AUMA SAR 14.2 Modulating Multi-Turn Actuator

Overview

AUMA SAR 14.2 is an AUMA NORM multi-turn actuator for modulating duty (class C, ISO 22153) with a tripping-torque window of 120 to 250 Nm and 10 output speeds from 4 to 90 rpm. SAR 14.2 is the first modulating AUMA actuator on the F14 flange, with a 120 to 250 Nm tripping-torque window and a 58 mm stem bore. It serves control valves that are too large for the SAR 10.2.

Customers in Oman and the GCC buy the SAR 14.2 from Seven Star LLC, a trusted supplier of AUMA products, which checks the valve data with them before the order is placed.

Operating Principle

Short pulses from an AM or AC positioner move the SAR 14.2, and self-locking holds the position. The modulating torque of 120 Nm (S4 – 25 percent) is reduced to 100 Nm at the highest speeds, and pulses must last at least 70 ms.

Engineering Design of the AUMA SAR 14.2

Modulating torque is 120 Nm (S4-25 percent) and 90 Nm (S4-50 percent) at the lower speeds and 100 Nm and 70 Nm at the highest speeds. Starts per hour fall from 1,200 to 400 as the speed rises, so for loop-controlled positioning a mid-range speed is usually best.

Key Features

Specifying the SAR 14.2 comes down to these points:

• Modulating F14 multi-turn actuator for medium-size control valves.
• Tripping torque is adjustable in each direction from 120 Nm to 250 Nm (ratio 2.1 : 1).
• The permitted torque falls to 180 Nm for S4 – 50 percent duty, 72 percent of the 250 Nm maximum.
• With 44 to 48 kg of weight, it delivers 5.2 to 5.7 Nm per kilogram at maximum torque.
• An illustrative stroke of 25 turns takes about 68.2 seconds at 22 rpm.
• Step down to the SAR 10.2 for lighter valves or up to the SAR 14.6 for heavier ones.
• AUMA keeps dimensional and electrical details in separate sheets rather than in the technical data.

Selecting the AUMA SAR 14.2

The AUMA SAR 14.2 can be confused with the older SAR 14.1 because both occupy the same torque band, but the current data sheet is a different generation: the sizes are labelled .2, the speed list extends from 4 to 90 rpm, the starts per hour are 1,200 down to 400 depending on speed, and pulse durations of 70 ms minimum and 80 to 280 ms on reversal are stated. Weight is quoted at 44 to 48 kg and the handwheel is 315 mm. Specify by the .2 designation when ordering a current actuator.

Typical partners are medium-size globe control valves, modulating gate valves, and rising-stem control valves for water, condensate and cooling circuits in industrial plants.

Replacing an existing actuator with the AUMA SAR 14.2 on a SAR 14.1 position is a frequent request in Oman, where many plants have valves automated years ago. Both sizes use the F14 flange, but the stem capacity is 57 mm on the older SAR 14.1 and 58 mm on the AUMA SAR 14.2, and the new generation should be commissioned with its own data sheet because the pulse durations, the starts per hour and the weights differ. The wiring diagram of the new unit should be requested using its own order number rather than reusing the old drawing. After mounting, perform a slow full stroke and then a series of small steps in both directions; this reveals backlash in the stem nut and in the valve linkage, which the positioner dead band must be set to cover so that the loop does not hunt.

Sizing example for the AUMA SAR 14.2

Take an illustrative control valve with 105 Nm running torque and 190 Nm seat torque. The running torque is below the 120 Nm modulating limit (S4-25 percent) at the lower speeds, and the seat torque is within the 120 to 250 Nm window of the AUMA SAR 14.2. At the highest speeds the modulating limit drops to 100 Nm, which would be exceeded, so a moderate speed such as 16 or 22 rpm is chosen. A 30-turn stroke at 22 rpm takes about 82 seconds. These numbers are an illustrative calculation and not AUMA data.

Installation and Mounting of the AUMA SAR 14.2

With 44 to 48 kg the AUMA SAR 14.2 needs a hoist when lifted above shoulder height. The F14 flange and 58 mm stem bore are common, and the 315 mm handwheel needs swing clearance. When replacing an older SAR 14.1, compare the flange and stem dimensions before ordering, and remember that the starts-per-hour limit of 1,200 falls to 400 at the highest speeds, so loop tuning should avoid excessive hunting.

Industrial Applications

Examples are cooling-water flow control at gas-processing facilities, process-water pressure control at fertiliser and petrochemical plants, and bypass control at independent power producers. In Salalah and Sohar the AUMA SAR 14.2 can replace legacy modulating actuators on F14 control valves without changing the valve flange.

Seven Star LLC, a trusted supplier of AUMA products for Oman and the GCC, can combine the SAR 14.2 with the AUMA SAR 14.1 multi-turn actuator, the AUMA MATIC AM/AC integral actuator controls and the AUMA SAREx explosion-proof modulating actuator.

Neighbouring sizes and counterparts: AUMA SAR 10.2 modulating actuator, AUMA SAR 14.6 modulating actuator and AUMA SA 14.2 multi-turn actuator.

Technical Specifications

Data of the AUMA SAR 14.2 from the AUMA technical data sheet for 3-phase AC motors.

Setpoint guide for the SAR 14.2 (illustrative calculation, not AUMA data)

Stroking time for 25 turns at the SAR 14.2 (illustrative calculation, not AUMA data)

Request a Quote for AUMA SAR 14.2

The AUMA datasheet is downloadable here.