Solenoid Valves

Solenoid Valve Coils.

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.

Solenoid Coil Sizing.

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.

Solenoid Coil Voltages.

Coils are manufactured for specific voltages, it is very rare that a coil will work on more than 1 voltage weather 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 over come spares shortfall's.

Helpful hint - check your supply voltage rather than guessing or trying to read the coil voltage.

Solenoid Coil Temperature Ratings.

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 down time) 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:
- Class H: 30 000 hours
- Class F: 20 000 hours

Class F coils

are rated to 155C, basically the copper wire windings can withstand a working temperature up to but not exceeding 155 C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 20 C and media up to 100C.

Class H coils

are rated to 180C, basically the copper wire windings can withstand a working temperature up to but not exceeding 180C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 50 C and media up to 180C.

Class N coils

are rated to 200C, basically the copper wire windings can withstand a working temperature up to but not exceeding 200C. This are the most common form of solenoid coil and are ideally suited to working ambient temperatures up to 80 C and media up to 200C.

Helpful hint - replace brand like for like if experiencing short life check supply voltage and application parameters.

Power Levels for solenoid coils

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.Its a bit like weight lifting lifting a weight requires more energy than holding it up arms locked.

Helpful hint Watts = volts x amps.

You need to pay attention the the power ratings, under rated 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 then if need be consult your supplier.

Solenoid Coil Protection Levels

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.

IP protection levels explained

Some examples of standard solenoid coil types are shown below, you can see more about valve coils here.

 

Nass Magnet System 8 Coil

 

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.

 

Nass Magnet System 13/30 Coil

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. 

 

 

Nass Magnet System 13/36 Coil

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.

 

 

11630 T30 Italian 10 Watt Coil

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. 

 

 

 

31400 T36 20 Watt Italian Coil

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.

 

 

M16 Queen Solenoid valve coil

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.


 

Nass Magnet System 8 ATEX Coil

ATEX encapsulated EExmIIT4 IP65 Solenoid Coil

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.

 

Nass Magnet System 13 ATEX Coil

ATEX encapsulated EExmIIT4 IP65 Solenoid Coil

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.

 

IP54 round solenoid valve coil

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.

 

Why do solenoid coils burn out?

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. 

 

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