Purge Test: Gas Detection & Purge Testing

When taking a gas pipeline offline or installing a new one, utility crews must first treat the confined space with inert gas, such as nitrogen, to limit the chances of combustion. After the pipeline has been treated, workers should test the space for the presence of hazardous gases. This is what’s known as purge testing. However, this is not the same as conventional gas detection. The pipeline will contain little oxygen and high concentrations of natural gas, which could damage the gas detection equipment.

Why Conventional Gas Detection Isn’t Enough

Most gas detectors and monitors are designed to detect small traces of hazardous gases. The typical sensors (catalytic bead or pellistor) used on the device need oxygen to accurately record how much gas is in the air. When exposed to high concentrations of gas, this will overwhelm the sensors, damaging the device in the process.

Some teams may not be aware that they are damaging their equipment when using these devices for purge testing. The sensors may not work properly thereafter, which could endanger crew members.

Configuring Your Equipment for Purge Testing

When you order the Purge Testing Instrument, you can choose your configuration based on what’s best for you and your team, including those with chargers and battery packs, so you can use this equipment effectively in the field.

To complete the purge testing process, follow these steps:

For existing pipelines:

Start by purging the line with nitrogen (N2). Use the GX-2012 in % Vol. only (purge mode) to verify that oxygen levels are at 0.5 or less, and the gas reading is at 2% or less.
Open the line and start the purging process by introducing air into the main line.
Purge again with Nitrogen and use the GX-2012 in % Vol. only mode to verify that oxygen levels are at 0.5% or less.
Open the upstream valve to charge the line with gas. Use the GX-2012 in % Vol. to verify that the gas reading is at 98% or more.

For new pipelines:

Purge the line with Nitrogen. Use the GX-2012 in % Vol. only mode to verify that oxygen levels are at 0.5 or less.

Open the upstream valve to charge the line with gas. Use the GX-2012 in % Vol. to verify that the gas reading is at 98% or more.

Conventional gas detectors will not work properly in oxygen-deprived environments. Use special gas detector accessories, including the RKI “T” fitting adapter, to protect your equipment sensors from damage caused by high concentrations of hazardous gases.

PK Safety Supply has been keeping people safe for over 70 years. Feel free to reach out to our team of experts with help on your gas detection devices and calibration.

SHOP RKI GX-2012 PURGE TESTING INSTRUMENT

Sep 8th 2020 PK Safety Team