Alpha Moisture Systems SADPminiEx User manual

Model SADPminiEx
Instruction Manual
Alpha Moisture Systems
Alpha House
96 City Road
Bradford
BD8 8ES
England
Tel: [phone]
Fax: [phone]
Email: [email protected]
Web: www.amsystems.co.uk

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Instruction Manual
For the
SADPminiEx Automatic Dewpoint Hygrometer
1405 SADPminiEx User Manual.doc
Issue 7.2
31/10/14

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Table of Contents
1GENERAL INFORMATION.........................................................................................................1
2FEATURES ............................................................................................................................1
2.1 RANGES ................................................................................................................................... 2
2.2 CASING .................................................................................................................................... 2
3SAFETY INFORMATION............................................................................................................2
3.1 WARNING ................................................................................................................................. 2
3.2 SPECIAL CONDITIONS OF USE -(DENOTED BY THE XAFTER THE CERTIFICATE NUMBER) ..................... 2
3.3 PRESSURE EXPOSURE ................................................................................................................ 3
3.4 BATTERY .................................................................................................................................. 3
3.4.1 Lithium-Polymer................................................................................................................................. 3
3.4.2 Initial Charging................................................................................................................................... 3
4INSTALLING THE AIR/GAS SAMPLING SYSTEM ..........................................................................3
4.1 GASES TO AVOID ....................................................................................................................... 4
4.2 PIPING INSTALLATION SCHEMATIC ............................................................................................... 5
4.3 PIPING SCHEMATIC COMPONENT INDEX ....................................................................................... 5
5PURGING THE SAMPLE CONNECTION .......................................................................................6
6USING THE SADPMINIEX TO TAKE A MOISTURE READING .........................................................6
6.1 TAKING A MEASUREMENT ........................................................................................................... 8
7SAMPLING INFORMATION........................................................................................................8
7.1 SAMPLE PIPE ............................................................................................................................ 9
7.2 SAMPLE CONDITIONING .............................................................................................................. 9
7.3 PRESSURE AND FLOW CONTROL................................................................................................... 9
7.4 PARTICULATE CONTAMINATION.................................................................................................... 9
7.5 LIQUID CONTAMINATION ........................................................................................................... 10
8SADPMINIEX INITIAL CONFIGURATION ..................................................................................10
9THE NORMAL DISPLAY SCREEN.............................................................................................11
10 SADPMINIEX OPERATING PRINCIPLES ...................................................................................11
10.1 NAVIGATING THROUGH MENUS.................................................................................................. 11
10.2 ENTERING NUMERICAL DATA .................................................................................................... 11
10.3 ENTERING ALPHANUMERICAL DATA ........................................................................................... 12
10.4 SECURITY PROTECTION SCREENS .............................................................................................. 12
11 OPERATING THE SADPMINIEX..............................................................................................12
11.1 THE SETUP MENU ................................................................................................................... 12
11.1.1 Select Units ..................................................................................................................................... 12
11.1.2 Pressure Calc................................................................................................................................... 13
11.1.3 4-20mA Output (4-20mA and Full Logging versions only) .................................................................... 13
11.1.4 AutoCal........................................................................................................................................... 14
11.1.5 SPC (Single point Calibration)........................................................................................................... 15
11.1.6 Security........................................................................................................................................... 16
11.1.7 Time and Date ................................................................................................................................. 17
11.1.8 Set Clock ........................................................................................................................................ 17
11.1.9 Information ...................................................................................................................................... 17
11.1.10 Temperature ............................................................................................................................... 18
11.1.11 Exit............................................................................................................................................ 18
11.2 THE LOGGING MENU (FULL LOGGING VERSIONS ONLY) ................................................................ 18
11.2.1 Internal Logging ............................................................................................................................... 19
11.2.2 Review Data .................................................................................................................................... 19

