GazCal

Why a Generator for Chlorine

Some gases are difficult, or even impossible, to supply reliably in a compressed gas cylinder, because they’re very chemically reactive. Chlorine is one of them. It reacts with the cylinder walls and with other gases in the mixture, so the concentration can’t be relied on over time.

That matters most for the sites that need chlorine detection: water treatment plants, swimming pools, chemical manufacturers and laboratories. They need reliable calibration and test gas, often at low concentrations.

The GazCal solves the storage problem by making the gas where it’s used. A solid state electrochemical cell produces a small quantity of chlorine while the unit is running, and a closely controlled airflow from the internal pump dilutes it to the concentration you’ve set. Switch the unit off, and the cell stops producing.

Because no gas is stored, there’s no cylinder to go out of date. Cell life is measured in use, not in months.

Cell Life

The generating cell is rated at 500 ppm hours. At 5 ppm, that’s 100 hours of generation, and one cell can carry out literally thousands of calibrations.

A cell life indicator on the control panel shows how much is left. When it reaches zero, the cell can be replaced, either by returning the GazCal to Gastech, or by fitting a new cell yourself, using the instructions that come with it.

Concentration Range

A cylinder gives you one concentration. The GazCal is adjustable from 0.5 to 20 ppm, in 0.1 ppm steps, set with a dial and shown on a digital display. Accuracy is ±10% or 0.25 ppm, whichever is greater.

That covers low level alarm checks through to higher concentrations from a single unit, and it produces the low concentrations where chlorine alarm levels sit.

Calibration options are low range (1 and 3 ppm), mid range (5 and 10 ppm) and full range (10 and 20 ppm). Flow rate is set at the factory to either 0.5 or 1.0 litres per minute, so it’s chosen when you order, not adjusted afterwards.

No measuring device is needed inside the generator, because the cell and controlled airflow deliver an accurate concentration.

Using It

Operation is simple, so it doesn’t need a technician.

Check the cell life indicator, connect the outlet tube, and switch the unit on. Turn the ppm dial to the concentration you need, and allow 3 minutes for it to stabilise before use. The GazCal works upright, with the front cover open or closed.

After use, purge the unit by turning the dial to 0.0 ppm and running it for one minute before switching off.

A blockage LED warns if the outlet is restricted. Keep the outlet tube to 1 metre or less, as supplied, and check that calibration cup adaptors don’t restrict the flow. The internal air filter should be replaced at 3 monthly intervals at most, or sooner in dirty conditions.

Safety

Chlorine is harmful, even at low concentrations. Use the GazCal with adequate ventilation, and don’t breathe the output gas. Under extreme fault conditions, the unit could produce up to 100 ppm chlorine, so it should always be used where the output is controlled.

Practical

The GazCal runs on mains (110 or 240 V) or its internal rechargeable battery, which typically lasts 12 hours between charges and takes eight hours to recharge. It can also run from the charger. It’s designed for field use, with rugged construction for aggressive environments, and operates from 0 to 50°C.

It’s supplied with a shoulder strap, 1 metre of polyurethane tubing, a charger and the operating manual. PTFE or polyurethane delivery tube is recommended.

Where It’s Used

Water treatment. Desalination. Swimming pools and aquatic centres. Chemical manufacturing. Laboratories. Test and calibration of chlorine gas detectors on site and in the workshop.