nVent RAYCHEM NGC-20-C-E Guide D'installation, D'utilisation Et De Maintenance page 13

2.3.2.2.2 On an artificial HOT-SPOT
The second way of surface temperature limiting is to create an artificial hot-spot.
In order to guarantee the limiter sensor measures the highest possible temperature of the installation, the temperature sensor of the
limiter shall be installed on an artificial hotspot.
Figure 7: Artificial hot-spot
Important guidelines on sensor positioning and installation:
• The correct position is on top of the pipe. See Figure 7.
• Fix the insulation pad with sufficient glass tape. (GT-66 or GS-54)
• Guide the heater from the bottom of the pipe to the insulation pad and fix it well so that it keeps its position.
• The sensor needs to be attached with sufficient glass tape to the heater. Use two bands of glass tape to ensure its position.
• The lead wire needs to leave the insulation so that no moisture can enter the cladding-insulation system. Fix the lead wire to the
pipe with glass tape if needed to ensure the stability of the hot spot system.
• Make sure that the nominal insulation thickness is respected over the hot spot, it might be necessary to use oversized
insulation shells.
Limiter temperature setting:
• The limiter value (T ) needs to be set at the maximum allowed surface temperature (T
lim
• T = T – 10. Temperatures in Kelvin or Celsius.
lim max
RAYCHEM-OM-INSTALL130-NGC20CLE-ML-2204
) minus 10 K.
max
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