Multipass Monitor (extractive trace measurements)

The Multipass Monitor combines a long measurement path length with a compact analyser design. The long path will enhance the detection limits considerably. Thus, the MP is the analyser of choice for measurement of trace levels of gases, offline in a controlled environment.

The monitor consists of the same modules (transmitter, receiver) as the other LaserGas analysers but includes the additional Multipass cell. The laser beam is coupled into the measurement cell, a so-called Herriott cell, where it is reflected multiple times between two spherical mirrors. Subsequently a detector collects the transmitted light for further analysis and calculation of the gas concentration.

The standard Multipass cell is made of stainless steel. Special (e.g. heatable) versions of this cell are available on request.

The LaserGas II MP monitor is a turn-key instrument. Connecting sample gas tubes and optional purge is all that is required during installation. To avoid fouling of optical parts inside the Multipass cell the cleanliness of the sample gas must be ensured. Appropriate sampling systems to remove condensates or dust may be necessary for some applications.

Measurement readings are provided through standard 4-20 mA current loops, or as options the fibre-optic output and the Ethernet interface. The latter enables instrument communication via local area networks or the Internet.

The LaserGas II MP is available as Cabinet and 19" Rack version. As option heated cell solutions can be provided.

Based on the well-proven tuneable diode laser (TDLAS) technology the instrument has a number of unique features.

Features

• Very low detection limits (ppb for most gases)
• Offline gas analysis in controlled environment
• Turn-key instrument
• Low cost of ownership
• Approved for ATEX zone 2 (EEx n)
• Approved for CSA Class 1 Div 2 (non incendive)

Table of Principal Gases

Gas	Detection limit
O2	3 ppm
H2O	10 ppb
H2S	0.3 ppm
CH4	20 ppb
CO	50 ppb
CO2	50 ppb
NO	1.5 ppm
N2O	0.5 ppm
NH3	20 ppb
HCl	5 ppb
HF	2 ppb