Flowserve Automax SXL Stainless Steel Pneumatic Actuator

Automax SXL stainless steel rack-and-pinion actuator: what the SXL designation means

The SXL is the stainless steel pneumatic rack-and-pinion quarter-turn actuator in the Flowserve Automax range. It combines a 316 stainless steel body and end caps with a double-piston rack-and-pinion drive, and it is meant for butterfly, ball and plug valves in corrosive surroundings. Seven Star LLC supplies SXL actuators in Oman and the GCC as an independent supplier in Muscat. The SXL is a family of seven sizes, and the action, spring set, seal and options are fixed in the model code.

In the maker’s ordering scheme the letters tell you the build: SX is the stainless SuperNova series, L is the ISO 5211 square pinion, then the three-digit number gives the size (050 to 150). A letter for the action follows (D for double acting, S for spring return fail clockwise, C for spring return fail counterclockwise), and then the number of springs. The maker’s own example is SXL100S10, meaning a size 100 spring-return fail-clockwise actuator with spring set 10.

SXL technical specifications

How the SXL works

Compressed air acts on two opposed pistons whose racks drive a single pinion. In a double-acting unit, air to one port pushes the pistons outward and turns the pinion counterclockwise, while air to the other port pushes them inward and turns it clockwise. In the spring-return versions, air drives the pistons against the springs and the stored spring force returns the valve when air is exhausted, so the valve moves to its fail position on loss of supply. Reversing the fail direction in the field only needs the pistons turned 180 degrees. Because the same body serves both actions, springs can be added or removed to convert the unit.

SXL double-acting torque, weight and mounting by size

The maker’s product specification gives double-acting output in in-lb at five air pressures. Spring-return torque at start and end of stroke depends on the number of springs, from 4 to 12 depending on size, and is read from the spring charts for each model.

Torque values are in-lb. Cycle times with no load are given by the maker as 0.5 to 2 seconds depending on size and direction. Air consumption and volumes per stroke are listed for each size, and a stainless steel air purge module is available for spring-return units.

Selection and ordering checklist for the SXL

• Valve torque at operating differential pressure, with safety factor, in in-lb or N·m.
• Double acting or spring return, and the fail direction (clockwise or counterclockwise).
• Available air supply pressure at the actuator, to select the spring set.
• ISO flange size and drive square of the valve.
• Seal material for ambient and process temperature (Viton or low-temperature).
• Whether stainless steel pistons or springs are required for internal corrosion resistance.
• Finish: standard, K-mass coated or polished.
• Accessories: solenoid valve, limit switch box, positioner, manual override, air purge module.

Installation, commissioning and maintenance of the SXL

Mount the actuator on the valve with the ISO pad using studs, because the maker does not recommend bolts for mounting. Set the open and closed positions with the adjustable travel stops, then stroke the valve several times and look at cycle time. NAMUR holes make direct mounting of solenoids and switch boxes possible without tubing. For service, the maker recommends keeping seal-kit parts on hand: the pinion O-rings, piston and end cap O-rings, pinion bearings and thrust washers are the typical wear items. The standard lubricant for normal service is a polymer-fortified multi-purpose grease, while low or high temperature units use an O-ring lubricant specified by the maker.

Typical SXL applications in Oman and the GCC

The stainless body is the point of the SXL: salt-laden coastal air, washdown and chemical splash attack aluminum actuators. In Oman and the GCC, that suits seawater intake and brine valves in desalination plants, chemical dosing skids, offshore and marine installations, and food and beverage or pharmaceutical lines where a polished finish is requested. The maker lists chemical processing, pulp and paper, marine and offshore, food and beverage and nuclear service for the stainless series. For high ambient heat, remember that the standard Viton seals are rated to 149 °C but the air supply should still be dry and clean.

SXL compared with other Automax rack-and-pinion actuators

Standard SuperNova aluminum actuators cover 25 to 58,000 in-lb, with a hard-anodized body and optional PTFE-impregnated MaxGuard coating for chemicals and coastal sites. The SXL stays in the smaller range to 7,279 in-lb, so for larger torque the Automax RG scotch-yoke series applies. Choose the SXL when the whole body must be stainless, not just coated.

Information to send with an RFQ for the SXL

• Valve type, size, and torque requirement including safety factor.
• Single or spring return, fail direction, and air supply pressure.
• ISO flange and drive dimensions.
• Ambient and process temperature range.
• Required accessories and finish.
• Quantity and delivery location in Oman or the GCC.

Documents and quotation

The maker’s product specification for the SX series, with torque tables, dimensions, materials and the ordering code, is attached on this page. Use it to shortlist a size, then confirm the full model code with us.

Send the SXL size, action and air pressure to Seven Star LLC and we will prepare a quotation for Oman and the GCC.