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11.2.3 PC Comms...................................................................................................................................... 20
11.2.4 Delete Data ..................................................................................................................................... 21
11.2.5 Create TAG..................................................................................................................................... 21
11.2.6 Edit TAG ........................................................................................................................................ 21
11.2.7 Delete TAG ..................................................................................................................................... 22
11.2.8 Printer LOG .................................................................................................................................... 22
11.2.9 Unit Address.................................................................................................................................... 23
11.2.10 Free Space.................................................................................................................................. 23
11.2.11 Exit............................................................................................................................................ 23
12 PRESSURE CORRECTION ......................................................................................................23
13 BATTERY CURRENT STATUS.................................................................................................23
14 PERFORMING AN AUTOCAL ..................................................................................................24
14.1 AMBIENT CONDITIONS .............................................................................................................. 25
14.2 REFERENCE GAS...................................................................................................................... 25
15 SADPMINIEX 4-20MA .........................................................................................................25
15.1 SADPMINIEX 4-20MACIRCUIT................................................................................................. 25
15.2 CALCULATING MAXIMUM OUTPUT LOAD (REXT)........................................................................... 26
16 RS485 COMMUNICATIONS ...................................................................................................26
17 SADPMINIEX LOGGING SOFTWARE CABLES AND INTERFACES.................................................26
17.1 RS232 TO RS485 CABLES &INTERFACE ................................................................................... 27
17.2 USB TO RS485 CABLES &INTERFACE....................................................................................... 28
18 TECHNICAL DETAILS OF THE RS485\4-20MACONNECTER (CON066)....................................29
19 SADPMINI PROTOCOL .........................................................................................................30
20 INSTRUCTIONS FOR REPLACING DESICCANT IN THE SADPMINIEX............................................30
21 APPENDIX C–SADPMINIEX SETUP MENU MAP.....................................................................33
22 APPENDIX D–SADPMINIEX LOGGING MENU MAP ................................................................34
23 APPENDIX E–TROUBLE SHOOTING ......................................................................................35
24 APPENDIX F–SADPMINIEX SPECIFICATION ..........................................................................36

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1General Information
The SADPminiEx is a battery powered portable instrument, consisting of an aluminium
oxide sensing element and associated printed circuit boards. Also incorporated in the
device is LCD indication, membrane keypad, RS485 interface, 4-20mA interface,
charger socket and sample inlet and outlet ports.
Certified as intrinsically safe 04ATEX0290X
2Features
Basic SADPminiEx
128 x 64 dot Backlit LCD Graphics Display.
Tactile membrane keypad, coupled with an easy to operate user interface.
Operates from an internal rechargeable Lithium Polymer battery.
Battery life in excess of 70 hours* continuous use, from fully charged.
Full charge time approximately 14 hours. Only use the Charger supplied with
SADPminiEx. CHARGE IN SAFE AREA ONLY
7 selectable moisture units (ºC, ºF, ppm(V), ppm(W), ppb, g/m3 and lb/MMSCF).
Pressure compensated moisture readings in 4 selectable units of pressure (psig, barg,
kg/cm2g and Kpag).
Battery life Indicator.
Built in Automatic Calibration (AutoCal).
Built in Single Point Calibration (SPC).
On board Real Time Clock.
User settable security access.
Sample gas flow temperature indication.
4-20mA Option (all the Basic SADPminiEx features plus)
4-20mA Loop Powered output. FOR USE IN SAFE AREA ONLY
Full Logging Option (all the 4-20mA option features plus)
Stores up to 16000 data points.
20 definable alphanumeric TAG references, including 1 preset.
Up to 20 blocks of data stored under each TAG reference.
Review stored data in tabular and graphical form.
RS485 Serial Communication to dedicated PC software. FOR USE IN SAFE AREA
ONLY
Download stored data in CSV format. FOR USE IN SAFE AREA ONLY
Real Time logging to connected PCs. FOR USE IN SAFE AREA ONLY
Thermal printer driver facility. FOR USE IN SAFE AREA ONLY

