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After determining required performance characteristics, it is critical to identify other variables that may influence the performance of a solenoid valve. Both the internal conditions and external environment of the system can affect the performance of a solenoid valve in a variety of ways. These factors may impact every aspect of the valve’s functionality and even limit available options for overall construction.
Liquids and gases have unique fluid properties, such as specific gravity and , that impact flow rate, leakage, and potentially the movement of the valve’s internal components. Material compatibility between the operating fluid and the solenoid valve components is important. An incompatible operating fluid may cause damage to the valve, alter the properties of the fluid, or even negatively influence system performance. Metallic components may corrode, polymers may become embrittled, and elastomers may swell or lose mechanical strength. For example, a system that analyzes blood or chemicals must use components that are inert to the fluids being analyzed. Similarly, a system that flows a flammable gas may need to avoid components with metals that may spark.
Both the temperature of the operating fluid and the ambient temperature may impact the performance of a solenoid valve. These effects are described below and can be separated into three distinct categories, which are described below.
When selecting a solenoid valve, minimum and maximum temperature ratings should be specified for valve performance, normal operation, and survivability. |
External pressure can be a significant factor when selecting a solenoid valve. This term may refer to elevated environmental pressures or the pressure within a vessel housing the solenoid valve. A solenoid valve must be designed to withstand these pressures. Some examples of notable environmental pressures are in applications deep underwater, underground, or even in the vacuum of space. External pressures should be considered when evaluating the force balance equations of a solenoid valve design.
Solenoid valves are subject to forces external to the system in which they are installed, as well as the forces generated by the operation of the system. These forces typically include vibration, shock, and g-forces. Some systems generate levels of vibration during normal operation, such as a car driving. A shock may occur if the system suddenly encounters another object. G-forces may be generated during operation due to sudden or rotational movement or sustained acceleration. The magnitude, frequency, and direction of all potential forces must be considered. The valve’s internal components may move differently based on the direction of the force. The frequency of the vibration could be detrimental to the valve if it corresponds to the natural frequencies of internal springs. In all cases, a solenoid valve is required to withstand these forces and remain in a designated state during such events.
Vibration, shock, and g-forces can also determine the type of electrical connections needed in a solenoid valve. A system subjected to high shock or vibration levels may require a threaded connector, whereas a static setting may only need a simple press-fit connector.
Contamination may be introduced into a solenoid valve from many different sources – including from the system itself. Debris may already be present in the system prior to installation of the solenoid valve. Upstream components that come into contact with one another during normal system operation may wear, generating additional contamination into the system. For example, a recirculating lubrication system intended to apply oil to meshing gears will not actually eliminate the wear of those gears. The fluid itself may contain debris, particularly in an open system (such as a fuel system). When this contamination enters the solenoid valve, it may damage subcomponents in the flow path. The debris may also become trapped between components that translate during operation. Resulting damage to the valve from this contamination may vary in its general severity. The damage may be a simple scratch that increases leakage, or it may cause the valve to lock in a specific position and fail to operate entirely.
Understanding the potential contamination that may enter the system is critical to ensure solenoid valve performance. |
A solenoid valve may be designed to be more resistant to contamination (either by using more durable materials or by creating larger flow paths that allow debris to pass through). Alternatively, a solenoid valve may specify a required level of upstream filtration to catch debris large enough to cause damage.
Electrical power sources commonly have a tolerance associated with their voltage output. This tolerance must align with the required voltage input to ensure the performance of the solenoid coil. Batteries often have a decline in voltage as they discharge. In these cases, the solenoid valve must be designed to function even as voltage declines.
In order to ensure safety within a specific system, many industry associations have documented recommendations or requirements for the validation and verification of solenoid valve performance. Compliance to these specifications is typically required by governing bodies and passed down to suppliers of systems and components. When selecting a solenoid valve, it is important to ensure the valve meets the industry standards required for the application in question. Examples of industry associations that have created guidelines specific to solenoid valve performance are included in the list below:
The Lee Company designs and manufactures a wide range of valves from miniature plastic pneumatic solenoid valves intended for respiratory therapy applications to high pressure, high temperature hydraulic solenoid valves operating miles underground in oil wells. If you are searching for a valve to meet your needs and would like to learn more about solenoid valves offered by The Lee Company, click or contact a Lee Sales Engineer today.
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*There are many parameters to consider when determining V-Factor. Click here for more information.
