GB2257822A - Security system for test or monitoring equipment - Google Patents

Abstract

A security system for monitoring conditions experienced by a sensor responsive to a property the value of which is influenced by the conditions, the system including means for detecting an anomalous change in the conditions during a period for which the sensor is operative. A sensor 12 for radon gas is mounted in a housing, and means may be provided to determine if the housing is covered to close the ventilation holes 18, if the housing is moved to a different location and/or if the room in which the housing is placed is subject to excessive ventilation. An electronic unit 30 may be provided to detect when an anomalous as opposed to predictable change in conditions has occurred. The time during which the power supply is on and the total air flow through the housing may also be monitored. <IMAGE>

Description

SECURITY SYSTEM FOR TEST OR NONITORING EOUIPNENT The present invention relates to a security system for protecting equipment for performing a test or carrying out monitoring over a prolonged period of time in an environment which is not under the control of the person wishing to carry out the testing or monitoring.

The invention has been developed with a particular view to protecting equipment for monitoring radon levels in buildings but could readily be modified to provide protection for other monitoring equipment which is to be left unattended by the person carrying out the test.

In recent years, there has been a growing awareness that some properties, both domestic and commercial, have radon levels, and consequently background radiation levels, that are considerably higher than normal and, more particularly, higher than safe levels, The knowledge that such properties exist has led to a need to test buildings for the presence of radon gas. This need is particularly felt in high-risk areas and when property is to be sold: the buyer naturally wants reassurance that a property he is about to buy is not a health risk.

The test equipment currently used for radon-monitoring includes either a charcoal canister, which can produce a test result in a matter of days, or an alpha track etch canister which provides a result in several weeks. for either canister to give an accurate test result in a given environment, it must be left in that environment for the full duration of the test, it must be open to an unrestricted flow of air from that environment and, of course, it must be operational for the full duration of the test.

A problem with radon testing in the case of property to be purchases is that the test equipment must be left under the control of persons who have a vested interest in ensuring that the test results show the property to be safe and who might, therefore, be tempted to tamper with the equipment to obtain the desired result. The majority of such properties are domestic and it would not, in the circumstances, be feasible or economic to place a guard on the premises to prevent such tampering and the object of the present invention is to provide a simple and convenient system for preventing, or at least detecting, tampering with unattended equipment particularly, but not exclusively, for radon-testing equipment.

In order to resolve this problem the present invention provides a security system for monitoring conditions experienced by a sensor responsive to a property the value of which is influenced by the conditions, the system including means for detecting an anomalous change in the conditions during a period for which the sensor is operative.

The basic system of the invention indicated above may be used to detect tampering with a property, such as the radon content of an environment, by detecting anomalous changes in one or more associated conditions; in the case of radon testing, for example, anomalous air flows in the environment of the radon sensor may be detected. It will be appreciated that although the system may include means, such as a housing for preventing direct access to the sensor, it need not in fact prevent direct tampering, provided it is able to detect it in a manner which can make it clear to an authorised user of the sensor that tampering has occurred. The system may, for example, record changes in the conditions monitored in such a manner that the recording may subsequently be checked for anomalies by the authorised user.Alternatively, the system may incorporate an electronic unit which is programmable to detect anomalies in the conditions and to indicate when such anomalies occur.

In a particular aspect, the present invention provides a security housing system for equipment for monitoring and/or testing an environment including an enclosure for the equipment, an electronic unit associated with the enclosure, means for preventing and/or detecting and indicating any attempt to tamper directly with the equipment or the electronic unit, and sensors for sensing conditions indicative of an attempt to interfere with a property detected by the monitoring and/or testing equipment and for supplying the electronic unit with information on the sensed conditions, the electronic unit being programmable to differentiate between anticipated changes in the conditions sensed and anomalous changes due to attempts to interfere with the property detected by the monitoring and/or testing equipment.

In order to prevent or indicate any attempt to tamper directly with the equipment or the electronic unit, the electronic unit is preferably housed in the enclosure and the latter may simply be so shaped and sufficiently robust to prevent access to the equipment at least without the attempt being rendered obvious. Electronic safeguards may also be provided and, in particular, should include means for detecting any cut in the power supply to the equipment: a timing device which demonstrates that the equipment has been operational for the full duration of a test will suffice.

