Phymetrix dewPatrol User manual

PhyMetrix dewPatrol Moisture Analyzer
User's Manual

Please visit our website at www.phymetrix.com for other products that may be applicable to your
needs.
Every effort has been made to ensure accuracy in the contents of this manual. Should there be
any doubts to the accuracy of the content please contact the manufacturer.
The contents of this manual are subject to change without notice.
The instructions, procedures, drawings, specifications and concepts contained in this manual are
the property of Phymetrix Inc., and shall not be used as the basis for the manufacture or sale of
apparatus or services, or reproduced or copied or transmitted in any form or by any means
without written permission.
Read this manual before using the analyzer. For personal and system safety, and for
optimum product performance, make sure you thoroughly understand the contents
before installing, using, or maintaining this analyzer.

Warranty
This instrument is warranted, to the original end-user purchaser, against defects in materials and
workmanship. Liability under this warranty is limited to restoring the instrument to normal
operation or replacing the analyzer, at the sole discretion of the manufacturer. Batteries are
specifically excluded from any liability. This warranty is effective from the date of delivery to
the original purchaser. If Phymetrix determines that the equipment was defective, the warranty
period is:
• one year from delivery for electronic or mechanical failures
• one year from delivery for sensor shelf life
If Phymetrix determines that the equipment was damaged by misuse, improper installation, the
use of unauthorized replacement parts, or operating conditions outside the guidelines specified,
the repairs are not covered under this warranty.
Normal wear and tear, parts damaged by abuse, misuse, negligence or accidents are specifically
excluded from the warranty.
Purchaser acknowledges that in accepting and using this analyzer, notwithstanding any contrary
term or provision in the purchaser's purchase order or otherwise, the only warranty extended by
Phymetrix is the express warranty contained herein. Purchaser further acknowledges that there
are no other warranties expressed or implied, including without limitation, the warranty of
merchantability or fitness for a particular purpose; that there are no warranties which extend
beyond the description of the face hereof; that no oral warranties, representations, or guarantees
of any kind have been made by Phymetrix, its distributors or the agents of either of them, that in
any way alter the terms of this warranty; that Phymetrix and its distributors shall in no event be
liable for any consequential or incidental damages, including but not limited to injury to the
person or property of the purchaser or others, and from other losses or expenses incurred by the
purchaser arising from the use, operation, storage or maintenance of the product covered by the
warranty; that Phymetrix’s liability under this warranty is restricted to repair or replacement of
defective parts at Phymetrix sole option; and that Phymetrix neither assumes nor authorizes any
other person to assume for it any other warranty. The warranty shall be void if serial numbers
affixed to the products are removed, obliterated or defaced.
Return Policy / Procedures
If equipment malfunction is suspected or it is determined that the analyzer needs recalibration,
please contact Phymetrix.
Communicate the instrument model number, serial number, application including dewpoint
range being measured, and the details of the problem.
If the analyzer needs factory service you will be issued a RMA and shipping instructions.
The factory will diagnose the equipment and upon determining the problem will notify you
whether the terms of the warranty cover the required repair. If the costs are not covered you will
need to approve the estimated cost in order to proceed with the repair.

Revision #2 April 2021
Table Of Contents
1Introduction............................................................................................................................. 1
2Important Principles of Operation .......................................................................................... 2
2.1 Sensor Operating Principle............................................................................................... 2
2.2 Sampling Mechanism Operating Principle ...................................................................... 2
3Precautions ................................................................................................................ 2
4Moisture System Considerations ............................................................................................ 3
4.1 Integrity of the Materials of the User’s System ............................................................... 3
4.2 Moisture Backflow Along the Walls of the Exhaust Tubing ........................................... 3
4.3 Temperature Dependant Equilibrium............................................................................... 4
5Sampling Techniques.............................................................................................................. 4
5.1 Choosing a Measurement Site.......................................................................................... 4
5.2 Sample Conditioning........................................................................................................ 4
5.3 Tubing and Fittings .......................................................................................................... 5
5.4 Sample Pressure ............................................................................................................... 5
5.5 Measuring Gasses at Pressures above 50 psia.................................................................. 6
6User Interface Overview ......................................................................................................... 7
7Operating the Analyzer ........................................................................................................... 7
7.1 Mechanical Connections .................................................................................................. 8
7.2 Powering the Analyzer ON or OFF.................................................................................. 8
7.3 The Display Mode............................................................................................................ 9
7.4 Units to Display the Measurement ................................................................................... 9
7.5 Pressure Correction ........................................................................................................ 10
7.6 Navigating Through the Menus...................................................................................... 12
7.7 The Functions Available in the Menus .......................................................................... 13
7.8 External Connections ..................................................................................................... 15
7.8.1 USB - Battery Use & Charging .............................................................................. 15
7.8.2 4/20mA Loop .......................................................................................................... 16
7.8.3 Alarm Relay............................................................................................................ 16
7.9 AudioVisual Alarm (NFPA compliant) ......................................................................... 17
8Data Logging ........................................................................................................................ 17
8.1 Single Data Point Log .................................................................................................... 17
8.2 Continuous Data Logging .............................................................................................. 18
8.3 Retrieving the Data / Clearing the Memory................................................................... 19
8.4 Logging Data Directly into a Personal Computer.......................................................... 19
9Single Point Calibration........................................................................................................ 19
10 Troubleshooting and Maintenance........................................................................................ 20
10.1 Cleaning...................................................................................................................... 20
10.2 Recharging the Battery ............................................................................................... 20
10.3 Self Diagnostics.......................................................................................................... 21
10.4 Suspected Erroneous Measurements .......................................................................... 22
11 Specifications ........................................................................................................................ 24
Appendix A Mini-Demister ..................................................................................................... 25
Appendix B DewPatrol Rear View.......................................................................................... 26
Appendix C Manual Calibration Procedure ............................................................................ 27
Appendix D Analyzer Calibration Log.................................................................................... 28

