Gas testing kit

With Crowcon's Gas Testing Kit, users of the Tetra four-gas personal monitor can ensure that their instruments remain accurate at all times.

Supplied in a convenient carry case, the test kit automatically applies a standard four gas mixture to the Tetra to check that each sensor is working within acceptable response limits. If Tetra determines that any sensor is outside predefined response limits it automatically displays a message indicating the need for calibration. Users can also choose calibration mode in which all four sensors are simultaneously calibrated using the four gas mixture. If this is not possible, a message is displayed advising that the unit should be returned for servicing.

The kit features a 34 L cylinder of quad gas - a high-stability mixture of methane, oxygen, carbon monoxide and hydrogen sulfide - fitted with a 'trigger' valve for switching on the gas. Also included is a flow plate which attaches to the detector, an exhaust line and a magnet which is simply passed over the Tetra display to initiate testing.

With testing under way, the detector analyses its responses to the different gas components against values stored in its memory; as long as these are within predefined limits, a successful test is indicated on the instrument display. If the test is unsuccessful a message is displayed indicating that calibration is required. If the detector has been manually zeroed within the previous 15 minutes, the option to calibrate in the field is given when the magnet is applied. To accept the option and begin calibration, the user needs only to press Tetra's single push-button within ten seconds. No other controls are necessary.