Protecting workers from getting too close to dangerous machinery, such as assembly stations, robotic work cells, and automated production equipment, is the mission of the Ez-Screen Point and Grid perimeter guard safety systems, designed by Banner Engineering Corp. of Minneapolis.

The Ez-Screen consists of a microcontroller-based infrared emitter and receiver pair. When someone or some object breaks the light beam, it will respond within 24 milliseconds by shutting down the machinery.

Angled mirrors enable the Ez-Screen perimeter guard system to create two infrared beams, invisible in actuality, that protect workers from being injured by industrial machinery.

The emitter and receiver are optically synchronized to eliminate the need for an external controller or synchronizing wire. Installers can incorporate angled mirrors to create two beams, or use the Ez-Screen in conjunction with a safety light screen system to enhance safety.

The short-range version of the system can guard perimeters measuring 2.6 to 65 feet, while the long-range version covers perimeters measuring 49 to 230 feet. In either case, the emitter and receivers are compact—2 x 2.1 inches—to fit tight spaces, and can be mounted via wire terminal blocks or quick disconnects. All the sensors have a seven-segment diagnostic display and light-emitting diodes that indicate specific problems or conditions.

The receivers are equipped with two diverse-redundant safety outputs capable of switching 24-volt dc loads up to 0.5 amp each. An optional relay interface module is available to serve ac loads or loads that require higher currents.

An optional muting module is available to provide the guard system with greater flexibility in permitting material to pass through the sensing field, while not allowing personnel to be harmed.

Remote environmental monitoring of water supplies often requires multiple sensors to be placed in the field. Pressure Systems Inc. of Hampton, Va., created a digital communications interface for its Series 500 KPSI submersible level transducers, allowing them to be networked together to a single datalogger, to reduce systems cost. The company added an SDI-12, a serial data interface at 1,200 baud. SDI-12 is a protocol developed by the U.S. Geological Survey that supplies individual addresses to each submersible sensor, simplifying retrieval and storage of data.

The Series 500 submersible KPSI level transducer has a digital communications interface, allowing it to be networked in the outdoor environment.

Chris Lilly, the company's sales engineer for sensors and transducers, said the SDI-12 transducers have been installed in water management districts in southern Florida, where they are being used to monitor water levels in the Everglades. Other potential applications include monitoring wells, reservoirs, and tank levels.

Pressure Systems says that its submer-sible pressure transducer also comes with a microprocessor and an electrically erasable programmable read-only memory, which are used to implement compensation algorithms. The transducer can communicate to a datalogger from as far away as 200 feet. The unit has an accuracy of 0.05 percent and on-board surge protection. The transducers are available in pressure ranges from zero to 5 psig.

The SDI-12 is the company's first digital output for its transducers. Lilly said the company plans to follow it with transducers equipped with an RS-485 output that will support the MODbus communications protocol. It will be targeted for in-plant tank gauging applications in the municipal, industrial, and petrochemical industries, he said.

Not long ago, if a word started with "bio," most of the tech-minded had a 50 percent chance of guessing the rest. Either "technology" or "medicine."

Now anyone is just as likely to leap to "agent" or "terror."
Ever since the anthrax letters were discovered in October, there has been a new urgency in laboratories to perfect devices that will detect the presence of dangerous substances.

A current prototype of the Bio-Seeq is smaller than a shoebox, and can conduct a dozen DNA tests.

One of those devices is a portable sensor that weighs about as much as a laptop computer. It is being refined by a Baltimore company for use by hazmat teams for quick diagnosis of suspected pathogens. The company, Environmental Technologies Group, the detection and protection systems division of Smiths Aerospace, expects to have it on the market in a few months.

The device was nicknamed HANAA by its developers at Lawrence Livermore National Laboratory in California, who described it as a "handheld advanced nucleic acid analyzer." Environmental Technologies intends to bring it to market under the trade name Bio-Seeq.

The unit measures 11 1/2 x 3 x 7 inches and weighs 6 1/2 pounds. According to project engineer Doug Green, it can run as many as 12 polymerase chain reaction tests at once, or test samples from different points at a site.

An early prototype of the handheld DNA analyzer developed by the Lawrence Livermore lab.

Polymerase chain reaction uses a set of short pieces of DNA, called primers, to amplify target DNA. A set of primers will react only with the DNA of a specific organism, so when there's a reaction and the DNA starts to duplicate, the reading is positive.

If there is no reaction after a number of tries, the verdict is negative. Because of the recycling needed for corroboration, the negative often takes longer to determine than a positive.
According to Green, the device gets a negative reading within 16 minutes from "the lowest detectable sample," which may consist of a clump of only a few cells. Larger samples return results faster, he said.

Bio-Seeq will be packaged as a companion unit to the company's APD-2000, designed to detect nerve agents. It will have an aluminum extrusion with an ABS plastic facade. "It can stand to be beaten around a bit," Green said.
Pricing has not been decided, he said, but the unit is expected to come in under $20,000.

Another Livermore project with a similar goal is a year or two away from commercialization, according to Richard Langlois, the senior biomedical scientist on the project. This one is called the autonomous pathogen detection system.

An automated air monitor, about the size of a corner mailbox, may one day be used to check large public spaces for pathogens.

It is intended to provide automated early warning of any exposure to pathogens, Langlois said. The system fits a housing about the size of a lectern or mailbox. It could sit in an auditorium, a stadium, or any large public space, and continuously test air samples for a number of pathogens simultaneously. It will report results through a wireless signal.

According to Langlois, the technical challenge lies in testing for several different organisms simultaneously and repeatedly. The unit will conduct two types of tests, he said.

First, it will look at proteins on the surface of a bacterium or virus, while in the second test, suspect samples will undergo polymerase chain reaction analysis for confirmation.
Langlois said that researchers are still proving the concept.

A company in Pittsburgh is marketing a photoacoustic infrared sensing system to detect and moni tor gas emissions in the paint and plastics industries. According to Allan Roczko of the Mine Safety Appliances Co., the device can detect toluene and other aromatics, alcohols, chlorinated hydrocarbons, ketones, and esters, which pose hazards in those industries.

Roczko is product line manager for the product, called the Chemgard infrared gas monitor. He described the system as photoacoustic.

The unit can hold as many as eight samples, which are exposed to infrared light. Optical filters adjust the wavelength so that, only the target compound, if it is present, will absorb the light. The energy causes the gas to heat up and expand. The pressure change is detected by a microphone—hence, the classification as photoacoustic. The company claims it can detect concentrations in the single digits per million.

As an option, users can add another sensor, such as an electrochemical or catalytic bead device, to simultaneously monitor oxygen, carbon monoxide, or combustible gas.

While similar technologies are employed in a few other contexts, MSA's device is targeted to its particular industries, Roczko said. The device has been widely used in refrigerant monitoring, he said, and also by several companies in the paint and plastics industries.

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