Newport Hygrodynamics 8074A User manual

newport-scientific.com
P 301-498-6700
F 301-490-2313
email [email protected]
[email protected]
Newport Scientific, Inc
8246E Sandy Court
Jessup, MD 20785-9632
USA
Portable Dew Point Monitor
Model 8074A

8074A_B.docx October 2016

8074A_B.docx October 2016
Contents
Specifications............................................................................... 1
Product Overview........................................................................ 2
Features and Accessories ........................................................ 3
Operation .................................................................................... 5
Sample Tubing Connection...................................................... 5
Power Connection ................................................................... 6
Dryer Performance Testing ..................................................... 6
Material Dryness Testing......................................................... 7
Remote Monitoring/Data Logging........................................... 9
Maintenance and Adjustments ................................................. 10
Monitor Disassembly and Assembly ..................................... 10
Sensor Replacement.............................................................. 11
Display Units.......................................................................... 13
Alarm Set Point Adjust........................................................... 13
Troubleshooting ........................................................................ 15
Dry-Down Test....................................................................... 15
Troubleshooting Hints ........................................................... 16
Spare Parts & Accessories ......................................................... 19
Warranty.................................................................................... 20

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Specifications
DEW POINT RANGE
+10F to +70F (at 73F air temp)
(varies with ambient air
0F to +50F (at +50F air temp)
temperature)
+35F to +90F (at 100F air temp)
TYPICAL ACCURACY
±3F
MAX. PROCESS AIR TEMP.
275F
ALARM SET POINT
+50F dew point (adjustable)
SENSOR PART NUMBER
1826-2
ANALOG OUTPUT SCALING
-40F to +70F, 0-5V and 4-20mA
ANALOG OUTPUT PORT
3 pin M8 male jack
POWER REQUIREMENTS
115VAC 50/60HZ
0.15A max
(230VAC optional)
DIMENSIONS
10.75” X 9.75” X 4.75”
NET WEIGHT
7.0lbs

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Product Overview
The 8074A dew point monitor is used to test the moisture
content of industrial process air. The measurement range of
the 8074A makes it ideal for testing the function of refrigerant
dryers, dehumidifiers, and hot air dryers.
The 8074A has an integrated vacuum pump which continuously
draws in a small sample of process air and provides real-time
indication of dew point on an LED display. The sampling system
allows dew point testing of process air at atmospheric pressure,
typically seen in bulk material drying, food processing, and
environmental systems. Because the sensor is contained in the
monitor, only a thin tube is required to access and sample the
process air. This allows testing in applications where a sensor
won’t fit or its presence might disturb or contaminate the
underlying process.
In addition to the numeric LED display, the monitor includes
dew point condition indicator lights, an audible alarm, and a
linear signal output.

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Features and Accessories
The dew point monitor and its accessories are housed in a
heavy-duty portable carrying case. When not in use, all parts of
the product are contained within the case, protected from the
elements and safeguarded from loss.

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POWER SWITCH
Turns monitor ON and OFF.
ALARM SWITCH
Enables local audible alarm when dew
point exceeds the alarm set point.
LINE CORD
Provides connection to power.
BEEPER (not
shown)
Gives audible signal when the measured
dew point is above the alarm set point.
DEW POINT
CONDITION
INDICATORS
Green light is on when dry air is detected,
red light is on when measured dew point is
above the alarm set point.
SAMPLE TUBING
Six feet of heat resistant tubing draws in
process air to be measured.
AIR FILTER
Installed in-line with sample tubing,
removes fine particulates from sample air.
DESICCANT TUBE
Provides dry air for testing the monitor’s
response.
TUBING STORAGE
BRACKET
Allows storage for sample tubing and
desiccant tube when not in use.
ANALOG OUT
4-20mA and 0-5V output for remote
monitoring or data logging. Mates with
standard 3 pin M8 female cable.
NOTE: The 8074A is shipped with a paper desiccant pack
which can be discarded when the unit is unpacked.

