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Glassblowing Data, Tables, and Resources

This is a collection of handy conversion tables and other technical data that a scientific glassblower will find useful. On this page you will find:
• Spherical Volumes including a calculator
• Cylindrical Volumes including a calculator
• Fractional Inches to Millimeter Conversions
• Temperature Conversions
• Pressure Conversions
• Glass Tubing Pressure Nomogram
• Physical Properties of Common Glasses
• Glass to Metal Sealing Combinations
• Vacuum Formed 0.500" OD Quartz Tubing
• Glass Frit Porosities
• Glass Properties and Technical Data Sources
• General and Miscellaneous Technical Resource

General Glassblowing Resources Page which covers books, organizations, tool suppliers, glass suppliers, descriptions of laborator glassware, and art glass links.

Spherical Volumes

This handy chart correlates the nominal volume (V) of a sphere in milliliters to the internal diameter in millimeters:

V (ml)	1	5	10	25	50	100	125	150	200	250	300	350	400	500	800	1,000
ID (mm)	12	21	27	36	46	57	62	66	72	78	83	87	91	98	115	124

The relationship between volume and radius/diameter is given by V = (4/3)πr³ where V is the volume, r is the radius of the sphere and π = 3.1415…. This JavaScript calculator gives a precise conversion between volume in mL and inner diameter in mm:

Spherical Volume Calculator
Enter a volume or diameter: The number above represents a: Diameter (mm)   Volume (ml)	Enter a number, select what it represents and click Calculate. The answer will appear here.

If you need them, we also have some unit conversion calculators for distance and volume.

Cylindrical Volumes

Glassblowers sometimes need to calculate the volume of a cylinder of a given length or diamter. This handy chart lists the height and ID required to give a volume of 1 mL. For example, by looking at the chart we can see that a cylinder of ID 42 mm has volume of 1 mL for every 0.72 mm of height.

ID mm	Height mm		ID mm	Height mm		ID mm	Height mm		ID mm	Height mm		ID mm	Height mm
1	1274		21	2		41	0.760		61	0.340		81	0.194
2	318		22	2.630		42	0.720		62	0.330		82	0.190
3	141		23	2.450		43	0.690		63	0.320		83	0.185
4	79		24	2.210		44	0.658		64	0.310		84	0.180
5	51		25	2.030		45	0.630		65	0.300		85	0.176
6	35		26	1.880		46	0.600		66	0.292		86	0.172
7	26		27	1.740		47	0.580		67	0.283		87	0.168
8	20		28	1.620		48	0.550		68	0.275		88	0.164
9	15		29	1.510		49	0.530		69	0.267		89	0.160
10	12		30	1.410		50	0.510		70	0.260		90	0.157
11	10		31	1.320		51	0.490		71	0.252		91	0.154
12	8		32	1.240		52	0.470		72	0.245		92	0.150
13	7		33	1.170		53	0.450		73	0.239		93	0.147
14	6		34	1.100		54	0.437		74	0.232		94	0.144
15	5.660		35	1.040		55	0.420		75	0.226		95	0.141
16	5		36	0.982		56	0.406		76	0.220		96	0.138
17	4		37	0.930		57	0.392		77	0.215		97	0.135
18	3		38	0.880		58	0.378		78	0.209		98	0.133
19	3		39	0.837		59	0.366		79	0.204		99	0.130
20	3		40	0.790		60	0.356		80	0.199		100	0.127

The relationship between the height, radius/diameter and volume of a cylinder is given by V=hπr² where V is the volume, h is the height, r is the radius (half the inner diameter) and π = 3.1415…. In the JavaScipt calculator below, you can enter any two of the three variables and it will determine the value of the third one for you.

Cylindrical Volume Calculator
Enter any two of the three variables and then hit the Calculate button next to the value you wish to determine. Height (mm) Inner Diameter (mm) Volume (mL)

If you need them, we also have some unit conversion calculators for distance and volume.

Fractional Inches to Millimeter Conversions

Glassblowers routinely use calipers to measure glassware, and some of these even read in both inches and millimeters. However, most calipers do not handle fractional measurements such as 11/16". This table is list of fractional measurements along with their decimal and millimeter equivalents that you may want to print and hang by your workbench. This table is great for woodworkers,too!

Fraction (Inches)	Decimal (Inches)	Millimeters
1/64	0.015625	0.396875
1/32	.03125	0.7938
1/16	0.0625	1.5875
1/8	0.125	3.1750
3/16	0.1875	4.7625
1/4	0.250	6.3500
5/16	0.3125	7.9375
3/8	0.375	9.5250
7/16	0.4375	11.1125
1/2	0.500	12.7001
9/16	0.5625	14.2876
5/8	0.625	15.8751
11/16	0.6875	17.4625
3/4	0.750	19.0501
13/16	0.8125	20.6375
7/8	0.875	22.2251
15/16	0.9375	23.8125
1	1.00	25.4001

Temperature Conversions

Most digital thermometers and optical pyrometers read in both Farenheit and Celsius, so we won't preent a table here. You can convert temperature units with our handy JavaScript temperature conversion calculator. And here are the conversion formula if you are really Old School and want to use your TI-30 or slide rule:

