SOP No. 14. Recommended Standard Operations Procedure for Gravimetric Calibration of Volumetric Ware Using an Electronic Balance

Transcription

1 /5/006 SOP No. 4 Recommended Sandard Operaion Procedre for Gravimeric Calibraion of olmeric Ware Uing an Elecronic Balance Inrodcion Table.. Prpoe of Te Thi procedre decribe he calibraion of eiher he "o deliver" or "o conain" volme of mearing conainer ha may be ed a volmeric mearing andard. The procedre e gravimeric calibraion principle o minimize calibraion ncerainie. Accordingly, he procedre i epecially efl for high accracy calibraion. The procedre doe no incorporae mearemen conrol ep o enre he validiy of he andard and he mearemen proce; addiional precaion m be aken. The procedre make e of an elecronic balance and i iable for all ize of gravimeric calibraion only limied by he capaciy and reolion of he balance.. Prereqiie.. erify ha valid calibraion cerificae are available for he andard ed in he e... erify ha he andard o be ed have fficienly mall andard ncerainie for he level of calibraion. Reference andard hold no be ed for gravimeric calibraion... erify ha he balance ed i in good operaing condiion wih fficienly mall proce andard deviaion, a verified by a valid conrol char or preliminary experimen, o acerain i performance qaliy when a new balance i p ino ervice. The accracy of he balance and weighing procedre hold be evalaed o minimize poenial bia in he mearemen proce...4 erify ha he operaor i experienced in preciion weighing echniqe and ha had pecific raining in SOP, SOP 4, SOP 9, GMP, GMP 0, and gravimeric calibraion...5 erify ha an adeqae pply of diilled or deionized waer (ee GLP 0) i available...6 erify ha he laboraory faciliie mee he following minimm condiion o enable meeing he expeced ncerainy ha i achievable wih hi procedre: Laboraory environmenal condiion Procedre Temperare Relaive Hmidiy Gravimeric 0 C o C, a e poin ± C, maximm change C/h 40 % o 60 % ± 0 % max change / 4 h SOP 4 Page of

2 /5/006 Mehodology. Scope, Preciion, Accracy The procedre i applicable for he calibraion of any ize of mearing conainer ha, when filled wih waer, will no overload he elecronic balance ed. Typical conainer range in capaciy from ml o 0 L; however, hi procedre i alo applicable for larger prover provided ha faciliy, eqipmen and andard mee he reqiremen in hi SOP. When larger prover (e.g., 00 gal or more) are eed, alo ee he Te Noe in SOP 5. The preciion of calibraion will depend on he care exercied in adjing he vario volme and ric adherence o he vario ep of he procedre. The accracy aainable will depend on he ncerainie of he andard weigh and he air boyancy and hermal expanion correcion ha are made.. Smmary The elecronic balance ed i fir calibraed by weighing a andard ma. The volmeric veel o be calibraed i hen weighed dry or weed down, depending on wheher he calibraion i o be made on a o conain or o deliver bai. The conainer i filled wih pre waer of known emperare and re-weighed. The difference in ma i ed o calclae he capaciy of he conainer a vario neck gradaion. The procee of hi ecion and ecion hold be repeaed a reqired o verify all neck gradaion for which a calibraed volme i deired.. Eqipmen and Sandard.. Elecronic balance having fficien capaciy o weigh he loaded veel. The eniiviy of he balance will be a limiing facor in he accracy of he mearemen. The reolion and repeaabiliy hold be maller han he acceped ncerainy of he calibraion... Calibraed ma andard wih adeqae accracy and raceable o NIST. Ordinarily, andard of ASTM Cla or weigh pecificaion are reqired... Calibraed hermomeer accrae o ± 0. C wih recen calibraion vale ha are raceable o NIST o deermine waer emperare...4 Calibraed hermomeer accrae o ± 0.5 C wih recen calibraion vale ha are raceable o NIST o deermine air emperare...5 Calibraed baromeer accrae o ±5 Pa ( mm Hg) wih recen calibraion vale ha are raceable o NIST o deermine he air prere...6 Calibraed hygromeer accrae o ± 0 % wih recen calibraion vale ha are raceable o NIST o deermine relaive hmidiy. ale from he hermomeer, baromeer and hygromeer are ed o calclae he air deniy a he ime of he mearemen. The air deniy i ed o make an air boyancy correcion. The accracie pecified are recommended for high preciion calibraion. Le accrae eqipmen can be ed wih only a mall degradaion in he overall accracy of he mearemen. SOP 4 Page of

