Phymetrix PPMa User manual

PhyMetrix Portable Moisture analyzer
User's Manual for Models PPMa and PPBa

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.

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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........................................... 4
4.3 Temperature Dependant Equilibrium............................................................................... 4
5Sampling Techniques.............................................................................................................. 4
5.1 Choosing a Measurement Site.......................................................................................... 4
5.2 Sample Conditioning........................................................................................................ 5
5.3 Tubing and Fittings .......................................................................................................... 5
5.4 Sample Pressure ............................................................................................................... 5
5.5 Measuring Gasses at Pressures above 50 psia.................................................................. 6
5.5.1 Model PPMa ............................................................................................................. 6
5.5.2 Model PPBa.............................................................................................................. 9
6User Interface Overview....................................................................................................... 10
7Operating the Analyzer......................................................................................................... 10
7.1 Mechanical Connections ................................................................................................ 11
7.2 Sampling and Dry Storing the Sensor............................................................................ 11
7.3 Powering the Analyzer ON or OFF................................................................................ 11
7.4 The Display Mode.......................................................................................................... 12
7.5 Units to Display the Measurement................................................................................. 12
7.6 Pressure Correction........................................................................................................ 13
7.7 Description of “STABLE” indication on the right side of the graph............................. 15
7.8 Navigating Through the Menus...................................................................................... 15
7.9 The Functions Available in the Menus .......................................................................... 17
7.10 External Connections: USB – 4/20mA Analog Out – Battery Use & Charging........ 19
8Data Logging ........................................................................................................................ 20
8.1 Single Data Point Log.................................................................................................... 20
8.2 Continuous Data Logging .............................................................................................. 21
8.3 Retrieving the Data / Clearing the Memory................................................................... 22
8.4 Logging Data Directly into a Personal Computer.......................................................... 22
9Single Point Calibration........................................................................................................ 22
10 Troubleshooting and Maintenance........................................................................................ 22
10.1 Cleaning...................................................................................................................... 22
10.2 Recharging the Battery............................................................................................... 22
10.3 Self Diagnostics.......................................................................................................... 23
10.4 Suspected Erroneous Measurements.......................................................................... 24
11 Specifications........................................................................................................................ 26
11.1 Specifications for Model PPMa.................................................................................. 26
11.2 Specifications for Model PPBa................................................................................... 26
11.3 ATEX Certification - Intrinsically Safe for use in Explosive Atmospheres .............. 27
Appendix A Mini-Demister..................................................................................................... 28
Appendix B Vacuum Pump Option on Model: PPBa ............................................................. 30
Appendix C Analyzer Calibration Log.................................................................................... 34
Revision #3.2 2020

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Revision #3.2 2020

1Introduction
Thank you for purchasing the state-of-the-art Phymetrix Portable Moisture Analyzer models:
PPMa or PPBa. Model PPMa is a weatherproof handheld analyzer, while model PPBa is a
benchtop portable analyzer which includes a built-in metering valve and flow meter; otherwise
both analyzers operate the same. This User’s Manual describes the functions of both of these
analyzers as well as their operating methods and handling precautions. The minor differences
between the two models are addressed as necessary within the document. There are also some
sections that review general knowledge and concepts of water vapor science. Read this manual
thoroughly before using the analyzer. There is also a Quick Setup Manual describing the main
functions and basic procedures for performing measuring operations. Check our website
“www.phymetrix.com” for latest versions of documentation regarding these analyzers.
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 located on the front label and also displayed upon power-up and in
the About screen, the dash numbers following the main part number signify options as follows:
–Ifor intrinsically safe certification, the analyzer will be appropriately labeled
PPMa:Ex ib IIC T4 or PPBa:Ex ib IIA T4 (refer to section 11.3 for details)
-Pfor internal pressure sensor, -Afor analog output 4/20mA,
-Vfor vacuum pump option (available with model PPBa only, without “-I”).
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.
Model: PPMa with accessories Model: PPBa with accessories
Save the packing materials until you have verified that there is no concealed damage, it may also
be useful for future transportation.
1

