aas (change of contact cylinder & graphite tube

7/25/2019 AAS (Change of Contact Cylinder & Graphite Tube

http://slidepdf.com/reader/full/aas-change-of-contact-cylinder-graphite-tube 1/11

Technical NoteInstrument: AAS (Perkin Elmer AAnalyst 700)

Graphite Furnace System Maintenance ChangingCntact Cylin!er " Graphite #u$e%ersin : & 'ate: April 0&&

1. Checklist for Regular Maintenance Task.

Graphite Furnace Maintenance Checklist

No Part Maintenance plan EstimateTime

PartNumber

1 Graphite tube Once the tube is contaminated,because of dirt deposit/accumulatearound the injection hole on theintegrated platform, it is can be cleanup but it is more recommended to

replace the tube to reduce the samplemeasurement risk (accuracy).Normally after hundred (>!!) ofsample measurement the tube "illha#e potential to get pitted andcracked, as "ell as the niobiumcoating also "as already not "ork"ell, replacement of graphite tube isimportant before this happen.

$fter %!!measuremen

t(&eekly)

'O !!**

2 Graphitecontacts

(+G$ ontact

-et)

erform a monthly #isible check, tosee if any pitted and crack on thecontact cylinder surface

#ery time that the furnace is opened,remo#e any particles/dirt from insidethe contacts using a small #acuumcleaner or a cleaning s"ab.0eplace the contact cylinder for e#ery!!! measurement (include duplicatemeasure)

$fter !!!measuremen

t

'O 123%*

Table 1 Maintenance checklist

2. !tan"ar" proce"ure

2.1 Graphite furnace replacement

2.2 Graphite contacts replacement #contact c$lin"er%





2.1 Graphite furnace replacement

4o open the furnace to install/ change graphite tube and also to clean inside the graphitecontacts

2.1.1 5ake sure furnace surface is cool enough to start the maintenance "ork

2.1.2 arefully remo#e both of furnace lenses ("indo"), "ithout touch the surface of lens"ith the 6nger. (clean them if necessary)

Figure 1 &pen close furnace lens.

2.1.' 7n standby furnace position, 7n the 8urnace ontrol "indo", click on 9&pen(Close:,then the furnace opens and the graphite tube is accessible

2.1.) 0emo#e the graphite tube and also the Graphite shield ring at the left contactcylinder (clean them if necessary)

Page 1





Figure 2 Remo*e Graphite Tube + !hiel" Ring

2.1., 'efore install the ne" graphite tube "e need to clean the surface/"all of thecontact furnace as normally there many deposited burn sample (fat) accumulate onthe surface.

8igure ; < lean furnace.

2.1.- 7nstall back the ne" graphite tube, by putting it into the hole of contact cylinder"ith the correct alignment as sho"ed on 6gure % (using tube alignment tool)

Page 1





8igure %< Graphite tube installation

2.1. 7n the 8urnace ontrol "indo", click on 9&pen(Close:, then the furnace "illautomatically close, and back to the standby position.

2.1./ $fter that, again in the 8urnace ontrol "indo", click on 0Con"ition tuberecommend that to run the graphite tube conditioning program e#ery time, "echange the graphite tube or platform. 4he conditioning procedure remo#esadsorbed gases and surface contamination from the graphite, and ensuresreproducible performance.

$t this stage the system uses a special furnace program to heat the tube tosuccessi#ely higher temperatures

2.1.3 'y using the niobium method (select this method) run the niobium sample to coatthe ne" graphite tube installed earlier. Niobium able to protect the graphic tube forthe shelf life purpose.

Page 1





8igure < Niobium oating

2.1.14 7n the 8urnace ontrol "indo", click on 05lign auto sampler to $lign

back the auto sampler. 8urnace system ready for the ne=t sample measurement.(done)

2.2 Graphite contacts replacement #contact c$lin"er%

hange the graphite contacts "hen one or both contacts are badly contaminated orsho" #isible pits and small cracks. $l"ays change both contacts at the same time.

-ummary standard procedure

• Open the furnace and remo#e the graphite tube

• 0emo#e the righthand contact

• 0emo#e the lefthand contact

Page 1





• 7nstall a ne" lefthand contact

• 7nstall a ne" righthand contact

• 7nsert the graphite tube and close the furnace

• ondition the graphite tube

• $lign the auto sampler

-pecial tools to change the contacts are pro#ided "ith the furnace. 4hese are used indi?erent con6gurations for di?erent procedures as depicted in the follo"ing illustrations.

