A valve in physics and engineering is a device used to control the flow of a fluid (liquid, gas, or liquid-solid "slurry") inside an enclosed space, such as a pipe. The valve can be in a system in which the fluid circulates, such as a series of interconnected plumbing pipes, or in a simple object such as a basketball in which the fluid (air in this case) would rush out of the ball and into the environment without the help of the valve thanks the greater pressure inside the ball.
- Your own circulatory system has a great many valves to prevent the unwanted backflow of blood during periods of net positive upstream blood pressure.
Types of Valves
Valves in mechanical systems come in seven primary types: globe, gate, needle, plug, butterfly, poppet and spool. A number of these can be used to make a valve called a check valve, which is a one-way valve that requires no active manipulation (that is, input of external work) owing to its strategic shape.
Various types of valves are required to maintain optimum function of water and air pumps, and among these valves are foot valves. Foot valves are used to prime up centrifugal pumps; they are known for their efficacy and affordability.
Foot Valve Description
Foot valves are a type of check valve and are placed at the pump’s wet well. Unlike other valves, a foot valve is created with a larger flow area than the actual pipe size to make sure that there is less head loss. Foot valves are either made of PVC plastic or stainless steel, and they are known for keeping the continuous presence of suction within the pump.
Foot Valve Function
Foot valves are used to maintain hydraulic pressure to keep the water flow in accordance with the given settings or configurations. There are instances where the pressure can actually pop the valve out and cause major leakage; thus, it is important to use the right kind of material in the tubing to be able to support the force within the valve.
Foot Valve Features
Being an important part of a centrifugal pump, foot valves come with easily manageable features. Most foot valves are designed with a self-tapping male and female threads to ensure easy installation; internal balls for quick sealing and valve reaction; and flexibility to fit various types of water pump uses, such as well development and volatile organic compounds sampling and purging.
Although they are cheaper to use, as compared to other valves used to prime a pump, foot valves are usually made up of heavy duty cast iron and bronze, as well as PVC (depending on the type) so that they will last longer while submerged in the water.
Foot Valve Types
There are three types of foot valves. The micro-flow system valves are used in direct push technology micro wells and multi-level well installations. These are usually made of stainless steel and are either of fluorotherm (FEP) or high-density polyethylene (HDPE) tubing. The high-flow system valve is used on 2-inch wells or larger and can stand high pumping rates and very deep wells. On the other hand, low-flow system valves are used in small diameter piezometers, which lift up to 100 feet of water.
Foot valves usually come with surge blocks. A surge block is a tool used to press the body of a valve to remove the residues that may block smooth flow of water within the pump during operation. It also helps the valve expand while being used, thus enabling the presence of increased pressure without causing damage to the valve itself.
About the Author
Hailing from Arizona, William Hanz has been writing on a wide variety of subjects for nearly 2 years. His articles have appeared on several popular websites such as AssociatedContent.com. Hanz attended the University of Arizona majoring in computer science with a minor in English.