WO2002090939A1

WO2002090939A1 - Equipment for determining weight per unit area

Info

Publication number: WO2002090939A1
Application number: PCT/IN2002/000116
Authority: WO
Inventors: Vinod Unnikrishna Kurup
Original assignee: Vinod Unnikrishna Kurup
Priority date: 2001-05-09
Filing date: 2002-04-29
Publication date: 2002-11-14

Abstract

A floatation based equipment for determining the weight per unit area of two dimensional entities like fabrics, paper, films, laminates and sheets. It consists of a float (3) having a long stem (5) and a spherical portion (6). The spherical portion (6) is always under a liquid inside a transparent vessel (1) and was devised such as to keep the stem (5) almost vertical and has the minimum friction when in contact with the vessel (1). The stem (5) has markings to indicate weight per unit area directly and there is a means for adjusting zero error. The material to be tested was cut to a specified area by means of a template provided and placed on the top platform (4) of the stem (5). Depending upon the weight per unit area, the liquid displaced indicates the same directly and this can be reads by reading the marking of the stem (5) coinciding with the liquid meniscus (2).

Description

EQUIPMENT FOR DETERMINING WEIGHT PER UNIT AREA

TECHNICAL FIELD

This invention relates to a floatation based equipment for determining the weight per unit area of two dimensional entities like fabrics, paper, films, laminates and sheets.

One quality parameter in the specification of two dimensional entities like a fabric, paper, film, laminate or sheet is the weight per unit area expressed in units like grams per square metre (commonly known by the abbreviated form GSM) and the above equipment has utility in easily determining this parameter from quantities less than one square metre of the above mentioned materials.

BACKGROUND ART

In the known art, one of the methods adopted is the Quadrant type balance on which any two dimensional entity (like fabrics, paper, laminates, sheets and films) of a specific predefined area is placed. The Quadrant balance works on the principle of counter balancing of levers and weights. Depending on the weight per unit area of the material, the pendulum of the quadrant moves over a quadrant scale marked directly to give the weight per unit area in units like grams per square metre. Another known art for the above determination is the use of a conventional weighing balance like the double pan physical or chemical balance, torsion (working on the principle of torsion of a wire) balance or electronic balance working on the basis of electronic sensors. A fabric of known area is weighed on the above mentioned weighing balance and depending on its weight and area, the weight per unit area is calculated.

INVENTION AND DESCRIPTION OF DRAWING

The above invention, a novel equipment for determining the weight per unit area is based on a principle different than those used in the prior art for measuring weight per unit area. Other objects of the invention are to have an alternate equipment which is easy to make , easy to operate and also available at affordable prices

The principle used is the principle of floatation according to which the weight of liquid displaced by a floating body is equal to the weight of the body. The invention concerned can be easily understood by referring to figure 1 , figure 2 and figure 3 accompanying this specification as part of it. Figure 1 shows the equipment consisting of a transparent vessel (1) which contains a liquid whose meniscus (2) is near the brim of the vessel. Inside this vessel, there is a float (3). The float consists of a platform (4) , a long stem (5) which has markings calibrated at a specified temperature mentioned indicating the weight per unit area directly, a spherical portion (6) inside the liquid and a weight (7) at the bottom of the spherical portion which helps in keeping the entire float vertical. Besides the above, the equipment is provided with zero adjusting masses as shown in figure 2 and a template as shown in figure 3.

BEST MODE OF WORKING THE INVENTION:

The zero reading on the stem of the float is observed to see whether it is coinciding with the liquid (say water) meniscus. If not, the zero reading is made to coincide with the liquid meniscus by placing the zero adjusting masses on the platform. With the help of the template and blade, a sample whose area is equal to the area of the template is cut from the two dimensional entity whose weight per unit area is to be determined .Then the cut specimen is placed on top of the platform, approximately centrally. When this is done, the stem will sink into the liquid and the weight of the liquid thus displaced will be directly proportional to the weight per unit area of the material tested since the area of the material tested is always kept a constant. The weight per unit area ( say in grams per square metre) of the specimen can be directly read by looking at the marking \ reading on the stem coinciding with the liquid meniscus.

During the above determination , one can expect the spherical portion of the float to come in contact with, the sides of the vessel . However research done with different shapes has confirmed that in this invention , the contact of the float with the sides of the vessel is a point contact which in this instance has minimum adverse effect on the accuracy of the equipment.

It was found during research conducted that variations in the temperature of the liquid from time to time caused a change in the density of the liquid used and so also the float. This caused a significant difference in zero reading which has been overcome by devising the zero adjusting masses to be placed on the top platform of the float. Even though the scale is calibrated at a specific reference temperature; when the zero is adjusted (according to the procedure outlined earlier), there is no significant influence on the weight per unit area determined, if the ambient temperature differs from the reference temperature.

Claims

CLAIM/S I claim

1) a floatation based equipment for determining the weight per unit area of two dimensional entities like textiles, paper, sheets, films and laminates comprising of a vessel containing a liquid having a float with a long stem with markings directly reading weight per unit area, a bottom portion capable of only a point contact with the vessel during its operation\ use and zero adjusting masses to place on the top of the stem to nullify any zero error occurring due to change in temperature from time to time .