Pt/Co scale
Platinum-Cobalt Scale (Pt/Co scale ma ọ bụ Apha-Hazen Scale ) bụ akara agba nke onye na-emepụta kemịkal Allen Hazen (1869-1930) webatara na 1892. Emepụtara ndeksi dị ka ụzọ iji nyochaa ọkwa mmetọ na mmiri mkpofu.  Ọ gbasaala ka ọ bụrụ usoro a na-ejikarị atụnyere ike nke ihe nlele na-acha odo odo.  Ọ bụ kpọmkwem na agba odo ma dabere na dilutions nke ngwọta platinum cobalt 500 ppm.  Agba nke otu milligram nke platinum cobalt gbazere n'ime otu liter nke mmiri na-emepụta ka edobere ka otu nkeji agba na nha platinum-cobalt. ASTM nwere nkọwa zuru ezu na usoro na ASTM Designation D1209, "Ụzọ Nnyocha Standard maka Agba nke Mmiri Dị Iche (Platinum-Cobalt Scale)

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