PH!SENSOR!BT61i!
USER’S!GUIDE!
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CENTRE FOR MICROCOMPUTER APPLICATIONS
http://www.cma-science.nl
2!|!BT61i!pH!Sensor!User’s!Guide!!
Short!description!
The! CMA! pH! Sensor! is! a! general;purpose! pH! measurement! system! that! allows!
measuring!the!degree!of!acidity/pH!value!of!a!solution!in!the!range!between!0!and!14.!
The!sensor!consists!of!a! pH!amplifier!and!pH!electrode .!The!pH!Electrode!(031)!is!not!
delivered!with!the!pH!sensor!and!has!to!be!purchased!separately.!!
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The!pH!Sensor! can!be! directly! connected!to! analog!BT!inputs! of!the!CMA! interfaces.!
The!sensor! cable! BT! ;! IEEE1394! needed!to! connect!the! sensor! to! an! interface!is! not!
supplied!with!the!sensor!and!has!to!be!purchased!separately!(CMA!Article!BTsc_1).!!
Sensor!recognition!!
The!pH! Sensor! has!a! memory!chip! (EEPROM)! with! information! about! the! sensor:!its!
name,! measured! quantity,! unit! and! calibration.! Through! a! simple! protocol! this!
information!is!read!by!th e!CMA!interfaces!and!the!sensor!is!automatically!recognized!
when!it!is!connected!to!these!interfaces.!!!
If!your!pH!Sensor!is! not!automa tically! detected !by!an!interface!you!have!to!manually!
set!up!your!sensor!by!selecting!it!from!the!Coach!Sensor!Library.!!
pH!Amplifier!!
The! CMA! pH! amplifier! is! a! device,! which! allows! a!
standard! combination! pH! electrode! (such! as! the!
CMA!pH! Electrode!(031))! to! be! monitored!by! a! lab !
interface.!The! pH!electrode! is ! connected! to! the!pH!
amplifier!via!BNC! connector!located! on!one! end! of!
the!sensor!box.!The!pH!amplifier!adjusts!the! voltage!
produced!by!the! pH!electrode!to!a!range!between!0!
to!5!V,!which!can!be!measured!by!an!interface.!
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pH!Electrode!!!
The! CMA! pH! electrode! is! designed! to! make!
measurements! in! the! pH! range! of! 0! to! 14.!!
It! has! a! coax! cable,! with! a! BNC! con n ec to r.! !
The!electrode!(made!from!glass)!is!built!in!a!plastic!
tube! with! an! opening! at! the! bottom! side.! It! is!
supplied!in!a!bottle!filled!with!a!protective!solution.!
When!the!pH!electrode!is!not!being!used,!it!must!be!
kept!in! this!liquid.! For! use!and! maintenance!of!the!
CMA! pH! electrode! follow! instructions! given! in! its!
User’s!Guide.!!
Figure!1.!The!pH!Amplifier!(BT61i).!!
Figure!2.!The!pH!Electrode!(031).!
BT61i!pH!Sensor!User’s!Guide! |!3!
Calibration!!
The! CMA! pH! sensor! is! supplied! calibrated.! The! output! of! the! sensor! is! linear! with!
respect!to!pH!value.!The!supplied!calibration!function!is:!!!
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pH!=!;4.04!*!V
out
!(V)+!13.68!
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The! Coach! program! allows! selecting! the! calibration! supplied! by! the! sensor! memory!
(EEPROM)!or!the!calibration!stored!in!the!Coach!Se ns or!Library.!For!better!accuracy!a!
new!user!calibration!can!be!performed!in! the! Coach!program.!In!order!to!calibrate!a!
pH!Sensor,!you!should!have!a!supply!of!pH!buffer! solutions!that!cover!the!range!of!pH!
values!you!will!be!measuring.!To!perform!a!two;point!calibration:!
• Rinse!the!tip!of!the!electrode!in!distilled!water.!!
• Place! the! electrode! into! one! of! the! buffer! solutions.! When! the! voltage! reading!
stabilizes,!enter!the!pH!value.!
• For!the!next!calibration!point,!rinse!the!electrode!and!place!it!into!a!second! b uffer!
solution.!!
• When!the!voltage!reading!stabilizes,!enter!the!second!pH!value.!!
• Test!your!calibration!in!different!known!pH!buffer!solutions.!
Suggested!experiments!!
The! pH! sensor! can! be! used! for! various! experiments! in!
biology,!chemistry!and!environmental!science!such!as:!!
• Measuring!pH!values!of!different!acids!and!bases,!
• Acid;base!titration!experiments,!
• Monitoring!pH!during!chemical!reactions,!
• Investigating!of!water!quality!in!streams!and!lakes.!
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Practical!information!
• Do! not!place! the!electrode! in!base! solution! (pH! >! 10)!for! longer! than!few! hours.!
This!can!affect!the!glass!of!the!electrode.!!
• The! pH! electrode! has! a! limited! operational! life! and! can! be! ordered! separately.!!
During!a!m easuremen t!the!end!of!the!plastic!tube!of!the!electrode!has!to!be!held!
approximately!1!cm!in!the!liquid.!!
4!|!BT61i!pH!Sensor!User’s!Guide!!
Technical!Specifications! !
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Sensor'kind'
Analog,!generates!an!output!voltage!between!0 - 5 V !
Measuring'range''
0!..!14!!
Resolution'using''
124'bits'5V'AD'converter'
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0.005!pH!
Temperature'range'
5°C!and!80°C!
Isopotential'pH'
pH!7!(point!at!which!temperature!has!no!effect!on!output)!
Calibration'function'
pH!=!;4.04!*!V
out
!(V)+!13.68!
Connection'
IEEE1394!connector!for!BT;IEEE1394!sensor!cable.!!
Sensor!cable!not!delivered!with!the!sensor.!!
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Warranty:!!
The! pH! Sensor! BT61i! is! warranted! to! be! free! from! defects! in! m ateria ls! and!
workmanship!for!a!period!of!12!months!from!the!date!of!purchase!provided!that!it!has!
been! used! under! normal! laboratory! conditions.! This! warranty! does! not! apply! if! the!
sensor!has!been!damaged!by!accident!or!misuse.!!
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Note:!This'product'is' to' be' used' for' educational'purposes'only.' It'is' not' appropriate'for'
industrial,'medical,'research,'or'commercial'applications.'' ' ' ' '
Rev. 20/11/2014
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