Endress+Hauser TM402 iTHERM ModuLine Imperial Hygienic RTD

TM402 iTHERM ModuLine imperial hygienic RTD thermometer

The Endress+Hauser TM402 is the imperial-dimension member of the iTHERM ModuLine basic hygienic thermometers. It is a direct-contact Pt100 resistance thermometer with a fixed, non-replaceable insert, built from 316L stainless steel, with probe diameters in fractions of an inch and tri-clamp style connections that match inch-based sanitary tubing. Seven Star LLC supplies the TM402 in Oman and the GCC as an independent supplier in Muscat.

The family logic is simple. A model ending in 2 uses inch dimensions, one ending in 1 uses millimetres, and the "0x" numbering stands for basic technology while "1x" stands for the higher-end design with replaceable insert and hazardous-area approvals. The TM402 therefore replaces thermometers in plants built to US-style hygienic piping, such as dairy, beverage and pharmaceutical lines, and it carries an additional distinction: the manufacturer states that it meets the PMO (Pasteurized Milk Ordinance) requirements for a recording thermometer in dairy applications.

TM402 technical specifications

The figures come from the manufacturer technical information and product page. The head, gland and transmitter chosen determine the limits of the finished assembly.

How TM402 measures and what the ordering options change

A thin-film platinum element sits in the tip of the probe. Its resistance is 100 Ω at 0 °C and rises in a known pattern with temperature, which a head transmitter or the DCS converts to a reading. Because the element sits close to the wall of a thin tip, a reduced tip of 3/16 inch gives the quickest response: 3.5 s to 50 % and 9 s to 90 % of a 10 K step in flowing water, against 5 s and 11 s for a straight 1/4 inch tip.

The main choice for the buyer is therefore about the tip and immersion length. A thinner reduced tip suits fast temperature control and small pipes. A larger 3/8 inch probe is stiffer for longer immersion in a tank with agitation. The TM402 table lists the tip options by probe diameter, and any non-standard length is checked with the supplier.

When a head transmitter is mounted, the iTEMP range offers 4–20 mA, HART and fieldbus options, and the SIL-capable HART 7 transmitter version is limited to –40 to +70 °C ambient at the head.

TM402 process connections and hygiene compliance

The imperial connections are mainly clamp types. Tri-clamp 3/4 inch (form A), 1 to 1.5 inch (DN25 to 38) and 2 inch (DN40 to 51) connections are listed, with a maximum pressure of 16 bar and dependence on the clamp ring and suitable seal; the listed clamp sizes carry the 3-A symbol, and the 2 inch size is shown with EHEDG certification in combination with a Combifit seal. A clamp to ISO 2852 is also listed for 1/2 inch (DN12 to 21.3) pipe. In addition there are Varivent connections (types B, F and N, including versions for VARINLINE housings) with 10 bar rating, and G¾″ and G1″ threads for Liquiphant weld-in adapters, with pressure limits of up to 25 bar at 150 °C and 40 bar at 100 °C for the G¾″ adapter.

The hygiene paragraph in the technical information lists ASME BPE with a certificate of conformance for designated options, 3-A authorisation number 1144 (Sanitary Standard 74-07) for listed connections, EHEDG type EL Class I for certified connections, FDA compliance, and conformity of process-contact parts with the European guidance on animal-derived material. Materials in contact with product also comply with the EU food-contact regulations the document names. The buffed 15 µinch finish is not compliant with ASME BPE, so choose the standard finish when BPE is required.

TM402 selection and ordering checklist

• Metric or imperial: if the plant uses millimetre tubing and fittings the TM401 is the matching model.
• Probe diameter 1/4 inch or 3/8 inch, tip shape and immersion length up to 15.5 inch.
• Process connection: clamp size, Varivent type, or Liquiphant adapter thread, and the seal.
• Surface finish: 30 or 15 µinch, and whether ASME BPE conformity is required.
• Hygiene documents required: 3-A, EHEDG, ASME BPE, FDA and, for dairies, PMO compliance.
• Terminal head material and cable entry thread, plus a head transmitter and output if wanted.
• Calibration or sensor matching service, if the application needs a certificate.

Installing and maintaining the TM402

Place the thermometer so the vessel or pipe drains fully; a leak-detection opening, if there is one, belongs at the lowest point. Make sure the tip reaches into the flow and is not shielded by the vessel wall, because a short immersion causes heat-conduction error. In smaller pipes, an elbow or angled installation gives more immersion length. The counterpieces and seals are usually not supplied with the thermometer.

Cleaning agents named in the technical information for the housing include the P3-topax and P3-topactive products and demineralised water. The thermometer withstands CIP and SIP steam cycles with a jump from +5 to +130 °C in 2 seconds. Calibration covers the insert only; the standard range is –80 to +600 °C on ITS-90, and a head transmitter requires a minimum immersion length at higher temperatures. Because the insert is fixed, a failed sensor means replacement of the whole thermometer, so keep a spare on a critical dairy or pharma line.

TM402 for dairies, beverage and pharma plants in Oman and the GCC

The TM402 is relevant to facilities that follow US-style sanitary standards. In Oman and the Gulf this includes dairies and long-life milk plants, juice and soft-drink bottlers, imported-equipment food lines built to inch dimensions, and pharmaceutical or biotechnology units. The PMO statement is useful when a milk pasteuriser needs a recording thermometer, though local approvals still apply.

Hot ambient temperatures and washdown routines place demands on the terminal head. A 316L head with high ingress protection tolerates frequent hosing, while a polypropylene head suits clean, drier areas. If a process area has a hazardous classification, the basic TM402 is not suitable and the TM412 should be reviewed instead.

TM402 compared with TM401

What to send with your TM402 RFQ

• Full order code or a nameplate photo of the existing thermometer.
• Probe diameter, tip shape and immersion length.
• Process connection type, size and seal.
• Hygiene documents and surface finish required.
• Terminal head, cable entry and head transmitter, if any.
• Quantity, delivery site and calibration needs.

Documents and quotation

A datasheet (Technical Information) for the TM402 is attached on this page, with the dimension drawings, connection tables, response times and hygiene certification details.

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