Samson Type 3204 Pneumatic Actuator with Rotary Lever

Samson Type 3204 pneumatic actuator with rotary lever

The Samson Type 3204 is a pneumatic diaphragm actuator with a yoke and a rotary lever, designed to drive butterfly valves, louvers (shutters) and other final control elements with a rotary closure member. It is assembled from a Samson Type 3271 or Type 3277 rolling-diaphragm actuator and a yoke carrying a pivoted lever, so the straight stem movement is turned into a swing of the lever. Seven Star LLC supplies the Type 3204 in Oman and the GCC as an independent supplier in Muscat.

The family has two versions on the same datasheet. The Type 3204-1 is the standard form with fastening for a positioner, solenoid valve and limit switches to IEC 60534 and NAMUR practice. The Type 3204-7 is built for an integral positioner attachment, and its overall height is about 100 mm greater with approximately 2 kg more weight.

Decoding the suffix and the options

• 3204-1: actuator with rotary lever, standard positioner attachment.
• 3204-7: actuator with rotary lever prepared for integral positioner attachment.
• Actuator area: 350 cm² with 15 mm rated travel, or 700 cm² with 30 mm rated travel.
• Direction of action: actuator stem extends (FA) or retracts (FE).
• Diaphragm material: NBR as standard, EPDM as a special material.
• Further version: handwheel on the outer diaphragm case.

Type 3204 technical specifications

How the 3204 lever actuator works

Signal pressure acts on the diaphragm and works against the springs. The number of springs and the compression applied to them set the bench range, in other words the signal pressure that moves the stem across its travel. The position of the actuator stem is passed through a stem connector, linear shaft and adjustable coupling to the lever, which pivots in the yoke. The free end of the lever has three holes for the forkhead pin; the hole chosen sets the balance between thrust and the travel available to the linkage.

The direction of action depends on the spring installation and the position of the signal connection. In the FA version the springs push the stem down and the signal connection is on the bottom diaphragm case; in the FE version the springs push the stem up and the connection is on the top case. The fail-safe action of the actuator follows the same arrangement.

Bench ranges and thrust of Type 3204

The datasheet lists thrust at the lever holes F1, F2 and F3 at 0 % travel and 0 bar for each bench range. Selected values are shown for the normal bench ranges.

The 1.2 to 3.6 bar range is available only with the stem-extends fail-safe action, and the datasheet recommends a positioner for all ranges except 0.2 to 1 bar.

Where the 3204 fits and related Samson parts

The Type 3204 is placed between a conventional linear diaphragm actuator and a quarter-turn valve. It is therefore a different approach from the Samson Type 3278, which is a direct rotary diaphragm actuator. A lever type such as the 3204 offers a low overall height, high thrusts and a fast stroking speed, and it is useful for butterfly valves and louvers where an external linkage is acceptable.

Typical accessories are a pneumatic or electropneumatic positioner, a solenoid valve for emergency shutdown and limit switches. The datasheet directs the buyer to the Type 3271 and Type 3277 actuator datasheet for the detailed actuator specification, and to a separate document for integral positioner attachment on the 3204-7.

Selection checklist for Type 3204

• Determine valve torque and the lever arm needed at the chosen forkhead hole to calculate required thrust.
• Select the 350 or 700 cm² actuator and the bench range that gives enough thrust at the available supply pressure.
• Define the fail-safe direction (FA or FE) and check the signal connection position.
• Choose the 3204-1 or the integral-positioner 3204-7.
• Decide NBR or EPDM diaphragm according to the temperature and the quality of the air.
• Add handwheel if local override is required.
• Specify fastening bracket, forkhead and accessories.

Installation, commissioning and maintenance

Fit the actuator on the valve bracket so that the lever and the valve lever are aligned through the middle of the stroke, then connect them by the forkhead. Set the coupling so that full lever travel matches full valve travel. The datasheet notes that no special tools are required to change the bench range or reverse the direction of action, and the plain-bearing joints are maintenance-free.

Keep the supply air oil-free if EPDM is specified. Replacement diaphragms, stem sealing and a forkhead set are the typical spares. Remember that a pre-compressed spring set holds stored energy, so depressurise and follow the manufacturer procedure before opening a diaphragm case.

Typical applications in Oman and the GCC

Lever actuators of this kind are used on large butterfly valves and dampers in cooling-water systems, flue-gas and ventilation ducts, combustion air, and process-air louvers in power and desalination plants. High ambient temperatures in Oman and the GCC make the EPDM option with a +120 °C limit useful where equipment is near hot ducting. Dust and humidity call for sealed accessory connections and clean instrument air.

Information to send with an RFQ

• 3204-1 or 3204-7, actuator area, quantity
• Valve type, size and required torque
• Supply pressure and signal range
• Fail-safe action and lever hole requirements
• Diaphragm material and ambient temperature
• Positioner, solenoid valve and limit switch details

Documents and quotation

A datasheet for the Samson Type 3204 is attached on this page.

Send us the part number 3204 with the version, actuator area and signal range, and Seven Star LLC will prepare a quotation for supply to Oman and the GCC. We act as an independent supplier, not as a Samson representative.