Revision #2 April 2021
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1 Introduction
Thank you for purchasing the state-of-the-art Phymetrix DewPatrol Moisture Analyzer, it is a
weatherproof handheld analyzer which includes a built-in liquid separator, metering valve and
flow meter. This User’s Manual describes the functions of this analyzer as well as its operating
methods and handling precautions. There are also some sections that review general knowledge
and concepts of water vapor science. Read this manual thoroughly before using the analyzer.
Check our website “www.phymetrix.com/” for latest versions of documentation regarding this
analyzer.
Conventions used in this manual:
 When using the word “system” in this manual we are referring to the user’s system in which
the moisture content is being measured. This could be a simple configuration of a pressurized
gas bottle with a pressure regulator, or a complex system of dryers, filters, regulators, long
tubing, valves etc.
 When referring to text that is displayed on the analyzer screen, it is presented in this manual
using a font that makes it stand out.
The analyzer part number is displayed upon power-up and in the About screen, the dash numbers
following the main part number signify options as follows:
-P for internal pressure sensor, -A for analog output 4/20mA, R- for alarm relay or AV alarm
Check to see that your analyzer has arrived intact with all accessories. The international plug kit
is supplied only when shipped outside the USA. The rechargeable batteries are factory installed,
and are not user serviceable.
Swiveling Quick-Connect
Inlet Metering Valve
Glass Bowl Demister
Drain Valve
Weatherproof Battery
Charger Connector
DewPatrol Side View
Model: PDPa
Save the packing materials until you have verified that there is no concealed damage, it may also
be useful for future transportation.

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2Important Principles of Operation
2.1 Sensor Operating Principle
The nanopore sensor utilized in this analyzer measures the amount of water vapor molecules that
have entered its pores. This amount is directly proportional to the partial water vapor pressure in
the gas surrounding the sensor, and the partial water vapor pressure is dependent on the water
vapor content of the gas and the total pressure of the gas. Thus to compute the water vapor
content of the gas under measurement the analyzer has to “know” the total pressure of the gas. If
the analyzer was purchased with the pressure sensor option then the total pressure is measured
and utilized by the analyzer, if there is no built-in pressure sensor then the user should enter the
total pressure into the analyzer, this can be easily done by entering atmospheric pressure (the
analyzer default setting) and measuring at atmospheric pressure by allowing the outlet (exhaust)
port to vent without restrictions.
2.2 Sampling Mechanism Operating Principle
The analyzer is equipped with a built-in sampling system which has the required tight seals to
measure low moisture. The connection to the air system is simple, using existing quick connect,
allowing installation directly on the compressed air pipe or hose. The swiveling inlet port adjusts
for comfortable viewing under all installation conditions. Alternatively dewPatrol can be
permanently installed using its 1/4"NPT inlet port. DewPatrol includes integral sampling system
consisting of inlet flow control valve, flow meter, particulate filter, coalescing filter (glass 360°
view) demister with drain valve, and a convenient swiveling quick connect inlet port.
3Precautions
•Observe the appropriate electrical safety codes and regulations. Consult with National
Electrical Code, and/or other nationally or locally recognized procedures relevant to your
location.
•When measuring flammable, explosive or toxic gasses; vent the sample outlet to a safe
and appropriate location.
•When measuring high pressure samples (do not exceed 150 psia or optional 500 psia); be
sure that the system is depressurized before connecting or disconnecting the sample
tubing.
•Corrosives such as Ammonia, HCl and Chlorine should be avoided; H2S and SO2can be
present if the moisture content is below 10 PPMv.
•Avoid extreme temperatures, pressures and mechanical vibration, refer to specifications.
•Do not disassemble the analyzer.
•Do not use with contaminants and liquids, refer to section 5.2 for sample conditioning.
•The handheld analyzer is weatherproof and can be left in the rain, however the inlet and
outlet ports must be protected from ingress. Do not leave the analyzer exposed to rain or
other contamination sources while the inlet or outlet ports are unprotected. When
performing a measurement at atmospheric pressure, the outlet port is sufficiently
protected from rain if there is at least 1 LPM (2 SCFH) of flow. Be sure to have the USB
connector protective cap secured in order to meet the weatherproof specifications.

