Title of Invention

"A GAS FLOW MEASUREMENT DEVICE FOR USE IN AMBIENT GAS SAMPLING"

Abstract

The present invention provides a gas flow measurement device for use in ambient gas sampling which comprises a block made of a transparent, non-corrosive material of at least 1 inch wide, 1 inch thick and 6 inches long, having one end for inlet and the other end for outlet, and the said inlet and outlet are interconnected through an air passage of 10 mm diameter either machined or bored and being characterized in that having a venturi type of passage with a neck diameter of at least 1 mm designed to maintain a constant flow rate, and the said outlet connected to a conventional air suction device for drawing air from the device, the said air passages at inlet and out let having bottom central openings for suitably connecting through metal adapters to a graduated water manometer having 1mm graduations on a scale of at least 80 cm length for accurate measurement of gas flow.

Full Text

The present invention relates to a gas flow measurement device for use in ambient gas sampling The device is useful for measurement of gaseous flow in laboratory experiments as well as in field during ambient gaseous sampling. The utility of the device is due to its robustness, transparency, unbreakableness as it is made from acrylic solid block and is compatible with the ambient gases being sampled. Quantitative determination of amounts of gaseous components in the ambient air and in the industrial work place environment requires not only an accurate measurement of gaseous pollutants but also an accurate determination of the volume of air from which it is sampled. The volume of air sample is the product of flow rate and length of sampling period. Accurate knowledge of the flow rate and sampling time is necessary to obtain reliable results. The length of sampling period can be obtained accurately, but the flow rate measured by devices like rotameter deviate considerably when continuous gaseous sampling for longer time is required. The observation of variation in flow rates through different sampling devices used in field sampling necessitated development of rigid, easy to fabricate gas flow measurement device. The draw back of rotameter is inconsistent flow in the low range of 0 - 500 ml/min. when continuous sampling is carried out. A constant flow is desirable during gaseous sampling. The difficulty in adjustment of flow in the low range and necessity of recording the flow during air sampling requires a device to continuously record the flow with a graduated glass manometer. Some glass gas flow devices were also developed in-house, but they are likely to break during transit and during installation of the sampling train in the field. Other flow measuring devices such as, wet test meters are bulky and difficult to operate under field conditions. Hence, it is necessary to design and develop a gas flow meter out of a transparent solid piece of acrylic so that it is transportable, unbreakable and can be used under field conditions. The invention would lead to development of flow device for low flow rate maintenance for gaseous sampling with an improved accuracy. This will also help in determining concentration of gaseous pollutants at low levels so as to meet the regulatory standards. There is no such device has been reported in the literature. The device of the present invention developed by us is new and novel. The main object of the present invention is to develop a simple device for gaseous flow measurement in the laboratory experiments as well in the field where ambient gaseous sampling is carried out. Another object of the invention is to provide an unbreakable and easy to handle in the field conditions with a transparent and solid gas flow meter than the conventional glass orifice meters. The gas flow meter thus produced is precise at low level and gives reproducible results. In the drawings accompanying this specification, Figure 1 represents the commercially available rotameter, which is conventionally used in gas flow measurements, and Figures 2&3 represent the device of the present invention. Figure 2 of the accompanying drawings represents the gas flow measurement device consisting of Acrylic transparent block (1), a fine orifice of 1 mm diameter (2), an inlet (3) and an outlet (4) each of 10 mm diameter, and a manometer (7) connected through metal adopters (5 and 6 ). Figure 3 represents a gas flow measurement assembly consisting of gas flow measurement device (8), calibrator (9) with rubber bulb (10), graduated glass column (11), and an Impinger (12). Accordingly the present invention provides a gas flow measurement device for use in ambient gas sampling which comprises a block (1) made of a transparent, non-corrosive material of at least 1 inch wide, 1 inch