Dry cans or drying cans are pressurized metal cylinders filled with steam for the purpose of driving water out of fabric. The cans can be made to withstand steam pressure up to 125 psi. At that pressure, steam reaches a temperature of 344 degrees Fahrenheit. The cans in the picture are 23 inches in diameter, which is a common size. Steam, generated in a boiler, is conveyed to the cans by steel pipes. The steam goes from the pipe through a flexible hose to a rotary joint. The rotary joint is a rotary seal that enables steam to pass into the can while it is in motion. As the fabric passes over the surface of the can it causes steam inside the can to condense back into water. This water is called condensate. The condensate pools in the bottom of the can and the steam pressure forces it out of the can through a pipe connected to the center of the rotary joint. This pipe, called a siphon tube, is curved and reaches down to the bottom of the can on the inside. The water flowing out of the can goes through the center of the rotary joint and into a steam trap. The steam trap insures that only water, not steam, returns back to the boiler. The vacuum breaker on the end of the can insures that when the boiler is turned off and the cans are allowed to cool, air can enter the can and prevent it from collapsing. Cans are usually stainless steel or covered with Teflon to prevent fabric from sticking.