PMI

Supported Applications

The Dwyer Series PMI Particulate Matter Transmitter is designed to measure indoor air quality by detecting particulate matter in office environments or HVAC ducts. Using laser scattering technology, the series detects particles as small as 0.3 µm. Documented applications include educational institutions, healthcare facilities, corporate offices, hotels/restaurants, and integration with air purifiers.

Operating Conditions & Performance

The Series PMI operates within an ambient temperature range of 32 to 122°F (0 to 50°C) and a storage temperature range of -22 to 158°F (-30 to 70°C). Humidity limits are rated at 0-95% RH (non-condensing). The sensor utilizes laser scattering technology with a resolution of 1 µg/m³. Accuracy is specified as ±10 µg/m³ @ 0-100 µg/m³ and ±10% reading @ 100-600 µg/m³ at 25°C, 50% RH. The response time is <10 s in continuous service mode.

Measurement ranges are defined by particulate size:

• PMI-2.5: 0-500 µg/m³, particle size 0.3-2.5 µm
• PMI-10: 0-600 µg/m³, particle size 0.3-10 µm

The series offers a Mean Time Between Failures (MTBF) of more than 3 years in continuous service mode and a service life up to 8-10 years in auto (intermittent) service mode.

Configuration Options

The Series PMI is configurable across mounting styles, output signals, display options, and control features. The model number structure follows the format: PMI-<PARTICLE SIZE>-<MOUNTING>-<OUTPUT>-<RELAY>-<LCD DISPLAY>-<BUTTONS>.

Mounting and Housing

The series supports two primary mounting configurations with distinct enclosure ratings:

• Wall mount: Polycarbonate housing (UL 94 V-0), IP30 rating. Dimensions: 3-17/64 in [83 mm] width, 4-17/32 in [115 mm] height, 1-13/64 in [30.6 mm] depth.
• Duct mount: ABS and polycarbonate housing (UL 94 V-0), IP65 rating for the housing and IP30 for the probe. Dimensions: 4-21/64 in [110 mm] width, 2-61/64 in [75 mm] height, 3-13/16 in [97 mm] depth.

Outputs and Communication

Variants offer the following output signal combinations:

• Analog outputs: Current (4-20 mA) or Voltage (0-10 VDC).
• Digital communication: RS-485/Modbus® RTU.
• Relay output: SPST 3A, 30 VDC/250 VAC (optional).

The load resistance requirements are ≤500 Ω for current output and ≥2 kΩ for voltage output. Power supply is provided via 16-28 VAC or 6-35 VDC.

Display and Control Options

An optional 4-digit LCD display is available on select models. Models with an integrated relay support settable alarm and control parameters, allowing the unit to function as a stand-alone controller. Relay modes include actuation below or above a set point (with deadband), between high/low limits, or outside high/low limits.

Key Product Differences

The series distinguishes models primarily by particulate size detection and mounting style:

• Paticle Size: Models are designated as PMI-2.5 for PM 2.5 measurement or PMI-10 for PM 10 measurement.
• Housing Style: Wall mount units (e.g., codes WA, WC) differ from duct mount units (e.g., codes DA, DC). Duct mount models feature a removable terminal block; wall mount dimensions and materials vary accordingly.

The series carries CE and UKCA compliance certifications. A caution note specifies that the unit uses a laser particulate matter sensor and is not field serviceable; disassembly is prohibited due to eye injury hazards from direct laser exposure.