Pre-Entry Testing – Electronic Detectors vs Detector Tubes

by | Aug 4, 2015 | Gas Detection, Latest News

GD vs Gastec

Pre-Entry Testing

In the shipping and transportation industry, when carrying out pre-entry tests for air contaminants in freight containers, a standard four gas detector is often used to continuously detect Combustible gases (LEL), Carbon Monoxide (CO), Hydrogen Sulphide (H2S) and to determine Oxygen (O2) deficiency. Unless advanced gas detectors with PID or expensive exotic sensors are used, other dangerous contaminants such as solvents, Methyl Bromide or Phosphine may not be identified using a standard gas detector, which could potentially cause an unsafe situation.

a1-cbiss review the use of Electronic Gas Detectors Vs Gastec Detector Tubes

Operators conducting pre-entry tests must also check for these other contaminants that may be present to verify safe levels prior to entry. Other contaminants present can vary widely depending on the cargo being transported (Solvents, fuels, paints, clothing), fumigants used to protect cargo (Methyl Bromide, Formaldehyde) and so a single gas monitor cannot measure all of these possible scenarios.

In such instances, a gas detector tube should be used to conduct the other contaminant detection.

Benefits of Using Gastec Detector Tubes vs Electronic Gas Detectors

  • It’s much more cost-effective to replace a pack of detector tubes than an expired gas sensor.
  • Gas detector tubes do not have any electrical components; therefore can be used in any environment
  • Detector tubes don’t require calibration, so no service costs
  • The range of detector tubes available allows detection for around 200 gases, a much wider scope than electronic gas detectors.
  • Switching from one gas to another is much simpler using detector tubes.


Detector tube sampling accessories

To carry out pre-entry testing, the ends are broken from the Gastec detector tube, which is then connected to the sampling pump. The detection system is then positioned at the point of sampling, either through an ajar door or through the seal on the container door. A gas sample can then be drawn.

Occasionally, where containers are stacked and entry is not yet accessible, gas detection can still be carried out effectively. Gastec offers a telescopic extension pole that allows sampling in the region of three metres. The sampling pump is connected to the extension pole and the gas detector tube is located at the far end of the extension probe.

In other pre-entry applications such as storage tanks or silos where top entry is required, a flexible extension hose can be used to obtain the gas sample. Extension hoses are available for Gastec sampling pumps that connect to the front of the pump and position the detector tube at the opposite end of the hose. In this application, the tube is lowered into the tank.

Do you have to carry out pre-entry testing? Contact a1-cbiss for help with sourcing the right equipment for the job +44(0)151 666 8541

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