NVIS Nvis901 User manual

Nvis901
pH Meter User Guide
Nvis 901
Ver 1.1
Designed & Manufactured by:
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www.nvistech.com
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Nvis901
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Nvis901
Content
1. Introduction 
2. Features 
2. Technical Specifications &
3. Display and Inputs 
4. perating Procedure
5. PC commutation 
6. Accessories 
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Nvis901
Introduction
NV901 is a micro controller based pH meter designed to fulfill the need for modern laboratories.
NV901 is easy to use and contain features like PC interface,3 point calibration, Inbuilt electronic
buffer for calibration, Auto temperature compensation, Manual temperature compensation. It provide
resolution of 0.01pH and 0.1°C for temperature . NV901 come with software by which user can see
graph of pH vs. time and temperature vs. time. User can store pH and temperature reading on PC.
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Features
Micro controller based design
 Fast response time
Resolution of 0.01 pH and 0.1°C for temperature
3 point calibration
In built electronic buffers
PC software for storing data
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Technical Speci ications
pH Range 0 To 14 pH
pH Resolution ± 0.01pH
Temperature Resolution ± 0.1°C
Electronic Buffer 4 pH, 7pH, 9.18pH
Calibration 3 point
PC Interface RS-232 & USB
Power Supply 230 V ±10%, 50 Hz
Automatic Temperature Compensation (ATC) 0-80 °C
Manual Temperature Compensation (MTC) 0-80 °C
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Display and Inputs
Front Panel:
Keys:
1. Power n/ ff peration
2. UP, Down Temperature Cal, pH Cal
3. Enter For Enter in menu
4. Escape For Escape from Menu
Connectors:
1. pH pH Sensor input
2Temperature Temperature Sensor input
Rear Panel:
Connectors:
1. Green Connector 4 pH Electronic Buffer
2. Red Connector 7 pH Electronic Buffer
3. Black Connector 9.18 pH Electronic Buffer
4. Power Socket Mains Supply
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5. RS-232 Connector PC Interface
6. USB Connector PC Interface
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Operating Procedure
*Note :- Please read the direction to use of pH electrode before using the instrument.
1. Connect the ph electrode and Temperature sensor in BNC connectors
2. Press the Power Button and display appear on the LCD (Fig 1).
Fig 1.
3. If ATC is displayed mean auto temperature compensation is enable.
Fig 2.
4. For displaying the electrode potential press ‘UP’ key for two second and electrode potential appear
on the display.
Fig 3.
5. The electrode potential is display till the ‘UP’ is pressed when key is released the normal display
appear.
*Note-pH electrode response time is nearly about 15 second.
*Note- The displayed electrode potential is not calibrated value. So if user calibrate the instrument
even then the actual potential is displayed.
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MTC Mode:-
1. To enable MTC press ‘Enter’ key one’s and following screen appear (Fig 4.)
Fig 4.
2. For temperature adjustment use ‘UP’ for increasing temperature. And ‘Down’ key for decreasing
the temperature.
3. To out form temperature adjust press ‘ESCAPE’ key.
4. By this MTC is enabled and MTC appear on display in place of ATC (Fig 6.)
Fig 5
5. For disable the MTC press ‘Down’ key for three second.
6. The MTC range is form 0 to 80°C. So if user try to adjust above or below this range then “ ver
range” message displayed.
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pH Meter Calibration using pH bu er solution
Nvis 901 pH meter having three point calibration for correcting pH sensor error. For this three buffer
solution of 4pH, 7pH and 9.18pH is required. The pH buffer solution can be prepared form pH
buffer tabled or by chemical method. However pH buffer tablet are recommended for good accuracy.
Follow the procedure given below for calibration.
1. Clean the pH sensor by distill water and dip pH sensor in distill water for two minutes.
2. Clean the PT100 sensor by distill water. And dip in pH buffer solution with pH sensor.
3. Now prepare pH buffer solution of 4pH, 7pH and 9.18pH in three different clean beaker.(please see
the procedure given on buffer tablet container to how to prepare pH buffer solution).
4. Now on the instrument and dip pH sensor in 4pH buffer solution and then press enter button two
times.”Dip in 4 pH” message appear on LCD (Fig 6).
Fig 6
5. Wait for 1 minute and then press down button. Instrument start taking reading. After few second
“Press Up” message appear on LCD(Fig 7). Now press up key.
Fig 7
6. Now LCD display “Dip in 7pH”. Dip pH sensor in distill water for few second (without removing
form instrument). Then dip it in to 7pH buffer solution for 1 minute and then press down button.
Instrument take reading and then message appear “Dip in 9.18pH”.
7. Dip pH electrode in distill water for few second (without removing sensor form instrument). Then
dip in to 9.18pH buffer for one minute. Press down button, “Press Up” message appear on display.
8. Now press up button. The “Cal Active” message come on display second line(Fig 8). To activate
calibration press Escape button and for deactivate calibration press down button, “Cal Deactivate”
message come on display and then press Escape. If calibration deactivate option is selected then
calibration process is not effective.
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Fig 8
9. If pH buffer solution is not correct or pH electrode error is too large then “Check pH Bu er”
message come on display. In this case check your buffer solution or follow the procedure given in
“Direction or Use pH Electrode” section.