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Operation
The 8074A is designed to sample process air that is near
atmospheric pressure, NOT compressed air. If you are
attempting to monitor compressed air, consult the factory for
other model options.
CAUTION: The carrying case is not heat resistant. It may melt
or distort if left resting on the hot parts of a heated dryer. If a
surface is too hot to touch, it is too hot for the monitor!
Sample Tubing Connection
To enable testing of your process air, you must provide fittings
in your system that will accept the 8074A’s 3/16” ID sample
tubing. This can be a barbed hose fitting or a piece of ¼” copper
tube that provides access to the process air. The point of
attachment must be secure and leak-free.
The plastic sample tubing supplied with the monitor can
tolerate temperatures up to 275F (135C).Higher process air
temperatures can be cooled to a safe level by sampling through
a few feet of ¼” copper tubing.
Select the sample locations based on your testing needs (refer
to diagram below). It is suggested that you have permanently
accessible sample points at both the dryer output and return
hoses. If your dryer has threaded test ports on the inlet and
outlet connections (typically for thermocouples) use these to
make points of connection. Some dryer manufacturers provide
a port for air sampling.

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NOTE: When storing the 8074A, carefully coil the sample
tubing and tuck it behind the tubing storage bracket. This will
prevent kinks from forming in the tubing when the lid is
closed.
Power Connection
The 8074A is supplied with a 6 foot line cord for connection to
power. Always connect the monitor to the correct supply
voltage. Do not attempt to replace the line cord with a different
plug type to accommodate other supply voltages. The 8074A
will be damaged if connected to incorrect supply voltage.
Dryer Performance Testing
The performance of a dryer can be evaluated by measuring the
dew point of its output air.
Dryer testing
sample location
Material testing
sample location
Dryer
Hopper
Air flow
Typical material drying system

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Connect the 8074A sample tubing to a point on the dryer’s
output line, before the hopper. Make sure not to exceed the
sample tubing temperature rating.
Turn on the 8074A and allow the reading to stabilize. The initial
reading will reflect the current room dew point until all the
ambient air is purged from the monitor’s tubing and internal
fittings. After a few minutes, the reading should start to reflect
the actual process dew point. It can take 30 minutes or more
for the unit to stabilize when first turned on.
Leave the 8074A connected and turned on during material
drying and processing. The built in red light and audible beeper
will indicate dryer trouble within moments of a dew point rise.
A constantly high reading on the 8074A may indicate a
malfunctioning dryer or one that is overloaded by damp
material in the hopper. If you suspect that the 8074A is giving
an incorrect high reading, perform the Dry-Down Test described
in the Troubleshooting section of this manual.
Material Dryness Testing
The dryness of material in a hopper can be inferred from the
dew point of air exiting the hopper.
Connect the 8074A sample tubing to a point in the hopper’s air
output. Make sure not to exceed the sample tubing
temperature rating.
Turn on the 8074A. When a hopper is initially loaded with
material, high dew points at the hopper’s air return are normal
while moisture is removed. If drying time is expected to be all
day, leave the 8074A sample tubing connected, but keep the

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monitor turned off. Every few hours, turn on the 8074A and
allow time to obtain a stable reading. As the material dries, the
8074A dew point reading will start to drop. Material processing
can begin when the dew point reading is at an acceptable level.
If the 8074A reading is stuck at a high dew point, change the
sampling point to the output of the dryer. Follow the
instructions for Dryer Performance Testing described above to
make sure the dryer is providing low dew point air to the
hopper.

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Remote Monitoring/Data Logging
The 8074A analog output jack can be used to monitor or log
dew point over a period of time.
The output jack is a 3 pin male M8 type connector. This
connector accepts standard threaded or snap fit female M8
cables.
Pin No.
Wire Color*
Signal
1
Brown
4-20mA (current sourcing)
3
Blue
Ground
4
Black
0-5V
* standard wire color code of M8 cable assemblies
Note that the output scaling is -40F to +70F.
1
3
4
Connector pinout
(front view)

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Maintenance and Adjustments
Newport Scientific offers a maintenance and calibration service
for the 8074A. This service should be performed annually.
Alternatively, most wearable parts can be replaced by the user.
To access the serviceable parts inside the monitor, the 8074A
panel must be removed from the carrying case.
Monitor Disassembly and Assembly
WARNING: Unplug the 8074A from power before disassembly.
Even with the power switch off, voltages are present inside the
unit.
Slide the sample tubing off of the front panel elbow.
Use a screwdriver to remove the 5 screws along the perimeter
of the panel holding it in the case. Use the sample tubing elbow
to help lift the panel straight up and out of the case.
When re-assembling the panel into the case, make sure sensor
cable wires are tucked in and not pinched under the panel as
you lower it into the case.
Install the 5 mounting screws, taking care not to cross thread
the screws as you proceed. The screws only need to be snug to
the panel, do not overtighten!

