Portable 4-gas monitor

Dr. Blaise Champagne

The MiniWarn is equipped with four measurement channels: one catalytic sensor used for the detection of flammable gases and vapours; three electrochemical sensors of type XS EC, which are used for the detection of oxygen in % by vol and toxic gases at ppm concentrations.

The user can install one original Cat Ex sensor, which can measure numerous flammable gases and vapours in ppm, % LEL, and % by vol. concentration ranges.

With the leak-check ppm mode this 4-gas monitor can detect concentrations as low as 50 ppm methane, even during diffusion operation without the pump running.

The Cat Ex sensor is actually two sensors in one housing: for heat of reaction and heat of conduction. This combination, allows a user to unambiguously1 measure methane be-tween 0 and 100% by volume, increasing user safety in comparison to other catalytic sensors. A detailed listing of some of the many measurement possibilities for this sensor is given in Table 1.

The MiniWarn additionally allows up to five different, independent gas or vapour calibrations of the Cat Ex sensor. For instance, at a gas company, an user may want to measure methane in ppm, % LEL, and % by volume concentration ranges depending on the circumstances. These three measurement possibilities could be set up beforehand and easily accessed as needed in the powerful but easy-to-use MiniWarn Flex Menu.

The three electrochemical sensor ports are user-installable, „plug and play“, smart ports. More than 18 XS EC sensors and three PacSensor II electrochemical sensors are available for measuring over 40 gases and vapours.

The MiniWarn measurement unit comes in two versions:

• The basic model (B), which is equipped standard with an IR interface and all of the standard instrument functions required for normal use,

• the extended model (E), which includes all features of the basic model and is addi-tionally equipped with advanced data logging features that, in combination with the GasVision PC software, allow users to log and display their gas measurements.

The IR interface, standard in both the MiniWarn E and MiniWarn B measurement units, provides the user with a convenient link to a PC (without any cables or plugs needing to be hooked up to the instrument) for data downloading and parameter control. Additionally, new instrument software versions can be downloaded via the IR interface.

Both measurement units may be used for diffusion measurement or with an externally attachable pump for remote measurements.

The MiniWarn product family features an easily attachable, external pump. This pump is a small, light-weight slip-on device which can draw a sample from up to 10 metres away. The user attaches the pump to the top of the instrument and activates the mechanical positive-locking mechanism, which starts the pump automatically. The pump for the monitor is powered by the instrument, meaning that there is no additional set of batteries that needs to be charged or remembered by the user. The pump has a flow alarm function to help protect the user from incorrect meas-urements due to clogging or bending of the remote hose. The pump may be used with conventional hose, float probes and extend-able metal probes, among others.

Three different types of battery pack are available, namely:

• An advanced NiMHy rechargeable power pack. This battery pack gives even the most demanding user an extremely long running time (up to 15 h) in diffusion mode,

• a rechargeable NiCd power pack featuring a tried-and-tested, rechargeable technology for 10 h running time in diffusion mode,

• an alkaline power pack offering 10-12 h running time and using readily available, disposable, alkaline batteries.

All three of the above batteries are interchangeable with all B and E units.

Clearly, the ultimate purpose of the monitor is to warn you of the presence of gas dangers. The alarm philosophy has therefore been very carefully thought out. In the event of an alarm, the user is supplied with three items of redundant information to ensure an adequate warning:

• Visually: the entire red sensor cap lights up and is visible both from a great distance and from all directions,

• audibly: a very loud acoustic alarm sounds ($ 85 dBA at 30 cm),

• on the display: the display lights up and the measurement unit of the affected channel alternates with A1 or A2, depending on the severity of the alarm.

Additionally, all three alarm modes are co-ordinated with one another. In the case of an A1 alarm (first alarm threshold) the visual alarm, the audible alarm and the display are all activated with the same, repeated, single tone/pattern. In the case of an A2 alarm (second alarm threshold), all of the above modes are activated with the same, repeated, double tone/pattern. This means that, both audibly and visually, the user can recognise the severity and nature of the gas danger unambiguously and quickly.

The MiniWarn feels good and secure in the hand and works easily.

In addition, it permits easy access to the alkaline battery, as well as to the sensor cover in order to change sensors, with quick-release, quarter-turn screws. Day-to-day operation is child’s play with this 4-gas monitor. An easy-to-use, three button concept (there are no hidden button pads or templates) has been adopted for it: one press of the large button turns the monitor on. Press the two small buttons simultaneously for a few seconds and the monitor is switched off. The MiniWarn features a full alphanumeric graphical display. All four measurement channels are simultaneously displayed with the concentration value, measurement unit and symbols for the instrument status, for example, with pump operation indicated by a pump symbol. The user can display the instrument configuration and the battery status at all times (even when the instrument is turned off) simply by pressing the arrow up key.

The monitor offers a range of software features:

• More than 20 different languages,

• all of the required hygiene capabilities such as TWA and STEL,

• peak holding,

• silent alarm modes,

• leak-detection capabilities,

• multiple ranges and gases for the catalytic sensors.

Most of the advanced functions can be activated or hidden with the Flexmen software philosophy. If the user wants the feature it can be activated, and if not it is hidden. The monitor can be made as simple or advanced as the user needs. All of these features are operated via the simple 3-button keypad and the menu-driven software.

GasVision is a complete data logging and hygiene management software which features:

• A „Black Box“ overwrite or fixed-capacity mode,

• logging of up to 15 000 measurements, allowing more than 64 hours of measurements to be recorded with four active channels,

• the following data for each measurement: gas concentration, measurement location, user-id and any relevant alarms that have occurred,

• a database management system for searching for and organising data logging files.

MiniWarn will meet the needs of everyday confined-space entry and personal monitoring measurements in a variety of demanding settings such as:

• Gas utilities and transportation networks, thanks to its ability to measure methane in % by volume, ppm and LEL %, with complimentary features such as a mercaptan sensor without cross-sensitivity to H2S and a 0 to 10 000 ppm CO sensor,

• city works including sewage and water treatment,

• chemicals,

• oil and offshore,

• mining.

Dräger

Fax: ++49/451/8823122

Further information cpp-275