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2.1 Ranges
SADPminiEx - SR -110 to –20ºC Dewpoint ( -166 to -4°F Dewpoint )
SADPmini Ex - PL -100 to 0°C Dewpoint ( -148 to +32°F Dewpoint )
SADPmini Ex - RD -80 to -20°C Dewpoint ( -112 to -4°F Dewpoint )
SADPmini Ex - GY -80 to 0°C Dewpoint ( -112 to +32°F Dewpoint )
SADPmini Ex - BL -80 to +20°C Dewpoint ( -112 to +68°F Dewpoint )
2.2 Casing
The SADPminiEx housing is a moulded plastic enclosure with a cast aluminium sample
head.
The instrument is provided as standard with a padded anti-static carrying case with
shoulder strap for use in hazardous areas.
3Safety Information
Read the safety information below, before use.
3.1 Warning
The SADPminiEx is Intrinsically Safe. Therefore, it can be used in hazardous areas.
Certification: ATEX –II 1 G
Ex ia IIC T4 ( Ta = –20ºC to +40ºC )
Ex ia IIC T3 ( Ta = –20ºC to +50ºC )
It is the responsibility of the user to ascertain the suitability of the SADPminiEx for use in
hazardous areas. Risk assessments should be performed prior to use taking into account
the SADPminiEx certifications, the ‘x’ rating (Light alloy content) of the SADPminiEx, and
the location and the gas being monitored etc.
3.2 Special Conditions of Use - (denoted by the X after the certificate number)
The apparatus contains light alloy parts and must be protected from impact and friction
when used and transported in hazardous areas. The apparatus must therefore be carried
in the (antistatic) protective carry case supplied when being transported in a hazardous
area.
The ambient temperature Ta = –20ºC to +50ºC

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3.3 Pressure Exposure
The maximum pressure to which the telescopic measuring head is exposed
must not be more than
0.3barg, 4.35psig, 30kpag or 0.3kg/cm2g
Exposing the measuring head to higher pressures may damage the instrument
and result in injury to the operator or other personnel in the area
3.4 Battery
3.4.1 Lithium-Polymer
The SADPminiEx contains an encapsulated Lithium-Polymer battery which, to conform
to current legislation should always be partially discharged before shipping.
Note: There are no serviceable parts within the encapsulated battery.
3.4.2 Initial Charging
It is recommended that the SADPminiEx be put on charge overnight when first received,
the unit should be turned OFF during charging. Only use the Charger supplied with
SADPminiEx
To attain maximum battery life the SADPminiEx should always be re-charged at room
temperature, with the unit turned OFF.
The battery life (hours of use from a fully charged cell) will reduce when used in cold
conditions. * 70 hours is quoted as the expected battery life when used at room
temperature.
Note: The 4-20mA output should not be operated while the instrument is charging.
4Installing the Air/Gas Sampling System
The piping installation schematic diagram (see section 4.1) shows all components, which
could be used in a dry gas measurement application although not all the items shown will
be required for every installation.

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Care should be taken to ensure that the sample presented to the SADPminiEx is not
contaminated with any component that will damage, contaminate or affect the SADPminiEx
in a way that will impair the unit’s accuracy.
It is strongly recommended that the sample should not contain particulate matter, oil,
hydrocarbon or any other condensate. If these components contaminate the sample system
and/or the measuring sensor, the SADPminiEx response time will be lengthened, although
the sensor calibration will not be effected.
The flow rate, although not critical to the sensor measurement, should be low enough to
avoid abrasion to the sensor surface without being so low as to extend the SADPminiEx
response time to an unacceptable level. In general, a flow rate of between 5 and 8
litres/min at NTP will give the right balance.
The sensor used in the SADPminiEx is a variable capacitor, which is directly affected by
changes in partial pressure of water vapour, and these changes, that are proportional to the
dew/frost point temperature, are displayed on the instrument indicator.
pressure of water vapour, and these changes, that are proportional to the dew/frost point
temperature, are displayed on the instrument indicator.
4.1 Gases to Avoid
The moisture sensors are suitable for many different industrial and research applications.
Most gases can be checked for their moisture content with no need for the calibration to be
altered when changing between different gases, as the sensor operates only with reference
to the water vapour content. There are, however, some gases that must be avoided, as
they are not compatible with the material of construction of the sensor. Ammonia (NH3),
Ozone(O3) and chlorine (Cl) must be avoided at all times, even in small quantities.
Hydrogen chloride (HCl) also attacks the sensors very quickly. Some, less aggressive,
acidic gases, such as sulphur dioxide (SO2), can be monitored, as long as the moisture
content is low, generally less than 100ppm(v). If in doubt, please ask your supplier.
Sulphur hexaflouride (SF6) has no effect on the sensor. If the gas has been exposed to
arcing, however, it is possible that various acidic species will have been formed that will
corrode the sensor. When testing SF6that may have been arced, therefore, an acidity test
should be carried out first; if the gas proves to be acidic then the moisture test should not
be carried out.