In the case of an enclosure for radon testing, it will be appreciated that, although it must prevent human access to the enclosed equipment, it must also allow a free exchange of air between the equipment and the outside environment and must, therefore, incorporate suitable apertures.

The enclosure of the security system may be fixable in its position of use by, for example, security bolts but this might not be acceptable in a domestic environment and the unit may, therefore, include sensors for detecting any movement of the enclosure once it has been installed and the monitoring equipment has been put into operation. Alternatively, the other sensors associated with the enclosure may suffice to protect the equipment.

The types of sensors associated with the equipment will depend on the factors detected by the test equipment. In the case of radon-testing equipment, the results are dependant on the free flow of air to the test equipment and therefore sensors may be provided to check that this flow is neither reduced, for example, by a cover being placed over the enclosure, nor enhanced by forced ventilation. Light sensors may, for example, detect covering by an opaque cover but the electronic circuitry must be programmed to compensate for any customary light changes, such as natural diurnal changes. In addition to light sensors, audio sensors may be provided since even a transparent cover would affect the audio field surrounding the equipment.Temperature, pressure and vibration sensors may also be provided, the electronic unit being programmed to correlate the information from all these sensors, as necessary, in order to distinguish between attempts to tamper with the equipment and naturally changing conditions.

The invention further provides test and/or monitoring equipment housed in an enclosure of a security housing system as described above.

One embodiment of the invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a housing forming part of a security housing system of the invention, and Figure 2 is a cross section of the housing of Figure 1 on an enlarged scale.

With reference to the drawings, a housing of a security housing system is shown generally indicated 11 and encloses test apparatus, generally indicated 12, such as a charcoal or alpha track etch canister and associated recording equipment for detecting the presence of radon gas and providing a quantitative estimation of its presence in the environment surrounding the apparatus over a given period of time.

The housing 11 is formed from sheet material and includes a base sheet 13a bounded by upstanding peripheral walls 14 terminating in outwardly and horizontally-extending flanges 15. The base 13 is covered by a square-pyramidal cover 16 formed by four walls 17 each in the shape of an equilateral triangle with each edge typically 200mm long.

A trapezoidal area 18 occupying a substantial proportion of the lower part of each wall 17 is apertured or constituted by a grille which has an open area of approximately 50% of the overall area. The apertured area 18 allows air to be exchanged freely between the interior of the housing 11 and the external environment.

The cover 16 in fact surrounds the base flange 15 and is hinged to it along one edge 19 thereof so as to be pivotable about a horizontal axis between the closed position, shown in the drawings, and an open position, not shown, in which access can be gained to the test apparatus 12. The wall 17a of the cover 16 opposite that hinged to the edge 19 carries a horizontally-projecting plate 20 which seats on a plate 21 projecting outwardly from, and coplanar with, the base flange 15 when the cover 16 is closed. The plates 20, 21 are apertured to receive a bolt or padlock (not shown) to secure them together to prevent the cover from being opened and also to attach a security tay 22 to the plates to identify any attempt at opening the cover.

The base 14 and/or the cover 16 may have additional means (not shown) for securing the housing 11 in its intended position of use.

The radon detecting apparatus 12 is supported within the housing 11 by a support bracket 24 constituted by a metal sheet bent into a right-angled C-shape with a shorter limb, or shelf 27, which extends at a height slightly above the apertured areas 18 of the cover 16. The radon detecting apparatus 12 is fixed to the shelf 27 adjacent the wall 17a of the cover 16, which wall has several additional ventilation holes 28, therein. Apertures (not shown) are also provided in the shelf 27 itself, which does not, in any case, occupy the entire cross-section of the pyramidal cover 16 so that air can flow freely through the housing to the detector 12.

