News Letter
Sign Up & get 33% off your first order
Enter your preferred name & e-mail to subscribe
A solenoid valve coil is designed to convert electrical energy into lateral motion. The coil usually consists of copper wire wound around a hollow bobine or tube, so when electric current flows through the coil, a magnetic field is generated. By placing a solenoid valve coil over a ferromagnetic core (usually magnetic 430F stainless steel armature) the magnetic field generated causes the plunger to slide further up towards the magnetic field (into the coil) thus allowing an opening to be created. This in turn can be utilised to either to control direct acting solenoid valves, Assisted Lift Solenoid Valves or Servo/ Pressure Assisted solenoid valves.
Solenoid valve coils come in a huge range of sizes, voltages, IP protection levels, temperature ratings and power levels. Care needs to be taken when replacing solenoid valve coils because all these factors must be considered.
When measuring a coil, you need to measure accurately the internal diameter of the coil. Some solenoid coils may be fitted with a top plate with a reduced diameter to aid secure fitment to the armature / core tube. Then the depth of the internal core needs to be measured. If this matches up, you are at the first step of finding the right coil.
Helpful hint - when buying solenoid valve coils, try to replace according to brand.
Coils are manufactured for specific voltages, it is very rare that a coil will work on more than 1 voltage, whether it be AC or DC. There are some instances of "Dual voltage coils" which can work on for example 12vDC or 24vAC, 48vDC or 24vAC but these are quite rare and this cannot be relied on to overcome spares shortfall's.
Helpful hint - check your supply voltage rather than guessing or trying to read the coil voltage.
Coil winding have several temperature classes and are usually designed depending on the media, ambient temperatures and duty cycle (duty cycle being the power on time and power off cool downtime) as all coils generate heat when energised a bit like a light bulb the more power they consume the hotter they will get. Standard coils are available for insulation
classes E, F and H. The insulation class determines the coil’s maximum operating temperature for a specific life expectancy:
- Class H: 30 000 hours
- Class F: 20 000 hours
are rated to 155C, basically the copper wire windings can withstand a working temperature up to, but not exceeding +155C. This is the most common form of solenoid coil for pneumatic systems and are ideally suited to working ambient temperatures up to +20C and media up to +100C.
are rated to 180C, basically the copper wire windings can withstand a working temperature up to but not exceeding +180C. These are a common form of solenoid coil for standard and some steam valves and are ideally suited to working ambient temperatures up to +50C and media up to +180C.
are rated to 200C, basically the copper wire windings can withstand a working temperature up to but not exceeding +200C. These are more specialist solenoid coils and are ideally suited to working ambient temperatures up to +80C and media up to +200C.
Helpful hint - replace brand like for like if experiencing short life, check supply voltage and application parameters.
Solenoid coils come in a range of power levels, DC coils are measured in Watts, AC coils measured in VA (Volt Amps) and will have a higher Inrush current and lower Holding Current. It's a bit like weight lifting a weight requires more energy than holding it up arms locked.
Helpful hint Watts = volts x amps.
You need to pay attention to the power ratings, underrated coils will over load and burn out and too higher power rating may well do the same.
Helpful hint - try to stay with the same power level unless the coil fails quickly, then check voltage supply and current availability or consult your original supplier.
Solenoid coils come with a wide range of IP (Ingress Protection) ratings according to general protection and Dust and Water Ingress. Please find below a basic IP Protection chart.
Some examples of standard solenoid coil types are shown below, you can see more about valve coils here.
Standard DIN 43650B IP65 Rated coil Rectangular DIN connector required
8/11mm bore 22mm wide various power levels from 1 to 7 Watts.
Usually used on Small Miniature solenoid valves and primarily in the pneumatics industry.
Standard DIN 43650A IP65 Rated coil Square DIN connector required
14.6mm bore 30mm wide various power levels from 1 to 15 Watts.
Usually used on general purpose solenoid valves.
Standard DIN 43650A IP65 Rated coil Square DIN connector required
14.6mm bore 36mm wide various power levels from 15 to 18.5 Watts.
Usually used on general purpose solenoid valves.
Typical Italian Standard coil DIN 43650A IP65 Rated Square DIN connector required
13.5 mm bore 30mm wide various power levels from 8 to 10 Watts.
Usually used on Small Miniature solenoid valves and primarily in the pneumatics industry.
Typical Italian High Power coil DIN 43650A IP65 Rated Square DIN connector required
13.5 mm bore 36mm wide various power levels from 14 to 20 Watts.
Usually used on Small Miniature solenoid valves and primarily in the pneumatics industry.
Typical Italian Very High Power coil DIN 43650A IP65 Rated Square DIN connector required
13.5 to 16.0 mm bore 37.5mm wide various power levels from 26+ Watts.
Usually used on large solenoid valves and primarily in the hydraulics industry.
8/11mm bore 22mm wide various power levels from 3.8 to 5.1 Watts.
Usually used on Small Miniature solenoid valves and primarily in the pneumatics industry.
Fitted with 3 meter 3 core cable but can be found with 5 meter or terminal junction box.
10/14.6mm bore 36mm wide various power levels from 8.5 to 10.1 Watts.
Usually used on standard hazardous aea solenoid valves and primarily in the Oil and Gas and Food Industries
Fitted with 3 meter 3 core cable but can be found with 5 meter or terminal junction box.
Typical American or Asian IP54 coil with 30 cm flying lead no DIN connector required
8 to 16.0 mm bore various widths various power levels from 8 to 26 Watts.
Usually used on large imported non European solenoid valves.
Solenoid coils are designed to convert electrical energy into mechanical movement by means of a magnet field, which means as they consum power like a light bulb for example they will become hot, and the higher the wattage or power consumption or the longer they are swiched ON the hotter they can become.
If the coil becomes too hot or above its temperature rating (copper winding class rating) the copper or insulating material can fail to short circuit. Other reasons include high media or ambient temperatures preventing the coil from cooling sufficiently, water ingress between armature and coil or if the coil is removed whilst energised!!
Why does a coil get burnt when removed from valve?
This is because with AC 50/60Hz coils you are reducing the impedance or resuistance of the coil, as the shading ring within the armature or stem generates resistance within the coil. By removing the coil whilst powered the resistance is reduced thus the power consumption can easily increase above the coil winding class limits causing over heating.
A catalouge of articles covering all aspects of solenoid valves
Enter your preferred name & e-mail to subscribe