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4Moisture System Considerations
This section is offered as background information. There are several considerations in keeping
your system at a stable and pure moisture level, free of contamination from ambient air moisture:
•The integrity of the materials isolating the pure gas from the external air, including leaks
from poorly secured fittings.
•The backflow of moisture through the exhaust outlet, the exhausts of both the analyzer
and the user system under measurement should be considered.
•The effects of temperature on the equilibrium of moisture and the surrounding materials,
often observed as diurnal cycles in the measurement.
4.1 Integrity of the Materials of the User’s System
Before considering the materials of a system where a specified dewpoint level must be
maintained, one should review two concepts.
•Compared to the structure of solids the water molecule is much smaller. This is true
compared to even the crystalline structure of metals but especially important in the
polymer structure of plastics.
•Water vapor pressure in gasses obeys Dalton’s law of partial pressures, which states that
the overall pressure of a gas is the sum of its constituent gases. And each gas seeks to
equilibrate its pressure across gradients of only its own gas pressure.
Let’s consider air in a pipe at a total pressure of 100 psia, which has been dried down to -40°C
dewpoint. The partial water vapor pressure in the pipe is 0.13mB. If the ambient temperature is
22°C with relative humidity of 30%, then the partial water vapor pressure in the surrounding
atmosphere is 7.9mB or approximately 60 times greater than the partial water vapor pressure in
the pipe. Thus even though the total pressure in the pipe is much greater that the pressure outside,
the reverse is true for the water vapor pressure, and as we discussed earlier the water vapor seeks
to equilibrate its pressure thus it “wants” to flow from the outside to the inside and will do so
through the cracks in the joints (such as poorly tightened fittings, or NPT threads even if they are
properly taped), as well as through the walls of pipes tubes and other vessels. The integrity of the
system is extremely important in maintaining a stable low dewpoint; for dewpoints below -60°C
always use stainless steel or PTFE (Teflon), while for higher dewpoints you can use copper or
galvanized steel; but never use rubber, Tygon, Nylon or other plastic or tubing. Pressure
regulators often use rubber diaphragms, check and if necessary replace with a stainless steel
diaphragm regulator. Filter bowls should be stainless steel or glass, plastic bowls should be
avoided. If a flow meter is placed at the inlet of the analyzer it should have a glass tube and be
rated for the expected pressure levels, however in general it is best to place flow meters at the
analyzer exhaust.
Another material consideration relates to materials sealed in the system such as paper filters;
these may not contribute to leaks but will greatly slow down the measurement because they will
adsorb and desorb water molecules as the system dewpoint is changing.
4.2 Moisture Backflow Along the Walls of the Exhaust Tubing
The linear velocity of gas flowing in a tube is close to zero immediately along the wall of the
tube. This coupled with the previously discussed “need” for the moisture to flow from the higher
water vapor pressure to the lower one, allows for water molecules to flow against the flow
through the exhaust outlet into the sampling chamber of the analyzer. The fact that water

