Abstract: In a self-powered diffuser for a variable volume air distribution system, an installation for the control components which facilitate adjustment, modification and system start up. A Tee fitting located in the control compartment feeds through the bulkhead and into the diffuser to sense the flow rate of air in the diffuser. One leg of the Tee fitting is available to receive a tube in order to permit servicemen to actually measure the flow rate from below the ceiling. The maximum flow rate is adjustable from below the ceiling and is carried out by an adjustment mechanism having enhanced stability and reliability. A thermostat in the control compartment can be installed, serviced and replaced if necessary from below the ceiling.

Abstract: In a self-powered diffuser for a variable volume air distribution system, an installation for the control components which facilitate adjustment, modification and system start up. A Tee fitting located in the control compartment feeds through the bulkhead and into the diffuser to sense the flow rate of air in the diffuser. One leg of the Tee fitting is available to receive a tube in order to permit servicemen to actually measure the flow rate from below the ceiling. The maximum flow rate is adjustable from below the ceiling and is carried out by an adjustment mechanism having enhanced stability and reliability. A thermostat in the control compartment can be installed, serviced and replaced if necessary from below the ceiling.

Abstract: A temperature sensor which is flush mounted on a wall of a room in which the temperature is sensed. A mounting plate secured to the wall has a cavity in its face which receives an aluminum sensor plate and an insulating block which thermally insulates the sensor plate from the mounting plate. A temperature sensing integrated circuit contacts the back side of the sensor plate and has electrical leads which extend to the back side of a printed circuit board mounted in a pocket on the back side of the mounting plate. The integrated circuit acts as a current source having its output signal enhanced by active solid state circuit components mounted on the back side of the circuit board where their heat is dissipated by conduction through the mounting plate and wall and by convection and radiation into the wall cavity to avoid affecting the sensor plate. The circuitry allows active factory calibration and eliminates adverse effects on the signal caused by background environmental noise.

Abstract: A low pressure pneumatic pressure regulator having particular application to the control circuits of system powered air distribution systems. A diaphragm separates a control chamber located above the diaphragm from an underlying output. The chambers communicate through a fixed orifice. A vent line extending from the control chamber includes an adjustable orifice which may be thermostatically controlled. An output line extending from the output chamber leads to the load controlled by the regulator. Power to operate the regulator can be supplied from the load or from a separate pressure source which connects with the output chamber through a supply port. An exhaust port which bleeds pressure from the output chamber when open is closed by the diaphragm unless the pressure differential between the chambers overcomes the diaphragm weight and possibly the added force applied by an optional spring.

Abstract: A sound attenuator formed by a bank of at least three wall mounted tubes extending into a room from which noise originates and also into an adjacent occupied room. Each tube is cylindrical and has a length between one sixth and one third wavelength of sound in air at the highest frequency in the low frequency waveband in which the reactive acoustical properties of the tubes are effective. The diameter of each tube is less than about one sixth wavelength. The size, arrangement and spacing of the tubes are selected to take good advantage of the operative acoustical phenomena, including the quarter wavelength effect, the duct end loss effect and the multiple tube effect.

Abstract: A low temperature air conditioning system provides primary air through smaller than normal ductwork and at a lower than normal temperature (such as 40.degree. F.) at peak load conditions. The primary air is mixed in branch ducts with return air taken from the conditioned space. Low pressure fans pull the return air into mixing boxes equipped with dampers which maintain the downstream temperature in the branch ducts at a normal supply air temperature (such as 55.degree. F.). Variable air volume terminal units discharge the air into the conditioned space. The small fans require only low horsepower and allow a smaller than normal central fan to be used. The cooling coil is cooled by a variable suction temperature refrigeration system which may be operated at night in conjunction with an ice storage system to minimize the demand for mechanical refrigeration during peak daytime hours. This arrangement permits the refrigeration machine to be smaller than normal and to consume less power during peak daytime hours.

Abstract: The desirable features of self powered air distribution terminals and electronic controls are combined by providing an interface between the electronic controls and one or more self powered terminal units in an air distribution system. The electronic controls monitor temperatures and other conditions and provide electric signals each having a voltage which represents the difference between the sensed condition and a set condition entered into the system microprocessor. The interface may be an electro-pneumatic transducer or a set of solenoid valves. The interface responds to the electric signals by applying proportional pressure signals to one or more terminal units. The flow of conditioned air into the area or areas served by the system is then adjusted to conform the actual conditions with the set conditions.

Abstract: A method and apparatus for delivering conditioned air to hospital patient rooms or clean rooms which are maintained at a higher or lower pressure level than the adjacent halls. A constant volume delivery duct is provided to counter the constant volume toilet exhaust, and the flow rates in the constant volume ducts are selected to maintain the desired pressure level in the room. The room temperature is maintained by a variable volume system including a variable volume supply duct and a variable volume return duct. Dampers in the variable volume ducts are controlled in unison to control the room temperature as desired while always maintaining equal inflow and outflow in the variable volume system to maintain the pressure level in the room. A specially constructed and partitioned terminal unit provides a terminal for the variable volume supply and return ducts and the constant volume supply duct.

