Final Control Elements

Dosing valve

The corrosion-resistant pneumatic diaphragm valve is suitable not only for highly corrosive dosing applications, but also for open/close applications. The type 604/605 pneumatically actuated dosing valve is tested to surpass 2 million life cycles. In typical chemical dosing applications, low-cost solenoid valves save money, but they corrode and break down, requiring frequent replacement. High-end, corrosion-resistant solenoid valves for the same application last longer, but are very expensive. The dosing valve has a lower price point, but is already corrosion resistant, and with minimal metal parts, it has a longer, more reliable life span.

The ½-inch (d20) 604/605 valve is available in body materials PVC, CPVC, PROGEF standard PP, and SYGEF standard PVDF with a wide variety of end connections and custom assemblies. The valve is pressure rated at 90 psi unidirectional with operating temperatures ranging from –4°F to 284°F, depending on body material.

The threaded bonnet eliminates the need for both metallic body bolts and retorquing after hot line shut downs. Oversized pneumatic ports decrease cycle time to maintain accurate dosing with minimal overrun.
GF Piping Systems

Pneumatic rotary actuators

Nov Dec Products fig Automation Direct

The NITRA rotary actuators are available in four body sizes, with or without shock absorbers. All are double acting and have an adjustable travel range from 0 to 190 degrees. Anodized aluminum bodies include integral mounting slots for position switches, and a durable ball bearing hub and integrated piston magnets are standard. The compact rotary actuators are suitable for general material handling and other industrial applications, such as conveying, clamping, transferring parts, positioning, and controlling valves.

The pneumatic grippers are compressed air actuators with jaws (or fingers) to pick up, hold, and release objects. They are used in a broad range of general automation processes, such as pick and place, material transfer, clamping, and indexing. Two jaw parallel and two jaw angle grippers are available in seven body sizes and with side-mount or end-mount grips. Parallel grippers open and close parallel to the object, and angle (or angular) grippers open wider than parallel jaws, requiring more space. The pneumatic grippers are either double-acting, single-acting normally open, or single-acting normally closed. Anodized aluminum bodies include integral mounting slots for position switches.

Relief valve leak monitoringNov Dec Products fig fci

The inline FLT93L flow switch is suitable for relief valve leak monitoring in natural gas fractionation applications. It is a heavy-duty thermal dispersion flow, level, temperature switch. With an all-welded thermal sensing element, the FLT93L switch includes an advanced electronic control circuit, which is field configurable to satisfy any combination of application requirements. Unlike other flow switch technologies, the thermal sensor in this switch is suitable for both gases and hydrocarbon-based liquids.

The switch’s voltage output allows the user to “see” into the process and accurately set the desired trip point. The delta range between the switch’s two resistance temperature detectors provides a span for setting the switch trip points. The plant technician can set these flexible dual relays for any combination of flow, level, or temperature alarms.

The switch has a standard flow accuracy of ± 2% of the set point velocity over a ± 50°F (± 28°C) temperature range. Its repeatability of ± 0.5% reading is satisfactory for dependable operation in natural gas fractionation relief valve leak monitoring. All FLT93 series switches are temperature compensated for accuracy under rugged petrochemical plant operating conditions.

Electronic platforms

Nov Dec Products fig asco

The Numatics G3 series and 580 series electronic platforms have been expanded to control up to 128 solenoid valves on a single valve manifold assembly. The platforms have flexible process control architectures that permit the design engineer or end user to optimize the size of the control cabinet for the number of required valves.

The valve platforms can support 128 Numatics 501 series solenoid valves and 80 Numatics 502 and 503 series valves. They can support 80 18-mm and larger valve sizes on a single manifold. The valve platforms also have mid-station blocks with valve drivers and auxiliary power connectors, so customers pay only for the capacity and functionality they require. A wide variety of Numatics G3 and 580 series electronic protocols are supported, including Ethernet/IPTM DLR, Profibus DP, and valve sub-bus for distribution.

Field-based DC-control

Nov Dec Products fig UE Online

The company added two DC-voltage switching models to its One Series Safety Transmitter (ST) line. The devices can directly switch 24 VDC and 125 VDC as well as 250 VAC loads. The ST models can now provide SIL 2–certified control for many types of final elements, including pilot valves, actuators, motor controllers, and other SIS elements, without involving a DCS or safety PLC.

One Series safety transmitters reduce cost and improve safety by embedding a process sensor, logic solver, and safety relay in a single, SIL 2–certified field device. Although it looks like a traditional temperature or pressure transmitter, the ST can also switch final elements, such as valves, motors, and blowers directly from the transmitter, maximizing response time while eliminating the wiring needed to route a shutdown or alarm response through a PLC or another safety controller.

To address the growing demand for lower voltage switching of 24 VDC equipment, there is now a safety relay output (SRO) capable of handling 0–30 VDC at 6 amperes. To meet the needs of customers who were using 125 VDC equipment, most of whom are in the power industry, the company added an SRO capable of switching 0–130 VDC at 2.5 amperes.

All of the series safety transmitters have 4–20 mA NAMUR NE 43 standard output. The transmitters are certified for use in SIL 2 safety instrumented systems and are capable of SIL 3, per IEC 61508. They have configurable self-diagnostics and achieve a safe failure fraction of 98.8%. Additional low-level discrete outputs communicate health and set point status. Instrument response time is less than 100 milliseconds.
United Electric Controls