Designer's Corner 187

Low-pressure switch

With a calibrated dial and a set of high-low LEDs, the Model 390B differential pressure switch acts as either a precision manometer or adjustable-setpoint pressure sensor. Able to detect pressure differentials as small as 0.002 inH2O, the device can be used as a calibration instrument, air-flow filter monitor, touch sensor, and more. The 9-24 vdc device delivers plus or minus 0.5% repeatability, low hysteresis, and 1% FS on-off differential. Output is SPDT relay. It's available in 0.5- and 10-inH2O FS versions. Sister Models measure airflow up to 12 FPM. Henry G. Dietz Co., 14-26 28th Ave., Long Island City, NY 11102, (718) 726-7270.

Precision preloading

A differentially toothed ring mated between abutting nuts offers a simple and precise method of preloading the balls in high-accuracy ballscrew applications. On a 0.200-inch lead screw for example, moving the ring one tooth in a coupling with 100 teeth on one nut and 101 on the other produces a nut-distance change of 1/100 x 1/101 x 0.200, or 20 millionths of an inch.

The technique presents a less-complicated alternative to oversized balls, specially ground nuts, or precision spacers as a means of minimizing backlash or improving ball-screw stiffness. It also simplifies maintenance and adjustment for wear during overhauls. Thomson Industries, Inc., 2 Channel Dr., Port Washington, NY 11050, (800) 554-8466.

Quick-change furnace filter

Quick-when was the last time you changed the intake filter on your furnace or air conditioner? If you're like most people, it's been too long, and your air quality and heating efficiency have suffered for it.

In answer to the problem, the Drum-Storage Screen Filter features a length of 80%-arrestance filtration medium on supply and take-up reels sandwiched between plastic panels. Users simply dial up a length of clean filter as the old one soils. Its creator says that operating efficiencies gained by regular replacement makes the system cost-competitive with coarser conventional filters. The design is available for license. Enrique Lizano, 410 Longstreet Dr., Greer, SC 29650, (803) 322-9157.

Flame detector

Where there's smoke there's fire, but sometimes you can't wait for the smoke detector to let you know. The Pico Eye Fire Security Sensor scans a 45 degrees sector out to 10 meters distance for telltale UV radiation. An output pulse train corresponds to levels of ambient UV light. A pulse counter tracks sensor output, and a predetermined number of pulses within a given time frame triggers an 85-dB flame alarm. Designed primarily for embedded OEM applications, it can also be used in rooms with high ceilings, fuel tanks, or other high-risk, high-value environments. Michelle Zboray, Kanematsu USA, Inc., 400 Cottontail Lane, Somerset, NJ 08873, (908) 271-7361.

Quick hanger

Like a lumberjack's peavey, the Utility Hanger slips over a standard 2x4 at an angle, then grips the wood when rotated. Since it requires no tools, the Hanger speeds basement or garage clean-up, or lets you hang that trouble light just where you need it. Made from stamped and formed 18-ga steel with a PVC-coated hook end, the Hanger supports 80-lb loads and, unloaded, detaches with a push on its integrated release lever. Jack Kettlestrings, Tool-Less Hanger Corp., 900 Bainbridge Dr., Naperville, IL 60536, (708) 357-1464.