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molecules are highly polar further enhances their ability to migrate against the gas flow at the
sampling chamber outlet. To prevent this backflow of moisture from influencing the
measurement, a minimum flow of 2 SCFH (1 SLPM) should be maintained; higher flows will
produce faster equilibrium time and thus are desirable for quick measuring.
4.3 Temperature Dependant Equilibrium
The effect of ambient temperature on the gas partial water vapor pressure of a system can change
the moisture content of the gas. This is not the temperature sensitivity of the measuring analyzer,
rather the actual change of partial water vapor pressure in the user’s system due to increase in
ambient temperature and thus the increase of energy of the water molecules on and in the walls
of the system (tubing, vessels etc…). A typical example would be the observation of a daily
cycling of the measurement in a system with tubing or other components exposed to direct
sunlight. During the day as the sun transfers energy into the system, the dewpoint will appear to
increase, while at night the dewpoint will appear to decrease. There may be other reasons for this
daily dewpoint cycling such as the effect of sun/temperature on the efficiency of gas dryers etc.
It is possible to minimize this effect using sun shields and tubing insulators. Alternatively one
may study the response of the particular system to ambient temperature, by logging data over
several days during different seasons, and compensating the measurements for this effect. The
temperature effect will vary greatly depending on the size and materials of the system, for
example stainless steel walls will have a much smaller effect than brass or copper walls.
5Sampling Techniques
The amount of moisture measured will be influenced by the system moisture content as well as
leaks in the system and transient effects of adsorption / desorption from materials in the system
(as described in the previous section).
5.1 Choosing a Measurement Site
Portable analyzers because of the nature of the situation (spot checking) perform extractive
measurements. It is important to choose an appropriate sampling location that is representative of
the moisture content of the system of interest.
5.2 Sample Conditioning
Particulate and liquid contaminants can affect the measurement, especially the response time.
Sample conditioning may be necessary to remove contaminants and improve the measurement
and the longevity of the sensor. Make sure that sample conditioning components are made of
suitable materials. Avoid paper or other fiber filter elements, use stainless steel instead. For
expected dewpoints below -50°Cdp (39 PPMv), avoid plastic filter bowls, use stainless steel or
glass instead. Make sure that highly hygroscopic contaminants (e.g. Triethylene Glycol used in
drying Natural Gas) do not reach and coat the sensor as they will disturb the sensor to system
equilibrium and can greatly affect the measurement and response time when the analyzer is used
at other locations. Drain trapped liquids from filter bowls.
If the application is suspect of possible presence of liquids for example:
• Compressed air with possible oil and/or water,
• Gas Insulated Switchgear or Transformer, SF6or N2blanket with suspected oil carryover,
• Natural Gas with possible Triethylene Glycol carryover,

5
The built-in Gas-Liquid separator Mini-Demister provides a visible area of liquid separation and
a metering valve for draining the accumulated liquid. Refer to Appendix A for details on the use
of the Mini-Demister.
5.3 Tubing and Fittings
Make sure all tubing is constructed of materials suitable for low dewpoint measurement, i.e.
stainless steel or Teflon, do not use rubber or plastic tubing (refer to section 4.1 for more details).
If using quick disconnect on inlet, be aware that some female disconnects do not seal as tightly
as others.
Check for leaks after connecting.
Flow meters can be a source of moisture ingress especially if they have a plastic flow tube;
ensure flow meters are connected at the analyzer exhaust, not at inlet. However the metering
valve should be at the inlet in order to maintain constant atmospheric pressure in the sampling
chamber.
5.4 Sample Pressure
Pressure variations will affect the measurement. Higher pressure is more likely to produce
condensation and thus erroneous readings or even damage the sensor. If the sample pressure
needs to be reduced use a suitable pressure dropping device such as a stainless steel needle valve
or pressure regulator with a stainless steel diaphragm or a flow control orifice. Make sure Joule-
Thomson effects do not cool the gas below hydrocarbon and water dewpoints.

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5.5 Measuring Gasses at Pressures above 50 psia
When sampling gases from sources above 50 psia the user needs to exercise some caution.
The inlet metering valve eliminates the need for any pressure regulators while maintaining
sufficient but not excessive flows throughout the pressure rating of the analyzer.
Measuring with the DewPatrol, Near Atmospheric Pressure
It is recommended for most applications to perform the measurement at near atmospheric
pressure. Adjusting the inlet metering valve and allowing the outlet to be unrestricted (other than
the provided orifice), assures that the analyzer has sufficient but not excessive flow and the
pressure inside the sampling chamber is near atmospheric. This approach guarantees safe
conditions and eliminates the need for the optional pressure sensor. If there is no pressure sensor
the analyzer can be set with atmospheric pressure 14.7psia for the "Mea. at" setting of the
pressure correction (refer to section 7.5).
Measuring with the DewPatrol, at Pressure of Sample
If it is desired to perform the measurement at the same pressure as the sample, up to the rating of
the analyzer (300 psia standard), the analyzer must be ordered with an internal orifice in its
exhaust path, then fully open the inlet valve thus pressurizing the sample chamber and letting the
built-in orifice provide flow control.
In this mode of use, to perform accurate measurements, you must know the pressure and enter it
into the analyzer, or order the optional built-in pressure sensor which will perform the
measurement and correction automatically.
The dewPatrol can be ordered with a built-in orifice in its exhaust. This orifice can be used to
regulate the flow from various pressures. The 0.016” dia. orifice, has flows described in the
following table.
source pressure
psia - (Bar)
flow
SLPM
(0.016” orifice)
15 - (1.03)
0.7
25 - (1.72)
2
35 - (2.4)
3
55 - (3.8)
4.8
75 - (5.2)
6.6
100 - (6.9)
8.5
150 - (10.3)
13.4
Outlet adapter

