I am doing stress analysis on a pump. I put in all the information needed however, I would like to know which factor should I use for Table 4. I read in API that 1 should be used if its a heavy duty pump and 2 should be used if its a standard pump; however, I have not found any information on what are the requirements for each option.

You can use a factor of 2 per Annex F but a standard procedure is that you need to know from pump manufcturer/vendor if it allows such factor. Kind of negotiating sometimes that you can scale down to 1.5 if they will agree if they can't with 2x, else you really need to go with 1.0. Sometimes it would cost the buyer extra money to request for 2x allowable because the manufactuer/vendor simply reinforced the base frame of the pump so that higher loads (cause by 2x the allowable) won't create risk of shaft misalignment.