EMD-4000B humidity sensor the EMD-4000B is a bulk resistance-type humidity sensor based on the impedance change of a thin- flm polymer due to water vapor absorption. the polymer is deposited on bismuth alloy terminals, which are set on a ceramic substrate. the sensor is excited by a low voltage alternating current and the impedance measured as a function of relative humidity. the thin-flm polymer consists of chemical functional groups that disassociate into ionic species as water vapor is absorbed. this results in increased electrical conductance through the sensor or a decrease in impedance. the impedance is an inverse exponential function of the surrounding humidity. features ? excellent interchangeability ? standard accuracy 5% ? economical ? recovers from condensation ? good resistance to chemical vapors ? fast response ? low hysteresis a mphenol advanced sensors ?
the EMD-4000B is capable of withstanding environments where organic vapors are present. it recovers from condensing environments and may be used at temperatures up to 185f (85c). the emd- 4000b is also capable of in situ measurement of soluble water in organic liquids such as transformer oil, gasoline, toluene, acetone, and other compounds of varying hydrogen bond strengths. the EMD-4000B is highly repeatable and interchangeable. the sensor is manufactured in high yields to 5% rh or better tolerances. this results in a sensor that can be used in many designs without the need for humidity calibration, where the measuring circuit can be calibrated with external reference resistors. the EMD-4000B exhibits a well defned standard response curve as a function of humidity and temperature and has low hysteresis and fast response. the EMD-4000B is priced for original equipment manufacturers (oems) with requirements to incorporate humidity sensors in hvac controls, data loggers, appliances, automotive applications and consumer products. 5c 15c 25c 35c 45c 1.00e+07 1.00e+06 1.00e+05 1.00e+04 1.00e+03 1.00e+02 10 20 30 40 50 60 70 80 90 rh% impedance (ohms) emd4000 (1 v a c, 1 khz) response curves
%rh range at 77f (25c) 20% to 95% operating temperature 41f to 140f (5c to 60c) storage 0% to 95% rh, -40f to 185f (-40c to 85c) accuracy ? 5% rh standard ? 3% rh available on request repeatability 0.5% rh impedance 72k w at 77f (25c), 50% rh with 1 vac at 1 khz excitation response time <1 minute for 63% step change in non moving air hysteresis <1% rh at 77f (25c) for step change from 30% to 98% rh then back to 30% rh temperature dependence 0.5% rh/f (c, average) ordering information part number - emd4000b bulk resistance-type humidity sensor 5% long term drift 0.1% rh/year typical in clean, chemical free air dimensions 0.2 in (5.1 mm) wide x 0.4 in (10.2 mm) high x 0.02 in (0.51 mm) thick leads: 0.4 in (10.2 mm) long x 0.15 in (3.81 mm) wide x 0.01 in (0.25 mm) thick on 0.1 in (2.54 mm) centers exposure to saturated chemical vapors ? toluene, 25,200 ppm/3 days: <2% rh drift ? hexane, 152,000 ppm/3 days: <2% rh drift ? methanol, 127,000 ppm/3 days: <5% rh drift transformer oil; 60k w at 30 ppm at 77f (25c) ? 3 months at 77f (25c): <5% drift, 2% rh typical ? 1 month at 185f (85c): <5% drift, 2% rh typical water vapor saturation 100% rh/77f (25c)/1000 hours storage; <3% rh drift typical; 1/16 in (1.59 mm) water droplet covering entire sensor surface for 10 minutes followed by drying via air ventilation; <5% drift caution dc current should never be applied to the EMD-4000B humidity sensor. application of direct current will polarize the sensor and cause an irreversible shift. only a symmetrical ac excitation current should be applied. telaire recommends that application of a low level ac excitation (1 vac, 1 khz typical) to minimize self- heating effects. .200 in (5.08 mm) .400 in (10.2 mm) .80 in (20.3 mm) .100 in (2.54 mm) .060 in (1.52 mm) typical .025 in (.635 mm) EMD-4000B specifcations
www.amphenol-sensors.com ? 2014 amphenol corporation. all rights reserved. specifcations are subject to change without notice. other company names and product names used in this document are the registered trademarks or trademarks of their respective owners. a mphenol advanced sensors aas-920-060e 11/2014
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