The gas analyzer LDS 6 consists of a central unit and up to three in-situ sensors. The connection between the central unit and the sensors is established by a so-called hybrid cable, which contains optical fibers and copper wires. An additional cable connects the transmitter and receiver parts of the cross-duct sensor.

Central unit

The central unit is housed in a 19" rack unit housing with 4 fixing points for mounting

• in a hinged frame
• in racks with or without telescopic rails

Display and operator panel

• Large LCD field for simultaneous display of measurement result and device status
• Contrast of the LCD field is adjustable via the menu
• LED background illumination of the display with energy-saving function
• Easy-to-clean membrane touch pad with softkeys
• Menu-driven operation for parameterization and diagnostics
• Operation support in plain text

Inputs and outputs

• One to three measurement channels with hybrid connections for the sensors at the measuring points
• 2 analog inputs per channel for process gas temperature and pressure
• 2 analog outputs per channel for gas concentration(s). For selected versions, the transmission can be read out as an alternative.
• 6 freely configurable digital inputs per channel for signaling faults or maintenance requests from external temperature or pressure transducers or sensor purging failure.
• 6 freely configurable digital outputs per channel (signaling of fault, maintenance requirements, function control, transmission limit alarm, concentration limit alarm, store analog output)

Communication

Network connection: Ethernet (T-Base-10) for remote diagnostics and maintenance.

LDS 6 central unit, membrane keyboard and graphic display

Cross-duct sensors

Sensor CD 6, transmitter or detector unit

• In-situ cross-duct sensors, configured as transmitter and detector unit, connected via sensor cable
• Connection to the LDS 6 central unit via a so-called hybrid cable of max. 700 m length (total hybrid and sensor connecting cable length: max. 250 m in Ex Zone 0 and Ex Zone 1)
• Stainless steel, some painted aluminum
• IP65 degree of protection for sensor
• Adjustable flanges with flange connection
• DN 65/PN 6, ANSI 4"/150 lbs
• Optional flameproof window flanges with dimensions: DN 65/PN 6, DN 80/PN 16, ANSI 4"/150 lbs, other process interfaces available on request
• Purging facilities on the process and the sensor sides, configurable application with purging gas connections for:
  • Instrument air
  • Purging air blower
  • Steam
  • Nitrogen
  • Process gases to which the pressure equipment directive cat. 2 does not apply
• In combination with high-pressure window flanges, purging can be performed at the process end with instrument air or nitrogen
• Quick release fasteners for cleaning the measurement openings and the sensor window
• Optional: Version with explosion protection in accordance with ATEX / IEC Ex ia
• Sensor type CD 6 is compliant with the pressure equipment directive

Parts in contact with the process gas

The sensors normally do not come into contact with the process gas, since purging with a gaseous media is applied at the process side. Stainless steel purging gas tubes in front of the sensor windows are immersed slightly into the process gas and thus limit the purging volume. Special materials such as Hastelloy and plastics (PP) are available on request.

Hybrid and sensor cables

A combination of fiber-optic cables and twisted copper wires connects the sensors to the central unit. The hybrid cable connects the central unit with the detector unit of the sensor, the sensor cable connects the transmitter and receiver units of the sensor.

For installation in Ex-protected environments, the legislative regulations have to be complied with, such as the spatial separation of intrinsically-safe from non-intrinsically-safe cables.

In compliance with standard EN IEC 60079-14, systems with intrinsically-safe circuits must be installed such that their intrinsic safety is not impaired by electric or magnetic fields. Therefore the hybrid and sensor cables of the LDS 6 in an Ex application must be routed in such a way that they cannot generate electric or magnetic fields, e.g. by coiling them in more than one cable loop. To guarantee a good signal quality and to avoid impermissible inductance loops, the hybrid and sensor cables should be kept as short as possible.

• The distance between central unit and measuring point can be
  • up to 250 m for Ex units when used in Zone 0 and Zone 1 (total hybrid and sensor connecting cable length)
  • up to 700 m for Ex units used in Zone 2 and for non-Ex units
• Hybrid and sensor cables
  • Multimode fiber-optic cable, provided with SMA connections for transmission of the measured signal
  • Two-wire copper cable, in twisted pair version, for +24 V supply of the detector electronics (+12 V in the case of Ex-suitable instruments)
• Additionally for the hybrid cable:
  • Single-mode fiber-optic cable, configured double-sided with E2000 connectors for transmission of laser light
• Rugged cable sheath for laying in open cable ducts or ductworks
• Sheath material: oil-resistant polyurethane

Connections of the hybrid cable