Watson Smith Type 140 Failsafe I/P Converter, Explosion Proof and I.S.

A fail-safe electronic I/P converter built for explosive atmospheres

The Watson Smith Type 140 failsafe series is an electronic current-to-pressure (I/P) converter with closed-loop control for accurate, high-resolution pressure control in the field. It is offered in explosion proof (flameproof) and intrinsically safe versions and is weatherproof to IP66 and NEMA Type 4X. In the fail-safe mode the output pressure falls below 15 mbar within two seconds when the 4 to 20 mA signal fails, and the tight shut-off point can be set independently up to 4.5 mA.

Maintenance features are a modular electronics assembly, a field replaceable built-in filter and a jack socket for on-site monitoring. The body is aluminium and zinc die-cast with NBR diaphragms and black epoxy powder coating, and the unit weighs 2.07 kg with an integral bracket for flat-surface or 2 inch (50 mm) pipe mounting in any orientation.

Technical specifications

Models, certification and options

Standard models listed by Norgren are EX14001BJ4LE2 (G1/4, 0.2 to 1 bar, M20 conduit, Cenelec only), EX14001PJ4LE2 (G1/4, 3 to 15 psi), EX14001BK4EE1 (1/4 NPT, 0.2 to 1 bar, 1/2 NPT conduit, triple certification) and EX14001PK4EE1 (1/4 NPT, 3 to 15 psi). The option selector EX140 builds the code from output range (01 for 0.2 to 1 bar, 02 for 0.4 to 2 bar), pressure unit, certification (E1 triple agency, E2 Cenelec only), conduit entry and port type. A 2 inch pipe mounting kit ZZ0150 and an output pressure monitoring gauge are options.

The certification table shows Sira ATEX approvals for flameproof (Ex d IIC T4 Gb and Ex d IIB+H2 T5 and T6 Gb) and intrinsically safe (Sira 01ATEX2007X, Ex ia IIC T4 Ga, Ui 30 V, Ii 110 mA, Pi 0.84 W, Ci 6 nF, Li 100 microhenry) versions, with Factory Mutual and CSA classes as printed in the datasheet. Check which approvals apply to the code you order.

Selection and installation

The converter needs oil-free dry media filtered to 50 micron (an internal filter is built in) at a supply pressure of 1.2 to 10.3 bar. Response is under one second into a 0.5 litre load, and vibration changes output by less than 3 percent at 4 mm and 2 g. Conduit connections are 1/2 NPT or M20, with an internal terminal block for conductors up to 2.5 square millimetres. Confirm the required output range, port thread, conduit, certification marking and ambient temperature before ordering.

How the Watson Smith Type 140 works

The converter takes a 4 to 20 mA signal and turns it into an air pressure. A sensor inside reads the output and a control loop corrects it until it matches the signal. If the signal is lost, the output falls to nearly zero within two seconds, so the valve goes to its safe position.

Where the Type 140 is used

• Control valves in hazardous areas
• Pneumatic actuators needing a safe position
• Emergency shutdown valves
• Process plants and refineries
• Offshore platforms

Selection checklist for the Type 140

• Explosion proof or intrinsically safe version
• Output range, 0.2 to 1 bar or 0.2 to 2 bar
• Port thread, G1/4 or 1/4 NPT
• Conduit thread
• Supply pressure
• Flow capacity
• Fail-safe shut-off point
• Mounting type

Installation, commissioning and maintenance notes for the Type 140

Fix the bracket to a flat surface or a 2 inch pipe. Connect clean, dry air filtered to 50 micron. Wire the two-wire loop to the terminal block. Set the zero and the span, and set the shut-off point if needed. Replace the built-in filter when it is dirty.

Requesting a quotation for the Watson Smith Type 140

Please send the model, the output range, the threads and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

Type 140 output pressure

The output is 0.2 to 1 bar, or 0.2 to 2 bar as an option.

Type 140 supply pressure

The supply is 1.2 to 10.3 bar of air filtered to 50 micron.

Type 140 flow capacity

The flow is up to 300 Nl/min.

Type 140 linearity

The linearity is typically below 0.1 percent.

Type 140 response time

The response time is below 1 s.

Type 140 temperature range

The range is minus 40 to plus 85 degrees C.

Type 140 protection

The housing is rated IP66 and NEMA Type 4X.

Type 140 input signal

The input is 4 to 20 mA on two wires, with an overload of 100 mA.

Type 140 weight

The converter weighs 2.07 kg with its bracket.

Converter records for the Type 140

Record the model, the calibration values and the date of each filter change.

Choosing the right Type 140 shut-off

Set the shut-off point so that the valve closes tightly when the signal falls below it.

Type 140 port threads

The main and gauge ports are G1/4 or 1/4 NPT, and the exhaust is 1/8 NPT.

Type 140 conduit entry

The conduit entry is 1/2 NPT or M20.

Type 140 body material

The body is aluminium and zinc die-cast with a black epoxy coat.

Type 140 air consumption

The air consumption is below 2.5 Nl/min.

Documents and quotation

The Norgren datasheet is attached. 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 items: Pressure Instrumentation.