Abstract: An apparatus for maintaining a relatively moist ambient gas in intimate contact with a humidity sensing element includes a control nozzle for flowing relatively dry pneumatic control gas therethrough. The nozzle is adapted to be modulated for controlling the humidity within a space. A rigid control cone is coupled to the nozzle for defining a cavity therebetween and having a fixed volume. The cone includes a pin member which is movable with respect to the cone for effecting nozzle modulation. A discharge spigot is disposed in fluid flow communication with the cavity, the spigot being arranged for exhausting the pneumatic control gas to a region remote from the humidity sensing element.

Abstract: A vacuum operated sewage system includes a static pressure sensor establishing a trigger signal at a selected first level in a standpipe. The sensor is connected upstream of a discharge control valve and actuates a trigger and timer controller at the selected sensed pressure to establish flow for a predetermined period. A separate air admission control is provided to separately actuate the timer controller if the vacuum level in the sewage flow line drops below a selected level, to thereby reset the system vacuum pressure. The air admission control includes a level trigger valve operable to actuate the controller. A by-pass pressure sensing valve has an input connected to sense line pressure and holds the trigger valve in standby until the line pressure drops below a selected vacuum pressure. A resettable fluid timer is also connected to the level trigger valve and is charged under normal pressure system conditions.

Abstract: A vacuum operated sewage system includes a static pressure sensor establishing a trigger signal at a selected first level in a standpipe. The sensor is connected upstream of a discharge control valve and actuates a trigger and timer controller at the selected sensed pressure to establish low for a predetermined period. A suitable time delay capacitor in the controller prevents transient signal actuation. A system pressure interlock senses the vacuum level of the system to disable the timer controller if system pressure is below a selected level. The interlock may include a pressure level control valve connected to bleed the capacitor and disable the timer controller. A system pressure sensing valve in parallel with the level control valve decouples the latter as long as the system level is above the selected minimum and thereby permits normal controller operation.

Abstract: A vacuum operated sewerage system includes a static pressure sensor establishing a trigger signal at selected first level in a standpipe. The sensor is connected upstream of a discharge control valve and actuates a timer at the selected sensed pressure. The timer is connected to actuate the discharge control valve after a suitable time delay to prevent transient signal actuation, and establish flow for a predetermined period. An air admission valve is connected in series with the sensor to the timer to actuate the timer if the system vacuum drops below a selected level in the same manner as an increased hydrostatic pressure. The sensor can be eliminated for separate air admission control directly in response to the vacuum condition of the line.

Abstract: A vacuum-operated sewer system includes an integrated main valve and controller upstream of a collection unit for admitting sewage into the system. An in-line valve unit has a piston-cylinder operator. A vacuum-operated controller and a pilot valve unit are mounted on the operator. A pressure sensor is connected to the gravity side of the valve. A surge tank and check valve connect the vacuum side to a supply port of the controller. A water trap tank is located between the bottom end of an intake air line and the connection to the valve operator and controller assembly. A mesh fills the tank to increase the heat transfer of the moisture laden air such that the moisture condenses out in the tank. A drain system is connected to the trap tank and the operator to discharge accumulated water from the control system into the sewer system during each cycle of the valve unit.