Abstract: A pollution/smoke detector apparatus is disclosed having a sample chamber of two part molded plastic construction having a pair of matching interlocking pairs including a series of interfitting baffles forming a series of irises spaced along the chamber, the apparatus including at one end a light receptor and a light absorber at the other end, and an air sample area between the subject of a flash light emitted from a light source module having a novel reflector element. The overall construction is easily assembled and disassembled for maintenance and yet provides effective and efficient operation.

Abstract: A pollution monitoring device including a fluid sampling chamber (21), a collimated light source (14, 15) directing a light beam (10, 11) into the chamber, a port (23) for introducing sample fluid into the chamber exposed to the light beam, a light detector cell (16) separated or shaded from the light beam and focussing apparatus (17) for directing scattered light produced by the presence of suspended particles and molecules in the chamber towards the detector. The source may be two lasers with co-linear beams or an LED. There is also disclosed a sample area of small diameter in which a light beam traverses the area across the flow path of a sample fluid and a projector projecting scattered light from particles into a light receiving zone of notional triangular shape having an included angle of less than 60.degree., to enable discrimination of particle size discrimination.

Abstract: A gaseous fluid aspirator/pump apparatus including a rotary impeller (10) with radially extending blades, the impeller being mounted in a housing having a gaseous fluid inlet and outlet wherein gaseous fluid moving from the inlet (15) to the outlet (14) is turned from axial flow into the impeller to radial flow from the impeller, said impeller and an associated portion of the housing (16) being shaped to prevent flow separation and turbulence in the gaseous fluid stream while under the influence of the impeller. The impeller inlet (15) includes an inlet configuration of curvate conical from matching the configuration of the housing (16) in the area of the inlet opening. This configuration acting to prevent flow separation while turning the fluid flow through a large angle of approximately 90.degree. and acceleration and deceleration of the fluid flow is substantially prevented.

Abstract: A solid state temperature and/or anemometer measuring instrument for a fluid medium such as atmosphere the instrument including a pair of semi conductor junction means such as a zener diode one of which is exposed to fluid flow the other being isolated therefrom and providing outputs which are a function of the temperature of the fluid and a measuring device for measuring the respective outputs the differential being an indication of temperature or fluid speed. Such a device has specific application in an optical air pollution monitor to give a continuous indication of fluid flow thus ensuring that the monitor is sampling fresh batches of fluid from a monitored space.

Abstract: There is provided a flash reflector for maximizing the intensity of light passing into an air sampling chamber of a smoke detector which enables a reduction in power requirements for the light source. The reflector includes a concave reflecting element to focus light from each infinitesimal cross-sectional element off the arc of ionized gas in a flash tube the light output from the whole length of the tube which is optionally of U-shape being focused into the central region of the sampling chamber.

Abstract: In a smoke detection system, smoke density in a sampling chamber is measured by flashing a strobe light through the chamber and sensing light flux emitted from the chamber and comparing it with light flux from the strobe light itself. The measurements are performed by peak detectors which load sample-and-hold circuits to provide steady signals. The two signals are combined in mathematical manner to compensate for zero-offset and rate error between the two signals. The combined and corrected output is used to actuate a visual alarm signal, such as a segmented bargraph display to indicate air pollution. The bargraph has programming pins for tapping off each individual bargraph segment to achieve plural preset alarm thresholds.

Abstract: A light sensing apparatus comprising a solid-state photocell responsive to low levels of light connected to an impedance matching buffer stage, a gain controlled amplifier stage and an output amplifier stage; a gain control network controlled by a temperature sensor for receiving an amplified signal from said output stage, the gain being adjustable to compensate for temperature dependance of the photocell signal.

Abstract: A light absorber for use in a sampling tube used with sensitive optical pollution detectors the light absorber including a central light receiving conical surface inclined by at least one annular truncated conical surface to provide at least one annular groove or valley surrounding the central cone and wherein one wall of the groove or valley is undercut to shade the base of the groove or valley from direct impinging light.

Abstract: A heat sensitive air/gas sampling device including an apertured housing for connection to a pipe leading to a smoke detector device the housing including a blocking device for preventing air/gas to enter the housing, the blocking device being ineffective to prevent ingress of air/gas when the surrounding temperature exceeds a predetermined maximum for a predetermined period of time. The blocking device may be held by, or composed of, a low melting point wax. The blocking device may be comprised of a bimetallic strip.

Abstract: An automatic centralized monitoring security system having a plurality of detectors each capable of detecting and advising a malfunction of any given situation of either a routine or emergency nature and a responder associated in circuit with each detector, the arrangement being such that during normal operation the circuit is in dynamic equilibrium, and that upon a malfunction occurring to influence one or more detectors in the circuit an imbalance is created adapted to give rise to an alarm situation.

Abstract: An automatic centralized monitoring system capable of monitoring various sensors in a plurality of premises with rapidity; this is accomplished by combining the premises into a plurality of groups; the central station is provided with as many computer-controlled line drivers as there are groups; all of the line drivers are able to simultaneously read the sensors in one premise of each group. The sensor readings are multiplexed and returned to the computer which interprets the readings.

Abstract: The reflected signal of a microwave or ultrasonic Doppler intrusion detector is split into two different channels, each containing a mixer for hetrodyning the received signal with a reference signal. The reference signal for one mixer is the transmitted signal, while the reference signal for the other mixer is the transmitted signal with a phase shift. Thus the outputs of the mixers are of the same frequency but different phase. A phase comparator produces two mutually exclusive pulse trains as a function of the outputs of the two mixers, one said output representing motion toward the detector and the other representing motion away from the detector. These pulse trains are applied through a bidirectional counter to upper and lower limit sensors. An alarm circuit is activated if either limit is exceeded, thus providing an alarm in response to sufficient motion in either direction.

Abstract: An intrusion or movement detector including an oscillator for generating a radio signal, an antenna for transmitting said radio signal into an area to be surveyed by said detector, said antenna exhibiting a variable radiation resistance relative to the position and movement of objects in the area to be surveyed resulting in a variable loading on said generator when in use, a monitor for monitoring said variable loading and activating a signal or alarm when said variations in loading reach a predetermined threshold level to indicate an intrusion or movement in the area surveyed.

Abstract: A microwave movement detector which is capable of discriminating between progressive or unidirectional movement such as that by an unauthorized intruder and reciprocating movement such as by a curtain. The detector includes a pair of receiver/mixer diodes into which a transmitted signal is mixed with a surveying signal causing a phase difference so that the resultant signals have a different phase relationship amplifying the resultant signals feeding the signal into an integrating circuit in similar counter so that an alarm is sounded when the counter reaches a high or low threshold level.

Abstract: In a smoke detection system, smoke density in a sampling chamber is measured by flashing a strobe light through the chamber and sensing light flux emitted from the chamber and comparing it with light flux from the strobe light itself. The measurements are performed by peak detectors which load sample-and-hold circuits to provide steady signals. The two signals are combined in mathematical manner to compensate for zero-offset and rate error between the two signals. The combined and corrected output is used to actuate a visual alarm signal, such as a segmented bargraph display to indicate air pollution. The bargraph has programming pins for tapping off each individual bargraph segment to achieve plural preset alarm thresholds.