Actuator, Electric (EVA-1)

DESCRIPTION

The Model EVA-1 is a small, electronically controlled valve actuator developed specifically to fit 1/4…1 in. (6…25 mm) Research Control Valves. Its accurate positioning and compact size make it especially suited to flow control in research and small process
applications. The unit features:

Microprocessor-controlled, linear stepper motor
4…20 mA analog input
Position 4…20 mA analog output (optional)
Choice of 12 speeds
Up to 40 pounds of stem thrust
Accurate and repeatable positioning
Adjustable split range
Quick and simple zero and span input and output adjustments
Adjustable stroke range 0.1875…0.5625 in. (4…14 mm)
User-adjustable direct or reverse action
RS-232 Serial Port for all adjustments without removing
the cover*
Controlled seating force to prevent inner valve damage
Built-in temperature compensation
Stainless steel yoke and rugged epoxy-coated
aluminum housing
115V AC/12V DC, 230V AC/12V DC, and 24V DC
models available

Description

SPECIFICATIONS

OPERATION

The Model EVA-1 consists of a microprocessor-controlled, linear stepper motor that responds to an input signal of 4…20 mA DC. It also has an optional isolated loop powered 4…20 mA position output for signaling back to an indicator or control panel. The standard Model EVA-1 requires a 115V AC power supply with 230V AC and 24V DC models available. A stroke of 0.437 in. (11 mm) for the 1/4 in. (6 mm) unit or a stroke of 0.562 in. (14 mm) for the 1/2…1 in. (12…25 mm) units is standard and can be adjusted quickly and easily with two switches under the actuator cover or via the communication port. This ease of calibration can be used to split the range of the input or limit the up or down travel of the valve. The unit uses a dual-speed operating mode. The low speed mode generates high thrust for seating the valve and overcoming packing friction while the high speed mode allows the valve to respond quickly to large input signal changes.