Note:
1. During pH Calibration, temperature automatically set on 25° C.
2. Always use fresh buffer solution for calibration 
3. If given sequence is not followed or buffer are of wrong value then ‘Check the sol’ message come
display.
4. pH electrode response time is nearly about 30 second
5. Before and after using the pH & temperature sensor clean it by distilled water.
6. Buffer tablet of 4,7, 9.18pH is provided with instrument. User can calibrate this instrument using
these tablet.
Break tablet and put them in 100ml o distill water or hal hour and then use them.

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pH Meter Calibration using electronic bu er
Nvis 901 having electronic buffer for calibrating the instrument. Three connector are provided on
back side of instrument. These are voltage source for 4,7 and 9.18pH.
pH Voltage
4 +178mV
7 0V (GND)
9.18 -129mV
Electronic calibration can only calibrate the instrument. I error is in sensor, then calibration
should be done with pH sensor and bu er solution. Electronic calibration not work in case o ph
sensor error.
Electronic calibration procedure
The calibration procedure using buffer solution and electronic buffer is same. In electronic calibration
electronic buffer provided on back side of panel are used instead of pH sensor. Electronic buffer of 4
pH, 7pH, 9.18pH are connected one by one using a cord (provided with Nvis901) with pH connector
on front panel and follow same procedure explained in section “pH Meter Calibration using pH buffer
solution”.
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Nvis901
PC inter ace
NV901 can be connected with PC via RS232 or USB. NV901 come with a pc interface software, by
which user can take the pH and temperature reading on PC. User also store pH and temperature
reading on PC. This software also show duration on which reading taken and plot pH vs. time and
temperature vs. time graph (Fig 9).
Operating Procedure-
1. Install the software on PC.
2. Connect Nvis 901 USB probe with PC. And install USB driver provided in CD.
3. Open the so tware. select the comport (This may di erent on your PC) and click on 'Connect'
button (Fig 10). The 'Connect' button change to 'Disconnect'.
Fig 10
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To disconnect form instrument press 'Disconnect' (Fig11).
Fig 11
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 Fig 12
5.To start the sampling set the sampling time text box (Fig 12). 'MM' is for minute and 'SS' is for
second.
Fig 13
6. Press start button then a massage come to give file name and then press save button (Fig 14).
Fig 14
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7.Give the file name and press ‘Save’ .In this file all data coming form instrument is saved.
8.The reading coming form ph meter is come on left hand side of screen.
9.Counter given on right hand side of screen, display the duration of data collection.
10.Use ‘Stop’ button for stopping the data collection
11.’Reset’ button is for resetting the counter and ph and temperature graph.
11. ‘Import’ button display the saved reading and plot the ph and temperature graph w.r.t time on
screen (Fig 15).
Fig 15
Note: When MTC is active then instrument display the MTC set point & send the MTC set
point to PC.
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Direction or Use pH Electrode
1. Remove the bottle/protective cap at the bottom of the electrode.
2. Shake the electrode gently to ensure that the internal buffer solution covers the whole pH
bulb and no air bubbles are entrapped.
3. pH combinational electrodes should be filled with the appropriate electrolyte to a height of
about 1 cm below the filling port.
4. Wash off any salt film present on the exterior of pH combination electrode, using distilled
water.
5. To ensure pressure equalization, the stopper of the filling port should be removed or
perforated with a pin.
6. Soak the electrode in 7 pH buffer or saturated KCL for some hours (preferably overnight)
below use.
7. Electrode which have developed problem of slow response due to drying out of the
membrane or use under extreme conditions, may be re-activated by soaking in 0.1 N
hydrochloric acid for 8 to 10 hours.
Electrodes, which fail to respond to the above treatment, can be further activated by dipping
them to 2% hydrofluoric acid for 5-10 seconds and immediately washing with distilled water.
This drastic treatment should however be applied only as last resort as it reduces the life of
the electrode.
8. After conditioning the electrodes as in (7) above, if it is not to be used it should be kept in
7pH buffer or saturated KCL. To prevent the entry of measuring media through the
diaphragm of the reference junction of pH combination electrode, the stopper of the filling
opening/ port should be removed or perforated with a pin.
Important or pH combinational Electrodes:
1. Always keep the electrode dipped in saturated KCL solution, when not in use.
2. Since the shelf life of the buffer is very short, for correct results it is strongly
recommended to use freshly prepared buffers for calibration
3. In any case, kindly do not take any step not mentioned in our “Direction for use”
(Moreover, do not remove the cap on top of the electrode which will make the electrode
ineffective).
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Important Point
1.Please read the direction to use of pH electrode before using the instrument
2.The response time of ph meter is about 30 second.
3.Do not put the pH electrode in high temperature for long time.
4.During MTC setting and calibration process instrument stop sending the data to pc.
5.When MTC is active the instrument display the MTC set point and send the MTC set
point to pc.
6.During calibration process the instrument automatically take temperature at 25°C.
7.Before and after using the ph & temperature sensor clean it by distilled water
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pH vs Temperature Error Table
Values in gray are temperature and pH in which there is no error in pH from temperature.
pH vs mV Table
This table show the different value of mV form electrode vs pH
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Accessories
1. pH sensor 1No
2. Temperature Sensor 1No
3. Stand 1No
4. Software CD 1No
5. USB Cable 1No
6. RS232 Cable 1No
7. Main Cord 1No
8. Cable for Electronic buffer Calibration 1No
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