Abstract: Apparatus for detecting a discontinuity in a pipe and for supplying a sealant to seal the discontinuity so detected. The apparatus includes a circuit means for generating an electrical drive current, a sonde having a body with a transmitting coil to be subjected to the drive current and adapted to induce a magnetic field in two adjacent portions of the pipeline, and receiving coils adapted to have induced therein voltages from the portions and to provide a signal when the magnetic field in one portion of the pipeline differs from that in the other portion of the pipeline due to the fact that the discontinuity lies in the vicinity of one or other of the portions and means for detecting the signal. The sonde body has a surface at which there terminates at least one sealing compound jetting nozzle drillings extending through the body and circumferentially around the sonde body.

Abstract: SnO.sub.2 gas sensors are described incorporating Bi.sub.2 O.sub.3 in an amount less than 35% but sufficient to confer hydrogen sensitivity and selectivity to the sensors described comprises 25% by weight Bi.sub.2 O.sub.3 and incorporates a platinum catalyst.

Abstract: A fluid measurement system includes two transducers which are located in a duct to provide a measuring path through a measuring tube. The transducers are switchable to allow each to be used for both transmission and reception and the speed of fluid passing through the measuring tube will be depedent on the difference in time periods for a signal from the transducers passing with or against the fluid flow. A calibration mechanism employing an auxiliary transducer with its own ultrasonic paths allows accurate measurment of speed of sound values to be determined to the particular system parameters including transducer delay.

Abstract: A method is provided for replacing a length of a branch gas main 1 joined to a spine main 2 with a length of replacement main 7 having an outer diameter smaller than the inner diameter of the branch main. In the method access is gained to the bore of the branch main and one end of the replacement main 7 is fed along the branch main 1 via the access point and towards the spine main 2 until the branch main 1 has been replaced. During and after the feeding step gas is prevented from entering any clearance 20 between the mains 1 and 7 by means of a head 9 attached to the leading end of the main 7. After the feeding step a sealant 25 is injected into the branch main 1 to form a seal within the clearance 20.

Abstract: A method of converting a reactant gas mixture of CO.sub.2, O.sub.2 and CH.sub.4 comprises contacting the reactant gas at 750-850.degree. C. with a solid catalyst, which is a d-block transition metal or oxide such as a group VIII metal on a metal oxide support such as alumina, and which selectively converts the reactant gas into a product gas mixture comprising H.sub.2 and CO.

Abstract: Cutting apparatus is provided for cutting a hole or `window` in the wall of a pipe, for example prior to joining a branch pipe to a host pipe. The apparatus comprises a chassis frame 14 carrying a cutter unit 42 supporting a cutter tool 62. The chassis is attached to and movable around the pipe 12 by means of `roller` chains 24. The cutter unit is movable with respect to the chassis frame by means of the associated slider block 38 which is slidable along longitudinally extending chassis frame members 16. Thus, the cutter tool 62 can be moved relative to the workpiece in one sense by movement of the chassis frame 14 and in another sense by movement of the cutter tool relative to the chassis frame. A combination of such movements enable the hole or `window` to be cut.

Abstract: Tin oxide sensors are made by mixing antimony bearing material with tin oxide powder and formation of the sensor by deposition of a slurry of the mixture onto a substrate and drying and sintering the slurry, the antimony bearing material being present in an amount sufficient to render the sensitivity of the sensor to one or more of the gases H.sub.2, CO, or CH.sub.4 , relatively independent of the concentration of oxygen in the range P.sub.O2 10.sup.-1 -1 atm. A further type of a tin oxide gas sensor is disclosed having a resistivity that at a measuring temperature increases with concentration of at least one gas to be measured, the sensor is made by calcining the tin oxide in air at a temperature in excess of 1400.degree. C., or otherwise treating the tin oxide so that it has a state of physical aggregation consistent with being formed in such manner. At a second measuring temperature the resistivity of the sensor to said one gas decreases with increasing gas concentration.

Abstract: A measuring probe to detect the presence of electrically conducting liquid or granular material includes a first metal electrode (4) comprising a tube (5) which is adhered to a porous, ceramic insulator (12) adhered in turn to a skirt (10) forming a second metal electrode (6). First electrode (4) is connected to a gas supply (58) supplying gas, for example nitrogen, under pressure which emerges into a space (26) in the probe and which then passes through insulator (12) to emerge from face (20) thereof. A heat resistant cable (46) has its conductor (52) brazed to cap portion (8) of second electrode (6). Cable (46) and first electrode (4) are connected into an electrical circuit (66) in which current flows when a conducting bridge of granular material simultaneously contacts both electrodes (4 and 6). Should the level of the granular material drop below second electrode (6), gas emerging from face (20) blows away any granular material trying to preserve the conducting bridge, and circuit (66) is interrupted.

Abstract: A concrete mortar is formed by mixing together sand, cement, water and a sewage sludge ash. A foam is added to the mortar to form a foamed concrete composition.

Abstract: A package burner has a fan rotatably driven at constant speed. Air from the surrounding atmosphere is induced by the fan through an open end of a conduit which guides the air to the fan from which the air is propelled down an outlet passage to mix as combustion air in a chamber with fuel gas from a gas supply nozzle so that flames issue from the chamber. A valve in the conduit or outlet passage can be set to regulate how much air is supplied as combustion air. A fluidic oscillator has an inlet open to the atmosphere and has an outlet open to the interior of the conduit. The observed frequency of the fluidic oscillator is a function of the flow rate of air through the fluidic oscillator and is also a function of the flow rate of air along the conduit. Therefore the measured frequency of the fluidic oscillator can be used to calculate the amount of combustion air being supplied along the conduit in unit time.