In addition to the test apparatus 12, the shelf 27 carries on electronic control unit 30 connected to various sensors, not shown, for detecting any attempt to tamper with the operation of the test apparatus 12. The sensors may include: - a light sensor for detecting any change in light level due to the covering of the housing 11 to restrict the air flow therethrough.The control unit may be programmed and/or connected to additional light sensors to take account of other light changes, such as changes in natural light levels; - a doppler transducer for detecting any change in the audio field around the housing due to an attempt to cover the housing; - temperature sensors inside and outside the housing and possibly outside the building for indicating whether the environment under test is subject to abnormally high levels of ventilation, for example due to the opening of doors or windows; - pressure sensors inside and outside the housing for purposes similar to the above; - a vibration sensor for detecting any attempt to move the housing.

The housing 11 may also house a quantity of a material which oxidises at known rates under given air-flow conditions. At the end of a test period, the oxidation of the material may be checked to ensure that it agrees with the expected values.

The control unit 30 also incorporates or is connected to a timer which is activated when the test apparatus 12 is connected to a power supply, normally the mains electricity supply, and is deactivated should the supply to the test apparatus be switched off so that any attempt to deactivate the apparatus is indicated.

In use, one or more of the housings 11 and associated equipment would be installed by an authorised user in a building to be tested. The authorised would also programme the control unit and locate and set any sensors required to ensure that the housings were not tampered with during the test run. The test apparatus would then be switched on and left for the required time to obtain the necessary test results. The authorised user would then be able to collect the apparatus on his return and check the results in the secure knowledge that they were correct.

Claims (18)

1. A security system for monitoring conditions experienced by a sensor responsive to a property which is influenced by the conditions to which it exposed, the system including means for detecting an anomalous change in the conditions during a period for which the sensor is operative.

2. A system as claimed in Claim 1, including means for recording changes in the conditions monitored in such a manner that the recording may subsequently be checked for anomalies by an authorised user.

3. A system according to Claim 1 or Claim 2, incorporating an electronic unit which is programmable to detect anomalies in the conditions and to indicated when such anomalies occur.

4. A system as claimed in any preceding claim, including means, such as a housing, for preventing direct access to the sensor.

5. A system as claimed in any preceding claim, adapted to detect the radon content of an environment, and including means for detecting anomalous changes in one or more associated environmental conditions.

6. A security system as claimed in any preceding claim, including a housing for equipment for monitoring and/or testing a property of an environment, including an enclosure for the equipment, an electronic unit associated with the enclosure, means for preventing and/or detecting and indicating any physical disturbance of the equipment or the electronic unit, and sensors for detecting conditions indicative of an attempt to interfere with a property detected by the monitoring and/or testing equipment and for supplying the electronic unit with information on the sensed conditions, the electronic unit being programmable to differentiate between predictable changes in the conditions sensed and anomalous changes which may be due to attempts to interfere with the property detected by the monitoring and/or testing equipment.

7. A security system as claimed in Claim 6, in which the electronic unit is housed in the enclosure and the latter is shaped to prevent access to the equipment.

8. A system as claimed in Claim 6 or Claim 7 further including electronic means for detecting any interruption in the power supply to the equipment;

9. A system as claimed in Claim 8, in which the said means for detecting an interruption in the power supply comprises a timing device which indicates the time for which the equipment has been operational.

10. A system as claimed in any preceding Claim, including an enclosure for the enclosed equipment and apertures to allow a free exchange of air between the equipment and the external environment.

11. A system as claimed in any preceding Claim, adapted to be fixable in position of use.

12. A system as claimed in any of Claims 1 to 10, including sensors for detecting any movement of the enclosure once it has been installed and the monitoring equipment put into operation.

13. A system as claimed in any preceding claim, including means for determining whether a flow of air through a casing housing the equipment is interrupted or inhibited and/or for determining whether the air flow is modified by a forced ventilation.

14. A system as claimed in any preceding claim, including light sensors for detecting whether the incident electromagnetic radiation in the visible spectrum is modified from its dianol variation.

15. A system according to any preceding claim, including audio sensors for detecting a variation in the audio field surrounding the equipment.

16. A system according to any preceding claim, including at least one of temperature, pressure and vibration sensors, the electronic unit being programmed to correlate the information from all these sensors, as necessary, in order to distinguish between attempts to tamper with the equipment and naturally changing conditions.

17. A system according to any preceding Claim, including a quality of material the oxidation rate of which is affected by the rate of flow of air.

18. A system substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.