Trace Heated Sample Line; Enclosure Cooling - Michell Instruments PROMET EExd Installation, Operation & Maintenance Manual

PROMET EExd Process Moisture Analyzer Sampling Systems
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4.2

Trace Heated Sample Line

As an option a trace heated sample line can be supplied with sampling systems to
ensure the sample gas temperature from the process take-off point to the analyzer is
maintained at a constant temperature of at least 10 o C above the highest envisaged
dew point temperature independent of surrounding temperature variations.
The trace heated sample line consists of 6mm OD 316L stainless steel seamless tube
and BSX™ self-regulating heating cable with non-hygroscopic glass fibre insulation and
polymer outer jacket.
The self-regulating heat output of BSX™ cable varies in response to the surrounding
conditions along the entire length of a circuit. Whenever the heat loss increases (as
ambient temperature drops), the heat output of the cable increases. Conversely when
the heat loss decreases (as ambient temperature rises), the cable reacts by reducing its
heat output. BSX™ cables are approved/certified for use in zone 1 & 2 (category 2 & 3)
classified areas.
The trace heated sample line is connected directly onto the Gas Inlet Isolation Valve
(via bulkhead entry seal gland when fitted to an enclosure) within the sampling systems
and the heating cable is terminated onto terminals within the „POWER CIRCUITS‟
junction box. Cable entry into the junction box is provided through an M25 EExe plastic
cable gland.
1 Channel version terminals are marked:
2 Channel version terminals are marked: 2 & 3 Live (either conductor – no polarity)
4.3

Enclosure Cooling

As an option an enclosure cooling kit can be fitted to the stainless steel enclosure. The
cooling device is a Vortex tube driven by instrument grade (liquid and particulate free)
compressed air. An adjustable preset thermostat controls a solenoid valve permitting
the flow of compressed air through the vortex tube. A manifold (clear plastic pipe)
positioned around the internal walls of the enclosure distributes the cooling air
throughout.
The cooling thermostat operates when the internal temperature within the enclosure
rises above 40°C and falls below 30°C – switches on and off respectively.
Operation of the enclosure cooling system is fully automatic once a compressed air and
mains power supply are provided then no further adjustment is required.
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Installation, Operation & Maintenance Manual and User Guide
2 Live (either conductor – no polarity)
5 Neutral (either conductor– no polarity)
E Earth (green/yellow conductor)
6 & 7 Neutral (either conductor– no polarity)
E Earth (green/yellow conductor)
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