Abstract: Particle traps and meters fitted with particle traps are described for removing particles from a gas flowing through a gas meter, for example, removing particles from a gas flowing through an ultrasonic gas meter serving a domestic property. In one example, the particle trap has a body which defines a space defined by first and second portions of the body and housing a filter, an inlet through which gas can enter the space, and an outlet through which the gas can exit the space. The inlet and outlet are defined in the first portion and second portion is spaced away from the outlet.

Abstract: A detector is provided for detecting the interruption of a light path, the detector comprising a light emitter, a light receiver, and a light guiding arrangement disposed opposite the light emitter and receiver. A gap is defined between the light guiding arrangement and at least one of the light emitter and receiver to receive a movable part capable of interrupting the light path there between. Also provided is a light guide for use with such a detector and a utility meter comprising such a detector. In one specific embodiment, an opto electronic detector for detecting rotation of a coding wheel in a utility meter is provided.