GAS FLOW DETECTION APPARATUS
FIELD OF INVENTION
The present invention relates to gas flow detection apparatus and a method of detecting gas flow.
BACKGROUND OF INVENTION
Many working environments involve the use of gases through reticulation systems which, if not regulated and monitored, may be hazardous. Typical environments include hospitals administering oxygen to patients, metal work environments carrying out welding with oxy-acetylene torches, and science laboratories using flammable gases such as methane.
It is important to constantly check these reticulation systems to ensure that gas is passing through the system correctly. In particular it is necessary to signal any unwanted flow of gas which indicates a possible gas leak, and signal when gas flow is desired but is not actually occurring which indicates a possible blockage.
SUMMARY OF INVENTION
The present invention provides an improved or at least alternative apparatus and method for detecting gas flow.
In broad terms the invention comprises gas flow detection apparatus comprising a body having at least one gas inlet port, at least one gas outlet port, and a conduit to carry gas flow from the inlet port to the outlet port; a radiation source arranged to project a beam of highly focused light or radiation across or through the conduit; a radiation detector arranged to receive the light or radiation emitted by the radiation source; an opaque member impermeable to the beam located in the conduit and arranged to move between a rest position in the absence of gas flow through the conduit to an active position in the presence of gas flow; and signal means interfaced to the radiation detector arranged to produce a signal when the opaque member is in an active position.
In another form the invention broadly comprises a method of detecting gas flow comprising the steps of connecting at least one gas inlet port to a gas outlet port
through a conduit to carry gas flow from the inlet port to the outlet port; arranging a radiation source to project a beam of highly focused light or radiation across or through the conduit; arranging radiation detector to receive the light or radiation emitted by the radiation source; arranging an opaque member impermeable to the beam in the conduit to move between a rest position in the absence of gas flow through the conduit to an active position in the presence of gas flow; and interfacing signal means to the radiation means to produce a signal when the opaque member is in an active position.
BRIEF DESCRIPTION OF DRAWINGS
The apparatus and method of the invention will be further described with reference to the accompanying drawings, wherein:
Figure 1 is a side elevational view of the apparatus;
Figure 2 is an exploded view of one part of the apparatus;
Figure 3 is a view of the apparatus of Figure 1 in the direction indicated by A; and
Figure 4 is a view of the apparatus of Figure 1 in the direction indicated by B.
DETAILED DESCRIPTION OF PREFERRED FORMS
The preferred form gas flow detection apparatus 2 is shown in Figure 1. The apparatus 2 comprises a body 4 provided with a gas inlet port 6, a gas outlet port 8 and a conduit to carry gas flow from the inlet port 6 to the outlet port as will be further described. The preferred form body 4 is formed of metal and is mountable on a wall or other support. Body 4 may be provided with mounting aperture 9 for this purpose.
It will be appreciated that the body 4 may be provided with more than one gas inlet port and/ or gas outlet port and that the position(s) of the port(s) within the body 4 may be varied. For example, body 4 may be provided with gas outlet port 10 to carry gas flow to another body 4. Outlet port 10 is sealed with a suitable plug when it is not required to join two or more bodies together.
The preferred form conduit as shown in Figure 1 is arranged to carry gas flow from the inlet port 6 down shaft 12 to outlet port 10. If outlet port 10 is open some of the gas will exit the body 4 through the outlet port 10. The rest of the gas will travel along shaft 14, through a detection chamber 16, into shaft 18 and exit the body 4 through the outlet port 8.
Located in the detection chamber 16 is an opaque member 20. The preferred form member 20 comprises an opaque plastic ball. The body 4 is preferably arranged so that while gas is not flowing through the conduit in the body, the ball 20 will be in the rest position shown in Figure 1 due to gravitational forces.
When gas is flowing through the conduit in the body, the ball 20 will be propelled by the force of gas flowing up the detection chamber 16 from a rest position to an active position indicated at 22 within the detection chamber.
The apparatus for controlling movement of the ball is more particularly described in Figure 2. A tube 24 has a tube gas inlet 26 and a tube gas outlet 28. The preferred form inlet 26 is smaller than the diameter of the ball 20, while the gas outlet 28 is larger than the ball. As shown in Figure 2 the inlets 26 and 28 may be provided with projections on which may be fitted rubber sealing O-rings 30 and 32.
The interior of the preferred form tube 24 is tapered so that the diameter of the tube 24 adjacent the inlet 26 is less than the diameter of the tube adjacent the outlet 28. The tube 24 may be formed of clear plastic or perspex.
