EMD 4000 General Eastern Humidity Sensor

EMD-4000
General Eastern
Humidity Sensor
The EMD-4000 is a bulk resistance-type humidity
sensor based on the impedance change of a thinpolymer 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.
Features
• Excellent interchangeability
• Available in 5% accuracy
• Economical
• Recovers from condensation
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.
• Good resistance to chemical vapors
• Fast response
• Low hysteresis
Page 1 of 3
Willow Technologies Ltd.
+ 44 (0) 1342 717102
Unit 3 Borers Yard, Borers Arms Road, Copthorne, West Sussex, RH10 3LH, United Kingdom.
+ 44 (0) 1342 717014  [email protected] http://www.willow.co.uk
W42014
The EMD-4000 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-4000 exhibits
function of humidity and temperature and has low
hysteresis and fast response.
The EMD-4000 is priced for Original Equipment
Manufacturers (OEMs) with requirements to incorporate
humidity sensors in HVAC controls, data loggers,
appliances, automotive applications and consumer
products.
Response Curves
EMD4000 (1 VAC, 1 kHz)
1.00E+07
1.00E+06
Impedance (ohms)
The EMD-4000 is capable of withstanding
environments where organic vapors are present. It
recovers from condensing environments and may
be used at temperatures up to 185°F (85°C). The
EMD-4000 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.
5C
15C
25C
35C
45C
1.00E+05
1.00E+04
1.00E+03
1.00E+02
10
20
30
40
50
60
70
80
90
RH%
Page 2 of 3
Willow Technologies Ltd. Unit 3 Borers Yard, Borers Arms Road, Copthorne, West Sussex, RH10 3LH, United Kingdom.
+ 44 (0) 1342 717102
+ 44 (0) 1342 717014  [email protected] http://www.willow.co.uk
W42014
EMD-4000
.200 in
(5.08 mm)
%RH Range at 77°F (25°C)
.400 in
(10.2 mm)
20% to 95%
Operating Temperature
.80 in
(20.3 mm)
41°F to 140°F (5°C to 60°C)
Storage
0% to 95% RH, -40°F to 185°F (-40°C to 85°C)
Accuracy
• ±5% RH standard
.100 in
(2.54 mm)
Repeatability
.060 in
(1.52 mm)
typical
.025 in
(.635 mm)
±0.5% RH
Impedance
72K Ω at 77°F (25°C), 50% RH with 1 VAC at
1 KHz excitation
Response Time
<1 minute for 63% step change in non
moving air
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 Ω at 30 ppm at 77°F
(25°C)
• 3 months at 77°F (25°C): <5% drift, 2% RH typical
• 1 month at 185°F (85°C): <5% drift, 2% RH typical
Hysteresis
<1% RH at 77°F (25°C) for step change from
30% to 98% RH then back to 30% RH
Water Vapor Saturation
100% RH/77°F (25°C)/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
Temperature Dependence
0.5% RH/°F (°C, average)
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
Caution
DC current should never be applied to the EMD-4000
humidity sensor. Application of direct current will
polarize the sensor and cause an irreversible shift.
Only a symmetrical AC excitation current should be
applied. Amphenol recommends that application of a
low level AC excitation (1 VAC, 1 KHz typical) to minimize
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
Page 3 of 3
Willow Technologies Ltd. Unit 3 Borers Yard, Borers Arms Road, Copthorne, West Sussex, RH10 3LH, United Kingdom.
+ 44 (0) 1342 717102
+ 44 (0) 1342 717014  [email protected] http://www.willow.co.uk
W42014
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