The development of an ATEX zone 0 encoder for explosive environments(ATEX Encoder)

Vital to any NDT inspection is pinpointing the precise location of the defects found. Advanced inspections, such as phased array or full matrix capture, need the precise location of the sensor as it is moved during the inspection. This is to allow the data collected to be viewed as a map or 3D segment. The odometry of the robot or probe is handled by an encoder. An encoder is a transducer that sense the position or orientation for use as a reference or even as a feedback to control position.

If these advanced techniques are to be used in potentially explosive environments, such as the oil and gas industry, then ATEX certification is a pre-requisite. ATEX certification demonstrates component/system suitability for use in an explosive environment. Current ATEX encoders are not suitable for NDT applications as they are bulky and have a very high torque that necessitates some force to enable the shaft to rotate and the encoder to record precise position. They can also be prone to slippage which may affect the position of the robot or probe, especially in an environment where hydrocarbons are present.

ATEX environment: explosive atmospheres can be caused by flammable gases, mists or vapours or by combustible dusts. In these environments the smallest source of ignition such as a spark or a hot surface can cause an explosion resulting in significant damages, serious injuries and loss of life. Using the correct equipment can prevent this. In some circumstances, these environments must be entered to work or inspect. The equipment used in these environments must be ATEX certified -- designed and certified to prevent any explosions and not become a potential source of ignition.

The goal of the project is to develop an ATEX-certified contactless magnetic encoder. Physically, the new encoder will much shorter than the conventional designs. Eliminating of the need for a mechanical coupling (via a shaft) further reduces overall package size and will considerably reduce the encoder torque. That means it will be much easier to integrate the new encoder into applications where space is an important factor, it will be appropriate to NDT applications, the potential for accidental damage to the encoder in challenging industrial environments will be significantly reduced.