Abstract: There is provided a pilot valve (50), suitable for use in water and gas supply systems, the valve including biassing means (57), to control a gate (55), for controlling fluid flow through a control chamber (51), and a second chamber (52), which is sealed by a diaphragm (53), the second chamber (52), in use, receiving a control pressure for controlling the operation of the gate (55), such that an increase in control pressure acts to reduce fluid flow through the gate (55). The side of the diaphragm (53), against which the control pressure is not applied, is in fluid communication with the control chamber (51).

Abstract: In one aspect, the prevent invention provides control apparatus for controlling the pressure of a water distribution system. Typically the apparatus will be connected to a main pressure reducing valve in the system, which main valve is under the control of a dual diaphragm pilot valve. The control apparatus includes variable gas pressure output pipes which, in one embodiment, are connected to the pilot valve. There is also provided a relatively high gas pressure source and a relatively low gas pressure source, each of which are selectively connectable to the variable gas pressure output means in order to vary the pressure of the variable gas pressure source.

Abstract: The present invention provides a compound or complex comprising at least two moieties, each moiety being comprised of two or more thiophenes fused directly to each other. Also provided is a method for the production of the compounds of the present invention, which method comprises the coupling of one fused thiophene derivative to another fused thiophene derivative.

Abstract: A rotary machine has two rotors (16,18) mounted for rotation on parallel axes, each in one of two intersecting cylindrical chambers (12,14). The rotor (16) has a hub (24) and a flap (26) extending radially from the hub into close proximity with, but not into contact with, the cylindrical wall of chamber (14). The rotor (18) has a hub and a radial recess (30) which accommodates the flap (26) as the rotors rotate. The rotors are linked to one another so that they rotate at the same angular speed but in opposite angular directions. The flap (26) divides the chamber (14) into two volumes, one either side of the flap. Working fluid is introduced through the first rotor and passes along a radial passage through the rotor to direct incoming working fluid from one side of the flap. into a volume on one side of the rotor. The working fluid can be provided from an external combustion chamber.

Abstract: This application discloses apparatus for logging the operation of a valve (10) of the type having a spindle (16) rotatable by a key (20) to effect opening and closing thereof, the apparatus including operative means (36) which are in use carried on a key (20), the operative means being operable independently of any other apparatus or electronic equipment to detect rotary motion of the key during operation of the valve. Preferably, the operative means includes sensor means (40, 42) sensitive to the earth's magnetic field, and is operative to determine rotation of the key by analysis of signals generated by the sensor means. By detecting valve operation with operative means on a key, the expense of providing detection apparatus for each valve is avoided (the total number of keys being much less than the total number of valves), as is the need to provide potentially delicate equipment in the hostile environs of the valves.

Abstract: A fluid supply pressure control apparatus for use in conjunction with a pressure control valve (10) of a fluid supply system is disclosed which includes: first sensor means (26, 28) for sensing the pressure of the fluid at a first point (12, 14) in the system, and first control means (16) for controlling the pressure control valve (10) to adjust the pressure of the fluid at the first point in the system in accordance with a difference between the pressure sensor by the first sensor means and a predetermined pressure valve. The apparatus further includes second control means (24) for controlling the predetermined pressure value to reduce fluctuations in the fluid pressure at a second point in the system.The aim of this apparatus is to maintain the lowest possible pressure in the supply pipes commensurate with maintaining a reasonable pressure in outlying and elevated areas and with meeting the demand for water.