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4.2 Piping installation Schematic
4.3 Piping Schematic Component Index
1. Sample Isolation Valve - This is a recommended item as it allows access to the sample
system without interrupting the main process line.
2. Sample Tube –This should be stainless steel for dry air or gas applications but copper
or carbon steel can be used where wetter gases are to be measured. If any section of the
sample tube must be flexible then PTFE should be used. In most cases, 3mm OD
(1/8”) is sufficient as it provides good system response time with minimum flow. 6mm
OD (1/4”) tube can be used where pressure drops across the 3mm tube are too high
1
2
3
4
5
6
7
8
Main
Process
Line
Notes
a. The sample point should be on the upper surface of the horizontal pipe, or from a
vertical section of pipe, wherever possible.
b. The sample tube should run upwards from the sample point. If this is not possible,
then an inspection port or drain tap should be installed at the lowest point in the
sample system.
9

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3. Filter Unit –A filter unit is recommended when the samples are likely to contain
particulate matter. If the air/gas sample contains heavy hydrocarbon condensate, the
filter must be of the coalescing type with a drain. The filter unit should be positioned as
close to the sample point as practical.
4. Pressure Reduction Valve or Pressure Regulator –the sample is measured at
atmospheric pressure requiring that valve 4 is fitted to the system.
5. Flow Control Valve.
6. Sample Connection
7. SADPminiEx.
8. Flow Indicator –The recommended sample flow is 5 to 20 L/M.
9. Sample Exhaust –The exhaust is vented to atmosphere or returned to an atmospheric
pressure line.
5Purging the sample connection
Refer to the sample system schematic in section 4.2.
It is advisable to carry out an initial purge of the sample loop, before connecting the
SADPminiEx, in order to avoid the possibility of sensor damage on start-up.
Open the sample isolation valve (1) slowly, until a there is a small flow of air/gas at
atmospheric pressure from the pressure reduction valve (4) into SADPminiEx line. Allow
the air/gas to exhaust through the sample connection (9).
The SADPminiEx is not flow sensitive however the sample flow needs to be enough to
purge the sensor head effectively, so anything less than 1 litre/min would mean that the
instrument would take too long to settle to a stable reading. The flow should also not be so
high that the gas velocity could physically damage the sensor or cause backpressure in the
sensor head, so should not exceed about 20 litres/min.
Allow this purge to continue for 2 minutes to remove any residual moisture from the sample
pipe work and components. Check that no liquid or particulate contamination, which could
damage the sensor, is passing through the sample pipe. Directing the sample onto a piece
of white paper (such as a filter paper) will make it easier to see any dust or oil mist in the
sample.
6Using the SADPminiEx to take a Moisture Reading
Refer to the sample system schematic in section 4.2.
The first purpose of the SADPminiEx is to provide a rapid, easy and reliable means of
carrying out moisture content measurements, of gases. To ensure rapid response the
sensor is kept dry by surrounding the sensor with desiccant in the head assembly when it is
not in use.

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The SADPminiEx can display moisture readings in any one of six Engineering Units and
can also display pressure compensated readings. The SADPminiEx should be setup as
required (See The Setup Menu section) before progressing to take sample readings

