Skinner Solenoid Valves
Solenoid valves are relatively simple devices. A solenoid valve is operated by opening and closing an orifice in the valve body. This action permits or prevents flow through the body, which is installed in a pipeline and is part of the main pressure bearing component of the valve.

Although simple in operation, great care must be taken in the selection process because a solenoid valve is a highly engineered product which can be applied to a wide variety of diverse and unique applications. In addition to operational functionality, selecting the best product for a given application must also consider safety, reliability, media compatibility, and be suitable for the operating environment.

Skinner plunger assemblies incorporate the use of floating top and bottom seals to enhance performance. Floating seals permit the plunger to travel and build momentum before the orifice is opened. This generates a larger available force to lift against the pressure differential in the valve to operate at higher pressure ratings. This action can be illustrated by affixing a suction cup to a smooth flat surface. If it is simply gripped by it's tab and pulled, it requires a great deal of force to remove it. However, if a short piece of cord is attached to it and the cord is gripped and pulled rapidly, the suction cup will "snap" off of the smooth surface. "A body in motion, tends to stay in motion."

A competitor's valve with standard flat fixed top and bottom seals on its plunger will require greater magnetic force to cause it to shift, again requiring "oversizing" the valve and leading to frequent overheating and premature coil burnout.

Skinner Coils
Solenoid valve coils are the heart of the operating mechanism of the valve. The coil is constructed of magnetic wire wound in uniform layers around a centre spool called a bobbin. Magnetic wire comes in a number of diameters and is coated with a thin layer of insulation which prevents the wire from shorting when different layers come in contact with each other.

All Skinner coils are engineered to optimize their ability to shift the plunger while reducing heat gain. Because Skinner coils operate well within their maximum allowable coil class temperature rating, they do not suffer from premature coil burnout.

Fluxtron Coils
The Fluxtron Electronic Coil - an exclusive offering of Skinner, contains an electronic circuit designed to minimize power consumption. The electronic circuit is an energy management feature that produces an instantaneous inrush of power sufficient to fully actuate the valve. This initial inrush, which is less than 100 milliseconds duration, will shift the plunger in the exact same manner as a conventional coil. The power is then reduced to the level required to retain the plunger position which can be as low as 0.5 watt.

The lower power consumption of Fluxtron coils also results in low coil temperature rise. A Fluxtron coil will have a coil temperature rise of only 9 degrees F (5 degrees C). Lower temperature rise equals longer coil life.

Coil Types
Skinner offers a wide selection of coil types to meet a vast array of application requirements.

Integrated Coil - A coil and yoke assembly which is completely encapsulated in an epoxy compound. No additional housing or enclosure is required. Its construction is similar to that of a DIN coil.

Potted Coil - A coil encapsulated in an enclosure with potting compound to protect it from vibration and moisture. The terminators are also encapsulated as part of the assembly, and can be leads, automotive terminals, military connectors, and others.

Molded Coil - After the coil is wound and the lead wires attached, the entire assembly is encapsulated in a molded epoxy resin, completely sealing the assembly from moisture.

Taped & Varnished Coil - After the coil is wound, it is vacuum impregnated with varnish to seal it from moisture and then wrapped with electrical tape.

Coil Electrical Terminations
Skinner offers a wide array of electrical connection options for your application.

Leads - Lead wires are soldered to the ends of the coil wire. Lead wires are generally 18 - 24 inches long, custom lengths are also available.

Screw - The ends of the coil wire are soldered to screw terminals located on the coil, permitting screw connections to the power source.

DIN - A European design, the ends of the coil wire are soldered to two flat metal terminations arranged in a specific pattern and a third connected to a ground in accordance with DIN specifications, permitting connection to a plug-in connector. The coil along with a yoke are molded together in a heat resistant plastic compound, eliminating the need for an additional housing.

Tab - Flat metal connectors permitting wiring to appliance connectors.

NEMA Classifications
The National Electrical Manufacturers Association (NEMA) has standards for the construction of electrical enclosures for installation in non-hazardous and hazardous locations.

Skinner manufactures all of its enclosures (housings) in accordance with these standards for specific applications. A brief summary of each of the major NEMA Types of enclosures can be found here: NEMA Enclosure Types.

Valve Characteristics and Types
There are three basic types of solenoid valve actuation - direct acting, direct lift, and pilot operated. The method by which a solenoid valve is opened and closed is known as the type of actuation.

Direct Acting In direct acting valves the solenoid operator acts directly on the plunger, which opens and closes the orifice (see Figure #3). These valves are generally of simple construction and operation and have the fewest parts.

Direct Lift In direct lift valves the main orifice of the valve is controlled by a diaphragm and spring assembly that is mechanically connected to the plunger (see Figure #4). When energized the plunger moves upward against the stop raising the diaphragm assembly. The mechanical linkage between the diaphragm and plunger allows the valve to open without the need for an internal pressure differential to exist across the valve. For this reason, these valves are also referred to as "Zero-Delta-P" valves. Direct lift valves are designed with a pilot orifice that allows the process media to assist with actuation when a pressure differential is present across the valve. Opening of the pilot orifice allows fluid above the diaphragm to evacuate. This results in reducing the pressure above the diaphragm, and allows the line pressure to help lift the diaphragm with the plunger. The entire operation takes place in milliseconds.

Pilot Operated In pilot operated valves, line pressure, in the form of pilot pressure, is required to open and close the main orifice in the valve. Pilot pressure is controlled by a pilot orifice that is used to pressurize a diaphragm or piston (see Figure #5). In each case actuation of the plunger creates a pressure imbalance across the diaphragm (or piston) to initiate movement by the process fluid. Pilot operated valves will not work without system pressure, they require a minimum of 3-10 PSI differential to actuate.

CBVL
Christenson-Bellows Valvair Ltd. stocks a wide selection of Skinner Valves; 2, 3, and 4-way; 1/8 to 1-1/2" NPT; NO/NC; All voltages, most enclosures; Low and high pressures; For air, water, oil, gas, and other media.