Differential pressure controller, selectable engineering units: .2500" w.c., 6.350 mm w.c., 0.635 cm w.c., 0.467 mm Hg, 0.623 mbar, 62.28 Pa, 0.623 hPa, 0.114 oz/in².The Series DH Digihelic® Differential Pressure Controller is a 3 in 1 instrument possessing a digital display gage, control relay switches, and a transmitter with current output. Combining these 3 features allows the reduction of several instruments with one product, saving inventory, installation time and money. The Digihelic® controller is the ideal instrument for pressure, velocity and flow applications, achieving a 0.5% full scale.The Digihelic® controller allows the selection of pressure, velocity or volumetric flow operation in several commonly used engineering units. Two SPDT control relays with adjustable dead bands are provided along with a scalable 4-20 mA process output. In velocity of flow modes, a square root output is provided on the 4-20 mA signal to coincide with the actual flow curve. The Series DH provides extreme flexibility in power usage by allowing 120/220 VAC and also 24 VDC power which is often used in control panels.Programming is easy using the menu key to access 5 simplified menus which provide access to: security level; selection of pressure, velocity or flow operation; selection of engineering units; K-factor for use with flow sensors; rectangular or circular duct for inputting area in flow applications; set point control or set point and alarm operation; alarm operation as a high, low or high/low alarm; automatic or manual alarm reset; alarm delay; view peak and valley process readings; digital damping for smoothing erratic process applications; scaling the 4-20 mA process output to fit your application's range; Modbus® communications; and field calibration.With all this packed into one product it is easy to see why the Digihelic® controller is the only instrument you will need for all your pressure applications.Product Applications SCFM Flow in Ducts Air Flow for Industrial Ovens Filter Status Clean Room Pressure Fume Hood Air Flow Medical Room Pressures Static Pressures in Ducts or Buildings Damper Control Fan Control.