LABORATORY GLASSWARE — the ware of the general and special purpose used for analytical, preparative and other laboratory works. L. the item is made by hl. obr. from chemical and laboratory glass and porcelain, and also from plasts, platinum, oxides of metals and other materials.
Ware from chemical and laboratory glass has the high chemical and thermal stability and small crystallizational ability allowing to process it on a glass-blowing torch. On composition of chemical and laboratory glass L. the item can be divided into 5 groups.
1. L. the item from quartz glass. Quartz glass contains not less than 96% of silicon dioxide; it is received melting of very pure grades of quartz in electric furnaces or in an oxygen-hydrogen flame. Quartz glass is most thermally resistant, possesses small coefficient of thermal expansion (5,7*10 - 7 ), high fire resistance, inertness in relation to a number of chemical reagents, napr, kislotoustoychivostyo, dielectric and acoustic properties, passes visible, ultraviolet and infrared rays. However L. the item from quartz glass it is very brittle, unstable to caustic alkalis, carbonates of alkali metals and to hydrofluoric to - those, during the heating to temperature of St. 1200 ° loses transparency. Main types of quartz glass — transparent, opaque, optical, especially pure, ceramic and alloyed. From vitreous silica produce flasks, crucibles, retorts, glasses, cups, tubes of different diameter etc. The L concerns to the same group. the item from the kvartsioidny glass received by lixiviation by solutions of acids of some glasses of the Na system 2 O — B 2 O 3 — SiO 2 , and sodium borate is leached. Make of this glass thin-walled chemical. L. the item, tubes for ultra-violet (quartz) torches.
2. L. the item from sodium-kaltsiysilikatnogo of glass — brands No. 23, No. 29 B2, Ts32, TsL, KS-34, etc. 13 — 20% of alkaline oxides are a part of glass (in the main Na 2 O), 5 — 10% of CaO, 1,5 — 4% of Al 2 O 3 . Make of this glass thin-walled L. item, devices, devices and thick-walled products: exsiccators, gasometers, measuring cylinders etc.
3. L. the item from alyumoborosilikatny and borosilicate glass with the lowered content of alkalis. Heat-resistant glass of the Victory of Work plant — pyrex No. 846, etc. contains 6 — 18% of B 2 O 3 , there are not enough alkalis (4 — 10% of Na 2 O). L. the item from it has the high thermal stability, but very small stability to solutions of alkalis. Make L of this glass. the item and products with normal shlifa, the chemical equipment, glass wool for filtering and some products applied in microbiology (Petri dishes, Koch, etc.).
4. L. the item from silica-alumina bezborny and low-boric N13, AT24 glass, etc., having the increased mechanical strength, thermal stability, high temperature of a softening and insulating properties. Make a lab of this glass. tubes.
5. L. items from alkali-proof zirconium glass of the Shch14, Shch23, Shch26 brands, to-rogo are a part zirconium oxides, strontium, lanthanum. Glass for L. items receive by means of cooking of furnace charge (components of glass) in special bathing furnaces at a temperature apprx. 1400 °. At introduction to furnace charge of oxides and carbonates of various metals receive the special grades of glass differing in the optical, mechanical, chemical and other characteristics. L. the item is developed manually on semiautomatic devices and automatic machines, is exposed to annealing (to gradual cooling within several hours in special furnaces). Quality of annealing is checked on a polyarioskopa.
Glass L. the item shares on thick-walled, thin-walled and measured.
Besides, make vessels of the Dewar of chemical and laboratory glass (see. Dewar vessel ).
China it is made of porcelain, has big mechanical strength, high thermal stability, chemical stability. However it is opaque, heavy, cost is higher than it the cost of glasswares.
High-fire-resistant ware, hl. obr. crucibles, it is made, except porcelain, of quartz, graphite, corundum (pure alumina, Al 2 O 3 ), oxides and carbides of metals. Make mortars, crucibles, cups of platinum, copper alloys, cast iron and other alloys.
