Joshua Turner was asked to calibrate two level measurement instruments (DP cells) on vessel V401. He calibrated an electronic DP cell and a pneumatic DP cell. For each calibration, he took the DP cell back to the workshop and followed a multi-step process to adjust the zero and span. His calibration records showed small errors within tolerance for both instruments. Photos provided evidence that he safely performed the calibrations according to procedures.

1. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
Scenario:
I have beencontactedandrequestedtoworkonvessel V401 andcalibrate twoDP cells,apneumatic
and electroniccell.Ihave beenaskedtomake sure thatthe vessel loopsaccuratelymeasure the
level inside of the vessel.
a) Documentationthat I will need
I will need3piecesof documentationtobe able tocomplete thisjob,theyare listedbelow;(See
appendix1)
 Instrumentloopsheets
 Instrumentdetails
 Calibrationdetailsof bothDPcells
I wouldalsoneedthe rig400 instrumentsettings(Seeappendix2) andblankcalibrationsheets
whichwouldbe filledinasI make my waythroughthe calibrations(See appendix3).
b) The DP cellsthat I will be calibrating are:
An electronicDP cell
Rosemount–Serial No.E120119
Calibrationrange –0 –150” WG
Output– 4 – 20 mA (supply12-45V DC)
Maximumworkingpressure –2000 psig
A pneumatic DP cell
Foxborro – 13A – MS2
Serial Number–E253500
Output– 3 – 15 PSI
Range – 0 – 150” WG
Maximumworkingpressure –1500 psig
316SS capsule (Stainlesssteel)

2. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
c) Health and Safety requirements
I needtoundertake some necessaryactionstomake sure thatthe correct safetyprecautionsare in
place,firstof all I needtomake sure that I acquire a workpermit frommy supervisor(See appendix
4); thiswill informme of the conditionsIwill be workinginandthe PPEthat I will have towear.The
PPE islistedbelow:
 Overalls –Used to stopany oils/chemical orgrease gettingonmyclothes
 Boots– To protectmy feetfromanythingbeingdroppedonthem suchasthe DPcell
 Gloves– To stop me fromcuttingmy hands
 LEP – If there isany burst of air fromthe psi thenI wouldneedtoprotectmy
eyes.
(Asyoucan see fromthe photo(right) thisisme in full correct PPE)
Anotherhealthandsafetyprecautionwouldbe tomake sure that youisolate the
loopscorrectly;the isolationsthatshouldtake place are anelectrical isolationwhichis
liftingthe knife edgesforthatloopwithinthe control room.Forthe pneumaticisolation,youwould
have to turn the supplyof air off byturninga leverat a pointacross the loop/system. The process
linesmustalsobe safelyisolatedastheycouldcontaintrappedair.
d) Equipment
The equipmentthatcould be usedforthe calibrationswouldbe:
Test benchcomparator: This ismade up of the following,
 30 psi 0 – 100”WG regulatedair– I will connectthisupto the high
pressure side of the DPcell and pumppressure intothe instrument.
 30 psi supply – I will connectthe DPcell inputto the supply.
 “WG digital indicator–Thisis usedtoshow a readingwhenthe
pressure ispumpedintothe DPcell viathe regulated0-30 psi / 0-100”WG
supply.
 30 psiggauge – Thispiece of equipmentisusedtomeasure the 3-15
psi outputpumped fromthe DP cell,itwill alsoindicate tome isthe
span/range needsadjusting.
 24 voltDC supply – Is usedto provide avoltage tothe systemwhenconnectedup.
Druck DPI 601 portable calibrator: The Druck is usedonsite to provide the pressure tothe DPcell.
 Range 0–2 bar, 0-30 psig,0-800”WG; I can use the 0-800”WG range.
 Serial number5996/91/10

3. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
Multi-meter,MastechMas 830BC: This isusedto give anindicationof voltage,
currentand resistance. Ican connectit upin series withthe 24 voltDC suplyto the
electroniccell.
 Serial numberMBED021531
I couldhave gone ontothe site andcompletedthe joboutthere,orI couldhave disconnectedthe
DP cell andtook itback to the workshopandcalibrate itin there.Ihave decidedtogo forthe latter
of the 2.
e) WhyI decidedtouse certain equipment
As I have statedintask 1e,I have decidedtocalibrate the DPcell back inthe workshop,Icame to
thisdecisionfornumerousreasons.Firstof all,takingenvironmental conditionsinto considerationI
believethatprogressionwouldbe made ata much quickerrate withinthe workshopif the weather
was poor.It iswarmerin the workshopthanout onthe site whichwouldmeanthatthe jobwould
be completedata higherlevel of competencyas some people mayrushthe jobonsite if theywere
workinginbadconditions,if the weather,forexample,wasrainy,thenaproblemthatI wouldhave
to solve wouldbe the opencoverof the DP cell andall of the electrical interiorof the DPcell being
coveredinrain. Secondly,if Iwere tocalibrate the DP cell inthe workshopthenIwouldonlyhave to
isolate the looponce,whereasif Iwasto complete the calibrationonsite,Iwouldhave tomake a
total of 3 isolationsof the loopfordifferentreasons.Movingonfromthis,Iwouldhave tocarry out
differentpiecesof equipmentsuchasa Druck and a multi-meter;thiswouldleadtocomplications
out onsite because Iwouldhave to hookthe Druck up to the DP cell andpump pressure intothe DP
cell alongwithusinga multi-meterandtryingtofill outa calibrationsheet.Havingaworkbenchalso
meansthat itis a betterplace to fill inthe calibrationsheet,the resultswouldbe setoutalot neater
on the sheetthanwhattheywouldbe if I had to fill the sheetoutonsite.Ialsobelieve thatanother
logical reasonforcalibratingthe DPcell wouldbe thatI wouldnothave to constantlypumpthe
Druck to insertpressure intothe DPcell,insteadof that,all Iwouldhave to dois turnup the
regulatoronthe testbenchcomparatorto the amountof pressure thatI want.Finally,the Druckis
sometimesconsideredasunreliablebecause they canleak,anissue thatariseswiththisisthatI
wouldbe pumpingpressure fromthe Druckintothe DP cell butthe pressure would be decreasing
due to the leak.

4. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
Task 2 – P9
A) To calibrate the pneumaticDP cell I completedthe followingsteps:
Step 1) I beganby gatheringawork permitandhavingitsignedoff bymysupervisor.
Step 2) In myfull andcorrect PPE, I wentontothe site andlocatedthe correct pneumaticDPcell
that I wouldbe workingon.
Step 3) I isolatedthe loopthatthe DP cell waslocatedin;to dothisI useda loopdrawing.
Step 4) Afterthe isolation,Iremovedthe DPcell fromthe site and tookitback to the workshop.
Step 5) NextIsecurelymountedthe DPcell tothe workshopbenchsothat it wouldnotpossiblyfall
and hitmy feet.
Step 6) I thenconnectedupthe DP cell toa 20 psi supply asthiswouldsupplythe inputontothe DP
cell
Step 7) Afterthat,I connecteda 3-15 psi outputto a gauge that read 0-30 psi on the comparator
panel onthe workbench.
Step 8) I thenconnectedaregulated0-50”WG airsupplyto the highpressure side of the DPcell.
Step 9) I applied0”of waterto the highpressure side of the of the DP cell
Step 10) I had to make sure that there wasa 3 psi output,todo this;I adjustedthe zeroscrew onthe
DP cell.
Step 11) I applied50”WG to the highpressure side of the DPcell.
Step 12) I also adjustedthe range screwsoI couldget a 15 psi output
Step 13) I had to make sure that the readingswere spoton,the way I couldconfidentlyprove this
was to repeatsteps10 and 12 until the readingswere accurate.
Step 14) I had to record the resultssoto do thisI useda calibrationsheet.
Step 15) The final stepthatI completedwastodisconnectthe cell fromthe workshopandtake it
back out ontosite,refitthe DPcell to V401 and re-commissionit.

5. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
B) To calibrate the electronicDP cell I completedthe followingsteps:
Step 1) I beganby gatheringawork permitandhavingitsignedoff bymysupervisor.
Step 2) In myfull andcorrect PPE, I wentontothe site andlocatedthe correct electronicDPcell that
I wouldbe workingon.
Step 3) Next,Iisolatedthe loopbyliftingthe knife edgesinreference tothe DPcell.
Step 4) I thensafelyremovedthe electronicDPcell andtookit back to the workshoptocalibrate it.
Step 5) I made sure that the DP cell wassecured on the testbench;thiscompliedwithhealthand
safetybecause nowitcouldnotfall of the benchonpossiblyontomyfeet.
Step 6) I connectedthe DPcell up toa 24 voltsupplyandmA in series.
Step 7) Whenthe DP cell wascorrectlyconnected up;I applied0pressures tothe DP cell and
adjustedthe 0 to give me a readingof 4mA on the digital screen.
Step 8) NextIappliedatotal of 50”WG to the cell andadjustedthe range screw until Ihad a reading
of 20mA.
Step 9) Before Imove on to anyothersteps,I had to make sure that the 4 to 20 mA was spoton, to
make sure of thisI wouldkeeprepeatingsteps7and8 until readingswere accurate.
Step 10) I thenrecordedmy resultsandtodo thisI filledinacalibrationsheet.
Step 11) At thisstage,I disconnectedeverythingfromthe DPcell,tookthe DPcell back outon to the
site andre-commissionedit.

6. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
C) Proofof calibrations (Photographicevidence)
D) My tutor completedanobservation report on me (Appendix5)
Task 3: Distinction2
a) On completionof tasks1 and2, youshouldattach the calibrationrecord sheetsforthe level
systemcalibrationandevaluate the datatodetermine the overall systemerror
performance.
AfterI hadundertookandcompletedthe calibrationIfilledin2 calibration sheets;one forthe
pneumaticDPcell andone for the electronic DPcell.
The detailsof the ElectronicDPcell as are follows:
Make: Rosemount
Serial Number:E120119
As I wentbackoverthe sheetsandanalysedthem, Ifoundaslightzeroerrorand there wasalsoan
error at 100% (rising) of 0.01 mA and thiscan alsobe seenas a 0.06% error,this happenedwhenI
appliedatotal of 50”WG, the digital screenwasshowing20.01 mA insteadof 20mA.I attemptedto
adjustthe range;howeverIcouldnot getthisspot onand therefore settledforthe extra0.1 mA.
AlthoughIwascertainthat thisreadingwaswell withinthe tolerance,Ishowedthe resultstomy
supervisorwhowasalsofine withthem.
The other calibrationthatIundertookwasof a pneumaticDPcell,the detailsof thisare asfollows:
Make: Foxborro
Serial Number:E253500
The image above
showsme calibratinga
pneumaticDPcell.
The image above
showsme calibrating
an electronicDPcell.
Thisis an image of
me removingthe DP
cellsoff the site.

7. JoshuaTurner
14 Eli
Unit 24 ProcessmeasurementAssignment3
Task 1 (P8and M3)
AfterI hadfilledinthe calibrationsheetwithmyresults,Ithenwentbackoverthemand lookto see
if I couldspot anyerrors; I foundone errorat 50% (rising);itshouldhave been9psig,howeverthe
readingIgatheredwas9.1 psigwhich had a percentage errorof 0.83%. Thisdifferencewasonly
small andas I did withthe electronicDPcell error,Icheckeditwithmysupervisortomake sure he
thoughtit wasacceptable.Due tothisDP cell onlyhavinga zeroand spanadjustmentscrew itmeant
that I couldnot fix thiserror.
b) Foundat the back of my assignmentwill be the calibrationsheetsthatIfilledinwhenI
completedthe calibrationof the pneumaticandelectronicDPcells.Ihave alsoprovided
evidence of me undertakingthe calibrationsandthese photoscanbe foundwithintasks1
and 2.