Posiflow two-way, direct-acting proportional solenoid valves are suitable for applications in which precision flow control is required

The core (plunger) in a traditional on/off valve moves completely up or down when current is applied. As a result, there are no intermediate flow rates; many flow-control valves operate on an all-or-nothing basis. In Posiflow valves, as current is applied the electromagnetic pull force exerted on the core soon exceeds the opposing force of the spring that is holding it closed. At this point, the core moves upward and the valve opens. How much the valve opens depends on how much additional current is applied after the spring force has been overcome. With a power failure, the valve closes.

Posiflow valves can be used in any domestic or industrial application in which the flow of gas or air must be controlled and where precision flow control of a liquid is needed. According to Automatic Switch, the valves should find applications in fuel and alcohol blending and dispensing; vending and dispensing machines; environmental control and heating, ventilation, and air-conditioning units; medical equipment; and industrial-process-control systems. In addition, company representatives said that there is an increased market interest in proportional solenoid valves to take advantage of microprocessor-based controllers.

The Power-Packer electrohydraulic pump consists of a bidirectional motor powered by a 12-volt dc reservoir gear pump. Weighing 14 pounds without oil, the pump unit features relief valves in both ports. It can produce 160 cubic inches per minute of flow at 600 pounds per square inch. The recommended working pressure is 800 pounds per square inch, and the maximum is 1,200 pounds per square inch. Relief valves can be set anywhere between 0 and 1,200 pounds per square inch.

If an electrical source is unavailable, the system includes a manual-override bidirectional hand pump with a displacement of 0.37 cubic inches per stroke.

The new unit can be used in gas, liquid, or steam applications as hot as 550°F, according to Stephanie Law, Fisher Controls product manager. For steam applications, high-temperature ethylene propylene elastomers, which provide class 6 steam-shutoff capability, are installed in the valve. If the device is used in corrosive fluid service, DuPont Zalak and Kalrez perfluoroelastomers (Teflon)—which offer superior resistance to heat and most chemicals—are available as options, she said.

Fisher Controls' type 63EG-98HM throttling relief valves are made for applications in high-temperature, corrosive environments

Fisher Controls' 63EG-98HM model features a pump bypass valve suited for overpressure protection in pump-recirculation applications and a versatile back-pressure regulator. Its rapid-response, high-gain piloting system is ready for differential back-pressure control use with the addition of a sealing washer to the adjusting screw, according to the company. Carbon-steel, stainless-steel, and Hastelloy C construction is available. Hardened 416 stainless-steel trim is standard for steam/water applications. The unit's maximum inlet design pressure is 600 pounds per square inch gauge and the maximum outlet pressure is 450 pounds per square inch gauge.

The Indonesian company PT Caltex has used the throttling relief valve for a year in the jungles of Indonesia to hold steam back pressure in a self-operating system to inject steam into oil wells, Law said. The Fisher Controls unit was selected for its rugged construction and resistance to elevated temperatures, she added.

Bosch Whisper Pumps are designed to be quieter than axial-piston pumps with similar capacities

The enhanced pumps are rated at 3,000 pounds per square inch (continuous). Nine sizes are available, ranging from 1 to 10 cubic inches, as are a variety of compensator controls. Theoretical flows range from 4.44 to 78 gallons per minute.

Although vane pumps offer some design advantages over their axial-piston counterparts, in general they cannot match the maximum pressure capabilities of piston pumps. Bosch engineers claim that their VPV pumps can compete head to head with comparably sized piston pumps. The main challenge in increasing pressure of a variable-displacement vane pump, they said, was improving the tribology characteristics of the pressure ring and vanes, and reducing loads on the vanes.

Vane pumps generally have good suction characteristics and high volumetric efficiencies, and are generally less sensitive to contamination. In addition, they are inherently quieter at equal pressures. Noise has become a critical issue due to government regulations to limit noise levels on the factory floor. Whisper Pumps offer low noise even at maximum flow. The VPV-16 (1 cubic inch) generates 67 decibels at 3,000 pounds per square inch and 18,000 rpm. The VPV-164 (10 cubic inches), operating at the same pressure and speed, generates 77 decibels.

Consolidated Process Machinery, a medium-size machine shop in Crawfordsville, Ind., has used Bosch VPV pumps in manufacturing equipment for nearby animal-feed-pellet mills for about two years, said maintenance supervisor Clyde Endicott. "We're using them to pump high-pressure (mineral-oil) coolant," he added. "We've had very good luck with VPVs. They're very efficient, and they're much quieter than most pumps."

A new sampling ball valve that isolates the operator from fluids, provides flexibility in mounting, and is always sealed on the process side is being marketed by H+ Valves in Lozanne, France. This valve unit has been designed for use with particulate-free liquids in chemical, petrochemical, pharmaceutical, and petroleum processing.

French-made sampling ball valves protect operators from contact with hazardous fluids

The new sampling valve can be used to obtain a representative sample a pressurized processing pipe while it ensures the safety of the operator. It dispenses liquid into any kind of bottle, thanks to its thread-adapting outlet. Samples are dispensed by gravity, not pressure, by rotating the low-torque handle 180 degrees.

At the same time, because of its specially designed ball and floating seats, the valve remains closed on the process side regardless of handle position. This makes it suitable for acids, aromatics, benzene, benzol, cyclohexane, methanol, phenol, and a variety of other solvents.

Standard sample capacities are 25, 50, and 100 cubic centimeters. The valves are available in carbon steel, stainless steel, or several corrosion- resistant alloys.

Mounting options include horizontal or vertical piping, tank wall, or tank floor. Connection is via ISO PN10-16 or ANSI 150/300-pound-per-square-inch flanges at diameters of 1, 1.5, 2, 3, or 4 inches. Maximum working conditions are 232 pounds per square inch at 68°F or 159.5 pounds per square inch at 356°F.

According to Vickers Inc. in Maumee, Ohio, its new KB series of proportional directional valves provides higher performance than conventional proportional valves but are more cost-effective, more easily installed, and more compact. They are also said to have smooth response, low maintenance costs, outstanding durability, and greater contamination tolerance.

These new Vickers valves combine advanced electrohydraulic technology with integrated electronics in an single package. Available in NFPA sizes 03 and 05, KB valves carry a 5,000-pound-per-square-inch rating. Vickers engineers integrated all electronics and transducers into the valve envelope, thereby eliminating "stuck-on" electronics that make the package much less susceptible to external damage. Users can place KB valves directly on the motor or cylinder, which lowers installation costs. In addition, the KB series provides protection against moisture and washdown, allowing full submersion in 1 meter of water for as long as 30 minutes.

The 03 and 05 models are aimed at the high-performance motion-control market with bandwidths of 50 to 70 hertz. Other KB units to be introduced in the future will address the ultrahigh-performance segment, according to Vickers.

Georgia Pacific Corp. in Atlanta is said to be using KB valves in stacking machines, where they undergo 7,000 operating cycles every work shift.

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