IMI STI SA/CL Analog Valve Positioner

The IMI STI SA/CL is an analog valve positioner in a pneumatic version and an electro-pneumatic version. It has a heavy-duty metallic design for very harsh conditions and serves as the control element of a pneumatic valve package in oil and gas, refining, chemical, power, metal production and other automated plants.

The pneumatic version (listed as UP-2) accepts a 3-15 psi (0.2-1 bar) signal. The electro-pneumatic version adds an I/P converter on the pneumatic positioner, so a 4-20 mA signal pilots it. Seven Star LLC supplies IMI STI positioners from Muscat; if an inquiry says only model SA, we ask for the nameplate to identify the variant.

How the SA/CL positions a linear actuator

The positioner works on the balanced-forces principle, and air is distributed to the actuator chambers by an internal spool. It is designed for linear actuators with a stroke length of up to 70 mm. It is double acting but can be used single acting if required. Action can be inverted, and action inversion without inverting the valve tubing is listed for the ND 1/4 in. version, and a full stainless steel spool valve is listed for the ND 1/2 in. version.

Other features listed in the brochure are a metallic case, an air purge version, a sandstorm execution, versions for standard or copper-free environments, a split range signal, special characterisation or range, and suitability for large or fast-stroking actuators. Optional accessories include an integrated Air-Lock on ND 1/4 in., a change-over plate with bypass valve, a customised cam, pressure gauges and special construction for corrosive environments. The electro-pneumatic version is available in intrinsically safe and explosion proof forms.

Technical specifications

Choosing the variant and what to confirm

Confirm whether the control signal is pneumatic or 4-20 mA, the actuator stroke (the SA/CL covers strokes up to 70 mm), single or double acting, the air connection size (ND 1/4 in. or ND 1/2 in.), the supply pressure within 2.5 to 7 bar, ambient temperature, hazardous-area approval required for the I/P converter, and whether a bypass, Air-Lock, gauges or special characterisation are needed. A photo of the existing positioner label with the cam and linkage helps for a like-for-like replacement.

Documents and quotation

To request a quotation for the SA/CL positioner, send Seven Star LLC the full model or order code, quantity, and any nameplate data from an existing unit that is being replaced or matched. Our Muscat team checks the request against the manufacturer document, which can be downloaded from this page, and replies with a formal quotation. Prices, stock and lead times are confirmed per inquiry.

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