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6.1 Taking a Measurement
After purging the system to be monitored fit the SADPminiEx sample pipe to the sample
connection (6). Allow the gas to purge for a further 2 minutes with the head down.
Restrict the outlet of the SADPminiEx (7) by placing a finger over the sample exhaust (9),
so that the pressure of the sample lifts the telescopic head. As soon as the head is fully
extended remove the finger, to prevent pressure build up. Pull gently on the head to make
sure it is fully extended. If there is not enough pressure to lift the head assembly, assist it
by pulling it up; do this very slowly so that ambient air is not drawn in through the outlet. It
may help to turn the head to break the “sticktion” be sure to turn clockwise, so as not to
loosen the locking ring.
The sensor will respond to the moisture level present in the sampled gas. The displayed
moisture value will continue to change until the sensor reaches equilibrium; at which point
the displayed value is representative of the moisture level in the sampled gas.
When the test is finished push down the telescopic head fully, turn off the sample flow and
disconnect the sample pipe. With the head in the down position the desiccant will dry the
sensor, ready for the next test.
NOTE - It is important that the head assembly is either fully up, or fully down to keep the
desiccant isolated from ambient air, so avoiding wetting it. When the SADPminiEx is not in use
it should be stored with the head in the down position.
7Sampling Information
Refer to the sample system schematic in section 4.1.
The SADPminiEx sensor will respond to the water vapour pressure of a gas in contact
with it. It is important to ensure that the gas passing through the sensor head is the same
as the gas being sampled.
SADPminiEx
Head Raised
SADPminiEx
Head Lowered

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7.1 Sample Pipe
The SADPminiEx is supplied with 2 connections: a “fir tree” on one side and a
Swagelok®compression fitting for 1/4 in, 1/8in, or 6mm OD pipe (as specified on your
order) on the other. Either can be used as the inlet connection (6).
PTFE and stainless steel are recommended materials for sample pipes. Some specialist
flexible tubing may be suitable as sample pipe, but common flexible tubing, such as pvc,
nylon, polythene or rubber, should not be used, as they are permeable, and water vapour
from the atmosphere will diffuse through them into the sample gas.
A 2m PTFE sample pipe is supplied for use with the “fir tree” connection. The first time
this is used it is advisable to warm the end that will go over the “fir tree” for a few
seconds with a heat source to soften it slightly, which helps to get a gas tight seal.
7.2 Sample conditioning
The main principle when considering the presentation of the gas sample to a portable
dewpoint meter is to keep the sample system as simple as possible and of minimum swept
volume, so that it has the least possible influence on the gas sample.
7.3 Pressure and flow control
In most cases the gas to be sampled will be at a positive pressure, which will need to be
reduced to atmospheric pressure. At low pressures, up to around 10 barg, this can be
done by including a simple needle valve (5) to control the flow and thereby, the pressure
dropping across it. Ideally this would be the isolation valve (1) on the sample point, thus
keeping the number of joints and glands, which are points of potential moisture ingress,
to a minimum.
At higher pressures it is advisable to reduce the pressure across a pressure regulator (4).
Any regulator used should be stainless steel and of a low swept volume. Typical
laboratory or welding type regulators are not suitable because they have elastomeric
diaphragms, which are permeable to water vapour, and the high swept volume will be
slow to purge.
7.4 Particulate contamination
If the sample gas is likely to contain particulate material this should be kept away from the
sensor by including a small in-line particle filter (3) in the sample system.
If the surface of the sensor becomes partly coated with particles it will not affect the
calibration of the sensor, but will restrict the movement of water molecules across the
surface, so increasing the time it takes for the sensor to come to equilibrium with the

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water vapour concentration around it. If the solid material is hygroscopic, such as
desiccant dust, whenever there is a change in the moisture concentration in the sample
this material must come to equilibrium with the moisture content before the sensor can
respond to the change, which will cause delays in obtaining accurate results.
7.5 Liquid contamination
If the sample gas may contain liquid contamination, such as oil mist, this should be kept
away from the sensor by including a coalescing filter or an appropriate membrane filter
(3) in the sample system.
If the surface of the sensor becomes partly coated with liquid, again it will not affect the
calibration of the sensor. It will restrict the movement of water molecules across the
surface, so increasing the time it takes for the sensor to come to equilibrium with the
water vapour concentration around it. If the liquid is hygroscopic, such as glycol, the
buffering effect described for desiccant dust may be so great that the sensor becomes too
slow to use.
8SADPminiEx Initial Configuration
Each SADPminiEx is set up prior to despatch to the end users specification. The following
values will be preset: -
The specified sensor type is pre-selected.
The calibration data will be set to values that are applicable to the specified
installed sensor.
The AutoCal value is set to match the installed sensor.
The clock will be set to the correct date and time GMT.
Moisture units set to oC Dewpoint.
Pressure units set to barg, pressure value set to 0.
Security codes are set to 1000.
No Single point calibrations.

