merging 4 data sets into 1 with all 4 having a different timestamp

[dmear]

I have pressure logging data at 1 minute interpolations for a full year for a pumping station that has 5 pumps. each pump is running and/or on standby at different times. sometimes pump 1 will run for more than 10minutes and other will not. the time stamps are not in 1 minute interpolations. I am not sure how to combine these together.

[alansidman]

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