If you use a 4-quait cooker, simply divide the recipe in half. When cooking at high altitudes, increase cooking time by 10 percent for every 2,000 feet above sea level. For the pressure cooker to work properly, there must be sufficient room inside the pot for the steam pressure to build. Therefore, cookers are filled anywhere from halfway to three-quarters of total capacity, depending upon the type of ingredients and the particular design. After the ingredients are assembled in the cooker, nest the lid into the pot, using arrows or other visual clues that are provided by the manufacturer, then turn the lid until the lid and pot handles line up.
Some cookers have an additional locking mechanism that involves pushing a small lever into place.
Most cookers are designed so that if the lid is not properly locked in place, the pressure won't rise. And remember, there's no peeking once the lid is locked in place and the pressure is up, it will be necessary to bring the pressure down to assess doneness or add more ingredients. High pressure is achieved as rapidly as possible by setting the cooker over maximum heat. Depending upon the quantity and type of food you are cooking and the size of the cooker, it can take from 30 seconds to 20 minutes for the cooker to reach high pressure. When the meal is cooked, bring down the pressure by placing the cooker under cold running water.