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6 User Interface Overview
The analyzer user interface consists of a backlit graphic LCD display, an audio sounder, four
metal dome tactile buttons, an inlet metering valve and a demister drain valve. The button
functions are dependent on the required selection choices thus appropriate legends appear on the
display immediately above the buttons.
Buttons
Legends describing button functions
Status Bar provides condition, warnings, errors etc...
Top half of screen, displays moisture measurement
Bottom half of screen, displays moisture measurement
in different units
Special information area
displays graph time axis,
pressure or temperature
Note: A personal computer Virtual Analyzer program is available on our website
(phymetrix.com) allowing the user to familiarize themselves with the user interface and train on
its operation.
The icon is printed on the left most button, to indicate that it is used to turn ON/OFF the
analyzer. Momentarily pressing this button will turn ON the analyzer; to turn OFF the analyzer
the left most button must be held pressed for at least 3 seconds – then a message will appear on
the screen to indicate that the analyzer is shutting OFF. In normal operation momentary presses
of this button will cause the analyzer to display a context sensitive help screen, as indicated by
the Help legend above it.
Note that the analyzer distinguishes between long and short presses of the buttons. Normally
to operate the analyzer one must perform short presses (less than 1 second), the button must
be released after the beep.
7 Operating the Analyzer
Performing measurements with the analyzer is a simple process:
 Connect the sample gas to the analyzer (refer to section 5)
 Adjust the flow of the gas to be greater than 1 LPM (2 SCFH)
 Turn ON the analyzer
Instructions:
 Open Demister/Filter drain Valve.
 Close Flow Control Valve at rear.
 Quick-Connect to gas.
 Open Flow Control Valve > 2 SCFH (1 LPM).
 If liquids are forming in demister keep drain valve open, otherwise valve can be closed.
 Turn On Analyzer.
 Select the graphing display mode
 Observe the graph and take readings when it is stable (flattened)
 When finished turn OFF the analyzer, the analyzer has an auto turnoff feature thus if left
on it will turn off by default in 5 minutes if no buttons are pressed.

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7.1 Mechanical Connections
Connections for inlet and outlet of the gas being measured are made through ¼” NPT female
adjustable swivel. The dewPatrol inlet is supplied, as factory default, with a 40 micron
Particulate Filter and a Male Industrial 1/4 Quick-Disconnect Hose Coupling.
The inlet quick-disconnect and/or filter can be changed for the user’s particular needs.
Make sure that the analyzer case/enclosure is not stressed while loosening or tightening the
fittings, always use two wrenches. refer to Appendix B.
Note that the inlet particulate filter will cause a slowdown in the measurement as the element
will adsorb/desorb moisture.
7.2 Powering the Analyzer ON or OFF
To turn ON the analyzer, press the left button (marked with the icon) and hold for
approximately one second until the display comes on.
To turn OFF the analyzer, press the button and hold it for 3 seconds or more, when the
shutdown screen appears release it.
To conserve battery power, the analyzer will auto-shutoff if the user buttons are not pressed for 5
minutes.
The auto-shutoff is preceded by warning the user for 10 seconds, providing the ability to cancel
the shutoff. The 5 minute auto-shutoff is a factory default that may be disabled or modified by
the user through the Autoshutoff option available in MENU-3.
When operating from an external power source (USB connection to PC or wall transformer), the
analyzer will not shutoff.

