Gastec Sampling Pump

Why the Pump Isn’t an Accessory

It’s worth saying first, because the pump is often treated as an add on, and it isn’t.

A colorimetric tube works because a known volume of air passes through a known quantity of reagent. The length of the colour change matches the concentration only if that volume is correct. Draw too little, and the reading is low. Draw too much, and it’s high.

So the pump doesn’t just move air, it defines the measurement. A full stroke draws 100 mL and a half stroke 50 mL, with both positions marked exactly by the red line on the pump shaft, and the handle locks precisely at each.

That’s why a tube can’t be used without one, and why the pump is the first thing to buy, not the last.

The Flow Finish Indicator

This small feature removes a major source of user error.

Different tubes have different resistance, so the time taken for the sample to pass varies. A free flowing tube might take seconds, and a restrictive one considerably longer. Without knowing when the sample is complete, an operator either waits too long, or, more often, stops early and takes a short sample.

The pump’s flow finish indicator shows automatically when the stroke is complete. When the white disc pops out, the sample is finished, so the end of the sample is visible rather than guessed.

Built to Be Easy and Accurate

A built in tip breaker with a diamond edge cuts the surface of the tube, making tip breaking easier, safer and more convenient. Broken tips drop into a storage bin for safe disposal.

The pump piston has a smaller diameter, so the handle pulls out with less effort, and anyone can operate it easily.

Both pumps meet the leakage test of EN 1231, the European standard for short term detector tube measurement systems. The red line on the pump shaft also shows you the leakage rate. Gastec recommends an airtightness check before measuring, because a leaking pump gives wrong results.

Two Models

The counter earns its place in two situations. Where multi stroke tubes are used regularly, since some need several strokes, and counting them while holding a pump and watching a tube is where errors creep in. And where the measurement supports a compliance position, because a miscounted stroke produces a wrong result that looks entirely plausible.

Otherwise, the two pumps work the same way, and both work with Gastec colorimetric tubes and Polytec tubes.

Non Sparking by Design

The pump is hand operated, with no battery and no motor.

The body is covered with a soft elastomer, and the other outer surfaces are made of non sparking ABS resin, apart from the opening of the tube tip cutter, which is chromed stainless steel. Gastec describes the non sparking design as ideal for environments classed for intrinsic safety. Check your site’s requirements for use in a hazardous area.

With nothing electrical, nothing can run flat while the pump sits in a store between uses, which is the same reason tubes suit periodic measurement.

One Hand Operation

This accessory is worth knowing about, because it solves a specific problem.

Normal operation is two handed. One hand holds the pump and tube, and the other pulls the handle.

The GV-700 One Hand Operation Adapter changes that. It holds a vacuum of 50 mL or 100 mL in the pump body, so the tube can be attached and the sample taken using one hand. A small rod in the adapter is moved in or out with one finger.

That matters where the other hand is busy: on a ladder, holding an extension hose over a manhole, or handling a sample point while wearing gloves.

Accessories Worth Considering

An extension hose attaches to the pump for remote sampling, in 5 metre and 10 metre lengths. It lets a sample be drawn down into a manhole or tank without anyone entering it, which is a genuinely useful capability rather than a convenience. An extension sampling pole is also available, for reaching narrow or overhead spaces.

The No. 721 Tube Tip Holder works as a tip breaker and stores the broken tips, holding about 260 and stopping glass fragments scattering.

The Gastec handbook is designed to be easy to use and informative for anyone responsible for workplace, public or environmental health and safety, and helps with choosing the right tube, which is the harder half of using the system.

Where It’s Used

Anywhere Gastec colorimetric or Polytec tubes are used. Confined space entry. Occupational hygiene assessment. Emergency response. Fumigation clearance. Compressed breathing air testing. Process plant and laboratory work. Odour and complaint investigation.