Choosing an oil skimmer best suited for your application will maximize oil removal while minimizing capital outlay and oil skimming operation costs. The second step in selecting an oil skimmer is to know what you need or expect your removal capacity to be. Capacity should be based on the maximum amount of oil to be removed within the shortest available time. For instance, total oil influx may be 200 gallons in a 24 hour period, which averages about 8.3 gallons per hour. But if most of it comes during a single eight hour plant shift, you will probably need a removal rate that is three times as high, especially if you are trying to prevent an unwanted discharge of contaminated water to a sewer system. As a rule-of-thumb, specify approximately twice the maximum capacity you anticipate needing for normal conditions.