Dwyer, 475-3-FM, Series 475 Mark III Handheld Digital Manometer, 0-200.0' w.c., Max. Pressure 30 psig±0.5% AccuracyThe Dwyer® Series 475 Mark III Handheld Digital Manometer is ideal for field calibration, monitoring or trouble shooting HVAC systems, clean rooms or a wide range of other low pressure pneumatic systems. The Series 475-FM is approved and is intrinsically safe for hazardous locations, Class 1, Div.1, Group A, B,C, D, T4. Its simple operation and easy to read digital display make it an indispensable test instrument for the plant engineer, industrial hygienist and HVAC technician. When used with a Dwyer® Pitot tube, the Series 475 Mark III can also be used as an air velocity gage.The Series 475-FM Mark III is housed in a durable extruded aluminum case with its solid state circuitry mounted on a tough fiberglass epoxy circuit board. To meet the most demanding applications and to provide stability of instrument reading, the 1" w.c. range is compensated for position sensitivity through use of a unique dual sensor system. A standard 9 volt battery provides up to 100 hours of operation. Dual push pads on the front panel control on-off, auto zero, and pressure unit selection. No setup or leveling. The large 0.42" LCD display is easy to read, minimizing data collection errors. Units include a"low battery" indicator. The pressure sensor used is a highly stable silicon piezoresistive device. Standard connections are dual sized for 1/8" or 3/16" I.D. vinyl or rubber tubing. Complete instructions are conveniently printed on rear of housing.FeaturesNew Low Range Option 0-1.000 in. w.c.Measures Positive, Negative and Differential PressuresRugged, Extruded Aluminum CaseLightweight, Fast and Easy to UseSelectable English/Metric UnitsFM ApprovedApprovalsFM.