Excess or unnecessary quantities of liquid or gas have to release from a tank, vessel, or container using a drain valve. Most drain valves open by turning a screw or handle, but there are also automatic valves that open when a set temperature or pressure reaches to determine. Due to gravity or differential pressure, liquid or air drains from the storage tank when the valve is in an open position.
Usually, drain valves are hollow, cylindrical bodies with stems. A stem protrudes from the hollow portion of the body perpendicular to its axis. When the stem is open, liquid or gas flows through the hollow portion of the body. By turning the stem, shuts the liquid or gas path, effectively preventing escape. As part of some drain valve designs, the stem itself blocks the flow. While in others, the stem raises or lowers a gate that blocks it. Depending on the design, the gate can take the form of a disk or ball.
There are different types of drain valves, from simple screw plugs to automatic, electrically-controlled ones. The simple oil drain valve on an automobile is perhaps the simplest because it consists only of a threaded plug inserted into a corresponding threaded hole in the engine oil pan. Removing the plug from the oil pan functions as a valve stem. Alternatively, there are highly complex electronic valves that open when a temperature or pressure threshold reaches or when a preset time arrives.
There are many applications for drain valves. For example, air compressors and air supply lines make use of them. An air drain valve removes potentially harmful condensates such as water, oil, and rust. Contaminants can build up over time and cause airline obstruction or weakening of the storage tank. Steel tanks could rust if there is too much water in the system. On large trucks with air braking systems, automatic air drain valves are often used to drain oil and water that could harm the brakes.
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Water heater drain valves are used to drain water from hot water heaters periodically and remove contaminants. On the inside of a water heater, mineral scales consisting of calcium or other minerals may form over time. As well as sediments such as dirt and sand, sediments can build up in the bottom of the tank. This decreases the heating efficiency of the heating elements and can eventually cause permanent damage if left unattended. The hot water heater can drain most of these contaminants by periodically opening the drain valve.
The drain valve is set below the air compressors and is also set after the moisture separators. In the air compressors, utilize to drain water stored at the bottom. The moisture separators use to remove moisture from the airline. These moisture separators collect water particles and the drain valve drain that water.
Moisture separators come in a variety of shapes and sizes, from small cylindrical vessels to large vertical pressure vessels. The separator, sometimes called a moisture trap, removes only liquid water from compressed air. Separators usually contain impingement baffles, wire mesh, cyclonic devices, or filter elements. Their design causes the liquid to accumulate at a low point. The liquid can drain from here.