Abstract: Apparatus for indicating when a swimming pool filter needs to be cleaned, which comprises a flexible diaphragm covering an opening in the conduit on the inlet side of a pool filter and a housing covering the diaphragm with a movable piston member inside the housing and engaging the surface of the diaphragm. Spring means urges the piston against the diaphragm to counteract pressure of water in the conduit against the diaphragm. A movable flag is operated by the piston means to indicate through a window in the housing when the piston has moved a predetermined distance.

Abstract: An improved free-point measuring system for indicating whether a pipe in a borehole is free or stuck at various locations within the borehole is disclosed. The system employs an improved free-point tool in which is mounted a variable resistor having a wiper arm adapted to be displaced with a movement of the pipe. Displacement of the wiper arm causes a change in the resistance of the variable resistor, and this change is detected by a surface unit provided with balancing and calibrating resistors.

Abstract: A barrier for use as a breakwater or highway safety divider having a reinforced concrete base in which are embedded a plurality of tires extending outwardly of said base and means for joining a plurality of said bases in line.

Abstract: A unitary molded venturi flume unit, for use in measuring liquid flow through a conduit, has a closed-end well section at one end of the flume throat and a connecting nipple section defining an access passage which extends from the lower portion of the well for sealed connection with a conduit. The walls of the throat and well sections extend substantially above the access passage and cause all liquid flowing through the conduit to flow through the throat. In use, a tranquil flow pool of the liquid is formed at the inlet side of the throat section. The depth of this tranquil flow pool exceeds the depth of normal rapid flow in the conduit, and may substantially exceed the height of the access passage and connecting conduit, for accurate measuring of flow through the conduit over a wide range of flow rates by sensing of the amplified liquid head on the inlet side of said throat.

Abstract: An apparatus for intermittently sounding an audible alarm when the temperature within a deep freezer rises to a predetermined level which is less than the freezing temperature of most food products so that steps can be taken to prevent the food products from thawing. The apparatus includes a remote bulb element which intermittently opens and closes a container of liquefied gas which is permitted to expand and sound an alarm when the freezer malfunctions.

Abstract: A flow transmitter for monitoring pulsating liquid flow rates, such as intermittent or cyclic impulsion produced by reciprocating pumps, employs a short stroke, variable area flowmeter having an armature core mounted in the flowmeter stem. As the stem rises and falls with flow, the armature moves within a linear variable differential transformer coil to produce an A. C. voltage following core deflection. This A. C. deflection signal is converted to a milliampere D. C. signal by means of a demodulator which through a long-time constant RC filter network averages the pulsed flow variations to provide a continuous non-inferential measurement proportional to flow.

Abstract: A parachute canopy testing apparatus for aiding in the investigation of the dynamic behavior of parachute canopies includes a pair of splitter plates arranged parallel to an air flow created within a test housing in a preferred embodiment and at least one gore of a parachute canopy positioned between the plates in sealing relationship to the side walls thereof. The plates preferably form two V-shaped passages and opposed gores are respectively located in the passages. One of the plates preferably includes an array of apertures therein through which smoke is released to provide visual indication of the air flow patterns.