3 /5/ Diilled or deionized waer (See GLP 0)...8 Sopwach or oher iable iming device (doe no need o be calibraed.).4 Procedre.4. Cleanline check erify ha all conainer o be calibraed are clean a evidenced by niform drainage of waer. No waer drople hold remain on any inerior rface a he waer drain from he conainer. A reprodcible we-down weigh i evidence for cleanline in cae where i i no poible o vially check for niform drainage. Ue GMP 6 or 7 o clean veel a neceary..4. Drying procedre Ue GLP a he procedre o dry any conainer o be calibraed on a o conain bai..4. We down Fill he conainer o capaciy wih diilled or deionized waer, hen empy over a 0 period while avoiding plahing. Drain for 0 nle anoher drain ime i pecified. (Thi i commonly called a 0 por, 0 drain empying procedre.) A 0 (± 5 ) por followed by a 0 drain, wih he meare held beween a 0 degree and 5 degree angle from verical, i reqired dring calibraion and e for gla flak. A we-down i no reqired if a ranfer veel i ed o weigh a delivered volme of waer..4.4 Weighing (Opion A).4.4. Zero he balance and record reading a O. Place a andard ma, M S, on he balance plaform (M S hold be lighly larger han he ma of he filled veel.) Record reading a O Zero he balance. Place dry or we-down conainer on balance plaform, a appropriae, and record reading a O. Caion: all conainer m be dry on he oide for all weighing Fill conainer o i reference mark. Read and record he emperare of he waer ed o fill he conainer. Careflly adjing he menic (if preen) o minimize filling error (ee GMP No. ). Zero he balance. Weigh he filled veel and record reading a O Immediaely afer weighing, check he emperare of he waer in he filled conainer. If he emperare differ by more han 0. C from ha of.4.4., refill and reweigh a decribed in When calibraing o deliver veel, O4 may be meared before O. If a ranfer veel i ed, he drained ma or empy ma i ally meared before he filled ma. SOP 4 Page of

4 /5/006 Calclaion Record air emperare, baromeric prere, and relaive hmidiy a he ime of he above mearemen Make a dplicae deerminaion (Rn )..4.5 Weighing (Opion B).4.5. Zero he balance and record reading a O. Place a andard ma, M S, on he balance plaform (M S hold be lighly larger han he ma of he drained or dry veel.) Record reading a O Zero he balance. Place dry or we-down conainer on balance plaform, a appropriae, and record reading a O. Caion: all conainer m be dry on he oide for all weighing Afer removing empy veel, zero he balance and record reading a O 4. Place a andard ma, M S, on he balance plaform (M S hold be lighly larger han he ma of he filled veel.) Record reading a O Fill conainer o i reference mark. Read and record he emperare of he waer ed o fill he conainer. Careflly adjing he menic (if preen) o minimize filling error (ee GMP ). Zero he balance. Weigh he filled veel and record reading a O Immediaely afer weighing, check he emperare of he waer in he filled conainer. If he emperare differ by more han 0. C from ha of.4.5.4, refill and reweigh a decribed in Record air emperare, baromeric prere, and relaive hmidiy a he ime of he above mearemen Make a dplicae deerminaion (Rn ).. Compe he volme,, for each deerminaion ing he eqaion: Opion A M ρ a ( O ) 4 O O O ρ ρ w ρ a Eqn.. SOP 4 Page 4 of

5 0 [ -α ( - 0 ) ] /5/006 Opion B O 6 ( filled ) ρ a M ρ ( O O ) 5 4 O ( drained ) ρ a M ρ ( O O ) ρ w ρ a Eqn.. Table. ariable M, M, M ariable for volme eqaion Decripion ma of andard (i.e., re ma, vacm ma) (g) ρ deniy of M S (g/cm ) ρ w deniy of waer a he emperare of mearemen (g/cm ) ρ a deniy of air a he condiion of calibraion (g/cm ) repreen eiher he o conain or o deliver volme (depending on wheher O or O 6 repreen a dry or a we down conainer a he emperare of he mearemen) (cm or ml). Compe 0, he volme a 0 C, for each rn, ing he expreion: α [ ( 0 ) ] 0 where α i he cbical coefficien of expanion of he conainer being calibraed, (ee NISTIR 6969, Table 9.0), and,, i he emperare (ºC) of he waer.. Compe he mean 0 for he dplicae mearemen..4 If ing a differen reference emperare, e he following eqaion and be re o mach he cbical coefficien of expanion ni wih he ni of emperare: ref [ α ( ) ] ref SOP 4 Page 5 of