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9The Normal Display screen
When the SADPminiEx is ON, it displays the moisture level of the gas that the sensor is
exposed too. When the head is lowered, the sensor is no longer exposed to the gas and is
dried down by the desiccant in the head.
Examples of the Main Display Screen
The Display always shows the current moisture level that the internal sensor is exposed
too. The current engineering units are clearly indicated on the display as well as any
pressure compensation performed.
10 SADPminiEx operating principles
Two distinct and separate menus control the SADPminiEx. These menus are described in
separate sections below:
10.1 Navigating through Menus
The SADPminiEx is predominantly menu driven. To navigate around the menus use the
‘’ and ‘’ keys to move the cursor bar (negative image) through the options available
within the menu and use the ‘ ’ key to select the option required. The ‘’ key has no
function within menu screens.
10.2 Entering Numerical Data
The basic principle used to enter numerical values is described here.
The display will indicate a number in a format appropriate to the required input, the first
character of which will be displayed as a negative image to indicate it is active. Use the
‘’ and ‘’ keys to select the required number between 0 and 9 then press the ‘’
key to select and proceed to the next character. Continue this process until all characters
-27.4
ºC Dewpoint
@ 1.0barg
9144
ppm[V]
Moisture Reading
Moisture Units
Pressure Value and units

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are entered. Pressing the ‘ ’ key, at any point, enters the numerical value currently
displayed.
Notes
Where control values are entered (such as 4-20mA) the currently set value is displayed when
first entering the screen. This allows the user to simply press the ‘ ’ key and leave the screen
without altering any information. Useful when entering a function by accident.
The decimal point (dp) will always appear in the correct location.
On some screens when using ºC or ºF the first digit is the negative sign selector. This is either
ON or OFF.
Pressing the ‘’ key when the last character is active will make the first character active.
10.3 Entering Alphanumerical Data
(Full Logging SADPminiEx only)
Some functions such as the “Create TAG” allow the user to enter a combination of letters
and numbers. The principle for entering data is the same as that for entering numerical
data (10.2 above) except that the ‘’ and ‘’ keys scroll through the 26 letters of the
alphabet as well as the 10 numerical characters.
Note –There is a dual speed function when entering alphanumerical data. When either the ‘’
or ‘’ key is pressed and held, the speed of scroll will increase.
10.4 Security Protection Screens
Several of the SADPminiEx functions can be protected with security codes. These are the
main ‘Setup Menu’, the ‘AutoCal’ function, and the ‘SPC’ (Single Point Calibration)
function. Each of these functions can be protected with an independently activated user
defined 4-digit security code. Once activated, a screen requesting the correct code will be
displayed when the associated function is selected. Failure to enter the correct code will
prevent access to the function. Default setting 1000
11 Operating the SADPminiEx
11.1 The Setup Menu
(See Appendix C - SADPminiEx Setup Menu Map)
The setup menu it activated by pressing the ‘’ and ‘ ’ keys simultaneously. From this
menu, the user has the choice of several options detailed below:
11.1.1 Select Units
Description –This sub-menu has eight options allowing the user to select any one of
seven Moisture Engineering Units and to exit the menu.
Note: - 1) Once an engineering unit is selected, the SADPminiEx will only display and accept
inputs in that chosen unit. This means that 4-20mA settings (where fitted), offsets and
SPCs are all performed in the chosen units.