thick and 6 inches long, having one end for inlet (3) and the other end for outlet (4), and the said inlet (3) and outlet (4) are interconnected through an air passage of 10 mm diameter either machined or bored and being characterized in that having a venturi type of passage (2) with a neck diameter of at least 1 mm designed to maintain a constant flow rate, and the said outlet (4) connected to a conventional air suction device for drawing air from the device, the said air passages at inlet and out let (3&4) having bottom central openings (5 and 6) for suitably connecting through metal adapters to a graduated water manometer (7) having 1mm graduations on a scale of at least 80 cm length for accurate measurement of gas flow. In an embodiment of the present invention the transparent and non-corrosive material used may be such as acrylic. In still another embodiment of the present invention the transparent, solid, acrylic block may be of ¾ inch wide, ¾inch thick and 3 inch long and is bored to create an air passage with a venturi as a reliable gas flow measurement device. In yet another embodiment of the present invention the device is unbreakable, easy to operate, compact, portable and gives reproducible results of gaseous flow measurements in laboratory as well as field gas sampling. For the operation of the device of the present invention to determine gaseous flow rates during the sampling program, the gas flow measurement device is attached to a manometer (7) and the outlet(4) of the said device is connected to an irnpinger (12) containing the absorbing media and further to a suction pump for sucking the air /gas sample from the atmosphere. The basic principle of calibration of the device is with the help of a primary calibrator(9) wherein a soap bubble is made to travel through a graduated column (11) having graduations of 0 to 500 ml over a given period of time under the influence of suction. The suction pump is started and the suction rate is adjusted to minimum level on the manometer with the help of a needle valve. Some air is pushed into a flask with a rubber bulb (10) so that the soap solution is momentarily in contact with the glass column and a bubble is formed which travels upwards under the force of suction. The time required for travel between two graduated marks is noted with a stopwatch. This is repeated thrice. Again manometer level is adjusted to a new value and time required for bubble travel is noted. The experiment is repeated for various levels on the manometers and flow rate is determined. The gaseous sampling flow rate for a 24 hours sample is normally kept at 100 - 250 ml/min. The device thus operates at a minimum flow of 100 ml/min with an accuracy of 2%. The main advantages of the present invention are : 1. The present invention relates to the development of a simple device is compact and of proper size for monitoring gaseous flow at the field site as well in the laboratory. 2. It can measure gaseous flow as low as 100 ml/min such a flow is difficult to maintain with conventional flow meter for a continuous measurements. 3. It is unbreakable, easy to operate and gives reproducible results 4. The device is easy to fabricate in a small workshop. We claim: 1. A gas flow measurement device for use in ambient gas sampling which comprises a block (1) made of a transparent, non-corrosive material of at least 1 inch wide, 1 inch thick and 6 inches long, having one end for inlet (3) and the other end for outlet (4), and the said inlet (3) and outlet (4) are interconnected through an air passage of 10 mm diameter either machined or bored and being characterized in that having a venturi type of passage (2) with a neck diameter of at least 1 mm designed to maintain a constant flow rate, and the said outlet (4) connected to a conventional air suction device for drawing air from the device, the said air passages at inlet and out let (3&4) having bottom central openings (5 and 6) for suitably connecting through metal adapters to a graduated water manometer (7) having 1mm graduations on a scale of at least 80 cm length for accurate measurement of gas flow. 2. A device as claimed in Claim 1, wherein the gas flow measurement device is made up of acrylic or any other transparent, unbreakable and non-corrosive material. 3. A gas flow measurement device for use in ambient gas sampling substantially as herein described with reference to the drawings accompanying this specification.

Documents:

249-del-2000-abstract.pdf

249-del-2000-claims.pdf

249-del-2000-complete specification (granted).pdf

249-del-2000-correspondence-others.pdf

249-del-2000-correspondence-po.pdf

249-del-2000-description (complete).pdf

249-del-2000-drawings.pdf

249-del-2000-form-1.pdf

249-del-2000-form-19.pdf

249-del-2000-form-2.pdf

249-del-2000-form-3.pdf