GB1601775A

GB1601775A - Ambient pressure sensor

Info

Publication number: GB1601775A
Application number: GB1543678A
Authority: GB
Original assignee: FLAEKT Ltd
Current assignee: FLAEKT Ltd
Priority date: 1978-04-19
Filing date: 1978-04-19
Publication date: 1981-11-04

Description

(54) AMBIENT PRESSURE SENSOR (71) We, FCAKT LIMITED, a British Company, of Staines House, 158 High Street, Staines, Middlesex TW18 4AR, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which is is to be performed, to be particularly described in and by the following statement:- The invention relates to an ambient pressure sensor, particularly for the atmosphere.

It is often necessary to obtain as accurate a measurement of ambient pressure as is possible. This is usually the case where atmospheric air comprises primary air for air conditioning, or ventilation, installations.

On structures such as offshore platforms and other structures, (tall) buildings, and ships this measurement is often difficult.

This is because wind moving round the structure forms both positive and negative pressure areas immediately adjacent the structures, so in order to measure the ambient pressure the measuring point must be outside these disturbed areas. However, the wind speed at these remote points creates dynamic pressures on the sensor and this prevents the obtaining of an accurate reading of ambient pressure.

It is accordingly an object of the invention to seek to avoid these disadvantages.

According to the invention there is provided an ambient pressure sensor, comprising two spaced apart substantially parallel interconnected substantially identical hollow members each of which has a surface area which is great in comparison to its depth, holes in the facing surfaces of each member for countering dynamic pressure across the members, and means for monitoring the ambient pressure internally of the members.

It is possible to provide a sensor embodying the invention which is not effected by dynamic wind pressure of i5%, even up to upwash or downwash angles of 10 .

A sensor embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings, which shows a side elevational view of the sensor.

Referring to the drawing, the atmospheric ambient pressure sensor 1 shown is mounted at a position outside a structure being air conditioned or ventilated and to this end may be mounted atop a tall mast, which may be 200 feet above the structure. The sensor 1 comprises two substantially parallel members in the form of hollow circular averaging discs 2 and 3. The diameter of each disc 2 and 3 is the same, suitably between 200 mm and 400mm. The thickness of each averaging disc 2 and 3 is between 10 mm and 20 mm and their circumferences or edges are shaped to give minimum flow turbulence.

The distance between the discs 2 and 3 is between 8 mm and 30 mm and each has a series of facing holes 4, 5. There are between 10 and 40 holes 4 and 5 on each disc 2 and 3, their centres being at pitches of between 80 mm and 300 mm diameter. The discs 2 and 3 are connected to a support tube 6 which carries leads 7 to electrical heating elements 8, and a drain connection 9. The tube 6 has a connection 10 for equipment such as an ambient pressure monitor which may be remote from the sensor 1, e.g. in the structure. The heating elements 8 are thermostatically controlled to maintain both the internal and external temperatures of the sensor significantly above freezing point.

There is also a connector (not shown) for mounting the sensor on a mast.

In use, when wind blows over the sensor 1, a positive pressure is built up at the holes 4 and 5 in one disc 2 and an equal and opposite negative pressure is formed at the opposite holes 4 and 5 in the other disc 3. The nett result is that the interior of the discs 2 and 3 registers the correct ambient pressure, which is monitored by the ambient pressure monitor or recording equipment e.g. a digital print out 1 Ia connection 10. The pressure detected by the sensor is not effected by dynamic wind pressure by more than i5% even up to upwash or downwash angles of 10 .

