CMA ML39m User guide

Brand: CMA

Model: ML39m

Type: User guide

GASPRESSURESENSORML39M

USER’SGUIDE



CENTRE FOR MICROCOMPUTER APPLICATIONS

http://www.cma-science.nl

2|ML39mGasPressureSensorUser’sGuide

Shortdescription

TheGasPressuresensorML39misdesig nedtomeasurerelativegaspressureinthe

range between‐100 to 300 kPa (positive or negative differential changes in

pressure). The pressure is measured via a pressure port located on the side of the

sensor box. The end of the white pressure port has

 a  small threaded end called a

Luer‐lock. With a gentle half turn, you may directly attach the plastic  Luer‐lock

connectororthe20mLplasticsyringe(includedwiththesensor).

Thepressure sensoris a very precise piezoresistivepressuresensor.It consists ofa

silicon diaphragm withpiezoresistive

strain gauges diffused into it, fused to a glass

backplate. Applied pressure causes mechanical stress of the diaphragm, which is

transducedintoaresistancechangebymeansofthepiezoresistiveeffect.

The Gas Pressure sensor is fairly  durable, but it is designed only for use with non‐

corrosive,non‐ionic working

gassessuchasair,drygasesandthelike. Donotgetit

wet.

Thesensorisdeliveredwiththefollowingaccessories:

 oneplastic20‐mlsyringewithLuer‐lock,

 oneplasticLuer‐lockconnector,and

 oneplastictubewithaninsidediameterofcirca6mm.

Thistubecanbeattached 

totheotherendoftheLuer‐lockconnector.



TheGasPressuresensorisanI2Cdigitalsensor,whichgivescalibratedvaluesofthe

measured quantity. This sensor can only be connected to special interfaces that

supportI2C digitalsensorsliketheCMA MoLab interface.

Thesensorcableneeded

toconnectthesensortoan interfaceisnotsuppliedwiththesensor(sensorcables

aresuppliedwithinterfaces).

Sensorspecifications

TheGas Pressuresensor ML39m is a digital sensorthat converts the measured gas

pressure value to a digital value via 14‐bit analog‐to‐digital conversion. The

resolution of the sensor is typical 0.0244 kPa. The maximal sampling  rate of the

sensoris1000Hz.

Collectingdata

This Gas Pressure sensor works only with specific interfaces. The sensor will be

automatically detected when connected to such an interface. For detailed

information about measurements with sensors consult the User Manuals of the

interfaceandtheCoach6software.

ML39mGasPressureSensorUser’sGuide|3

Calibration

The Gas Pressure sensor is supplied with a factory calibration in kPa. The Coach 6

program allows shifting the pre‐defined calibration  or creating a new two‐point

linearcalibrationifneeded.The usercalibrationisstoredin non‐volatileusersensor

memory.

Suggestedexperiments

ThisGasPressuresensorcanbeusedinvariousexperimentssuchas:

 Investigatetherelationshipbetweenpressureandvolume,Boyle’slaw.

 Studytheeffectoftemperatureongaspressure,Gay‐Lussac’slaw.

 Measurevaporpressureofliquids.

 Measurementsofreactionratesasagasisproducedin

achemicalreaction.



Figure1.UsingthepressuresensorandtheplasticsyringeinanexperimenttoverifyBoyle’slaw.



PressureUnits

Pressure can be measured in many different units. Some equivalent values for  1

atmosphereare:

1atmosphere=101.325kPa

1atmosphere=760mmHg

1atmosphere=29.92in.ofHg(at0°C)

1atmosphere=14.70psi

1atmosphere=1013millibar



4|ML39mGasPressureSensorUser’sGuide

TechnicalSpecifications



Sensorkind Digital:on‐sensoranalogtodigitalconversion

(14‐bitsresolution,communicationviaI2C) 

Measuringrange ‐100..300kPa(‐1000..3000hPa) 

Resolution Typical0.0244kPa(0.244hPa)

Uncertainty

Linearitysensitivity error:Typical±0.3%offullrange

Sensitivity‐temperaturecharacteristics:±1.0%offull

rangeattemperature(compensation)range15to45°C,

wherezeroat30°C

Accuracy:Typical±1.0%offullrange

Connection PressureportfemaleLuer‐lock

Usage

Only for non‐corros iv e gasses, non‐ionic working gasses

suchasair,drygasesandthelike

Respondtime

90%ofappliedpressurevalue:typical,0.2ms

(beforedigitalconditionandconversion)

Maximalsamplingrate

1000Hz

Sensordimensions

Housing:68 x 18 x 16 mm (WxDxH)

Lengthoffemale Luer‐lockconnector:6.2mm

Connection 5‐pinsminijackplug



Warranty:

The Relative Pressure sensor ML39m is warranted to be free from defects in

materials 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.



Note: Thisproductistobeusedforeducationalpurposesonly.Itisnotappropriate

forindustrial,medical,research,orcommercialapplications.   

Rev. 17/11/2011

CMA ML39m User guide

CMA ML39m User guide

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