Description
The TBMD is a sheathed resistance thermometer with GL type approval, manufacturer type Müller WT-MK1G.
It is designed for systems where the sensor must carry a type approval from Germanischer Lloyd: GL TAA00002H5. Compared to the WT-MK1, the nominal length is limited to 200 mm and the connection cable to 6 m, but there is an additional diameter of 1.9 mm, which also fits into narrow boreholes. The sheath remains flexible with a minimum bending radius of 5 × Ø protection tube and reaches installation locations that a rigid protection tube cannot; the cable is fixed, and no connection head is required.
Protection tube 1.4401 (316), specified as a material up to 600 °C, and connection sleeve 1.4571 (316Ti) carry IP 65 up to 250 °C; the nominal length is standard at 100 mm. Connection is made via open ends with wire end ferrules; five cable versions from PVC to glass silk are available. Compression fittings and sheet metal flanges are accessories.
The measuring element is a Pt100 or Pt1000, single or double, insulated in metal oxide and wired in 2-, 3- or 4-wire circuitry. The sensor's operating range extends from -200 to +450 °C, and accuracy can be selected in five steps from Class A to B1/10DIN. The sensor outputs resistance directly; a transmitter is not documented; insulation is tested with 500 VDC.
Note before ordering: The approval is documented as a mark and number, not as a certificate; the certificate should be requested before any assurance is given to the classification society. Both versions bear the product identification KM; they are distinguished solely by the sensor element position: 4 ... 7 is the WT-MK1G, 0 ... 3 is the WT-MK1 - a digit reversal orders the sensor without approval. The operating range is determined by the cable, not the sensor: PVC ends at +70 °C, silicone at +180 °C, PTFE at +205 °C, glass silk at +550 °C - only the glass silk version reaches the sensor's +450 °C. The source does not specify a standard for the accuracy classes. IP 65 does not apply to the version with braided shield. Wall thickness, terminal assignment, process connection, system pressure, weight, response time, CE mark, and explosion protection are not documented. The version without approval, with a nominal length of 2000 mm, is the TBMC (WT-MK1).
Advantages at a glance
- Type approval GL TAA00002H5 documented as a mark and number
- Pt100 or Pt1000, single or double, -200 ... +450 °C
- Circuitry in 2-, 3- or 4-wire, Class A to B1/10DIN
- Four diameters 1.9 · 3 · 4.5 · 6 mm, one more than the TBMC
- Flexible sheath, bending radius min. 5 × Ø protection tube
- Nominal length 100 mm as standard, maximum 200 mm
- Protection tube 1.4401 (316), connection cable maximum 6 m