Gastec CG-1

Four Contaminants, No Power

The CG-1 is a measuring device, a set of Gastec Airtec detector tubes and a stopwatch, all in one carrying case.

It connects to a breathing air cylinder or compressor through a pressure reducer. Air passes through four detector tubes at a controlled flow. Each tube changes colour along its length in proportion to the contaminant present, and the reading is taken from the scale printed on the tube. Carbon monoxide, carbon dioxide, water vapour and oil mist are all measured at once.

No electricity or power source is needed for the measurement. There’s no battery to charge, no sensor to drift and no calibration to schedule.

The Four Tubes

Why That Matters More Than It Sounds

Breathing air testing on many sites happens at intervals rather than continuously, and an instrument that sits in a store for months has a particular way of failing.

An electronic analyser left unused still ages. Its battery runs down, its sensors drift, and its calibration expires. So the first thing that happens when someone needs it is finding out whether it still works, and sometimes it doesn’t.

Detector tubes don’t have that problem. The kit is ready when you pick it up, as long as the tubes are within their shelf life. For a site with one compressor tested quarterly, that reliability is worth more than a continuous readout it doesn’t need.

Test Downstream of the Filters

One practical point decides whether the test means anything, and it applies whichever instrument is used.

The measurement has to be taken downstream of the filtration, so the air being tested is the same air that will be breathed. Testing upstream tells you what the filters are dealing with, which is a different and much less useful question.

Oil Mist Is the Part People Forget

Oil mist is the contaminant most specific to compressed breathing air, and one a general purpose gas detector can’t measure.

A compressor fault can put oil into the air line, and the wearer breathes it in as a fine mist without noticing. The CG-1 measures oil mist directly, from 0.2 to 5.0 mg/m³, as one of its four parameters.

Where It Sits Against the ACG+

Both cover compressed breathing air, and they answer different questions.

The ACG+ monitors continuously, adds oxygen and VOCs, logs 90 days of data, and can shut the compressor down on alarm. That suits a critical or heavily used system where the air is breathed daily.

The CG-1 is a spot check. It tells you the air was acceptable at the moment you sampled it, at low cost and with no calibration or power needed. For a site with one compressor tested on a schedule, that’s proportionate.

The honest way to choose is by how a failure would be found. If a fault developing between quarterly tests would matter, monitor continuously. If a scheduled test is the control, tubes are the sensible answer.

Accessories

An optional pressure reducer, area flow meters and a conversion adapter are available, and all store in the CG-1 carrying case. Check which fittings your cylinders use before ordering, so the right connection arrives with the kit. Our Technical Consultants can help.

Where It’s Used

Breathing air compressor testing. Cylinder and SCBA filling station checks. Fire and emergency services breathing air. Commercial and recreational diving. Confined space entry using airline breathing apparatus. Spray painting and abrasive blasting. Marine and offshore. Mining. Any site testing breathing air to a schedule rather than monitoring it continuously.