SAMSON Type 3323 Three-way Mixing/Diverting Valve DN 15-100

SAMSON Type 3323 three-way mixing and diverting valve

The SAMSON Type 3323 is a three-way control valve of the Series V2001 that blends two flows into one or splits one flow into two. It is built for industrial plants in nominal sizes DN 15 to 100, with PN 16 and PN 40 ratings and a temperature range of –10 to +300 °C. Seven Star LLC supplies the Type 3323 in Oman and the GCC as an independent supplier based in Muscat.

Three-way valves replace a pair of two-way valves and a tee in temperature control loops. In a mixing application, hot and cold streams enter ports A and B and leave together through port AB. In a diverting application, the stream enters at AB and is shared out through A and B. The Type 3323 uses a metal-seated plug and a linear characteristic, which gives a predictable blend as the plug moves.

This page describes the DIN version. A separate SAMSON datasheet covers the ANSI version, and explosion-protected electric actuators are available on request.

Type 3323 suffixes and actuator options

• 3323-IP: electropneumatic valve with a Type 3372 actuator and Type 3725 positioner, 4 to 20 mA set point, up to 6 bar supply, fail-safe with stem extending or retracting.
• 3323-PP: pneumatic valve with a Type 3371 actuator, 120 cm² for DN 15 to 100 at 15 mm travel, or 350 cm² for DN 65 to 100.
• 3323-E1: Type 5827-N3 electric actuator, 230 V/50 Hz or 24 V/50 Hz, with optional limit contacts, resistance transmitter or positioner.
• 3323-E3: Type 3374 electric actuator for 230 V or 24 V at 50 or 60 Hz, optionally fail-safe (tested to DIN EN 14597 with the stem extending), with limit contacts, resistance transmitter and positioner.

A limit switch is available on the pneumatic versions. The valve and actuator are shipped separately and assembled on site.

Type 3323 technical specifications

Type 3323 flow coefficients as mixing or diverting valve

For the larger diverting valves the two values show port A and port B, because the seats differ in diameter. A two-way valve of the same series, the Type 3321, handles the straight-through duties.

Principle of operation and fail-safe action

Inside the body two seats face one plug, and the plug moves between them. As the plug leaves one seat it approaches the other, so the sum of the two flows stays almost constant while their ratio changes. That is why a three-way valve gives a stable total flow in a mixing loop.

When supply air or power fails, the actuator moves the plug to one end. With the actuator stem extending, port B is closed in a mixing valve and port A is closed in a diverting valve. With the stem retracting, port A is closed in a mixing valve and port B is closed in a diverting valve. For DN 15 to 25 diverting use, the valve has the same construction as the mixing valve, so port B closes with the stem extending and port A with the stem retracting.

The datasheet adds that the allowable differential pressure is given with identical pressure at ports A and B for mixing and at both outlets for diverting. Mixed streams with very different pressures need a closer check against the Table of differential pressures.

Where Type 3323 sits among related SAMSON valves

The Type 3323 is the three-way partner of the Type 3321 two-way valve in the same series, and the heat-transfer oil Type 3531 and the HVAC Type 3222 come from the same product group. For applications needing a three-way valve in different geometry, SAMSON also builds other valve families, and Seven Star LLC can compare them for you.

A positioner is optional on the pneumatic versions. The Type 3725 comes mounted on 3323-IP, and pneumatic Type 3371 versions can be fitted with other SAMSON positioners where fine positioning is wanted.

Type 3323 selection checklist

• Mixing or diverting duty, and which port carries which stream.
• Nominal size and KVS from the table, with allowance for pressure drop across each seat.
• Pressure rating, body material and flange standard.
• Medium temperature, and whether an insulating section is needed above +220 °C.
• Actuator and supply: IP, PP, E1 or E3, with air pressure or voltage and frequency.
• Failure direction: which port should close if power or air is lost.
• Allowable differential pressure for the chosen actuator, checked against the datasheet table.
• Accessories: limit switch, resistance transmitter, positioner.

Installation and service of the Type 3323

Fit the valve with the port labels A, B and AB matched to the piping drawing. Wrong port connection reverses the action, so check the arrow marks before welding or bolting. Mount the actuator using the crossbeam arrangement for DN 15 to 50, or without crossbeam for larger sizes on pneumatic versions, with the adapters listed in the datasheet for electric actuators.

Mixing valves often see large temperature differences between ports. Allow for thermal expansion in the pipe supports, and use the insulating section where the actuator would otherwise see hot body temperature. Because the plug seals with metal against metal at leakage class I, a small internal leakage is normal and the valve is not a shut-off device. For periodic service, inspect the PTFE packing and check plug and seats for erosion, especially in diverting duty with dirty fluids.

Typical Type 3323 applications in Oman and the GCC

In Gulf plants the main use is temperature control by blending. Typical examples are mixing hot and cold water for process heating loops, controlling lube-oil and seal-oil temperatures on compressors, and blending recirculated and fresh cooling water in power and desalination stations. Diverting service routes a flow either through or around a heat exchanger or cooler, a common arrangement in petrochemical utilities.

Large day-night and summer-winter swings in cooling-water temperature make a good three-way valve valuable here, and the –10 to +300 °C capability together with stainless steel bodies for corrosive service widens the range of fluids.

Information to send with an RFQ for the Type 3323

• Mixing or diverting, and the nominal size and pressure rating.
• Flow rates, inlet pressures at A and B, and medium temperature.
• Body material and flange standard.
• Actuator version, supply voltage or air, and failure direction.
• Accessories needed and the quantity.
• Delivery location.

Documents and quotation

A SAMSON datasheet (T 8113) for the DIN version is attached on this page with materials, flow coefficients, differential pressure tables and dimensions.

Send the duty and port arrangement to Seven Star LLC and we will confirm the correct size and issue a quotation.