Solenoids play an incredibly important and extensive role in a multitude of industries and are represented by an astounding array of types and models produced by an equally impressive group of manufacturers. This often makes the task of choosing a suitable solenoid a difficult one and, although it is impossible to generalize, there are several solenoid design specifics that can serve as a generic set of standards. These include coil voltage, the predicted mechanical loading for the solenoid, and its associated coil current ratings and actuation type. Many of the unknown quantities involved in choosing a suitable solenoid design are fairly easy to calculate with reasonable accuracy, and there are many printed and online resources to refer to in this regard. Of course, these issues are not important in installations using standardized parts where only a part number is needed.
The humble solenoid is probably one of the most commonly encountered actuation mechanisms in general use. Simple and cost-effective, the solenoid uses a minimum number of moving parts and relies on the generation of an electromagnetic field to supply the necessary actuation movement. Choosing a suitable solenoid design for any given project can, however, be a daunting task considering the enormous number of different models on the market. There are a couple of basic, generic specifications that apply to most solenoid installations that can help you to make the decision-making process a little easier.
The first of these considerations is solenoid type. There are three basic solenoid design categories in general use — linear, rotary, and holding solenoids — with linear solenoids being further sub-divided into push and pull categories. The exact type of motion needed must first be established before the best solenoid design can be chosen. For example, a poppet valve which requires a straight-line, up-and-down movement would require a linear, pull-type solenoid in most cases. A butterfly type valve that requires the valve gate to be turned to open would require a rotary solenoid, while a simple lifting mechanism would need a hold solenoid.
The second solenoid design consideration is maximum output. The solenoid needs to be able to physically exert enough pressure on the mechanism in question to cleanly actuate it without overheating. If no definitive information is available regarding this variable, the choice of solenoid size can be a bit of a hit-and-miss affair, with it always being wise to go bigger than is necessary. If the force required is known, then one of the many solenoid calculation resources can be used to establish a suitable solenoid size.
Solenoid coil voltage is the third basic point to consider when choosing a solenoid design. Most solenoid coils are rated to work correctly with one of a set range of voltages. Available power sources should be considered when making this choice. For example, it would not help including a solenoid with a 110-volt alternating current (AC) coil in an application designed to be used outdoors far away from a mains power point.
The physical design of the solenoid is the last of the basic considerations in solenoid design specification. Available mounting points and environmental conditions play an important role in deciding which type of solenoid is best suited for an application. This is particularly true of installations where the solenoid is meant to work in extremely moist, dusty, or explosive atmospheres. Fortunately, there are specialist solenoid designs which can cater for most conditions and user requirements.
