to the production manifold 22 thus timer 19 purges the main exhaust line 20 by a precise predetermined amount just prior to filling of the next bottle fig2 4 provide more details of the time interval automatic well fluid sampler 10 fig2 a vertical sectional view of the sampler 10 shows at least two bottles 12b and 12c for receiving a sample each of the well fluid from the one well 21 fig1 and two of the timers interval timer 17 fig2 and sample timer 18 all conventional electrical wiring between the timers and solenoid valves to permit them to operate as described above is deleted on this fig2 for clarity of disclosure exemplary interval timers may be ones set for intervals of 0 1 to 999 9 seconds 0 1 to 999 9 minutes or 0 1 to 999 9 hours for plugging in the housing 10 the first being preferred in seconds electrical panel 23 is illustrated on the left side of the sampler 10 carrying handles 27a and 27b are screwed on the top of the sampler 10 lights 29a 29f fig2 indicate which sample bottle is being filled fig3 a sectional view at 3 3 on fig2 illustrates the third timer purge timer 19 on the electrical panel 23 stepping switch.