Apparatus for Dispensing Particles

The present invention relates to an apparatus for dispensing particles and more particularly to an apparatus which dispenses particles in small quantities for use in testing hazard detectors such as fire and smoke detectors.

The testing of fire and/or smoke detectors has become routine and currently one of the most popular methods utilises a pressurised aerosol can for such purposes. However, the use of pressurised canisters is deemed hazardous as are the propellants and other chemicals which are currently used in such canisters.

There is thus a need for a new type of inexpensive and easy to use test apparatus which is not pressurised to the same degree as an aerosol and does not use hazardous propellants or chemicals.

The present invention provides apparatus which will generate small quantities of particles and then deliver a proportion of the particles generated under the influence of a manually induced pressure.

Preferably, the apparatus can also be used to blow clear air alone so as to flush any hazard detector perhaps after a test has taken place.

In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 shows a sectional side view of apparatus according to the present invention in a collapsed condition;

Figure 2 shows a perspective view of the preferred embodiment in an extended, operative condition; Figure 3 shows a larger drawing of a portion of the apparatus shown in Fig. 1;

Figure 4 shows a view similar to that shown in Fig. 3 but in a different configuration; and

Figure 5 shows a cross-sectional plan view taken on line A-A of Fig 4.

The present invention is based on the use of a manually operated pump to generate pressure which will result in a small quantity of particles being dispensed from a powder-containing cartridge. In the preferred embodiment airflow in the cartridge is split into two with one portion being used to agitate a supply of powder and cause some of the powder to move into a mixing chamber in the cartridge where it is mixed with the other portion of airflow and dispensed through a nozzle. In this way, a small quantity of particulate material is blown out of the cartridge and when the apparatus is disposed adjacent to a hazard detector, the quantity and velocity of particles blown from the cartridge is sufficient to cause the hazard detector to be activated and thus tested. The particles can be of any suitable solid particulate material.

Turning now to the drawings, Fig. 1 shows a sectional side view of an apparatus according to the preferred embodiment of the present invention. It consists of two major portions namely a pump portion 10 and cartridge portion 11. The pump portion

10 is broadly similar to a conventional bicycle pump and consequently will not be described in detail except to say that the pump is collapsible and in Fig 1 it is shown in its collapsed condition while in Fig 2 it is shown in its extended condition. It will be seen to be a three section pump but there could be more or longer as well as shorter sections if needed in order to improve the reach of the apparatus bearing in mind that it is intended for manual use It is to be noted, however, that in this embodiment, the pressurised air leaves the pump 10 through two apertures 14 and 15 (Fig 3) rather than through a single aperture as is conventional with bicycle pumps. The actual number of apertures is not critical as far as the pump body is concerned but it is to be noted that the cartridge in the example preferred embodiment has two inlet apertures 24 and 25 and the purpose of these will be described in more detail later.

In this embodiment, the cartridge 11 is located and retained on the end of the pump 10 in some convenient fashion e.g. by being a bayonet or snap fit. As shown in Figs. 3 and 4, the pump portion 10 is provided with a cartridge receiving member 20 which

provides the fitting to the end of the pump and this member 20 is provided with the inlet apertures 14,15.

The cartridge 11 consists of a powder chamber 22 which communicates with one of the inlet apertures 25 via a powder chamber valve 21. The powder chamber 22 has an exit aperture 23 provided with a filter member 24. In use, air entering the powder chamber 22 through the inlet aperture 25 and powder chamber valve 21 agitates the supply of powder in the powder chamber to create a cloud of particles. A proportion of the cloud of particles exits the powder chamber 22 through the filter member 24 and enters a mixing chamber 26 which has an inlet aperture 24 which is in register with the aperture 14 in the pump. In this way, the same stroke of the pump 10 which causes airflow into the powder chamber 22 to create the cloud of particles also creates airflow through the mixing chamber 26 which in turn carries a proportion of the small quantity of particles leaving the powder chamber 22 through the filter 24 out of the mixing chamber 26 through an orifice 28.

As described above, manual operation of the pump 10 will result in small puffs of powder being emitted from the orifice 28 and these can be used to test a hazard detector such a smoke detector. It is preferred to be able to flush the detector with clean air either before or after a test or simply as part of a cleaning programme and this is achieved by simply rotating the cartridge 11 with respect to the pump so that the inlet to the powder chamber 22 is no longer in registration with the aperture 15 in the pump which therefore prevents any further delivery of quantities of particles even when the pump is operated to create the fresh airflow. This flushing step means that any pre-existing dust or other contaminates may be driven out of the detector or the detector may be more rapidly re-set after test.

As shown, the cartridge 11 has a plurality of apertures and the section is rotatable with respect to the cartridge receiving member 20 so as to bring one or both the apertures in the cartridge into registration with corresponding apertures in the member 20. . It is also possible for the cartridge to be moveable between an "off position where both or all inlets are blocked, a "test" position and a "flushing" position.

As a further measure to ensure that the air used to flush the detector before or after test is uncontaminated, it is possible to provide the mixing chamber 26 with a dedicated clearing tube 30 one end of which is located at a dedicated aperture 31 in the base member 20 and the other end of which communicates with a shrouded orifice 33. Thus, when the powder section 21 is twisted to the clearing or flushing position, the aperture 31 is brought into register with the aperture 14 at the same time as the inlet aperture 25 to the chamber 22 is moved away from the aperture 15 in the pump and thus blocked. In this way, clean air from the pump passes to the outlet orifice 33 without any possibility of any residual particles in the mixing chamber 26 being entrained in this airflow as might occur if the tube 30 and shrouded orifice 33 were not provided.

The orifices 28 and 33 are located adjacent each other in a position of the wall of the cartridge which is shaped to assist with the physical connection against the smoke detector e.g. slightly concave.

As described above, the apparatus has the advantage that it is simple to operate, provides reliably small quantities of particles for test and can also be used to flush hazard detectors before or after test to ensure that they are not contaminated by the test particles or other contaminants already present.

The above described basic apparatus can be modified in a number of ways. For example, the piston and cylinder pump shown in Fig. 1 can be replaced by a bulb type pump. Further, while it is envisaged when using a piston and cylinder type pump that a single stroke of the piston will provide sufficient pressure to dispense a suitable quantity of solid particles or clean air for flushing, more than one stroke may be required. This means that it may be prudent to envisage the provision of means for building up and storing pressure from consecutive pumping such as might be required with, for example the bulb pump. Such stored pressure could either be released in one blast or perhaps on a slow release basis utilising a specific release mechanism which could be manually operated by the operator. In other words, with a stored pressure

system, it would be possible to build up the pressure using two hands and then raise the apparatus towards the hazard detector using one hand and release the pressure by simple finger or remote operation.

Instead of having a stored pressure system, another possibility is a spring release mechanism which could be cocked and then fired as a secondary action in order to release the piston and thus generate the required pressure from the pump.

The above modifications allow the use of extensions to the basic apparatus in order for the basic apparatus to be utilised at a greater height than might be achieved by simply using the apparatus shown in Fig. 1 at full stretch.

Various minor modifications can also be made such as the provision of some mechanism or means for indicating consumption of the particular material in the cartridge. This might be a simple viewing window but could be a more complicated indicator system.

Finally, while the combination of pump and cartridge has been shown as being two separable items, it is conceivable that they may be made as a unitary system so that the whole assembly may be disposed of when the powder has been consumed. Another possibility is that although we have given a description of the cartridge being completely disposable, it is also possible for simply the supply of particulate material or perhaps just the powder chamber to be replaced with the remainder of the cartridge including the mixing chamber and clearing tube being used a number of times before it is disposed of.