1.1This specification covers requirements for glass burets of precision and general-purpose grades suitable for laboratory use.

1.1.1Class A-Each buret of precision grade may be marked with the letter “A” to signify compliance with applicable construction and accuracy requirements in Table 1 and Table 2. Each buret may be marked with a permanent serial number at the option of the manufacturer.

TABLE 1 Requirements for Burets

		Graduated Scale
Capacity, mL	Subdivision, mL Class A and B	Class A Scale Length, mm 0 to Capacity	Class B Scale Length, mm 0 to Capacity	Distance, Top of Buret to “0” Graduation, mm^A	Class A and B Number Each, mL	Class A Volumetric Tolerance, ±mL	Class B Volumetric Tolerance, ±mL
10	0.05	350 to 450	250 to 450	30 to 75	0.5	0.02	0.04
25	0.1	350 to 450	250 to 450	30 to 75	1	0.03	0.06
50	0.1	500 to 600	500 to 600	40 to 100	1	0.05	0.10
100	0.2	550 to 650	550 to 650	40 to 100	2	0.10	0.20

^AStraight burets only, not applicable to self-zeroing burets.

TABLE 2 Minimum Delivery Time for Class A Burets Using Water

Length Graduated, cm	Time of Out- flow Not Less Than, s	Length Graduated, cm	Time of Out- flow Not Less Than, s
15	30	45	80
20	35	50	90
25	40	55	105
30	50	60	120
35	60	65	140
40	70	70	160

1.1.2Class B-General purpose burets are of the same basic design as Class A burets. However, volumetric tolerances for Class B burets shall be within twice the specified range allowed for Class A burets. These burets need not be marked with their class designation or serial number. See Table 1 and Table 3 for tolerances and dimensional requirements.

Note 1-The Twelfth General (International) Conference on Weights and Measures redefined the litre as a “special name for the cubic decimetre,” but agreed to permit continuance of the terms litre, millilitre, and mL, except in association with measurements of the highest precision. For volumetric glassware the difference between the old and new meanings of litre is negligible. Therefore, either mL or cm³ may be marked on ware covered by this standard.

TABLE 3 Minimum Delivery Time for Class B Buret Using Water

Capacity, mL	Time of Outflow Not Less Than, s
10	25
25	30
50	50
100	90

1.1.3Product with a stated capacity not listed in this standard may be specified Class A Tolerance when product conforms to the tolerance range of the next smaller volumetric standard product listed in Table 1.