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Sensor Replacement
The internal sensor should be replaced on a yearly basis. It is
difficult to verify the accuracy of the sensor in the field. For
most users, an annual sensor
replacement can assure good
operation of the monitor. It is
recommended to replace the sample
tubing and air filter whenever the
sensor is replaced.
With the panel removed from the
case, locate the sensor housing and
pull the individual sensor wires from
the 4 pin insert. The wires will unplug
straight out.
Unscrew the hex nut from the top of the sensor housing. With
the hex nut unscrewed, remove the sensor and 4 pin insert
along with gasket. The sensor
will then unplug from the
insert. You may use a non-
metal object to pry between
the sensor PC board and the
insert to start the separation of
the parts.

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Plug the new sensor into the 4
pin insert. Align the notch on
the sensor PC board with the
notch on the back of the 4 pin
insert. Push in firmly by
holding the PC board. The
sensor will not seat fully down
into the insert, this is normal.
Carefully replace the sensor, gasket, and insert back into the
housing and reconnect each wire as shown. Note the location
of the notch on the insert and use that as a reference point to
orient each wire as shown below.
Thread the hex nut into the housing, securing the 4 pin insert
and sensor. The nut should only be hand-tightened.
Notch
location
Black
Red
Green
White
4 pin insert wire connections
(viewed from wire side)

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Display Units
The 8074A is factory set to
display dew point in F. The
display can be changed to
C by jumper configuration.
With the 8074A panel
removed from the carrying
case, locate the
configurable parts near the
upper left corner of the PC
board. Move J6 and J7
jumpers to the C position to
display dew point in C.
Alarm Set Point Adjust
To change the dew point at which the monitor indicates an
alarm (high dew point indication), refer to the DISPLAY MODE
SWITCH labeled S1 and the ALARM ADJUST potentiometer
labeled SET1 located on the circuit board.
WARNING: The alarm set point adjustment is performed with
the 8074A powered on. Avoid touching live electrical parts
during this procedure as hazardous voltages are present!

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OPER
SET1
SET2
S1
Apply power to the unit and turn it on with care, making sure
not to touch any electrical terminals inside.
Configure the S1 switch as shown here, with
SET1 position ON and all others OFF. In this
configuration, the front panel display will
indicate the current alarm set point. Adjust the
SET1 potentiometer to the desired set point.
When the front panel display indicates your
desired set point, return the S1 switches to the
normal operating configuration. The front
panel display will now show the actual
measured dew point.
Remove power and reinstall the 8074A panel into the carrying
case.
OPER
SET1
SET2
S1

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Troubleshooting
Dry-Down Test
The desiccant tube is used to provide a reliable source of dry air
for field testing the monitor’s response. Follow this procedure
if the monitor indicates a constant high dew point but you
suspect that your process air is dry. The desiccant tube
generates a dew point well below the measurement capability
of the 8074A, so it won’t test the accuracy of the monitor, but it
can help troubleshoot a damaged sensor or internal air leaks.
NOTE: Make sure the desiccant is blue in color. If the
desiccant is fully pink, it will not produce dry air and you
should purchase a new desiccant tube before testing.
Remove the yellow caps from the ends of the desiccant tube-
save them for re-use. Connect the sample tubing to one end of
the desiccant tube, and the sample air outlet to the other end.
This will create a closed loop of dry air flow through the monitor
and desiccant tube. Turn on the dew point monitor. In a few
minutes, the reading
should start to drop.
If the monitor doesn’t
respond, refer to the
troubleshooting hints
for more information.
Replace the desiccant
tube caps when done.

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Troubleshooting Hints
Monitor display is stuck near 70F
Possible Cause
Corrective Action
Damp sample tubing or
sensor housing
If high dew point air was
recently sampled, there may be
condensation in the tubing and
fittings. Perform the Dry-Down
test to purge the system of
moisture.
Sensor damaged or
contaminated
Using a fresh desiccant tube,
perform the Dry-Down test. If
response is slow, replace sensor.

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Monitor reads near 0F when turned on and
doesn’t change
Possible Cause
Corrective Action
Sensor cable disconnected
Disassemble the monitor and
make sure sensor wires are
plugged into the 4 pin insert.
Confirm that the wires are in the
correct order (refer to Sensor
Replacement section).
Sensor or circuit board
damaged
Disassemble the monitor and
locate the white and green
sensor wires on the terminal
block (terminals A and B). Place
a jumper across terminals A and
B and turn monitor on. Check
for a high dew point indication
on display. If display responds,
the sensor is likely damaged, if
the display shows no response,
the circuit board may be the
problem.