9
7.3 The Display Mode
Once powered, the analyzer will enter one of three display modes (whichever was last used) that
show the measurements performed by the analyzer. Pressing the Disp button will change the
display mode. Use the mode best suited for your application, in most cases when making Spot
measurements the Graph Mode is best for determining when the measurement can be taken.
•Dewpoint Units and Graph
•
of the measured dewpoint in the last 3 or 90 minutes is
displayed. The graph span (Y-axis above shown 40°Fdp) will automatically resize to
accommodate the minimum and maximum measurements in the last 90 or 3 minutes.
Select the 90 or 3 minute time axis by choosing Continuous or Spot measurement modes
in the Mode Of Use option available in MENU-2.
Pressure corrected and at pressure measurements
•
, as well as the gas pressure in the
sampling chamber is displayed. The pressure correction selection in this display mode
will be also utilized in the other two display modes. If pressure correction is enabled, then
the status bar will provide an indication in all three display modes, so that the user is
made aware that the displayed measurement is pressure corrected. In the example shown
above, the pressure correction is disabled.
Dual Dewpoint Units and Temperature
7.4 Units to Display the Measurement
of gas under measurement is displayed. Allows
the user to view the measurement in two different units as well as the temperature in the
sampling chamber. In the right most screen in the example above the moisture content is
being viewed in °C and in ppm by volume, while the temperature is displayed to be
21.5°C.
Measuring water vapor content in gasses presents many challenges not the least of which is
understanding the units of measuring. Different industries require different units of measure for
various reasons some technical some historical. The units typically used are in several categories:
a) The ratio of the volume occupied by the water vapor to the volume occupied by the other
gasses in the mixture. These measurements are expressed in Parts Per Million by volume PPMv,
or Parts Per Billion by volume PPBv, or Volume Concentration %.
b) The ratio of the weight of the water vapor to the weight of the other gasses in the mixture.
These measurements are usually expressed in Parts Per Million by weight PPMw.
c) The density of water vapor in the mixture of gasses, is the ratio of the weight of the water
vapor to the volume occupied (at atmospheric pressure) by the total mixture of gasses. These
measurements are expressed in grams per cubic meter (g/m3), or pounds of water per million
standard cubic feet (LbsH2O/MMSCF) the analyzer displays these units as
If the analyzer has the
Audio Visual Alarm
Option then the “Disp”
button will also show
the A/V Test screen
which will allow the
user to test the audio
alarm as well as the
warning lights.

10
d) The partial vapor pressure of water vapor – the pressure exerted by the water vapor only,
without considering the other gasses in the mixture. These measurements are expressed in units
of pressure such a microBar, mmHg, or any other pressure units that may be convenient.
e) The dewpoint
There are other measurement categories for expressing water vapor content in gasses however
they are not central in the context of this analyzer, and are listed for completeness: Relative
Humidity, Mixing Ratio, Absolute Humidity, Humid Volume of Air, Weight concentration %,
Delta Dewpoint. A freeware program compatible with Microsoft® Windows, as well as Apple
and Android smart phones, is available for downloading at
of the gas mixture - the temperature at which the water vapor in the gas is
saturated. This means that if the gas temperature was above the dewpoint temperature and
contained water only in vapor form, then if the gas is cooled, when it reaches the dewpoint
temperature the water vapor will just start to form condensation. Dewpoint measurements are
expressed in units of temperature such as °C or °F.
phymetrix.com/software/ facilitating
easy conversions between the above categories of units of measure.
In this analyzer, moisture content of the gas being measured can be displayed in a variety of units:
°C & °F dewpoint, ppmV, ppmW, µB H2O vapor pressure, grams of H2O / m3, and
Lbs H2O /106standard cubic feet in Natural Gas. Use the Step button (right most) to highlight
the units of the measurement and use the ▲and ▼buttons to change the units to the desired
values. If the instrument is unlocked then the unit changes will be permanent even after the
analyzer is powered OFF.
The following diagram depicts the button presses required to change the units in which the
measurement is displayed on the bottom half of the screen from ppmV to °F.
Similarly the units for the top half of the screen or the temperature can be changed.
If the instrument is locked then the change will last for 5 seconds so the newly selected units can
be viewed, then the selection will revert to the original units. The status bar will indicate
Locked-change is temporary and will produce beeping sounds.
7.5 Pressure Correction
In the previous section the summary of the units of measure for water vapor content reveals that
the units can be organized in three groups:
1) Proportion of water vapor in the gas is measured in several different categories such as
PPMv, PPMw, or LbsH2O/MMSCF.
2) Pressure exerted by the water vapor.
3) Temperature at which the water vapor is saturated in the gas.
The measurements of group 1 are most intuitive as they can be visualized as a proportion of
water in a gas mixture. These units are independent of the pressure of the gas that is being
described. For example if we say that the gas has seven pounds of water per million standard
cubic feet, we are describing the water content irrelevant of the pressure at which the gas may be.

