D-Guard²S

Detection and Alarm in One Enclosure

Most fixed gas detection is a two part system: a detector at the hazard, a controller somewhere else, and cable between them.

That cable is often the biggest line in the install quote. Running armoured cable across a site, through a wall or up a duct can cost more than the detector at the end of it.

The D-Guard²S removes that. The relay board and sounder strobe are inside the detector, so it monitors, decides and alarms on its own.

For a single detection point, or a handful of points that don’t need a central panel, that changes the economics of the job.

What the Relays Do

Three relays, each with a defined job.

The fault relay is normally energised, and that matters more than it sounds. Because it’s energised in normal operation, a power loss, broken wire or dead board drops the relay and registers as a fault. A normally open fault relay would stay silent in exactly the situation you most need to know about.

The low and high alarm relays are changeover contacts, which gives you options. Drive extraction on low and a shutdown on high. Trip a solenoid. Signal a BMS. Light a beacon at the door as well as the one on the detector. Both alarm relays can be set as energised or de-energised.

An Alarm People Will Notice

The sounder is rated 98 dB, with a flashing red strobe.

Both matter. A sounder alone fails in a plant room with machinery running, or where hearing protection is worn. A strobe alone fails for anyone facing the other way. Together, they cover both.

Putting the alarm on the detector, rather than at a remote panel, also means the warning is where the gas is. Someone about to walk into a cool room or pump station is warned before they go in, not after.

15 Gases, One Board

The D-Guard²S uses a single electronics board across toxic gases and oxygen, with 4 series plug in sensors and configuration through the interface. Hydrogen tolerant CO sensors are also available.

That covers hydrogen sulphide at a pump station, ammonia in a chiller room, ethylene oxide in a sterilisation area, phosphine in fumigation and chlorine at a dosing plant. One detector type, one spares line and one procedure to learn.

For carbon dioxide or methane with a relay board, use the D-Guard²R.

Calibrate It Without Opening It

Calibration and configuration use a magnetic stylus against the closed housing. Nothing is unscrewed or exposed.

On screen prompts walk the technician through it, which reduces mistakes by someone who calibrates a detector twice a year rather than twice a day. A detector isolate feature takes a point out of service for maintenance.

It Tells You When It Has Failed

A detector that has quietly failed is worse than no detector, because the site believes it’s protected.

A sensor self test runs on a timer, or on demand over HART, and operating conditions are monitored continuously. Response time testing is built in, giving a real measurement of dynamic performance rather than assuming a detector that worked last year still works today. As standards begin to require this, the detector is already equipped for it.

Drift is less than 3% signal loss per year, which keeps calibration intervals long and predictable.

HART If You Want It

Optional HART 7.0 runs alongside the 4-20 mA output. It carries real time readings, diagnostics, remote sensor testing and current loop rescaling.

For a standalone installation, you may never need it. For a remote site, it saves a trip.

Important: Not a Hazardous Area Detector

The D-Guard²S is a general purpose detector and carries no Ex certification. Gastech’s documentation states that it must not be used in applications that need certified equipment.

If your installation is in a classified hazardous area, you need the D-Guard², which carries IECEx, ATEX and ANZEx certification across Group I for underground coal and Group II for surface industry.

If you’re not sure how your area is classified, our engineering team can work through it with you. Getting this wrong isn’t a compliance technicality. It’s a genuine safety issue.

Choosing Across the Range

Where It’s Used

Cool rooms and cold stores, pump stations and wet wells, chemical dosing rooms, plant and boiler rooms, carparks and loading bays, workshops and battery charging areas, laboratories, sterilisation areas, fumigation and grain handling sheds, commercial kitchens, and mineral processing and surface plant in non classified areas.