Abstract: An air conditioning terminal unit for directing heated or cooled air into a room. A duct which receives the air has two outlets which direct the air into an underlying plenum. The air in the plenum is discharged into the room through an air diffuser having two slots which diffuse the air to opposite sides of the terminal unit. Partitions and baffles in the plenum split the air flow and direct the conditioned air in a pattern carrying all of the air from one duct outlet to one of the diffuser slots and all of the air from the other duct outlet to the other diffuser slot. The duct outlets are individually controlled to vary the throw to opposite sides of the diffuser.

Abstract: An arrangement for attenuating noise in an air handling unit having a forwardly curved centrifugal fan and dampers downstream of the fan for varying the volume rate of air flow. The dampers are located downstream of the fan a distance L which is about 30 inches so that the critical acoustical frequency f=C/4L is relatively high (125 Hz). The discharge section of the air handling unit between the fan and the dampers is lined on the sides with acoustical panels that are effective in absorbing sound at the critical frequency.

Abstract: A distribution duct for conditioned air has elongate outlet slots which are opened and closed by a sound absorbing foam pad controlled by inflatable air bladders. The duct walls adjacent the slots are generally parallel to the face of the pad to create thin air flow channels which effect attenuation of noise when the pad is fully or partially open. When the bladders are fully inflated, they press the pad into the slots and into tight sealing contact with the slot edges.

Abstract: An improved adjustment mechanism for adjusting the maximum flow rate of conditioned air in an air distribution system controlled by a pneumatic control circuit. An air bladder controls the distribution of air, and the pressure is bled from the bladder under the control of a diaphragm against which pressure is fed back from the downstream side of the bladder. The control orifice through which the bladder pressure is exhausted is formed in the end of an exhaust tube that is axially adjustable. A cam and set screw arrangement provides a field adjustment for the exhaust tube to move the control orifice toward and away from the diaphragm for adjustment of the maximum flow rate. The cam has three point contact provided by a pair of feet and a second set screw which permits adjustment of the inclination of the cam surface. Rocking of the cam is prevented by a spring which counters the force applied to the cam by the first set screw.

Abstract: A pneumatic control circuit for controlling the discharge of conditioned air from an air distribution system. The circuit is arranged to apply the supply pressure to an inflatable bladder which controls the discharge of conditioned air from a ventilation duct. A diaphragm controls the bleeding of air from the bladder under the influence of the supply pressure, a thermostat, a velocity sensor at the duct outlet and a plurality of selectively sized orifices. The velocity sensor compensates automatically for variations in the main supply pressure so that the control function of the circuit is independent of the supply pressure.

Abstract: An adjustment mechanism for adjusting the maximum flow rate of conditioned air in an air distribution system controlled by a pneumatic control circuit. An air bladder controls the distribution of air, and the pressure is bled from the bladder under the control of a diaphragm against which pressure is fed back from the downstream side of the bladder. The control orifice through which the bladder pressure is exhausted is formed in the end of an exhaust tube that is axially adjustable. A cam and set screw arrangement serves to extend and retract the exhaust tube to move the control orifice toward and away from the diaphragm for adjustment of the maximum flow rate.

Abstract: The present invention encompasses a method and apparatus for assisting in the operation of air control dampers. An air deflector is positioned downstream from a rotatable damper in an air conduit. The deflector is positioned to direct air moving over one side of the damper against the damper during opening to assist in the opening movement and thereby reduce the amount of weight which would otherwise be required. The same deflector is positioned so that upon closing of the damper air will be deflected against the opposite side of the damper blade to augment the torque forces tending to close the damper while also reducing the pressure drop from one side of the damper to the other. In another embodiment of the invention a sail blade is provided upstream from the control damper to assist in closing the damper at low flow conditions.

Abstract: A device for reducing noise interiorly of air distribution ducts is comprised of at least one sound attenuating module which is adapted to be placed adjacent to a noise source or installed interiorly of conventional air distribution ducts. The module has a plurality of adjacently sandwiched glass fiber layers which are separated from each other by aluminum side walls. Each one of the layers is sealed by an aluminum membrane enclosure (with the outer membranes being substantially airtight to prevent any resultant friction between air passing through the duct and the glass fiber). Noise is reduced as the sound pressure (developed by the conditioned air flow in the duct) alternately contracts and expands the compliant glass fiber media interiorly of the module, thusly dissipating energy in the form of friction between the glass fibers that are in each layer.

Abstract: A slot diffuser is utilized to counteract large heat losses through a wall or window by producing a vertical blanket or curtain of air adjacent the wall or window. An elongate housing defines a plenum chamber delivering air to a uniquely constructed convergent-divergent diffuser slot. High velocity air exits from the diffuser slot and is rapidly intermixed with the induced cold air from the wall or window. The rapid mixing, resulting from the high discharge velocity, permits very hot air to be introduced into the room, yielding a high induction ratio so that a small volume of air counteracts a high rate of heat leakage. The specially shaped diffuser slot performs relatively noiselessly while permitting high velocity air to flow therethrough.