Abstract: A power line carrier communication system having a carrier current transceiver (CCT) interface with an electrical power line via a buffer which automatically provides a low output drive impedance while transmitting, and a high receiving impedance when receiving, all with solid state circuitry. The length of signal transmission by the CCT is monitored and automatically prevented from continuously loading the communication network in the event of a malfunction which causes a signal transmission to exceed normal maximum transmission time. Prevention of continuous loading of the communication circuit is accomplished without adverse affect on the CCT via a crowbar circuit connected to the buffer circuitry.

Abstract: A fence comprising a fence board support bracket having a base and having provided on the said base guide means adapted to receive removably inserted therein one or more fence boards, means for anchoring said base to the ground, and one or more fence boards adapted to be removably inserted into the said guide means, wherein the said base comprises a flat plate having provided therethrough a plurality of holes each of which is adapted to receive a stake removably inserted therethrough, and and wherein the said guide means comprises a channel formed by a pair of opposing side members, and wherein the said anchor means comprises a plurality of stakes each of which is adapted to be removably inserted through a hole of said plurality of holes in the said base and to be driven into the ground.

Abstract: A corner piece interfits with an approximately 90.degree. corner defined by two upright walls, a thin protective strip attached to the two walls and elongated vertically, the strip having a rounded nose extending outwardly from planes defined by the walls and around the corner, and two like base boards that respectively extend adjacent the lowermost side of the walls and toward the corner.

Abstract: A high pressure spray nozzle is provided having a central fluid stream that can be converted to a fan shaped fluid stream by rotation of a housing cap. Rotation of a second portion of the housing produces a cone shaped fluid stream which is coaxial with the central fluid stream.

Abstract: An addressable elevator communication controller which, when addressed by a valid input message, prepares a return message and has its return data interface enabled for one message. The return message is automatically clocked out of the communication controller via the enabled return data interface as the next input message is clocked into the controller, regardless of whether the incoming message is addressed to this communication controller or to another communication controller. The communication controller is operable in one of two completely different modes, simply by controlling the logic level of one input pin. Input messages, as well as message clocking input pulses, are screened through digital correlators which discriminate actual signals from line noise.

Abstract: A gas-extraction arrangement for a settling tank included in a wastewater treatment system, the tank having an outlet zone defined by an effluent trough at least one side of which has a weir to permit clarified water from the tank to spill therein. The trough is covered by a hood which acts to confine the atmosphere thereabove to the hood region, at least one side of the hood protruding into the tank water at a point spaced from the weir to create a scum baffle preventing grease and other floating matter from being discharged into the trough. The hood is coupled to a suction pump which acts to draw noxious gases emitted as the water spills over the weir into a gas-control system or other means for deactivating the gases.

Abstract: A package for a flowable material such as a plant growth medium and which can be converted for use as a container for growing plants therein. The package has an elongated or square flexible outer container and is filled with the flowable filling material. The container has markings for cutting out a pair of openings at either end of the top surface to thereby leave a carrying handle in the middle.

Abstract: A multi-nozzle high pressure fluid sprayer which can be safely indexed to a selected nozzle while the sprayer is under high fluid pressure. The sprayer head contains an offset member having at least one fluid nozzle therein. The offset member can be rotated to align a selected nozzle with a source of high pressure fluid.

Abstract: A high pressure spray nozzle is provided having a central stream of fluid that can be changed to a coaxial flow of fluid by rotation of the housing cap to thereby produce an outer stream of fluid which is a coaxial to the central stream of fluid.

Abstract: A multi nozzle high pressure fluid sprayer which can be safely indexed to a selected nozzle while the sprayer is under high fluid pressure. The sprayer contains separate seals at the inlet of each nozzle to permit a safe and effective indexing to either of the nozzles while the fluid is under high pressure or to provide a total shutoff of the fluid. The sealing arrangement includes a channel to provide back pressure to the seal area around each of the nozzles to prevent the seals from being disgorged or damaged as the sprayer head is indexed from nozzle to nozzle while under high pressure.