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 dependant 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 content while also allowing the sensor to move seamlessly between the
desiccant chamber and the sampling chamber. The gas under measurement is exposed only to the
stainless steel walls and Teflon seals of the sampling system. When not being used, with a simple
push of the actuator knob the sensor can be stored in the desiccant chamber and kept at moisture
levels well below 1 part per million.
This method of performing spot measurements by a portable analyzer allows the user to perform
the next measurement from conditions where the sensor will most likely be getting wetter from
its previous state, or does not have to dry down very much. Thus facilitating a fast measurement
by eliminating the requirement for lengthy sensor dry down.
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.
•When connecting gas with pressure greater than 50 psia to the PPMa while the sensor is
in desiccant store, make sure that the pressure is applied gradually (refer to section 5.5).
Hold on to the actuator while purging, as not to allow it to rapidly move out and hit its
internal stop and cause damage to the instrument.
•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 force the actuator knob; there is only approximately ¾” of travel.
•Do not use with contaminants and liquids, refer to section 5.2 for sample conditioning.
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•Avoid exposing the sensor to ambient air as it may slowdown your next measurement.
•The handheld analyzer Model PPMa is weatherproof and can be left in the rain, however
the inlet and outlet ports must be protected from ingress; this is normally accomplished
by the interconnecting tubing. 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
by the provided exhaust pigtail 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. The Model PPBa is not weatherproof and can not be left out in the rain.
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, 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.
3

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
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, the analyzer should have at least 12” in length of 1/8” dia. stainless steel tubing at
its exhaust port, and 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. A small pigtail
(coiled 1/8” dia. ss. tubing 12” long) is provided for use at the exhaust port of the Model PPMa,
the Model PPBa has internal tubing and exhaust flow meter thus does not require a pigtail.
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.
4

5.2 Sample Conditioning
Particulate and liquid contaminants can effect 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,
Then use the Phymetrix Gas-Liquid separator Mini-Demister which mounts directly on top of the
PPMa, it is constructed with materials suitable for trace dewpoint measurements and 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).
Check for leaks after connecting.
For Model PPMa use the supplied exhaust pigtail.
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 effect 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.
5

5.5 Measuring Gasses at Pressures above 50 psia
When sampling gases from sources above 50 psia the user needs to exercise some caution.
5.5.1 Model PPMa
The model PPMa has a built-in orifice in one of its SAE adapters. This orifice can be used to
regulate the flow from various pressures.
• The inlet adapter has a built-in flow control orifice and is
marked with notches on the wrench flats.
• The unrestricted outlet adapter does not have any notched
markings.
• If you remove the adapters, when placing them back on to the
PPMa make sure that adapter with the notches is placed on the
inlet port of the PPMa.
When sampling gases from sources above 50 psia, the inlet orifice assures that the analyzer will
not be suddenly pressurized. This also eliminates the need for any pressure regulators while
maintaining sufficient but not excessive flows throughout the pressure rating of the analyzer.
CAUTION: If the analyzer is pressurized from a source greater than 50 psia,
through a port without an orifice while the sensor is in desiccant store, the
sensor could act as a piston under pressure. If the orifice is not there to
restrict the flow, the sensor could rapidly move out of the desiccant store and
slam into the internal stop possibly causing damage to the analyzer.
A notched adapter with black paint in the notches has a 0.016” dia. orifice, with flows described
in the following table.
Other color coded notched adapters with various orifices
can be provided to accommodate different pressures and
flows. Consult PhyMetrix support for its proper sizing.
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
Inlet adapter
Outlet adapter
6

Measuring with the PPMa, Near Atmospheric Pressure
It is recommended for most applications to perform the measurement at near atmospheric
pressure. Placing the notched SAE adapter with the flow control orifice at the inlet and allowing
the outlet to be unrestricted (other than the provided exhaust pigtail), 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 7.6), the orifice and
unrestricted outlet will guarantee repeatable conditions for all pressures within the rating of the
orifice.
Measuring with the PPMa, 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 (150 psia standard – 500 psia optional), then reverse the orifice locations. Place the
notched SAE fitting on the Outlet port and the plain one on the Inlet port.
CAUTION: In this configuration the sensor must be pulled out of the desiccant before the
pressure is applied; otherwise there is the possibility for the pressure to act upon the sensor as a
pneumatic piston and drive it out with excessive force thus causing damage to the instrument.
The analyzer is now setup with the orifice at the outlet, thus the measuring chamber will be
pressurized to the same pressure as your sample. 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.
7

