Ancient measure systems were based on the human limb sizes and body’s capacities. These were function-related measures such as: foot size and walking, thumb and width, fingers and numbers, palm and holding capacity, head load or horse power and carrying capacity, etc.
In Indian context a weights series had a Maund made of 40 seers and each seer had 16 chhatanks. Monetary series had 1 Rupee consisting of 16 Annas and each anna had value of 4 paise. The Length series had a basic unit of Gaz which was as of 2 Hath, and each Hath was of 8 Girah or 24 Anguls. For example a 5 Gaz cloth was valued 12 rupees, it was difficult to calculate cost of 1 Hath length piece. In later period British unit Foot became common. A Foot was divisible to 12 inches, but the weight unit Pound (avoirdupois) was divisible to 16 ounces.
In a series of measure units, the sub units, though body related, were nearly independent. The interrelationships between sub units were simple, but enforced. Various measures’ series were mutually incomparable and to an extent incompatible.
Across the world there were innumerable measure systems, but the Foot-Pound system became dominant due to extensive colonization by the British Empire.
The Metric System (created in France, post Revolution period) was an abstract system with a Mathematical Order. It had the advantage of Logical Fractions. All measure units were divisible to 10X. But (early) Metric system had too many sub units, many of which were rarely used. For some people the rationale of Metric system was too contrived as its scale did not relate to human body and its parts-whole-parts relationship.
NEED FOR A COORDINATED MEASURE SYSTEM
'Raw materials or Finished products’ are transient terms for goods. A finished product is a raw material for some other process. Raw materials procured in a linear, square, volumetric, weight or liquid measures get processed into a different ‘measure’ entity. For products transiting from one measure phase to another, a persistent dimensioning system is very advantageous. Consistency of dimensions allows use of standard tools, equipments, plants and technologies. The dimensional consistency, if properly recognized and supported, can rationalize the conversion processes, storage, handling, and waste management.
For example metal ore is mined in volumetric measure, transported by its weight measure, bought for its yield rate value, refined into ingots for weight measures, rolled into metal sections to be used for their strength aspect.
In the ‘Post Industrial Revolution' period, trade and industry all over the world recognized the need for a Universal Dimensioning Discipline. At that time better coordination was also required for conversion and transmission from old measurement systems to the new SI system of measurements. First worldwide understanding emerged in the adoption of SI (Le Système international d'unitésas) as the Universal Measure System.
Organisation internationale de normalisation or International Organization for Standardization would have different acronyms in different languages. Its founders decided to give it a short, all-purpose name. They chose ISO derived from the Greek isos, meaning equal. ISO is a voluntary, democratic and non governmental organization for International Cooperation for Standardization. SI = Systeme Internationale stand for Universal Measure System and it is now accepted by nearly all countries of the world.
SI Recognized Measures: The SI system recognizes three sets of measures in each of the major categories. There is a 1000-factored gradation. The ISO Recognised Measures are:
Length: mm mt km
Weight: mg kg T
Volume ml Lt kl
ISO MODULAR PREFERENCES
The SI also recognized that, these measures (as above) are either too large or small for practical use. Such a widely spaced (1000 factored) measurement system was not amenable to unit formation for processes like planning, design, production, transportation, fabrication or execution, etc. ISO (International Standards Organization) as a result devised a practical modular system of dimensions known as ISO Modular Preferences. Most National Standards (including Indian Standards) are recommending and enforcing the same for various products and processes.
The ISO Modular Preferences help in both, dividing a whole into logical parts and combining parts into a rational whole. It also accommodates traditional modular systems, such as foot-Inch and earlier versions of the metric systems. Typically, the Foot (12"), the most popular measure of FPS has been accommodated (but not the 1/4 or 1/5 part of the Meter such as 20 or 25 cm or 200 or 250 mm). This was done for wider acceptance and to achieve a gradual changeover.
ISO's Four Preferences for Modular Coordination:
First Preference 30 cm or 300 mm = 12"
Second Preference 10 cm or 100 mm = 4"
Third Preference 5 cm or 50 mm = 2"
Fourth Preference 2.5 cm or 25 mm = 1"
▪ First Preference is favoured by the building materials' industry. Plywoods and other wood products are available in modules of 300 such as 600, 900, 1200, 1800, 2400 etc. Large buildings are designed with 300 as the modular measure. But, for smaller spaces such as Bedrooms, toilets, second preference of 100 is used as a module.
▪ Second Preference is considered to be the most appropriate one for Building components and Planning. Glazed Tiles are available in multiples of 100 mm, with sizes like 100 x 200, 200 x 200, 200 x 300 etc., and also in sizes such as 150 x 150, 150 x 200 etc. as a carry over from the old system. Fabrics have widths of 600, 900, 1000, 1200, 1800 etc. When we order Windows or Doors the width x height are measured in 100 mm increments.
▪ Third and Fourth Preferences are more preferred for objects smaller then 300 sizes. These preferences are not to be used for basic object sizes of more than 300, unless there are strong economic or functional reasons for doing differently.
IMPLICATIONS OF THE MODULAR COORDINATION OF DIMENSIONS
There are many products where smaller modulation or variations are desirable such as Garments and Shoes. ISO Modular Preferences, do not consider the variations in naturally available materials. Furniture, fittings and fixtures designed with ergonomic profile or serving anthropometric, inconsistencies have no specific accommodation in this system.
ISO is a modular system to form a grid or matrix for macro planning and in that sense takes a superior position. Components and parts are expected to fit in the system. As a result, work-sizes of components and assemblies should be determined by taking account of space for joint and allowance for tolerances.
The ISO modular system is based on SI system (a derivative of the metric system) which originally was rational and contrived, and continues to be so. This type of Modular Coordination of Dimensions, is unnatural and does not exactly relate to human body. Its implications to our senses are extremely limited. It creates an 'order that lacks beauty'. The system does not harmonize the variable tolerances’ requirements, and differences in fitment sizes.
ISO Modular system has very simple and predictable progression-digression, unlike many mathematical orders and systems like Corbusier’s Modulor system.
ISO Modular Preferences, as a universally agreed system of preferred measures, disciplines design, procurement, production, conveyance, handling, storage, distribution, usage, wastage and reuse or recycling of materials. The system has provided a level ground to compare standards of various countries, and evolve world standards (ISO) for various products, services and work or operational procedures. It has made the writing of specification lucid and logical. It simplifies taxation procedures, costing, estimating, and valuation. It also rationalizes deployment of human and energy resources. It has made quality control procedures very objective.
At any cross section of time, there are many creative people, who feel stifled by such an Abstract Dimension Modulating System. But one must also concede that by its universal acceptance (through ISO), a logical dimensioning tool has been made available to a vast majority of people. The Dimensioning Tool defies all localized traditions, cultural variations, anthropometric distinctions, racial biases and geographical peculiarities. The system is unaffected by time or space.