Series-AT-1800Configuration

Supported Applications

The Dwyer Series AT-1800 is an ATEX/IECEx approved low differential pressure switch designed for hazardous area applications. The series combines small size with ±2% FS repeatability to monitor air and non-combustible, compatible gases across nine operating ranges from 0.07 in w.c. (18 Pa) up to a maximum of 85 in w.c. (21.6 kPa). Flameproof enclosures are available for low-pressure service where explosion protection is required.

Operating Conditions & Performance

The Series AT-1800 operates within ambient and process temperature limits that vary by model range: the 1823-00 range supports -20 to 180°F (-28.9 to 82.2°C), while other ranges support -30 to 180°F (-34 to 82.2°C). The switch features a single-pole double-throw (SPDT) output with an electrical rating of 15 A @ 120-480 VAC, 60 Hz resistive; de-rate to 10 A for operation at high cycle rates or inductive loads.

Pressure limits depend on the port/valve configuration and whether one or both pressure ports are connected. For example, VS0 and VL0 configurations support up to 10 kPa continuous with either one or both ports connected, while VS2 supports 40 kPa (one port) or 20 kPa (both ports). The series includes an overpressure relief valve option for enhanced protection.

Key Performance Specifications

• Repeatability: ±2% FS
• Hysteresis (Dead Band): Varies by model; ranges from 0.05 in w.c. at minimum set point for the 1823-00 to 3.0 in w.c. at maximum set point for the 1823-80.
• Response Time: Increased response time is noted with LD port configurations (VL series) at low pressures.

Configuration Options

The Series AT-1800 offers configurable options to meet specific hazardous location requirements. The primary enclosure material is aluminum, rated IP66 (IP65 for versions VS1, VS2, VL1). Electrical connections are provided via two 1/2" NPT female entries; cable glands are not included.

Available Configurations

• Housing Material: Aluminum enclosure (code 101NA).
• Cover Type: Blind cover (B) or external set point adjustment knob, which allows setting changes without opening the flameproof enclosure.
• Port/Valve Materials: Brass (standard) or Stainless Steel (optional).
• Process Connections: 1/8" NPT female. Configurations include standard ports with no valve, low-differential (LD) ports with no valve, and combinations of STD/LD ports with valves.

Hazardous Location Approvals

• ATEX: 0080 Ex II 2G db IIC T5, T6 Gb (-60°C≤Tas≤+50°C for T6; -60°C≤Tas≤+60°C for T5); II 2D Ex tb IIIC T75°C Db.
• IECEx: Ex db IIC T5, T6 Gb (-60°C≤Tas≤+50°C for T6; -60°C≤Tas≤+60°C for T5); Ex tb IIIC T75°C Db.
• Certificates: ATEX Certificate INERIS 21ATEX0033X; IECEx Certificate IECEx INE 21.0064X.

Key Product Differences

The Series AT-1800 is distinguished from the general industrial Model 1823 by its ATEX/IECEx flameproof enclosure and hazardous area certifications. While both share similar internal switching mechanisms, the AT-1800 series utilizes a specific model numbering structure (e.g., AT-<ENCLOSURE>-<HOUSING MATERIAL>-<SERIES>-<RANGE>) to define explosion-proof configurations.

Within the Series AT-1800, variations are defined by:

• Ranges: Nine distinct differential pressure ranges (e.g., 0.07–0.22 in w.c. through 9–85 in w.c.).
• Port Configurations: Selection between standard ports and low-differential (LD) ports, which affect response time at lower pressures.
• Valve Options: Availability of overpressure relief valves integrated into the port configuration to manage surge conditions.