WHAT WE CLAIM IS: 1. An ambient pressure sensor, comprising two spaced apart substantially parallel

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. (54) AMBIENT PRESSURE SENSOR (71) We, FCAKT LIMITED, a British Company, of Staines House, 158 High Street, Staines, Middlesex TW18 4AR, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which is is to be performed, to be particularly described in and by the following statement:- The invention relates to an ambient pressure sensor, particularly for the atmosphere. It is often necessary to obtain as accurate a measurement of ambient pressure as is possible. This is usually the case where atmospheric air comprises primary air for air conditioning, or ventilation, installations. On structures such as offshore platforms and other structures, (tall) buildings, and ships this measurement is often difficult. This is because wind moving round the structure forms both positive and negative pressure areas immediately adjacent the structures, so in order to measure the ambient pressure the measuring point must be outside these disturbed areas. However, the wind speed at these remote points creates dynamic pressures on the sensor and this prevents the obtaining of an accurate reading of ambient pressure. It is accordingly an object of the invention to seek to avoid these disadvantages. According to the invention there is provided an ambient pressure sensor, comprising two spaced apart substantially parallel interconnected substantially identical hollow members each of which has a surface area which is great in comparison to its depth, holes in the facing surfaces of each member for countering dynamic pressure across the members, and means for monitoring the ambient pressure internally of the members. It is possible to provide a sensor embodying the invention which is not effected by dynamic wind pressure of i5%, even up to upwash or downwash angles of 10 . A sensor embodying the invention is hereinafter described, by way of example, with reference to the accompanying drawings, which shows a side elevational view of the sensor. Referring to the drawing, the atmospheric ambient pressure sensor 1 shown is mounted at a position outside a structure being air conditioned or ventilated and to this end may be mounted atop a tall mast, which may be 200 feet above the structure. The sensor 1 comprises two substantially parallel members in the form of hollow circular averaging discs 2 and 3. The diameter of each disc 2 and 3 is the same, suitably between 200 mm and 400mm. The thickness of each averaging disc 2 and 3 is between 10 mm and 20 mm and their circumferences or edges are shaped to give minimum flow turbulence. The distance between the discs 2 and 3 is between 8 mm and 30 mm and each has a series of facing holes 4, 5. There are between 10 and 40 holes 4 and 5 on each disc 2 and 3, their centres being at pitches of between 80 mm and 300 mm diameter. The discs 2 and 3 are connected to a support tube 6 which carries leads 7 to electrical heating elements 8, and a drain connection 9. The tube 6 has a connection 10 for equipment such as an ambient pressure monitor which may be remote from the sensor 1, e.g. in the structure. The heating elements 8 are thermostatically controlled to maintain both the internal and external temperatures of the sensor significantly above freezing point. There is also a connector (not shown) for mounting the sensor on a mast. In use, when wind blows over the sensor 1, a positive pressure is built up at the holes 4 and 5 in one disc 2 and an equal and opposite negative pressure is formed at the opposite holes 4 and 5 in the other disc 3. The nett result is that the interior of the discs 2 and 3 registers the correct ambient pressure, which is monitored by the ambient pressure monitor or recording equipment e.g. a digital print out 1 Ia connection 10. The pressure detected by the sensor is not effected by dynamic wind pressure by more than i5% even up to upwash or downwash angles of 10 . WHAT WE CLAIM IS:

1. An ambient pressure sensor, comprising two spaced apart substantially parallel and interconnected substantially identical hollow members, each of which has a surface area which is great in comparison to its depth, holes in the facing surfaces of each member countering dynamic pressure across the members, and means for connecting the sensor with apparatus for monitoring the ambient pressure internally of the members.

2. An ambient pressure sensor according to Claim 1, in which there are between ten and forty holes in each member.

3. An ambient pressure sensor according to Claim 1 or Claim 2, in which each member comprises a substantially circular disc.

4. An ambient pressure sensor according to Claim 3, in which the circumference of each disc is shaped to reduce flow turbulence over the sensor.

5. An ambient pressure sensor according to any preceding claim, in which there is means to maintain the sensor above freezing point.

6. An ambient pressure sensor according to Claim 5, in which the said means comprises an electrical heating element in each member.

7. An ambient pressure sensor according to any preceding claim, including a connector for connecting the sensor to a support such as a mast.

8. An ambient pressure sensor according to any preceding claim, including a drain for draining condensed moisture from the interior of the sensor.

9. An ambient pressure sensor, substantially as hereinbefore described with reference to and as shown in the accompanying drawing.