Volumetric apparatus is essential requirement for quantitative estimations. Accuracy and precision of your results is greatly dependent on correct use and regular calibration of volumetric apparatus.

Types of Glassware
Laboratory glassware is made from borosilicate glassware which is resistant to thermal shock and chemical attack.
Two categories of glassware are commonly used in laboratories:
Type A
Type A glassware is used for work requiring highest accuracy of results. It complies with requirements ASTM E694 standard. The glassware bears the letter A and is calibrated to half the tolerance level of Class B glassware. It come with a calibration certificate bearing a unique serial number for establishing traceability. Type A glassware does not require further calibration.
Type B
Double the tolerance limit of class A glassware. It is used for routine work and requires calibration before putting to use.
Cleaning of Glassware

Volumetric glassware must be washed and dried before use as unclean glassware can introduce contamination errors.
Soak used glassware in water and drain. Clean with a cleaning detergent.
Rinse with dilute potassium dichromate solution in sulphuric acid.
New glassware is slightly alkaline in nature so soak in slightly acidic solution e.g. in 1% HNO_3 or HCl for an hour, then rinse with distilled water
Cleaning machines save time when bulk cleaning is required. They accommodate a wide range of glassware shapes and sizes and permit a range of cycles including washing, rinsing and hot dry air cycles. Suppliers of laboratory glassware washing machine include:
Care in Handling of Volumetric Glassware
When washing take special care so that it does not break on striking wash basin walls
When shaking a volumetric flask, hold both neck and bottom using both hands to prevent breakage
Remove the stopper from volumetric flask before oven drying. Do not raise temperature above 60^0C and cool to room temperature before use.
Calibration of Glassware
Calibration of volumetric apparatus at specified intervals is an important task.
Volume, weight and delivery time at calibration temperature are common parameters for calibrations.
Maintain constant temperature(25 +/- 2^0C) during calibration and use calibrated weights
Read lower level of meniscus for clear liquid readings and upper level for colored solutions readings, keeping your eye level horizontal in line with the liquid level
Calibration of graduated pipette

At time of calibration, ensure no air bubbles are sticking to the glass walls and no water droplets exist above the graduation mark
Weigh a clean dry beaker (W_1)
Deliver water from calibrated mark till it is emptied or in case of graduated pipette till the calibrated mark.
Repeat 3-4 times till consistent reading is obtained for weight (W_2), volume and delivery time.
Volume collected = (W_2 - W_1) / D,
where D is density of water at 25^0C .
link: http://insidechemistry..com.ng/2016/10/lab-analyst-good-practice-use.html