Ware from plasts (polyethylene, polypropylene, a ftoroplast and other transparent and translucent plastics with high chemical resistance) finds more and more broad application. Make of these materials flasks, pipettes, washing bottles, test tubes, cylinders, funnels, tubes and other products, and also devices disposable for sampling biol, liquids and their transportation in laboratory which can be used in process a lab. analysis (centrifuging, dosing etc.). Preferential L. items from plastics use for work with solutions at the room temperature. Plastic L. the item has small wettability, but strongly adsorbs some chemical substances.
The characteristic the most widespread released in the USSR by L. the item is presented in the table.
Care of a laboratory glassware
To removal of rainfall and firm pollution is applied by mechanical methods with use of warm water, brushes and ruffs. For removal of the resinous and organic matters which are not dissolved in water use organic solvents (ethers, alcohols, gasoline and so forth). The dried-up remains of blood and another containing protein of substances delete from walls of L. item solutions of potassium hydroxide or sodium hydroxide. Chemical methods of cleaning of L are most widespread. the item using various mixes, napr, cleaning mixture (1 h the potassium bichromate dissolved in 3 h konts. a chamois to - you), the mix consisting of the equal volume of 6 N of solution hydrochloric to - you and 5 — 6% of solution pergidrolya; solution of potassium bichromate in konts. nitric to - those (200 g of potassium bichromate on 1 l to - you); solutions of synthetic detergents are widely used. During the work with enzymes for washing of L. the item is better to use mix of equal volumes nitric and sulfuric to - t with the subsequent repeated washing of ware water and a dist, water. The remains of detergents can affect results of analyses. From plastic 2 — 5% solution of a trinatriyfosfat, weak solutions of hydrosodium carbonate or hydrochloric to - you are the best of all to wash the dishes, it is impossible to use solutions konts. to - t, alkalis and strong oxidizers.
L. items wash in the manual way in bathtubs or on brush washing machines, and also on special devices for washing of the pipettes working by the principle of a siphon. These devices facilitate cleaning of L. items, but pe exclude completely manual skills. For washing of L. items use also ultrasonic installations: cars of drum type with set of holders, etc. which substantially exclude manual skills. Dry L. the item on special boards with pegs, on lattices, in a stream of a cold air if there is an eyeliner of compressed air, and also in drying ovens at a temperature of 80 — 100 °. For bystry drying of L. items use serial washing by its alcohol and ether or their mix. Measured L. the item, especially pipettes, burettes and microdosers, it is not recommended to dry in drying ovens. Plastic L. items dry at a temperature not over 40 — 50 °.
Table. Main types of a glass and porcelain laboratory glassware and its physical characteristic
- Nominal capacity (V), diameter (D), height (N), length (L)
Glass laboratory glassware
- Laboratory ware 21.png filtering with the sealed glass plate of various porosity (20) D =
Dephlegmators (nozzles) for differential distillation of liquids (21, 22, 23). Various forms and the sizes
- Laboratory ware 40.png graduated and not graduated (39) V =
Retorts with a tube (40) and without it (41) for carrying out reactions of V = 2000 - 3000 ml
calcium chloride tubes for protection of various substances and solutions from hit of impurity in them from air, straight lines with one sphere under a stopper (46), U-shaped with branches under a stopper (47), without branches (48), with prishlifovanny traffic jams (49) D = 13 - 30 mm of H = 60 - 200 mm
Cups biological (Petri) with covers low (54) — see. Petri cup D = 40, 100, 150 mm
Porcelain laboratory glassware
Bibliography: Voskresensky P. I. Technology of laboratory works, M., 1973; Katz A. M. and Kantorovich A. S. Guide to devices and equipment for medicobiological researches, M., 1976, bibliogr.; Rights of dynes of P. V. Laboratory devices and the equipment from glass, M., 1978; Glass, the Reference book, under the editorship of H. M. Pavlushkina, page 207, 277, M., 1973.
N. B. Sametskaya.