8

5.5.2 Model PPBa
The model PPBa has a built in metering valve rated for pressures up to 2000 psia (137 bar); this
valve can be adjusted to provide the analyzer with flow of >2 SCFH (1 SLPM).
CAUTION: The 2000 psia pressure limitation is for the inlet, and can be
utilized only if outlet is unrestricted. If the outlet is restricted, make sure not to
exceed the 50 psig limitation of the built-in flow meter.
9

6User Interface Overview
The analyzer user interface consists of a backlit graphic LCD display, an audio sounder, four
metal dome tactile buttons, and an actuator knob for moving the sensor between the sampling
and dry store position. The button functions are dependant on the required selection choices thus
appropriate legends appear on the display immediately above the buttons.
Note: A personal computer Virtual Analyzer program is available on our website
(www.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.
7Operating the Analyzer
Performing measurements with the analyzer is a simple process:
•Connect the sample gas to the analyzer (refer to section 5.2)
•Adjust the flow of the gas to be greater than 1 LPM (2 SCFH)
•Turn ON the analyzer
•Select the graphing display mode
•Wait for one minute for interconnecting tubing and analyzer to purge
•Pull out the sensor position knob all the way (moves approximately ¾”)
•Observe the graph and take readings when it is stable (flattened)
•To finish push the knob all the way in to dry storage
•Turn OFF the analyzer
10

7.1 Mechanical Connections
Connections for inlet and outlet of the gas being measured are made through ⅛” Swagelok®
tubing compression fittings.
On the Model PPMa make sure that the analyzer case/enclosure is not stressed while loosening
or tightening the fittings, always use two wrenches.
The Model PPBa has bulkheads fittings which are secured to the front panel and thus does not
require a backup wrench.
The handheld analyzer Model PPMa has a hook with a powerful magnet to temporarily secure
the analyzer to ferrous metal surfaces in the field. The hook can be pulled out from a recess on
the back of the analyzer. The magnet is most effective on flat ferrous surfaces.
7.2 Sampling and Dry Storing the Sensor
In order to provide rapid moisture measurement in dry gases the analyzer is equipped with dry
storage for the sensor. When the sensor knob is pushed-in the sensor is in dry store, should be
left there while not in use. When the sensor knob is pulled-out (it moves out about ¾” or 19mm)
the sensor is in the sampling chamber. While following these instructions leave the sensor in dry
store until the gas is hooked up and has flowed through the interconnecting tubing and analyzer
for a few minutes. For low dewpoint measurements a longer purge time may be required to dry
the interconnecting tubing before taking the sensor out of dry store.
7.3 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:
2 minutes when the sensor is in Dry Store (in desiccant) or
5 minutes when the sensor is in the measurement position.
The auto-shutoff is preceded by warning the user for 10 seconds and allowing them to cancel the
shutoff. The settings for 2 and 5 minute auto-shutoff are factory defaults 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.
11

7.4 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 ModeOfUse 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 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.
•Vacuum Pump Control screen appears if the “-V” option is installed on the analyzer. This
screen allows the user to control the vacuum pump by controlling the percent power
applied to the pump in steps: 100%, 90%, 75%, 60%, 45%, 30%, 15% and OFF. This
screen also shows the vacuum pump battery status. Refer to Appendix B for more details.
7.5 Units to Display the Measurement
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
If the analyzer has the
Vacuum Pump Option
then the “D
isp” button
will also show the
Vacuum Pump control
screen
which will
allow the user to
control the vacuum
pump.
12

measurements are expressed in grams per cubic meter (g/m3), or pounds of water per million
standard cubic feet (LbsH2O/MMSCF).
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 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.
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 is available for
downloading at www.phymetrix.com 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-changeistemporary and will produce beeping sounds.
7.6 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
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