Designer's Corner 123

Pipe restraint

Restraining a piping system to building structures is not easy. Conflicting requirements for thermal expansion, flow-induced vibration, and dynamic loads render snubbers, gapped supports, and viscous dampers only partially effective.

A better solution calls on a spring/damper arrangement. Components include two U-shaped plates and a helical coil of wire rope. The orthogonally-positioned plates move relative to one another, deflecting the coil to accommodate thermal expansion and contraction.

The coil also protects the piping system from flow-induced vibration, seismic events, water hammers, and other shocks. Strands in the wire rope provide a damping effect by rubbing together to dissipate energy.

Other advantages of Wire Energy Absorbing Rope (WEARa) pipe restraints: no maintenance, wide application temperature range, high fatigue life, and low cost.

Tom Zemanek, Enidine Inc., 212 Technology Drive, Irvine, CA 92718, (714) 727-9112.

Automobile assurance

To save space, surface mount circuitry can reside under dome. Pin-selectable connections offer analog or digital output.

Opposing quadrant pairs accurately reflect relative tilt in either X or Y axis.

Expensive security systems are not foolproof--especially if car thieves tow or truck their target away. Accordingly, auto manufacturers are looking at an on-board supplement to these after-market devices. It's called a dual-axis clinometer.

Two hermetically sealed domes and a captured fluid with high dielectric constant make up the AccuStar(R). The lower dome carries four conductive quadrants, while the upper dome acts as a ground.

An air bubble in the fluid triggers the sensor. Centered when the sensor is level, the bubble moves if a thief jacks up the car. The capacitance change generates an output signal to trip the alarm.

Schaevitz Products, 7905 N. Route 130, Pennsauken, NJ 08110, (609) 662 8000.

Solid solids pump

Pumping bulk solids may at first seem nonsensical, but the Positive Displacement Metering High Pressure Solids Feeder does just that. In tests, a specifically designed Feeder pumped coal continuously into pressures as high as 210 psi. The design could be a boon to pressurized coal-based power plants and have a strong impact on other bulk-solids industries as well.

Unlike conveyors or gravity-fed hoppers that jam or plug up easily, the Feeder uses a single rotating spool within a metal housing. Self-cleaning spiral grooves machined into the inner faces of the spool discs help drive the solid through the pump body. An accessory live-walled hopper ensures a steady supply of solids to the feeder. The hopper's independent halves feature an electric vibrator that prevents solids from jamming without over-compacting small-grained material--the vibrator only operates when a sensor indicates a void under the hopper.

Timothy Saunders, Stamet, Inc., 17244 S. Main St., Gardena, CA 90248-3130, (310) 719-7110.