The PointGard ­3720 is the optimal solution for all those who need a gas detection system but who do not want to go through the hassle of assembling all the necessary components. It contains the measuring function of a transmitter, the assessment function of an controller and the necessary alarm equipment such as flashing lights and horn. The AC versions of the PointGard ­3720 can be operated with the optional mains plug at any standard power outlet. To be able to position the PointGard ­3720 and the sensor optimally, they have been separated from each other. This allows the PointGard ­3720 with its alarm devices and display to be mounted at eye level, while the sensor can be placed as close as possible to the measurement location. The maximum cable length between PointGard ­3720 and sensor is 30 m. The sensor is the Dräger ­PIR ­7200, which may be installed in hazardous areas. Appropriate accessories are available for use in pipes and ventilation shafts.

The PointGard ­3720 is used where a gas concentration needs to be monitored locally. A typical application is the measurement of carbon dioxide (CO₂) in unventilated or closed rooms. For this, the PointGard ­3720 is installed outside the room at the entrance and the sensor in the room to be monitored. This way you are informed about the gas concentration before entering the room. If the set alarm limits are exceeded, the PointGard warns you with the integrated alarm devices. It can also trigger automatic ventilation so that the concentration is lowered and the room can be entered again without danger.

Inside the PointGard ­3720, the proven electronics of the Dräger ­Polytron ­8720 are used. Both hardware and software have been evaluated by TÜV (Nord) and have provided evidence of SIL2 capability. The sensor is the SIL2-capable Dräger ­PIR ­7200. This infrared transmitter with double-compensated 4-beam optics is characterised by excellent measurement quality and extreme long-term stability. It detects contamination of the optical system and warns in good time before the measurement fails so that the operator can remove the contamination. Depending on local conditions, the calibration interval can be up to one year. With this sensor, the PointGard ­3720 is able to measure carbon dioxide in ranges from 0-2000 ppm to 0-30 Vol%.The Dräger ­PIR ­7200 allow continuous measurement under atmospheric conditions in a temperature range from -40 °C to +77 °C.

The PointGard 3720 already includes visual and audible alarm devices. The bright and long-lasting flashing lights warn of danger from a distance in orange (pre-alarm) and red (main alarm). If a distinction is to be made between safe and unsafe conditions, there are combinations in green (safe) and red (unsafe) or green (safe) and blue (unsafe).The integrated horn has a sound pressure of 85-100 dB. The horn volume can be adjusted to suit either industrial or laboratory applications. The side mounted horn silence button can be set to reactivate the horn in 3 minutes, 6 minutes, or permanent off until the next gas alarm.

The PointGard ­3720 contains a 120 ... 230 VAC/ 24 VDC power supply.It can optionally be ordered with the power cable and country-specific plug. If a local 24 VDC supply is already available, a variant without power supply unit is also available.

The measured value, gas name and measuring unit are permanently shown on the display. If required, the concentration history of the last 15 minutes can also be shown. The display has a backlight in red or green to ensure readability even in poor lighting conditions. The colors can be set via a slide switch inside the device. Below the display are three status LEDs in green (operational), yellow (error) and red (alarm). All settings on the PointGard ­3720 are made via a password-protected menu. The three-button control allows quick navigation through the menu items. Measuring range and alarm thresholds are already set to the usual values after plugging the sensor. They can be adjusted at any time.

In addition to the integrated alarm means, the PointGard ­3720 also has dry contact switching relays. This enables additional automated switching measures. Relays are available for A1, A2 and faults. In addition, an external digital input, such as a fault contact of neighboring machines, can be read in and switch off the green light (safe status) on the PointGard ­3720. For integration into higher-level systems (visualization systems, data acquisition systems, PLCs, central gas warning systems), the analog 4-20 mA current interface according to NE 43 can be used. HART^® communication allows you to synchronize settings with a connected Dräger REGARD 3000 or Dräger ­REGARD ­7000. In addition, remote access is possible via HART^® using Dräger PolySoft software or other HART^® communication devices.