What happens if a solenoid coil is energized when it is not mounted on the valve plunger housing?

When a solenoid coil is energized without being properly mounted on the valve plunger housing, it can overheat and potentially burn out. This occurs because the solenoid is designed to create a magnetic field when energized, which in turn moves a plunger or armature. When the coil is not mounted on the plunger, it cannot complete the magnetic circuit effectively, leading to excessive resistance and generating heat.

In normal operation, the magnetic field generated is meant to act upon the plunger to perform a specific function, such as opening or closing a valve. Without this mechanical connection, the energy from the coil is not used effectively, causing the winding to continuously draw current without performing its intended action. This excessive draw of current without proper load can lead to overheating of the coil, increasing the risk of damage.

This explains why it's crucial for solenoid coils to be properly installed and connected to their respective valve plungers to function safely and efficiently.