North American petroleum-, chemical-, and food-processing companies will be able to measure the liquid levels in their tanks, the temperatures at multiple points, and pressure and density by using the FP 740 level indicator developed by Auxitrol in Saint Cloud, France, and the French Petroleum Institute in Rueil-Malmaison, France.

This technician studies the liquid level in a tank being measured by the FP 740 indicator.

The FP 740 consists of a sensor that is denser than the liquid being measured, located on the end of a cable attached to a take-up spool mounted on the tank roof or, in the case of floating-roof tanks, a fixed reference point. As the liquid level in the tank changes, it causes a variation in the sensor's apparent weight. A servo-controlled motor unwinds the cable if the sensor is suspended in the air to lower it into the liquid, or raises it if the sensor is immersed too deeply in liquid.

The length of paid-out cable indicates the tank's liquid level to within 1 millimeter. The device determines density by detecting the sensor position, corresponding to the depth to which the sensor sinks before the cable pays out. Pressure and temperature measurements are taken by associated sensors and a tank-bottom readout unit, all connected by an RS 485 local bus that transmits data to the process plant's control room. Local data can also be collected by a portable readout unit via an infrared transmission link.

The readout unit is used to transmit start-up and maintenance commands to the sensor. Automatic and continuos readouts can be seen on a display screen, and include alarm states, on/ off inputs, and the state of remote-control switches.

European end users of the level indicator include Elf Atochem in Gonfreville, France; Campsa in Alicante, Spain; and L'Air Liquide in Luxembourg.

The pressure-balanced expansion joints were chosen for this project to eliminate the pressure thrust forces applied to the piping anchors. The X-Press II's externally pressurized design provided requisite low spring forces and long axial movements as well as the lateral and angular movement required to accommodate the cryogenic bending of the piping. This bending occurs during system start-up because of temperature differentials at the top and bottom of the pipe. In addition, the joints were also equipped with a Red Top leak-detector system to notify operators immediately of any leaks.

Pathway engineers fabricated, inspected, and tested the entire run of 26-inch-diameter stainless-steel expansion joints within 60 days to meet the deadline set by the consortium of P.T. Inti Karya Persada Tehnik in Jakarta, Indonesia, and Chiyoda Corp. in Yokohama, Japan. This included impact tests on welds and base materials, ferrite control of all stainless-steel welds, and performance tests and spring-rate verification for each unit.

Wastewater from a semiconductor plant is piped to this reverse-osmosis treatment plant in Arizona before being injected into the groundwater supply.

Located in the Sonoran Desert, Chandler averages 7 inches of rainfall annually, so the city must rely on groundwater for more than 50 percent of its potable water. Although city officials wanted the economic boost from more than $1 billion that would be provided by the microchip plant, they could not overburden the city's aquifer with the new plant's water demands, nor its existing wastewater system with the resulting effluent. Black & Veatch solved both problems by designing and constructing an industrial process-water-treatment facility (IPWTF), capable of treating 2.3 million gallons of water per day.

The Black & Veatch design team segregated the wastewater from the Fab 12 plant into high-fluoride and high-calcium streams in the IPWTF to prevent the formation of calcium fluoride, which could foul the membranes. The high-fluoride stream is sent through conventional, high-pressure thin-film composite membranes that reduce fluoride concentrations from 15 milligrams per liter to less than 4, as established by the U.S. Environmental Protection Agency's Safe Drinking Water Act regulations.

The high-calcium stream is sent through Film Tech nanofiltration membranes. The treated water is injected into the groundwater supply, replacing up to 90 percent of the water sent to the IPWTF. The system supplier for the project was Ionics Inc. in Watertown, Mass.

Since its completion in July 1996, the IPWTF has reduced Fab 12's net water demands from 5 million gallons per day to 1 million, which eliminated the need for a larger water system. The Fab 12 plant has created more than 3,000 jobs, boosting Chandler's tax base, housing market, and overall economy.

These four Celesco transducers monitor the movement of gates and valves that control the current of the Rio Tajo in Spain.

Most of the four different Celesco models have been installed already in the Rio Tajo equipment. All the transducers send 4- to 20-milliampere electrical feedback signalsŃsuited to data collection in harsh environments—to a local telemetry point, then to a central control location via satellite. The PT9420 and PT8420 transducers will take direct linear measurements of the gates, while Celesco's RT9420 will measure the rotation of the gates' motor shafts. The IT9420 inclinometer will measure the tilt position of the rotating gates.

Both the PT9420 and PT8420 are mounted to a fixed surface, and their cable is attached to the movable object being measured. The gates draw the cable as they move, generating an electrical feedback signal in proportion to the distance the gate has moved. The RT9420 is mounted on the motor that rotates the gates. The device contains a rotational shaft that spins as the valve or gate rotates, generating an electrical feedback signal. The unit makes absolute rotational measurements in ranges of one-quarter to 50 turns, or 90 degrees to more than 18,000 degrees.

The IT9420 uses magnetic damping to take swift, stable measurements of 45 to 270 degrees. The device is attached directly to the gate or valve. When that object tilts, the pendulum within the inclinometer moves in relation to the angle of tilt, generating its feedback signal. The signals from all four transducers are transmitted via a telemetry point to a central control location.

The poppet-type plunger assemblies and resilient seating disks in this Elwood machine-coolant control valve prevents leaks during operation.

Engineers equipped the directional control valve with poppet-type plunger assemblies and resilient seating disks that close against heat-treated, stainless-steel-mitered seats. This provides a positive, drop-tight sealing to prevent leaks. The valve's dynamic poppet seals do not extrude into the ports during operation, extending their performance life.

Operators can control flow in and out of either valve port by turning the externally accessible stainless-steel flow-control screw to limit the poppet stroke. The passageways of the Elwood valve are designed to optimize valve efficiency and minimize pressure drops. The valve requires about half the manifold space of competitive valves.

PMC Industries Inc. in Wickliffe, Ohio, uses the Elwood valve to control coolant in its carbide-tooled, high-speed, three-station, indexing coupling-finishing machine. The computer-numerical-controlled machine automatically loads, bores, taps, and unloads well pipe couplings at the rate of two pieces per minute. The Elwood control valves regulate the flow of coolant—95-percent water and 5-percent soluble additive, pumped at 900 pounds per square inch and 50 gallons per minute—through the machine spindle to the tool/work-piece interface at each machining station. The coolant is filtered twice, cooled to ambient temperature, and recycled to the pump reservoir for reuse.

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© 1998 by The American Society of Mechanical Engineers