Industrial ppm CO measurements

Written by Scott Cowe of Dover Gas Technologies

Continued from page 1
higher temperature coefficient, this leads to zero instability making it unsuitable for our task. Carbon and chemical filters are often attached torepparttar face ofrepparttar 133520 sensor or added inrepparttar 133521 sample stream to diminishrepparttar 133522 effects of cross interference to many ofrepparttar 133523 commonly encountered such as H2S, SO2, NO x, etc.. This filter, itís efficiency and life span can be an important consideration when measuring CO inrepparttar 133524 0-50ppm range. In a number of applications background levels of Hydrogen given off by nearby processes have been found to cause major problems with accurate low level carbon monoxide measurements and alarms. While it is possible for hydrogen levels to cause safety concerns that should be reported,repparttar 133525 limit is magnitudes higher than what causesrepparttar 133526 CO alarms to trigger on most instruments. A hydrogen level of as little as 60ppm can triprepparttar 133527 CO alarms of many analyzers. The lower explosive limit (lel)for hydrogen is 4%, ten percent of that l.e.l. would be 4000ppm, so we see thatrepparttar 133528 60ppm is insignificant to personnel safety but remains problematic torepparttar 133529 carbon monoxide measurement. This cross interference can not be easily overcome with chemical filters and therefore required a different approach. It has been found that by measuringrepparttar 133530 hydrogen separately and using that signal in conjunction withrepparttar 133531 mixed CO/H2 signalrepparttar 133532 majority ofrepparttar 133533 interference can be nulled out, again manufactures deal with this differently with varying results. The use of two separate sensors can create a compensation lag time and there may be temperature coefficient differences betweenrepparttar 133534 sensors, either of which will cause errors inrepparttar 133535 readings and provide false alarms. Similar temperature problems can be found with units that use a single sensor but dorepparttar 133536 electronic nulling and temperature compensation remote ofrepparttar 133537 sensor itself.

There are sensors now available that have separate electrodes forrepparttar 133538 H2 and CO/H2 signals withrepparttar 133539 nulling and temperature compensation circuit attached directly torepparttar 133540 rear ofrepparttar 133541 sensor itself. The output of this surface mount board is inrepparttar 133542 millivolt range making it less susceptible to interference and change from wiring, connectors and temperature effects. Each sensor and attached PCB come completely pre-calibrated for H2 cross interference and relative CO output. Only a single calibration gas is required overrepparttar 133543 life ofrepparttar 133544 sensor (2 years) with no need for re calibration ofrepparttar 133545 hydrogen signal nulling found in any ofrepparttar 133546 units put into service. In addition,repparttar 133547 internal chemical filter provides excellent reduction of cross interference due to other common gasses found. This customer replaceable sensor has proven itself over time to provide consistently accurate results in demanding applications against competitors instruments.

Dover Gas Technologies Inc. incorporates such a sensor, we believe it best suitsrepparttar 133548 needs addressed above and use it in many of our portable, transmitter, and monitor products for low level ppm CO measurement.

President and operations manager of Dover Gas since 1991 with 8 years of prior experience in the gas analysis field.

Installing Nessus 2.0 on SuSE 9.0 Pro with KDE 3.1

Written by Lew Newlin

Continued from page 1

Download Nessus

  • Click "Local Network"
  • Change location to "/"
  • Right click and Create New directory titled "nessus-installer", close window
  • Using browser go to
  • From "The easy and less dangerous way" section download "" file saving torepparttar "nessus-installer" directory.

Compile Nessus

  • Click "Konsole" on task bar and change directories to "nessus-installer"
  • Type "sh"
  • Accept defaults by pressing (Duringrepparttar 133519 compiling process you may receive warning messages for "nessus_popen", "insert_nasl_func", and "extra tokens". These are warning messages andrepparttar 133520 compiling process should complete successfully.)
  • When compiling process is complete you will be prompted to press to quit.

Nessus Server Setup

  • Type "nessus-mkcert" to make a server certificate
    • Accept default for "CA certificate life"
    • Accept default for "Server certificate life"
    • Enter your 2 letter country code
    • Enter your state or province code
    • Enter your location
    • Enter your organization name
    • Certificate process completed message
  • Type "nessus-adduser" to create a user account
    • Enter login name
    • Accept default for authentication
    • Enter password
    • Press ctrl-D to end user creation process
    • "Is that ok?" message
  • Type "nessusd -D" to startrepparttar 133521 Nessus server service (It may take several seconds for Nessus to finish initializing. The command prompt will return oncerepparttar 133522 Nessus daemon is started).

If you wish to haverepparttar 133523 Nessus Server daemon automatically started whenrepparttar 133524 system is booted, editrepparttar 133525 "etc/init.d/boot.local" file and append "nessusd -D".

Nessus Setup

  • Type "nessus"
  • Enter login
  • Enter password
  • Click "Log in" button
  • "SSL Setup" window will appear, click
  • "Nessus" windows asking to accept this certificate, click
  • "Warning" message about plugins crashing remote systems will appear, click
  • Close "Konsole" window


  • Click "Start Applications" on task bar and select "Utilities", "Time", then "KAlarm"
  • Inrepparttar 133526 KAlarm window click "Actions", then New
  • Check "Command" and enter "nessus-update-plugins" asrepparttar 133527 command line
  • Check "Any time" check box
  • Check "Recur" for Repetition, then selectrepparttar 133528 "Recurrence" Tab
  • Enter "01:00" for "Recurr every" field
  • Select button, then
  • Close "Kalarm" window (Kalarm by default is automatically stated upon boot.)


KDE provides built-in firewall protection. Vulnerability scanners such as Nessus do not normally function well with software firewalls in place. To removerepparttar 133529 firewall:

  • Click "Control Center" on task bar
  • Click "YaST2 modules"
  • Click "Security and Users"
  • Click "Firewall"
  • Check "Stop Firewall and Remove from Boot Process"
  • "Firewall configuration - deactivate firewall", click
  • "The firewall is now turned off"

General Information

Uninstall executable: /usr/local/sbin/uninstall-nessus

Configuration file: /usr/local/etc/nessus/nessusd.conf

Certificate Authority: /usr/local/com/nessus/CA/cacert.pem

Certificate Authority - Private: /usr/local/var/nessus/CA/cakey.pem

Nessus Server Certificate file: /usr/local/com/nessus/CA/servercert.pem

Nessus Server - Private Key file: /usr/local/var/nessus/CA/serverkey.pem

Nessus uses port 1241 to communicate

You now have a fully functioning Nessus server daemon and client installed on SuSE usingrepparttar 133530 KDE desktop environment. Kalarm is setup to automatically update Nessus plugins once per hour to insure you haverepparttar 133531 latest vulnerability tests. Nessus is now fully operational to help with your security needs.

Lew Newlin is CTO of Information Solutions, Inc. that operates SiteRecon specializes in security, email monitoring, and web site monitoring for Internet service providers and businesses.

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