6 /5/006 4 Mearemen Arance 4. Dplicae he proce wih a iable check andard (See GLP, SOP 0, and NISTIR 6969, Sec. 7.4) 4. Plo he check andard vale and verify i i wihin eablihed limi OR a -e may be incorporaed o check he oberved vale again an acceped vale. 4. The mean of he check andard i ed o evalae bia and drif over ime. 4.4 Check andard obervaion are ed o calclae he andard deviaion of he mearemen proce, p. 5 Aignmen of Uncerainie The limi of expanded ncerainy, U, inclde eimae of he andard ncerainy of he ma andard ed, c, pl he ncerainy of mearemen, p, a he 95 percen level of confidence. See SOP 9 for he complee andard operaing procedre for calclaing he ncerainy. 5. The andard ncerainy for he andard,, i obained from he calibraion repor. The combined andard ncerainy, c, i ed and no he expanded ncerainy, U, herefore he repored ncerainy for he andard will ally need o be divided by he coverage facor k. When mliple ma andard are ed, ee SOP 9 for reamen of dependencie. 5. Sandard deviaion of he mearemen proce from conrol char performance (See SOP No. 7 or 0.) The vale for p i obained from he conrol char daa for check andard or eimaed baed on he range of dplicae mearemen over ime. Thi vale will incorporae a repeaabiliy facor relaed o he preciion of he weighing and he eing of he menic, b no relaed o he error in reading he menic. 5. Oher andard ncerainie ally inclded a hi calibraion level inclde ncerainie aociaed wih waer emperare mearemen, hermomeer accracy, calclaion of air deniy, andard ncerainie aociaed wih he deniy of he andard ed, coefficien of expanion, vicoiy or rface effec on he volme of liqid clinging o veel wall afer draining, improper obervance of drainage ime, and he lack of inernal cleanline. Addiional Reference: Bean,. E., Epina, P. I., Wrigh, J. D., Hoer, J. F., Sheckel, S. D., and Johnon, A. N., NIST Calibraion Service for Liqid olme, NIST Special Pblicaion 50-7, Naional Inie of Sandard and Technology, Gaiherbrg, MD, (006) SOP 4 Page 6 of

7 /5/006 Appendix A Gravimeric Calibraion Daa Shee (Opion A) Laboraory daa and condiion: eel ID Dae Balance Load Operaor Air Temperare Prere Relaive Hmidiy Proce andard deviaion from conrol char, p Ma andard() daa: ID S - filled Nominal Ma Correcion Deniy g/cm ID Nominal S - empy, and k facor, and k facor Ma Correcion Deniy g/cm Obervaion: Rn Weigh Balance Obervaion, Uni Zeroed Balance O 000 M S O Empy or Drained O 4 Filled O 4 w : Rn Weigh Balance Obervaion, Uni Zeroed Balance O 000 M S O Empy or Drained O 4 Filled O 4 Noe: doed line repreen decimal poin. w : SOP 4 Page 7 of

8 /5/006 Example Gravimeric Calibraion Daa Shee (Opion A) Laboraory daa and condiion: eel ID Operaor GH Dae 0//99 Air Temperare.5 C Balance LC 500 Prere mm Hg Load L Relaive Hmidiy 45 % Proce andard deviaion from conrol char, p 0.04 ml Ma andard() daa: ID Weigh Ma Correcion Deniy g/cm ID Nominal M - filled kg g 7.95 M - empy no ed, and k facor mg, k, and k facor Ma Correcion Deniy g/cm Obervaion: Rn Weigh Balance Obervaion, Uni g Zeroed Balance O 0000 M O Empy or Drained O Filled O w :.8 C Rn Weigh Balance Obervaion, Uni Zeroed Balance O 000 M O Empy or Drained O Filled O w :.6 C Noe: doed line repreen decimal poin. SOP 4 Page 8 of

9 /5/006 Calclae he air deniy (SOP ) ρ a : ρ a.70 mg/cm g/cm Look p or calclae he deniy of he waer, ρ w :.8 C.6 C g/cm g/cm Compe he volme,, for each deerminaion ing he eqaion: M ρ a ( O ) 4 O O O ρ ρ w ρ a Rn : ( ) ( ) ( ) ( ) ( ) ( ) ( ) ml Compe 0, he volme a 0 C, for Rn ing he expreion: [ ( )] α 0 0 [ (.8 0 ) ] ml Rn : ( ) ( ) ( ) ( ) ( ) ( ) ( ) ml Compe 0, he volme a 0 C, for Rn ing he expreion: [ ( )] α 0 0 SOP 4 Page 9 of

10 /5/ [ (.6 0 ) ] ml Calclae he mean 0 : ( ) ml Calclae he ncerainy for he calibraion: U c * c + p + o The ncerainy for he andard m be divided by he k facor for he andard,. All vale m be repreened in like ni. U mg, k mg / mg convered o volme ml p 0.04 ml o ml c ( ) + ( 0.04 ) + ( ) c ml U * ml The volme correcion and ncerainy wold be repored a follow when ronded o wo ignifican digi according o NISTIR 6969, GMP 9: ml ± ml SOP 4 Page 0 of

11 /5/006 Appendix B Gravimeric Calibraion Daa Shee (Opion B) Laboraory daa and condiion: eel ID Dae Balance Load Operaor Air Temperare Prere Relaive Hmidiy Proce andard deviaion from conrol char, p Ma andard() daa: ID M - filled Nominal Ma Correcion Deniy g/cm ID Nominal M - empy, and k facor, and k facor Ma Correcion Deniy g/cm Obervaion: Rn Weigh Balance Obervaion, Uni Zeroed Balance O 0000 M O Empy or Drained O 4 Zeroed Balance O M S O 5 6 Filled O 6 w : Rn Weigh Balance Obervaion, Uni Zeroed Balance O 0000 Zeroed Balance O M O 4 Empy or Drained O Zeroed Balance O 5 6 M S O 6 Noe: doed line repreen decimal poin. w : SOP 4 Page of