Abstract: The vehicle has two groups 24, 26 of foils which transfer flux to and return flux from a wall 10 of a pipeline. The flux is from a coil 20 or from a permanent magnet or magnets. Each group is a single group of common foil members 59 interleaved with spacers 69; or alternatively each group contains sets of common foil elements such as six sector-shaped sets, for example. Each foil 59 and each spacer 69 is cut from steel for example stainless steel. Each foil 25 is an outwardly-directed resiliently-deflectable foil integral with the common foil member forming an array around the vehicle. The foils are separated by slots 63 preferably V-shaped. The sets are clamped together by retainers 73 and pins 71. In the pipe 10 the foils deflect as indicated by broken lines 32, 34. The length of each foil is at least 200 times its thickness. The foil separation divided by their thickness is at least unity. Sensors 28 detect leakage flux due to metal loss from the wall.

Abstract: A method and kit is provided for temporarily blocking the bore of a pipe through which a fluid flows, the kit including an expansible flexible bag seal which is inserted through a hole provided in the wall of the pipe injecting into the bag seal. A quantity of a material adapted to expand in situ in the bag seal and inflate the bag seal to seal against the inside of the pipe is injected into the bag seal. The pipe may be a gas main and the material may be an expandable synthetic resin foam. The bag seal is removed by injecting thereinto a substance capable of dissolving the foam so that the bag seal can be at least partially deflated.

Abstract: A gas burner particularly intended to produce diffusion flames of good emissivity and luminosity in an industrial furnace, for example a reverberation furnace such as may be used in glass making. The burner has a plate forming a burner nozzle having a central through first bore surrounded by a circular array of six smaller diameter second bores. One of the second bores is parallel with the axis of the central first bore. Whereas the other five second bores are each respectively disposed at an acute angle of substantially 22.5.degree. to the axis of the central first bore. Fuel gas is supplied to the central first bore through a central tube and to the second bores through an annular passage between the central tube and a surrounding tube.

Abstract: A motion transducer for measuring the displacement of, for example, shafts in gas control modules. The shaft 14 carries two magnets 10, 12 each of hollow cylindrical form, the magnet 10 presenting a south pole everywhere over its external cylindrical face and the magnet 12 presenting a north pole everywhere over its external cylindrical face. The shaft 14 moves vertically past an array of Hall-effect sensors 18-24 to produce sinusoidal voltage outputs at the sensors. The outputs are combined in a summing amplifier (FIG. 3). The combined output is not affected by rotation of the shaft and magnets nor by tilting or sideways displacement of the axis 16 of the shaft. That is because no matter what the rotational position is the sensors are always subjected to the same magnetic field and, if the shaft tilts or is displaced sideways an increased field at some sensors is compensated by a decreased field at others.(FIG. 1 is suggested as the accompanying drawing).

Abstract: A thermoelectric sensor assembly 1 for use with a flamestrip 9 in a fuel gas burner. The sensor assembly may be in the form of a probe 2 having temperature sensors 5a,b,c,d downstream of the flamestrip 9 in and adjacent the flame region, and temperature sensors 6a,b,c upstream of the flamestrip. A voltage output signal from the sensor assembly is used as an indication of the aeration of the flame and/or of flame establishment and/or flame failure and/or flame lightback.

Abstract: Apparatus such as a cofferdam 1, intended to be partially buried in ground beneath water comprises a hollow structural framework. The framework includes chambers 12 which have inlets 29 via which pressurized water can be supplied to the chambers. Each chamber 12 communicates with a plurality of nozzles 36 from which jets of the pressurized fluid issue to break up the ground below. Each chamber 12 also communicates with a plurality of water operated pumps 25 via inlets 24. The pumps 25 are operated by the pressurized water to draw or suck water-suspended solids from below through the pumps via the inlets 32 and discharged from the pumps via outlets 28.

Abstract: A method and apparatus for abandoning a branch main 1 joined to a fluid-carrying spine main 2 comprises gaining access to the bore of the branch main 1 at an access point and then permanently blocking the bore of the branch main 1 at a blockage point closer to the junction then to the access point.

Abstract: A method for bonding together adjoining hollow glass spheres to form an acoustic matching member for a transducer comprises subjecting a mixture of adjoining spheres and a solution of a heat curable resin and a volatile organic solvent to a first temperature to drive off the solvent and then to a second temperature to cure the resin. This causes the spheres to bond together at their points of contact but otherwise voids are formed between the spheres.

Abstract: A method of lining a pipeline 24 intended to carry gas, oil, water, sewage or chemicals in which a cross-linked polymeric liner pipe 10, which has been reduced from its original diameter to a lesser diameter or to a shape of reduced maximum dimension, is pulled through the pipeline 24. The lesser diameter is less than the least inner diameter of the pipeline 24. After the liner pipe 10 has been fully pulled through, the pipe liner 10 is heated by means of a source 60 of visible or infrared radiation forming part of a pig assembly 50 to cause it to revert to the pipeline. The pig assembly or assemblies are stationary at zones 70 where service connections are to be made. Subsequently, the remaining liner pipe 10 is reverted by pulling the source 60 through the liner pipe 10.

Abstract: A detector for detecting joints (5) in a cast iron gas main for instance comprises a sonde (1) having a central transmitting coil (2) and the two receiving coils (3, 4) spaced one on either side of the transmitting coil. At a joint, the gap (6) between the sections of pipe causes differential magnetic coupling between the pipe and the two receiving coils (3, 4). After a pulse of drive current from a control unit is applied to the transmitting coil, comparison by subtraction of voltages induced in the receiving coils and measurement of an appreciable voltage indicates that the sonde (1) is at a joint. In a second embodiment, the sonde (101) is provided with a sealing compound supply pipe (115) and nozzles (120) from which sealing compound can be sprayed into the joint on detection thereof.