Centigrade to Fahrenheit	Fahrenheit to Centigrade
(C x 9/5) + 32 = F	(F - 32) x 5/9 = C

Pressure Conversions

You can convert presure units with our handy JavaScript pressure conversion calculator. Here's a conversion table in case you are allergic to JavaScript:

	mbar	Torr	inches Hg	psi	Pa
mbar	1	0.750	0.0295	0.0145	100
Torr	1.333	1	0.0394	0.0193	133.32
Inches Hg	33.864	25.409	1	0.491	3,386.33
psi	68.946	51.714	2.036	1	6,894.65
Pa	0.01	0.00750	0.000295	0.000145	1

Glass Tubing Pressure Nomogram

Glass can be used under vacuum or pressure, but the larger the pressure differential, the thicker the glass must be. Even so, every time the glassware is used under pressure differentials of more than one atmosphere (760 torr) it must be thoroughly inspected for defects, star cracks and other potential points of failure before pressurization. Safety shields and other forms of protection are also necessary.

This handy nomograph tells the glassblower how thick the wall of a borosilicate glass tube should be in order to withstand a given pressure. One should always build in an extra margin of safety when designing such apparatus:



See this diagram full size

Physical Properties of Common Glasses

All temperatures are given in degrees C	Soft Glass (Soda Lime)	Borosilicate (Duran, Kimax, Pyrex)	Quartz (Fused Silica)
Softening Range	696	821	1580
Working Range	1000	1200	1800
Annealing Range	514	565	1050
Max Service Temp.	450	490	1100

The information in this section should be used as a source of comparative figures only, representing a broad range of glasses within their respective family groups. For specific technical data each glass should be identified as to manufacturer and glass code number.

Glass to Metal Sealing Combinations

On occasion, a glassblower may be asked to construct a piece made of glass and some other material. For example, a conductivity cell might need an electrode embedded in the glass or a glass high vacuum manifold may need to mate to a metal thermocouple. Making such connections directly is nearly impossible because the two materials have to have very similar thermal coefficients of expansion and other properties. By using a graded seal like the one shown to the right, one can join extremely short lengths of glass that vary from each other by just a little bit and achieve a smooth transition from one material to another. These will span the range between the borosilicate or quartz and the other material. These table below contains some of the most common combinations.

Material	Material to Glass Seal
Platinum	7740 (not vacuum tight)
Tungsten	3320 - 7740
Kovar	7052 - 7720 - 3320 - 7740
Alumina	7280 - 7056 - 7052 - 3320 - 7740
	Tungsten to Quartz Seal
Tungsten 0.30 - 0.40 mil	7230 sleeve or GE#1 cane - Fused Quartz
Numbers refer to Corning code numbers

Vacuum Formed 0.500" OD Quartz Tubing

Start with a 0.374" graphite machined rod mandrel and 10 mm ID x 13 mm OD Quartz starting stock

Glass Frit Porosities

Fritted glass is a porus filter made of glass fibers or granules. They are widely used in inorganic and organic laboratories and come in many different forms. Fritted funnels are used for liquid/solid separation and purification. Fritted gas dispersion tubes are used to absorb/remove/dry gases, disperse gases in liquid solutions, and many other applications. They are typically found in disc or cylindrical form in borosilicate and quartz glass. You can learn more about glass fritted funnels and their care in the Glassware Gallery.

This chart shows the porosity designations and their meanings for glass frit proucts from Ace, Corning, and Kimble:

Porosity Range Cross Reference Chart (microns)
Common Uses	Ace	Corning	Kimble
Gas Dispersion, Coarse Filtration	A 145-174	EC 170 - 220	EC 170 - 220
Filtration, Gas Dispersion	C 25-50	C 40-60	C 40-60
Filtration, Extraction	D 10-20	M 10-15	M 10-15
Filtration, Extraction	E 4-8	F 4-5.5	F 4-5.5
Bacteria Filtration	VF 2-2.5	VF 2-2.5	xx

EC = Extra Coarse, C = Coarse, M = Medium, F = Fine, VF= Very Fine

Glass Properties and Technical Data Sources

• Quartz Properties at Momentive Performance Materials Inc.
• Technical information sheets at Kimble Chase (formerly Kimble-Kontes).
• Quartz properties and handling at Tosoh Quartz.
• Product information and specifications at Schott Glass.
• Propery Data Summaries for Oxide Glasses at NIST.
• Ceramic properties at Mindrum Precision.
• Simax (a division of Kavalierglass offers various types of tubing, capillary and rods.
• The American Vacuum Society has a chart of working pressures of vacuum gauges as well as a pressure conversion calculator.
• GE Quartz Calculators - Internal Stress, Transmission, Window Thickness at Momentive Performance Materials.
• Martindale's Reference Calculators, an extensive calculator database.

General and Miscellaneous Technical Resources

• O-Ring Database at Marco.
• Aremco Products manufactures high temperature glass/ceramic adhesives and coatings
• Modern Vacuum Practice has a list of vacuum links with interesting and handy information such as pump choices, how a thermos works, and more.
• Technical and Safety Data for Compressed Gases at Scott.

On our General Glassblowing Resources Page you will find books, organizations, tool suppliers, glass suppliers, descriptions of laborator glassware, and art glass links.

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