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2) The 4-20mA range settings are reset to full span whenever the moisture units are
altered.
Operation –In the ‘Setup Menu’ move the cursor bar to highlight the ‘Select Units’
option and press the ‘ ’ key. The ‘Primary Units’ sub-menu is displayed. Run through
the options until the required engineering unit is highlighted; confirm the selection by
pressing the ‘ ’ key. The SADPminiEx automatically reverts to the ‘Exit’ option in the
‘Setup Menu’.
Note: The PPB Moisture Engineering Units has an upper display limit of 10000 PPB, Change
units to PPM above this moisture level.
11.1.2 Pressure Calc
Description –This sub-menu has five options allowing the user to select any one of four
Pressure Engineering Units and to exit the menu. This function then allows the
SADPminiEx to display Dewpoint ºC and ºF at @ pressure. When this function is
selected, the main display screen will display the pressure at which the Dewpoint
reading is calculated.
Operation –In the ‘Setup Menu’ select the ‘Pressure Calc’ option. In the ‘Pressure
Units’ sub-menu run through the options until the required engineering unit is
highlighted; confirm the selection by pressing the ‘ ’ key. The SADPminiEx then
requires that a numerical pressure value be entered in the selected units. The display
format relates to the pressure units chosen. Once a pressure value is entered, the
SADPminiEx automatically reverts to the ‘Exit’ option in the ‘Setup Menu’.
Note: See ‘SADPminiEx Specification’ for detailed information on Pressure Engineering Units.
Warning: This function is purely an internal calculation and DOES NOT
allow an elevated pressure to be applied to the measuring head.
11.1.3 4-20mA Output (4-20mA and Full Logging versions only)
FOR USE IN SAFE AREA ONLY
Description –The 4-20 option allows the user to set the range over which the 4-20mA
output will span. The default setting is for the output range to cover the full operating
range of the sensor type fitted in the SADPminiEx e.g. for a ‘B’ type sensor 4mA equals
–80°C and 20mA equals 20°C. However, it is possible to set a more focused range,
such as 4mA equals -60°C and 20mA equals –20°C.
Operation –In the ‘Setup Menu’ select the ‘4-20mA Output’ option. The SADPminiEx
requires that a value be entered for the 4mA lower limit. The current value is displayed,
in the active moisture-engineering units. Once the new value is entered, the
SADPminiEx requires that another value be entered for the 20mA upper limit. Once

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that new value is entered, the SADPminiEx automatically reverts to the ‘Exit’ option in
the ‘Setup Menu’.
Note –1) The only way to leave this menu without altering any values is to press the ‘ ’ key
twice, accepting the current values for both the upper and lower settings.
2) The 4-20mA range settings are reset to full span whenever the moisture units are
altered.
3) The 4-20mA output should not be operated while the instrument is charging.
11.1.4 AutoCal
Description –AutoCal allows the user of the SADPminiEx to ensure accuracy between
laboratory calibrations by checking the span of the instrument and correcting for any
deviation.
The AutoCal facility uses the fact that each sensor is designed and manufactured to give no
further increase in response when it reaches its maximum moisture level. For example an
SADPminiEx with a full-scale value of -20°C dewpoint will read -20°C dewpoint when
exposed to a gas with this moisture concentration, and will continue to read -20°C dewpoint
as the moisture concentration rises above -20°C dewpoint. The SADPminiEx can,
therefore, be adjusted to read -20°C dewpoint on any gas with a moisture concentration
wetter than -20°C dewpoint, ambient air for instance, thus setting the span to match the
original calibration.
AutoCal should be operated periodically, every 2 to 3 months, say, or can be used to
verify operation of the SADPminiEx if confirmation of an unexpected result is required.
Operation –of SADPminiEx units with full scale values of -20°C or 0°C dewpoint
1. Select AutoCal from the Set-up Menu
2. Follow the on-screen instructions, i.e.:
i) Extend the desiccant head and press the ‘ ’ key.
ii) The SADPminiEx will display a moving bar until it assesses that the
sensor has stabilised. (Up to 10 mins.)
iii) The SADPminiEx will now display the full-scale value of the unit, either -
20°C or 0°C. If the unit is being checked against a known moisture level
such as from a moisture generator the scroll and ▲and ▼keys can be
used to enter the known moisture level, otherwise leave it set at the full-
scale value and press the ‘ ’ key.
iv) The SADPminiEx will display a moving bar whilst the calibration data is
modified. (Up to 5 mins.)
ACAL adjusts slope of curve.
New settings stored in SADPmini.
Inst Reading 100%