• &pen the furnace an" remo*e the graphite tube

2.2.1 arefully remo#e both of furnace lenses ("indo"), "ithout touch the surface of lens"ith the 6nger. (clean them if necessary)

2.2.2 7n standby furnace position, 7n the 8urnace ontrol "indo", click on 9&pen(Close:,

then the furnace opens and the graphite tube is accessible

2.2.' arefully push the black locking ring of the connector into the connector and pullthe tube out of the connector

2.2.) ull the righthand furnace block, the graphite tube is no" accessible. 0emo#e thegraphite tube do not touch the graphite tube "ith bare 6ngers.

2.2., @ery carefully, using a small scre"dri#er, le#er the graphite shield ring from thelefthand contact.

Figure - Remo*e Graphite Tube + !hiel" Ring

• Remo*e the right6han" contact

2.2.- 4ake the contact installation tool pro#ided and place the domeshaped e=tractor onthe bolt. ass the bolt from the internal side of the furnace through the rightcontact cylinder and out through the "indo" ca#ity the furnace block.

2.2. -cre" the traction nut "ith its long side to"ard the furnace block onto the free endof the bolt.

Page 1

Procedure 2.1.1 until

2.1.10





Figure Tool to remo*e right contact c$lin"er

2.2./ arefully turn the bolt clock"ise "ith the ratchet spanner pro#ided to dra" in thetraction nut and thus push the graphite contact out of the furnace block.

2.2.3 Aisassemble and remo#e the installation tool.

Figure / Remo*al right contact c$lin"er

• Remo*e the left6han" contact

2.2.14 4ake the contact installation tool pro#ided and place the domeshapede=tractor on the bolt. ass the bolt from the internal side of the furnace through thelefthand contact and out through the "indo" ca#ity. 4he lugs on the e=tractor 6to#er the furnace block.

Page 1





2.2.11 -cre" the traction nut "ith its long side to"ard the furnace block onto thefree end of the bolt. osition the traction nut so that the Bat side on the rim passesunder the optical sensor.

2.2.12 arefully turn the bolt clock"ise "ith the ratchet spanner pro#ided to dra"in the traction nut and thus push the graphite contact out of the furnace block.

2.2.1' Aisassemble and remo#e the installation tool.

Figure 3 Remo*al right contact c$lin"er

• 7nstall a ne8 left6han" contact

2.2.1) lace the long arm of the plastic alignment gauge and the replacement lefthand (short) contact on the bolt, so that the contact 6ts in the ring in the gauge.

Page 1





2.2.1, ass the bolt from the internal side through the lefthand furnace block andout through the "indo" ca#ity.

2.2.1- -cre" the traction nut "ith its short side to"ard the furnace block onto the

free end of the bolt osition the traction nut so that the Bat side on the rim passesunder the optical sensor.

2.2.1 arefully turn the bolt clock"ise "ith the ratchet spanner pro#ided to dra"in the traction nut and thus push the graphite contact out of the furnace block.5ake certain that the contact is not tilted.

2.2.1/ Aisassemble and remo#e the installation tool. 4ake care not to scratch ordamage the contact.

Figure 14 7nstallation left contact c$lin"er

• 7nstall a ne8 right6han" contact

Page 1





2.2.13 lace the short arm of the plastic alignment gauge and the replacementrighthand (long) contact on the bolt, so that the contact 6ts in the ring in thegauge and the lug in the ring inserts into the sample in the ring inserts into thesample introduction port of the contact.

2.2.24 ass the bolt from the internal side through the righthand furnace block andout through the "indo" ca#ity so that the long arm of the alignment gauge restsagainst the furnace block.

2.2.21 -cre" the traction nut "ith its short side to"ard the furnace block onto thefree end of the bolt.

2.2.22 arefully turn the bolt clock"ise "ith the ratchet spanner to dra" thecontact into the furnace block. 5ake certain that the contact is not tilted.

2.2.2' Aisassemble and remo#e the installation tool. 4ake care not to scratch or

damage the contact.

Figure 11 7nstallation left contact c$lin"er

2.2.2) -lide the graphite shield ring "ith its large Bat face to"ard the furnace blocko#er the lefthand contact.

Page 1





Figure 11 7nstall back cleane" shiel" ring

Page 1

aas (change of contact cylinder & graphite tube

Documents