Endress+Hauser TMT142B iTEMP HART Field Transmitter

TMT142B iTEMP HART field transmitter with display and Bluetooth

The Endress+Hauser TMT142B is a field-mounted temperature transmitter with one universal sensor input, a 4–20 mA output with HART 7 communication and an optional Bluetooth interface for use with the manufacturer SmartBlue app. The electronics sit in a single-compartment flameproof housing of die-cast aluminium or 316L stainless steel, with a backlit LCD that shows the process value, a bar graph and diagnostic status. Seven Star LLC supplies the TMT142B in Oman and the GCC as an independent supplier in Muscat.

It is the sibling that is mounted in the field rather than inside a thermometer head: the sensor wires come to its terminals, and the transmitter either sits directly on a sensor assembly or is mounted remotely on a pipe. Compared with the TMT182B head transmitter, the TMT142B adds a robust housing, a local display, an optional surge arrester module and wireless access.

TMT142B technical specifications

The data is from the manufacturer technical information; the product literature lists CSA and ATEX approval families (including intrinsically safe, flameproof and dust ignition-proof protection), but the approval that applies is the one printed on the certificate of the specific ordered version.

How the TMT142B works in the loop

The universal input handles RTDs in 2-, 3- and 4-wire connection, thermocouples, resistance transmitters up to 2,000 Ω and millivolt signals from –20 to 100 mV. The measured value is linearised, filtered and converted to a current, while the HART signal is superimposed for digital data. The HART device variables are the primary value, the device temperature and the sensor value, and the device registers as HART specification 7 (manufacturer ID 17, device type 0x11D1).

Alarm behaviour follows NAMUR NE 43, and the high-alarm level can be set between 21.5 and 23 mA to suit different control systems. A low-voltage detection function drops the output below 3.6 mA for about 5 s when the supply sags, then retries. A corrosion detection function per NAMUR NE 89 monitors thermocouples, mV signals and 4-wire resistance thermometers so a rising wire resistance can raise a warning before the value is corrupted. A sensor-load log records how long the sensor works in each temperature band, which helps judge ageing, and diagnostics can be simulated to confirm how the control system reacts.

TMT142B Bluetooth and local operation

The housing has no operating buttons on the display, a deliberate design to avoid tampering. Settings are made over HART, with the SmartBlue app over Bluetooth, or with a DIP switch on the electronics module that activates hardware write protection or switches the Bluetooth function off. Bluetooth communication is encrypted and password protected, and the interface can be deactivated for sites with a wireless policy.

The LCD is backlit, can be rotated in 90-degree steps, and shows the unit (K, °F, °C or %), a 20.5 mm high measured value, a bar graph and status symbols. Below –20 °C the display responds more slowly, and readability is not guaranteed below –30 °C, which is not a concern in Gulf sites but matters if a unit is shipped to a cold store.

TMT142B accessories, surge protection and related parts

Common accessories are blind plugs and cable glands (M20x1.5 or ½″ NPT), a cable gland adapter, a 316L pipe mounting bracket for 2″ pipe, and an optional overvoltage module that diverts surges from the signal and supply lines to ground. The surge module is rated for lightning surge current of 1 kA per wire and 5 kA nominal discharge per wire, and it adds 1.8 Ω series resistance per wire; it must be ordered with the unit.

On the system side the data sheet names the RN series active barrier and a HART modem or Commubox with FieldCare or DeviceCare for configuration. Related transmitters are the TMT182B (HART head transmitter), the TMT31 (analog head or DIN rail) and the TMT85 (FOUNDATION Fieldbus). The wireless SWA70 adapter can add WirelessHART access to an installed unit.

TMT142B ordering and selection checklist

• Housing material: die-cast aluminium for general use or 316L stainless steel for corrosive or offshore atmospheres.
• Cable entry thread: ½″ NPT, M20 or G½″, and whether Ex d plugs and glands are needed.
• Hazardous-area approval and the zone, gas group and temperature class of the site.
• Display window or blind cover, and whether Bluetooth is required.
• Surge arrester module yes or no.
• Sensor type, wiring and measuring range, and the required alarm level.
• Mounting: direct on the sensor assembly or remote on a pipe or wall.
• HART tools available on site: handheld, modem or SmartBlue.

Installing and commissioning the TMT142B

Connect the equipment to potential equalisation using the external ground clamp with at least 4 mm² cross-section, and use a shielded sensor cable earthed at both ends when the cable run is 30 m or longer. Terminals accept up to 2.5 mm² with a ferrule. Seal unused cable entries with the correct plugs, which for flameproof versions must be Ex d certified. Check that the load resistance on the loop meets the HART minimum of 250 Ω and does not exceed the maximum for the supply voltage.

Commission by configuring the sensor type, range, damping and alarm values with the SmartBlue app or HART tool, then simulate 4, 12 and 20 mA and check the DCS reading. Take care with the vibration limits: the use of L-shaped mounting brackets can create resonance, so a 2″ pipe bracket must be installed as described in the manufacturer notes. Keep the nameplate data with the loop dossier for spares planning.

TMT142B applications in Oman and GCC facilities

A field transmitter with its own display is useful where operators walk the plant and want to read a value at the measuring point without a handheld. Typical uses are crude and condensate heater outlets, compressor discharge lines, lube-oil coolers, desalination brine heaters and boiler or turbine auxiliary systems, along with petrochemical process skids.

The IP66/67 housing is a sensible match for dust, salt spray and washdown, and the stainless steel version is the better choice near the coast. In direct sun, the housing can run well above air temperature, so position the display away from the hottest pipework and consider a shade. Remember that the display is rated to 80 °C, which is lower than the 85 °C of the display-less unit.

TMT142B compared with other HART iTEMP units

What to send with your TMT142B RFQ

• Complete order code or a nameplate photo.
• Housing, cable entry thread and window or blind cover.
• Approval and hazardous-area classification.
• Sensor type and measuring range, plus pre-configuration needs.
• Quantity, delivery site and whether a surge module or mounting bracket is wanted.

Documents and quotation

A datasheet (Technical Information) for the TMT142B is attached on this page, with the input ranges, accuracy data, electrical connection, housing drawings and accessory list.

To obtain a quotation, send the order code or the points above and Seven Star LLC will confirm availability and lead time in Oman and the GCC.