Testing detectors

1. A hazard detector assembly for attachment to a surface within a protected zone, said hazard detector assembly comprising a detector unit and a test stimulus generator unit for testing said detector unit, said stimulus generator unit comprising a body receiving a source of stimulus material and a generator device for generating a stimulus from the source of the stimulus material, the body being provided with means for attaching said detector unit to be tested and with a means for directing the generated stimulus from outside the detector unit towards the detector unit when attached, wherein the body of the stimulus generator unit further comprises means for fixedly mounting the stimulus generator unit to said surface within said protected zone, said stimulus generator unit is positioned between said detector unit and said surface, and wherein the stimulus generator unit is adapted to generate a stimulus for testing the detector unit while being fixed to the surface.

2. A hazard detector assembly according to claim 1 wherein the body is provided with means for attaching the stimulus generator unit to a base member.

3. A hazard detector assembly according to claim 1 wherein the attachment means for attaching said detector unit is on a major surface opposite a further surface by which the stimulus generator unit is attached to a base member or a surface.

4. A hazard detector assembly according to claim 1 , wherein said detector unit and said test stimulus generator unit are connected together in a line normal to the surface.

5. An assembly according to claim 4 wherein the cross-sectional area of the stimulus generator unit is larger than the cross-section area of the detector unit.

6. An assembly according to claim 4 wherein the means for directing contains a duct extending generally normal to the plane of the surface.

7. A hazard detector assembly for attachment to a surface within a protected zone comprising a detector unit, a test stimulus generator unit for generating a stimulus for testing the detector unit and a base unit arranged to be attached to a surface of the detector unit, the stimulus generator unit comprising a body receiving a source of stimulus material and a generator device for generating a stimulus from the source of the stimulus material, the body attached to said base unit and including means for directing the generated stimulus from outside the detector unit towards the detector unit when attached, wherein the body of the stimulus generator unit further comprises means for fixedly mounting the stimulus generator unit to said surface within said protected zone and the stimulus generator unit is adapted to generate a stimulus for testing the detector unit while being fixed to said surface within said protected zone.

8. A hazard detector assembly for attachment to a surface within a protected zone comprising a detector unit, a test stimulus generator unit for generating a stimulus for testing the detector unit and a base unit, wherein the test stimulus generator unit is disposed between the base unit and the detector unit and is connected to the base unit, the base unit being attached to the surface within the protected zone and wherein electrical connections are provided to the base, the stimulus generator unit comprising a body receiving a source of stimulus material, and a generator device for generating a stimulus from the source of the stimulus material, the body being provided with means for attaching to said detector unit to be tested and means for fixedly mounting the stimulus generator to said base unit, the body further comprising means for directing the generated stimulus from outside the detector unit towards the detector unit when attached, the stimulus generator unit being adapted to generate a stimulus for testing the detector unit while being fixed to the base unit.