11
The measurements in group 2 are in units of pressure and may at first seem an unusual way of
measuring content but if we recall Dalton’s Law of gases it becomes evident of the usefulness of
this means of expressing water vapor content in gasses. Note however that if the total gas
pressure is increased the partial water vapor pressure will also increase, thus the content of water
vapor in a gas is not fully described by the partial water vapor pressure – we would also need to
specify the total pressure of the gas mixture.
The measurements in group 3 are units of temperature, describing the water vapor saturation
temperature in the gas mixture. This method of expressing water vapor content is also affected
by the total pressure; if the total pressure is increased the gas will become saturated at a higher
temperature. Thus we would also need to know the total pressure of the gas mixture in order to
describe its water vapor content with dewpoint units.
As we discussed earlier this analyzer measures the partial water vapor pressure in the gas and
computes the water vapor content in the chosen measurement units to display on its screen. To
make this computation the analyzer software needs to “know” the total gas pressure. This
pressure can be automatically measured by the optional internal pressure sensor, or if the
analyzer was not purchased with that option then the pressure can be entered by the user. To
simplify operation the user can enter atmospheric pressure and measure at atmospheric pressure
by allowing the exhaust of the analyzer to be unobstructed.
Let's consider an example where the gas under test is measured at atmospheric pressure, however
the gas is in a pipeline at much higher pressure, and the user wants to know if there could be
water condensation in the pipe. Reading the dewpoint at atmospheric pressure does not allow us
to compare it to the expected low ambient temperature in order to determine if condensation will
occur; we would need to know the dewpoint at the same pressure as is present in the pipeline.
The analyzer can compute this dewpoint by having its Pressure Correction feature enabled, and
having the user enter the pressure in the pipeline. This can be done by pressing the Disp button
until the analyzer displays the Pressure correct mode. By factory default the pressure correction
is disabled.
The above diagram depicts the steps required to enable the pressure correction and set up the
“Calculated to” pressure to 7 Bar (about 100 psia). This example shows the analyzer measuring
the gas at atmospheric pressure (1.013 Bar) to have a dewpoint of -69.5°C, and calculating that
the same gas when at 7 Bar will have a dewpoint of -51.5°C.
If the user switches to the Graphing or Dual Units display mode, the displayed measurements
will be -51.5°C; there will be a reminder that the computation is being performed with the status
bar message Pressure Corrected.
To disable the pressure correction computation; while in the Pressure Correct display mode,
press the Step button until the Calc.to pressure units are highlighted, and then press the
▲or ▼ button until the Pressure Correct Disabled message appears on the top half of the
screen.

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7.6 Navigating Through the Menus
While in any of the three display mode screens, press the Menu button to go to the MENU-1 screen.
This screen contains seven options; the last one is labeled Morepress the Step button six times
until the Moreoption is highlighted, then press the Goto button to go to the
MENU-2 screen (refer to example below).
Similarly by accessing the Moreoption of MENU-2 will navigate to MENU-3.
While in MENU-3 to go back to MENU-2 press the Back button. Similarly navigate back to the MENU-1
screen and back to the display screen.
If the analyzer is left in any of the MENU modes and the buttons are not pressed for 3 minutes
then it will revert back to the display screen.
While in any of the MENU screens press the Step button until the desired option is highlighted,
then press the Goto button to enter the edit / view mode for that option.

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7.7 The Functions Available in the Menus
MENU-1
Save 1 Data Point or Start-Stop Log
If Data Logging is setup for Single Point logging then this menu choice allows the user to
save a single point in the log. If the setup is for Continuous logging then this menu choice
allows the user to start or stop the logging. In both cases the user can choose the location
tag associated with the measurement. Refer to Data Logging section for more details.
Setup DataLogger
This menu choice allows the user to select the logging mode to be either Single Point or
Continuous, in addition in the continuous mode it allows selecting the sampling period
and the total number of samples to be saved.
View saved Log Data
This menu choice allows viewing the logged data on the analyzer.
Backlight
This menu choice allows selecting the intensity of the backlight. Keep in mind that the
lower the intensity the longer will the analyzer operate on a single charge. If the backlight
is turned off it will light at a 20% intensity for 10 seconds after a button is pressed.
Un-Lock
This menu choice allows the user to lock or unlock the analyzer. The user can setup the
analyzer, using the PhyAI.exe program, to require a password in order to unlock it or can
allow unlocking without a password. A locked analyzer will prevent the operator from
making permanent changes.
About
This menu choice provides information regarding the software version and copyright, as
well as the analyzer and sensor serial numbers. In addition the date when the analyzer
was last calibrated is displayed.
MENU-2
Set Analog Out
For analyzers equipped with the analog 4/20mA output option this menu choice allows
setting the measured dewpoint that will correspond to the 4mA and the 20mA values, as
well as testing the analog output interface.
Set Alarms
For analyzers equipped with Audio-Visual Alarm or Relays this menu choice allows
modifying the alarm set points.
Mode Of Use
This menu choice allows selecting either SpotCheck or Continuous modes of operation.
Use the Sel button to switch between modes of operation. In the SpotCheck mode it is
assumed that the sensor is normally kept in desiccant. Occasionally it is connected to the
gas to be measured and a single quick spot measurement is made. In this mode the
measurement graph spans 3 minutes to indicate if the reading is stable. When the line
seems flattened the reading can be taken. In the Continuous mode it is assumed that the
analyzer is normally kept attached to the gas to be measured. In this mode the
measurement graph spans 90 minutes to indicate the recent history of the measurement.
Cal dew

