Description
The THMA is a handheld temperature sensor with a stainless steel handle, manufacturer type Müller MKTS-HA.
It is designed for control measurements in liquids and soft substances: The operator dips the tube into the medium and reads the value – there is no installation point and no screw connection. The handle and protective tube are made of stainless steel 1.4571, and the protective tube measures Ø 6 × 0.5 mm. The tube length is available from 50 to 1000 mm, with the tube end flat, pointed, or optionally heated. The weight is approximately 450 g, and the protection class is at least IP 65 with the connection plugged in.
The same handle can be ordered with very different outputs: the Pt100(0) directly on the connector and thus without power supply, 4 … 20 mA with HART in the 2-wire loop, or digital CANopen, Modbus RTG, and PROFIBUS DP.
The input features a Pt100 or Pt1000 in 2-, 3- or 4-wire configuration in classes A, B, and B 1/2 DIN. The resolution is 16 bit, the accuracy 0.2 K or 0.08 % of the range, the response time 1 s; calibration is performed via 2 or 6 points, set via the HART tool. The HART loop requires 12 … 40 VDC.
Please note before ordering: For a handheld device, two safety-relevant specifications are missing: a permissible handle or hand temperature and a maximum immersion depth are not documented in the manufacturer's data sheet – anyone measuring at +200 °C must determine for themselves how far the tube may be immersed and whether the handle is still touchable. The ambient temperature is not the medium temperature: permissible are -40 … +85 °C ambient and -50 … +200 °C medium. The source does not state which of the two accuracy specifications – 0.2 K or 0.08 % of the range – applies. The fault message is 3.8 mA at the lower end of the usable range of 3.8 … 20.8 mA; a wire break cannot be distinguished from a measurement at the beginning of the range. The heated tip is in the order key, but not in any data line – neither power nor voltage nor control; it must be requested from the manufacturer. Not every connection carries every signal: Two sensors in 3-wire connection only work with M12 eight-pin, AMP MIL, and cable; Super Seal and Deutsch DT04 three-pin do not carry the heating. The source writes Modbus RTG; such a protocol does not exist, Modbus RTU is meant. The data sheet does not mention a system pressure, a protection class in the unplugged state, a CE mark, a declaration of conformity, or explosion protection.
Advantages at a glance
- Handle and protective tube made of stainless steel 1.4571, Ø 6 × 0.5 mm
- Tube length 50 to 1000 mm, tube end flat, pointed or heated
- Pt100 or Pt1000 in 2-, 3- or 4-wire connection
- Classes A, B and B 1/2 DIN, medium -50 … +200 °C
- Resistance directly, 4 … 20 mA with HART or digital
- Accuracy 0.2 K or 0.08 % of the range, response time 1 s
- IP 65 with plugged-in connection, weight approximately 450 g