A cap 34 is arranged to seat on O-ring 32 on tube 24. The cap 34 is preferably formed of steel and is hollow in part, being provided with at least one aperture 36. The cap 34 may be provided with a projection 38 extending downwardly within the hollow part of the cap 34. The projection 38 is preferably formed of plastic.
To assemble the apparatus 2, the ball 20 is placed through outlet 28 into tube 24. O-rings 30 and 32 are fitted on to the tube 24 and cap 34 placed on O-ring 32. The tube 24 and cap 34 are then placed in detection chamber 16 through an aperture in the body and sealed with sealing plug 40 as shown in Figure 1. The preferred plug 40 is formed of brass, having a screw thread at one end on to which O-ring 42 may be fitted.
When gas flows through the conduit the ball 20 will be propelled from a rest position to an active position. In an active position the ball 20 will travel at least partially through outlet 28 and contact projection 38 preventing the ball from travelling further up the detection shaft 16. When in an active position gas is able to flow around ball 20, through aperture(s) 36 and into shaft 18 where it will exit the body 4 through outlet port 8.
As shown in Figure 3, body 4 may be provided with a shaft 44 extending from the exterior of the body to detection chamber 16 in which the tube 24 is located. A radiation source (not shown) may then be arranged to project a beam of highly focused light or radiation along shaft 44 toward ball 20.
The preferred form radiation source is mounted on the end of a rod shaped to be inserted into shaft 44. A radiation detector is also preferably mounted adjacent the radiation source on the end of the rod. The preferred radiation source projects light or infrared radiation toward the ball 20 and the radiation detector is arranged to detect the light or radiation emitted from the radiation source.
The rod preferably extends from a circuit board arranged to be mounted flush with the body 4. As shown in Figure 3, the body 4 may be provided with fixing holes 46 for mounting the circuit board to the body 4. With the rod inserted in the shaft 44, the radiation source and the radiation detector are preferably adjacent the tube 24.
The shaft 44 preferably extends through the body 4 toward the rest position of the ball 20. In use the radiation source will project a beam of infrared radiation along shaft 44. The preferred tube 16 is translucent and therefore permeable to the beam. The ball 20 is impermeable to the beam and when the ball is in a rest position the ball will reflect the beam back toward the radiation detector located adjacent the radiation source. Once gas flows through the conduit, the ball 20 will move from the rest position to the active position shown in Figure 1. The ball 20 will no longer reflect the beam back toward the radiation detector and so the beam will be attenuated.
The radiation detector is interfaced to signal means arranged to produce a signal while the beam is attenuated. The preferred signal means comprises appropriate circuitry arranged to activate a light or lights while the ball 20 is in an active position indicating gas flow through the conduit.
In a further preferred form the shaft 44 may alternatively extend through the body 4 toward the active position of the ball 20. When the ball is in a rest position it will not reflect the beam back toward the radiation detector. Once gas flows through the conduit the ball 20 will move from the rest position to the active position and will reflect the beam back toward the radiation detector, activating a light or lights.
In another preferred form the shaft 44 may extend from one side of the body 4 to the other through detection chamber 16. In this arrangement the radiation source will be positioned on one side of the detection chamber and the radiation detector positioned on the other side, the radiation source arranged to project a beam of radiation toward the radiation detector.
In one form the shaft 44 extends through the part of the detection chamber 16 in which the ball 20 is supported in the rest position. When the ball is in a rest position it will block the path of the beam between the radiation source and the radiation detector. Once gas flows through the conduit the ball will move to the active position out of the path of the beam, activating a light or lights while the ball 20 is in an active position.
It will be appreciated that the shaft 44 could alternatively extend through the part of the detection chamber 16 in which the ball 20 is supported in the active position.
When the ball is moved to the active position it will block the path of the beam between the radiation source and the radiation detector, activating a light or lights.
The most preferred opaque member is a plastic ball 20. It will be appreciated that the ball 20 could be replaced by other suitable opaque members arranged for movement between a rest position and an active position, for example a hinged flap or valve.
The body 4 may be provided with more than one gas inlet port, for example inlet port 48 as shown in Figure 4. Both inlet ports 6 and 48 may be arranged to receive gas when the apparatus 2 is in use. Where only one of the ports is required, the port not required may be sealed with a plug.
It will be appreciated that different variations of the body 4 may be produced with different arrangement of ports and the shaft 44. For example the shaft 44 may be positioned on the opposite side of the body 4 to that shown in Figure 3. Where the body 4 is provided with additional port 48, the port 48 may alternatively or in addition be positioned on the opposite side of the body 4 to that shown in Figure 4.
The foregoing describes the invention including preferred forms thereof. Alterations and modifications as will be obvious to a person skilled in the art are intended to be included within the scope of the invention, as defined by the accompanying claims.