At some time there will be a large amount of records, about 50,000. with that in mind is the method GetEquipmentRecord up to the task. thanks for you opinions.

public enum EquipShift { day, night };

public class EquipStatusList : List<EquipStatus>
{
    string SerialFormat = "yyyyMMdd";

    int _EquipmentID;
    string _DateSerial;
    EquipShift _Shift;

    public EquipStatus GetEquipmentRecord(int equipmentID, EquipShift shift, 
                                            DateTime date)
    {
        _DateSerial = date.ToString(SerialFormat);
        _Shift = shift;
        _EquipmentID = equipmentID;

        return this.Find(checkforEquipRecord);
    }

    bool checkforEquipRecord(EquipStatus equip)
    {
        if ((equip.EquipmentID == _EquipmentID)
              && (equip.Shift == _Shift) 
              && (equip.Date.ToString(SerialFormat) == _DateSerial))
            return true;
        else
            return false;
    }
}