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This menu choice allows the user to enter a single calibration point, by exposing the
analyzer to a gas with a known dewpoint and enter that dewpoint value to create a single
point calibration.
Cal temp
This menu choice allows setting the slope and offset for calibrating the two temperature
sensors in the analyzer. ‘Td’ is the temperature sensor located at the dewpoint sampling
chamber and measures the temperature of the gas being sampled. ‘Tb’ is the temperature
sensor located on the circuit board.
Cal prsr
This menu choice allows setting the slope and offset for calibrating the pressure sensor
which measures the pressure of the gas in the sampling chamber.
MENU-3
Lockable Items
This menu choice allows selecting which items can be locked.
Status Bar
This menu choice allows selecting the items that will be displayed on the status bar.
Time-Date
This menu option allows setting the battery-backed clock calendar.
Autoshutoff
This menu choice allows selecting the auto shutoff times of the battery saver. The
automatic shutoff is meant as a battery saver, thus when it is disabled it becomes the
user’s responsibility to shut off the analyzer when the measurements are complete.
PPMw factors
This menu choice allows the user to select the method of PPMw computations. The user
can select measurement in gas and the molecular weight of the gas, or measurement in
liquid and Henry’s constant associated with the liquid.
Language de fr es
This menu choice allows the user the select the language in which the analyzer menus
appear. Available languages are English, German, French and Spanish.
MENU-4
COMs
This menu choice is provided for commonality with other analyzers
Dig. Out PWM
This menu choice is provided for controlling the pulse width modulation of digital
outputs such as relays or solenoids in order to facilitate power savings.
Set Thermostat
This menu choice is provided for commonality with on-line analyzers.
HART
This menu choice allows selecting the HART polling address.
Modbus
This menu choice allows setting the communications port for analyzers that have serial
communications RS-485/422 output options, also provides selections for Modbus operating
modes RTU/ASCII as well as the Modbus address.

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7.8 External Connections
7.8.1 USB - Battery Use & Charging
The first time a PC is connected to this analyzer, it may need to initialize its USB drivers, which
are available as a standard in all MS-Windows® XP and up operating systems. Please wait for
this initialization to complete before using the interface. After this initialization, some PC’s may
require that their USB devices be unplugged and plugged back in, to properly enumerate the
devices.
This driver initialization is required in order for the Analyzer to be able to properly charge from
the PC’s USB port.
If your PC does not have the driver and prompts you for a driver install, download the PhyAI.zip
file from phymetrix.com/software/ select "Analyzer Interface", and follow the instructions in the
“Driver READ ME.txt” file. The PhyAI.exe program is also contained in this zip file.
Digital Data - The analyzer can be connected to a personal computer and to the PhyAI.exe
program through the USB connector, using the provided USB cable. The USB connector has a
weatherproof cap which has to be unscrewed to gain access to the mini-B connector. The cap has
a captive strap so that the cap is not lost. Please screw the cap back on to the connector when not
in use in order to retain the weatherproof integrity of the analyzer.
External Power & Battery Recharging - The analyzer uses a rechargeable Li-Ion battery. A fully
charged battery will power the analyzer continuously for 35 hours without the backlight or 12
hours with backlight at 100%; thus a single charge can provide many months of operational use.
The amount of remaining charge appears on the upper-left of the MENU display screens, it is
shown with a graphic 10 step bar in a battery icon and as a percentage. In addition as necessary
the status bar displays a Low Battery message, indicating that the battery should be recharged,
which can be done by plugging the analyzer into any PC’s USB port (driver must be installed,
see above) or by using the provided wall transformer. Do not exceed 5.5VDC on USB connector.
The status bar indicates the states of the USB connection and battery charging. Normally USB
ports provide 0.5A at 5VDC, but some USB hubs provide only 0.1A thus charging the battery at
a slower rate. When connected to a 0.5A source a discharged battery will fully charge in 3.5
hours, when connected to a 0.1A source it will charge in 15 hours.