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DESCRIPTION

The INVALCO Series 596 Valve Actuators were designed specifically for use with butterfly valves, ball valves and other applications where powerful reciprocating motion is required. A wide selection of diaphragm sizes and spring rates provide economic automation and control to valves, dampers, louvers and other applications. All sizes of actuators have the same threaded mounting connection and the same stern threads making one standard mounting arrangement possible. The lower stem bushing is designed to serve as the adjustable travel limit stop providing the best stem thrust support possible.

Specifications

Diaphragm Case	Heavy drawn steel. Cadmium plated steel nuts and and
Diaphragm	Chemical resistant Buna-N with nylon reinforcing molded in for strength and durability. Peroxide cured Buna-N and Viton are available, consult factory.
Diaphragm Plates	Cast iron or steel designed to support, protect and align the diaphragm.
Stem	Stainless steel, polished for minimum friction and wear.
Clevis	The Clevis for mating the actuator stem to the valve shaft is steel, zinc plated for corrosion resistance.
Stem Packing	Cotton fiber reinforced Buna-N
Spring	Tempered steel, precision wound to provide the spring rate desired.
Mounting Connection	Steel, zinc plated for corrosion resistance. Brass and stainless steel bearings guide the stem.

OPERATION

Temperature
-40°F to 250°F
Containment Pressure
110 psi max.
Stem Load
1/2-20 NF, 4000 lbs max.
3/4-16 NF, 9800 lbs max.
Reaction Load, Diaphragm Case
No. 35 and No. 50 - 9000 lbs. max.
No. 80 - 7000 lbs. max.
No. 160 - 9800 lbs. max.
Operating Media
Air, Natural Gas, and Inert Liquids

STEM LOADS

For a fully restrained stem, the stem load is diaphragm pressure times diaphragm effective area, less the then attained spring force. INVALCO does not recommend stem loads which exceed the yield strength of the stem material. Standard stem material is Type 303 stainless with a yield strength of 30,000 psi. The stem load may be limited by the root diameter of the threaded portion or by the reaction force on the lower diaphragm case. (See Operating Limits)

During stem travel, the stem load is the prevailing torque divided by the effective lever length (1.256 in. for INVALCO Mounting Kits), plus 20 lbs. packing drag.

Reaction Load
Reaction load is concentrated at the center of the lower diaphragm case and is equal and opposite to the stem load. See illustration at right. Exceeding the reaction load limit (See Operating Limits) will cause permanent deformation of the lower diaphragm case.

EFFECTIVE AREAS

The effective area of a diaphragm changes during travel as the diaphragm turns upon itself. These areas are shown in the Diaphragm Response Chart to the left. Zero travel is defined at zero diaphragm pressure with the diaphragm at its extreme position toward the diaphragm case into which pressure will be injected.