Watson Smith 100X and 101X Series I/P Converter

An open-loop I/P converter for valve positioners and pressure control

The Watson Smith 100X and 101X series are proportional current-to-pressure (I/P) and voltage-to-pressure (E/P) converters. They turn a 4 to 20 mA, 0 to 60 mA or voltage signal into a regulated air output and are described as reliable, rugged, open-loop devices with minimum vibration effects and IP65 protection. The current literature is issued by Norgren as the 100X and 101X series of proportional pressure control valves; the 100X covers low output ranges and the 101X the higher ones.

Typical duty is feeding a pneumatic valve positioner or actuator from a 4 to 20 mA loop, or electrical control of regulated pressure. The unit is supplied with a mounting bracket and a DIN 43650 form A connector, and its failure mode is that the output falls to the zero signal state when the electrical supply fails.

Technical specifications

Standard models and ordering code

The Norgren sheet lists these standard models, all with 1/4-18 NPT ports: 400100R (3 to 15 psi, 4 to 20 mA), 400700R (3 to 27 psi, 4 to 20 mA), 402100R (0.2 to 1 bar, 4 to 20 mA) and 440100R (3 to 15 psi, 0 to 10 V or 1 to 10 V) for the 100X; and for the 101X 500400R, 502400R (0 to 60 mA), 540400R, 560400R, 562400R (1 to 10 V) and 570400R, 572400R (4 to 20 mA analogue 3 wire) with 2 to 120 psi or 0.14 to 8 bar output.

The option selector builds the code: for the 100X, 4, then the input signal digit (0 for 4 to 20 mA, 4 for voltage), the version 00 and the output pressure pair (01 for 3 to 15 psi, 07 for 3 to 27 psi, 21 for 0.2 to 1 bar), then R. Other options listed are flying leads, conduit entry with flying leads, a junction box, a 50 mm pipe mounting bracket, captured exhaust, reverse acting and split range.

Status, certification and what to confirm

The older 2006 Watson Smith sheet, issued through a UK supplier, mentions intrinsically safe ATEX and FM certified units, but the current Norgren sheet lists no hazardous-area certificate for the standard models. If the converter will go into a classified area, confirm the exact certified model with the manufacturer before ordering. Also confirm the supply pressure (at least 0.7 bar above the maximum output and not above 5 bar), the air quality (dry, oil-free, filtered to 5 microns), the signal type and the output range.

Documents and quotation

The current Norgren datasheet is attached for download. Seven Star LLC is an independent supplier in Muscat. Send the model or order code, quantity and operating conditions and we will request a quotation; availability depends on the model. Related instruments are listed in Pressure Instrumentation.