FLOW INDICATOR

Abstract: Flow indicator with the purpose to indicate direction of the air flow between two rooms separated by a wall. The indicator comprises a tube (12) that is mounted in an opening of the wall (10). Inside the tube is a smooth-running body (16) mounted that easily moves towards the end of the tube by pressure difference arised air flow. Both ends of the tube are provided with end-stops (18) that are constructed to prevent the body (16) to leave the tube and are provided with one or more openings (20) that admits air to pass into the interior of the tube.

Description: Flow Indicator The present invention refers to a flow indicator of the kind that is stated in the introductory portion of claim 1. Within many buildings, as industrial departments, laboratories etc, it is of importance to know the direction of the air flow between rooms. In manufacturing of pharmaceuticals as for an example this information is essential to prevent contaminated air to flow in the wrong direction. The flow indicators that are known have solved this with a "flap" or other suitable means in an opening between the rooms to show the direction of the air flow. A disadvantage is however that if an airflow is obtained in the wrong direction unacceptable air will flow in to the protected room before any steps to change the direction of the flow or the pressure difference has been taken. The object of the present invention is to achive an flow indicator that eliminates the disadvantages mentioned above in connection with known flow indicators. This task is solved by giving the flow indicator according to the invention the characteristics specified in the enclosed patent claims. The invention will now be described closer with reference to an embodiment shown in the drawing. Figure 1 shows the flow indicator cut lengthwised inside a wall. Figure 2 shows the flow indicator in a cross-cut view. In the wall 10 a hole is made in which a tube 12 is mounted. The material of tube can be for an example plastic, glass, or other similar material, preferably transparent. The tube 12 has a small tolerance in relation to the opening in the wall and is preferably sealed against both side of the wall with a suitable sealing material 14. Inside the tube 12 a smooth-running solid body 16 is placed which is the enbodiment shown has a spherical shape and which easily moves inside the tube under influence of an even light airflow. The body 16 can be made of a thin plastic material of the same kind as table tennis balls. At both ends of the tube there are end-stops 18 that prevents the body 16 to leave the tube. The end-stop is provided with an opening 20 that makes it possible for the air to pass into the tube 12 and move the smooth-running body 16. If the flow indicator is placed between rooms with different pressures the function of the described flow indicator is that the body 16 placed in the tube 12 moves towards the end-stop that faces the room with the lowest pressure because of the arised air flow. As the body moves with small tolerance in relation to the wall of the tube, only a fragment of the flow will pass between the rooms and when the body reaches the end- stop 18 it will generate a complete sealing that stops air to pass in to the room with the lower pressure. As the tube is made by transparent material the body 16 is easy to see and if the body is spherical, as in the example, a part of spheroids perimeter will pop out at the opening 20 of the end-stop 18 and the direction of the air flow can easily be detected. Of course the shown embodiment is only an example of the invention and can easily be changed within the scope of the enclosed patent claims. Thus can the body 16 instead of a spheroid be in a shape of an cylindrical piston that moves easily in the tube 12 and with its end surface seales towards the end-stop 18.

Claims: Claims 1. Flow indicator with the purpose to indicate direction of the air flov between two rooms sepatared by a wall, characterized by a cylindrical tube shaped cell (12) that is mounted with a small tolerance in an opening of the wall (10), a smooth-running body (16) mounted inside the tube that easily moves towards the ends of the tube (12) by pressure difference arised air flow, end-stops (18) that are constructed to prevent the body (16) to leave the tube and provided with openings (20) that admits air to pass into inside of the tube. 2. Flow indicator according to claim 1, characterized by the tube shaped cell (12) being cylindrical and the body (16) being spherical, such as a ball. 3. Flow indicator according to claim 1 or 2, characterized by the sealing of the cylindrical tube shaped cell (12) outer surface against the wall. 4. Flow indicator according to claim 1, 2 or 3, characterized by the cylindrical tube shaped cell (12), being of a transparent material such as a plastic tube as clear as glass. 5. Flow indicator according to claim 2, characterized by the end-stop (18) being provided with an opening with dimensions such that a part of the spherical indicator body (16) pops out outside the end-stop when the indicator body (16) is engaging the end-stop. 6. Flow indicator according to any of the claims 1 - 5, characterized in that the indicator body (16) at the othermost position engaging one of the end-stops is arranged to close the opening (20) of the end-stop to prevent air to enter the cylindrical tube shaped cell (12).

Inventors: NYBERG TORD, NYBERG, TORD
Applicants: NYBERG TORD, NYBERG, TORD
Application year: 1998
Main classification: G01P13
IPC codes: G01P13