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Instrument Database:
Mercury Instruments GmbH - Mercury Vapor Monitor VM 3000
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| Year of introduction |
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| Status |
available |
| Company |
Mercury Instruments GmbH
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| Categories |
Dedicated Analyzer: Mercury
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VM-3000 Detection of mercury in air and other gases
VM-3000 Mercury Vapor Monitor
FEATURES - Continuous operation
- Proven reliable detection method: UV absorption
- Easy operation
- Auto zero
- Measuring ranges 0.1-100 / 0-1000 / 0-2000 µg/m3
- Heated optical cell
- Integrated data logger (option), records up to 100 days of measuring
- Integrated battery for mobile use (optional)
- Can be converted into a LabAnalyzer Combination Model for liquid samples and sample digests.
Applications
The VM-3000 Mercury Vapor Monitor serves for continuous measurement of the mercury concentration in gases in laboratory as well as industry and mobile applications. It has a wide variety of applications, such as work place monitoring (threshold limit value), exhaust air monitoring in mercury recovery plants, emission monitoring in the chemical industry, ground air screening of contaminated soil, quality control of hydrogen and natural gas, detector for laboratory applications.
Measuring principle
The mercury concentration is measured in an optical cell made of fused
silica. A maintenance-free membrane pump continuously feeds the sample
gas to the optical cell where light absorption measurement takes place
at a wavelength of 253.7 nm.
This so-called "cold vapor atomic absorption spectroscopy (CVAAS)"
measuring method is extremely sensitive for mercury determination and
has been used successfully for many years. In contrast to the
occasionally propagated atomic fluorescence spectroscopy (AFS) method
it is low in interference and requires neither an amalgamation step nor
expensive noble gases as carriers.
Analytical Performance
The VM-3000 uses a high-frequency driven electrodeless Hg low pressure
(EDL) lamp as UV source. It generates emission lines of an extremely
narrow bandwidth which are congruent with the absorption lines of the
Hg atoms. Cross-sensitivities are thus minimized. The extremely high
stability of the UV source in the VM 3000 is a result of the reference
beam feedback control method. Total background noise is less than 0.1
µg/mł.
To prevent temperature drift both the lamp unit and the detectors are
temperature-stabilized. Because the optical cell is heated the VM-3000
is insensitive to water vapor.
Special Features
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Metal housing with sturdy handle
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Option: Rack version with mounting brackets for 19" racks
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Membrane pump with long service life
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Input filter with teflon membrane
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Stable optical bench
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Factory-calibrated
Easy to operate
The user controls the VM-3000 by menu-guided inputs via a waterproof
membrane keypad. After switch-on the light source is stabilized
(approx. 1 - 15 minutes). When the measurement mode is started, a zero
adjustment is first carried out automatically. Then the analyzer
switches to measurement and continuously indicates the measured mercury
concentration of the gas as a numerical value and a graphic bar. The
following settings are possible in the "parameters" menu: duration and
repeat interval of the zero adjustment, selection of the concentration
unit (µg/m3 or ppb), measuring range (0.1-100, 0-1000, 0-2000 µg/m3),
input of three different alarm levels, calculation of a mean value over
three freely selectable time intervals, printer activation, and, if
required, a sample dilution factor.
Display and Output of Measurements
The result of the measurement is displayed on an LCD in real time, both
numerically and graphically and is output as an electrical signal of
4-20 mA. The device has outputs for alarm, status and measurement
values for full integration in plant control systems. The device also
has a serial interface (RS 232) for data collection on a PC.
Self Diagnosis System
If an important component of the VM-3000 malfunctions the user is
warned via the display (blinking messages: clean cell, lamp, low
battery, alarm) and via output signals.
Battery Operation
For operation independent from mains power the VM-3000 is also
available with a built-in rechargable battery and a charger unit. This
option allows mobile battery-powered applications of up to approx. 5
hours.
Data Logger Function
A data logger function can be integrated into the VM-3000 as an option.
Up to 30000 readings can be stored in the data memory. The logging
interval can be set from 1 - 16 seconds revealing a total recording
capacity of 4-60 hours. The stored data can be read out with a PC using
the serial interface of the VM-3000 according RS232 standard.
Multiplexor operation
A multiplexor unit can be connected for automatic monitoring of
multiple measuring points, e.g. as a cellroom monitoring system for
chlorine plants. Such a Mercury Monitoring System MMS consists of the
Mercury Vapor Monitor VM-3000 , the multiplexor valve unit , the sample
bypass pump and two flowmeters. These components are optionally mounted
in a industrial grade (IP 65; NEMA 4X) enclosure. Upon demand it can be
shielded against magnetic fields.
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| Specifications |
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Technical Specifications
Measuring principle: UV-Absorption
Wavelength: 253.7 nm
UV source: electrodeless low-pressure mercury lamp
Stabilization method: reference beam feedback lamp control method and thermal stabilization
Optical cell: fused silica (Suprasil), 23 cm long
Optical cell heating: approx. 50°C
Measuring range:
lowest range: 0.1...100 µg/mł (0.01-10 ppb)
highest range: 0...2000 mg/mł (0-200 ppb)
Sensitivity: 0.1 µg/mł (0,01 ppb)
Response time (99% signal): < 1 second
Computation of mean value: automatically via three freely selectable time
Alarm: when concentration is exceeded, 3 levels programmable
Status alarms: measuring cell soiled, battery state, UV source
Control pad: waterproof membrane keypad
Measurement Display: graphical LC display with background illumination
Signal outputs: 4...20 mA for recorder;
RS 232 bidirectional for PC, data logger etc.;
parallel for printer
Pump: membrane pump, approx. 2 L / min., optional Flow meter with alarm message
Filter: PTFE, 1 µ, 47-50 mm diameter
Power Supply: 230 V / 50 Hz (115 V / 60 Hz option)
Battery operation: external 12 DC source; optional 12 V batteries integrated, ca. 5h capacity
Power consumption: 30 VA
Dimensions: 45 x 15 x 35 cm (WxHxD)
Weight: approx. 7 kg
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