Provided are flow-and-leveling agents for powder coatings which provide the coated surfaces with a flow-and-leveling property by blending into powder coatings taking a serious view of finishing and which improves coating defects such as ruptures and craters to contribute to a rise in the appearance in powder coating. Holder holes are formed in the holder hole forming member, and a coil spring and electroconductive needle members are installed in each holder hole to thereby provide a contact probe having two moveable ends. A detected change in the condition of the fluid is correlated to a failure of the airfoil, which for example can be detected by measuring the static fluid pressure. The positions of the switches on the two bus controller cards are compared, and the servant card is disconnected if its switches are not set to positions compatible with those of the master card. The moveable door in combination with the valve mechanism provides a continuous flow of water to the water reservoir and allows animals to receive fresh water that is maintained at a desired level throughout the year.