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Messtechnik Regeltechnik Reckmann
Mess- und Regeltechnik
Mess und Regeltechnik
Installation and Operating Instructions

With regard to all installation/attachment options mentioned on the Installations page, Reckmann GmbH recommends to ensure that the connections with the process are tight, firm and securely in accordance with the recognized rules of technology and the regulations applicable at a given time.

Furthermore, you should take note of the following information:

  • The lifetime of thermocouples can be extended in many operating circumstances by fitting an additional ceramic inner tube to the thermocouple assembly.
  • To avoid deflection in the case of longer metal protection tubes (particularly at temperatures above 500 °C), the latter should preferably be fitted vertically; if the fitting position is horizontal, corresponding supports should be provided.
  • Ceramic protection tubes must not be subjected to a mechanical load (e.g. bending or impact effect) or to a rapid change in temperature (temperature shock). To avoid cracks, ceramic protection tubes that, for example, need to be inserted into a hot furnace should only be inserted very slowly or in pre-heated mode, avoiding direct contact with the flames. According to DIN 43 724, no visible damage should occur to the ceramic protection tubes if, depending on the outer diameter, they are inserted into a furnace that has been heated to the permissible constant temperature of the protection tube (depending on the material, 1,500°C or 1,600°C) with the following insertion speeds: if D = 10 mm, 100 cm / min; if D = 15 mm, 50 cm / min and if D = 24 and 26 mm, 1 cm / min. Reckmann GmbH recommends (particularly with D = 10 and 15 mm) that the protection tube be inserted much more slowly into the hot process and also removed again in the same way. In addition, if operating temperatures are above 1200°C, ceramic protection tubes should only be fitted vertically.
  • Standard aluminium/plastic connection heads are equipped with rubber seals and suitable for ambient temperatures up to 80°C. Aluminium heads can, on request, also be supplied with silicon seals, which can be used at up to around 130°C. The permissible ambient temperature is reduced to around 80°C if a measurement transducer / transmitter is fitted on the connection head.
  • To keep measurement error caused by heat dissipation (e.g. via the protection tube or the sheath tube) negligibly small, the tip of the temperature sensors should be immersed as deeply as possible into the medium to be measured. For thermocouple assemblies and standardized resistance thermometers, the immersion depth in fluids should be at least 6 times the diameter of the protection tube, while with air and gas it should be at least ten times that. In the case of sheathed thermocouple assemblies and sheathed resistance thermometers, the minimum fluid immersion depth is 5 times the sheath tube diameter or 20 times the sheath tube diameter in air/gas, with the immersion depths having to be increased for sheathed resistance thermometers by the temperature–sensitive lengths each time (usually around 35 to 40mm). If tube cables with small diameters do not allow sufficient immersion depth in vertical installation, the temperature sensors should be fitted diagonally or in a tube elbow against the direction of flow.
  • The connection between the (sheathed) thermocouple assembly and the measuring equipment or the external reference junction may only be established using a compensating or extension cable matching the thermocouple (see the page about compensating and extension cables). You must ensure that the cables are connected in the correct polarity.
  • Resistance thermometers allow standard copper cables to be used to connect to the measuring equipment. The number of wires depends on the configuration of the resistance detector (single or dual) and the circuit technology. Where possible, copper cables having a cross-section of 1.5mm2 should be used.
  • When fitting sheathed resistance thermometers and similar configurations, you must ensure that there is no bend in the sheathed cable at a range of around 50mm behind the rigid metal tube welded to the sheathed cable (see Figure 6, parts i and k on the "Configuration of Resistance Thermometers" page. It is advisable, however, to enlarge this unbent area, if possible.

You can bend the remaining sheathed cable without impairing the technical properties (this also applies to sheathed thermocouple elements), as long as the bend radius is greater than 5 times the outer diameter of the sheathed cable.


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