Power Blower/Pufer Bulb

Power Blower / Pufer Bulb: Applying Dry Magnetic Powder

The Power Blower or Pufer Bulb is a simple, non-electrical accessory used in Magnetic Particle Inspection (MPI) to apply dry magnetic powders to the surface of a ferromagnetic component. This method is typically used when inspecting rough or hot surfaces, or when large areas need to be covered quickly.

Design and Function

1. Design: It consists of a flexible rubber or plastic bulb (the “pufer” or pump) attached to a container that holds the dry magnetic powder. The container often has a nozzle or spout for directional control.

2. Application Method: The inspector squeezes the bulb, which forces a blast of air through the powder reservoir. This air blast picks up the fine magnetic particles and disperses them in a uniform cloud over the magnetized test surface.

3. Key Principle: The goal is to apply a light, thin film of the powder. After the cloud settles, any excess, non-held powder must be gently removed using a light puff of air from the bulb itself or a different air source. The particles held by the magnetic leakage fields (over the defect) will remain, forming the visible indication.

Advantages in MPI

• Portability: Highly portable, requiring no external power source, making it ideal for remote or field inspections.

• Rough Surfaces: The dry powder method is often preferred for rough surfaces like as-welded or sandblasted components, where wet methods might be difficult or produce excessive background indications.

• High Temperature: Dry powder systems are effective on components that are too hot for liquid (wet) magnetic particle solutions.

Proper technique is vital; if the powder is applied too heavily, it can mask fine defects, leading to unreliable results.