Dwyer Instruments 3000MR-00 Photohelic Switch/Gage 0-.25" WC

The Dwyer Instruments 3000MR-00 Photohelic Switch/Gage is used to measure and control very low differential air pressure in duct and filtration setups. It combines a pressure gauge with dual adjustable switching relays that provide visual indication and automatic control when preset limits are reached. The unit operates in a 0 to 0.25 inches water column range and uses a diaphragm sensing mechanism that responds to minute pressure changes, converting them into mechanical movement for accurate reading and switching output within HVAC systems. It is mounted on control panels linked to air handling units for airflow and filter monitoring.