Abstract: A lid for an underdrain block that has a top surface defining an opening for receiving fill material. The top surface forms a ridge circumscribing the opening, the lid comprising a top, a bottom and a peripheral edge, the peripheral edge comprising a rim adapted to interlock with the ridge. The ridge of the underdrain block can have a flange perpendicular to the top surface and the rim on the lid is adapted to tightly fit over the flange so that the rim interlocks with the flange. Alternatively, the underdrain block for a filter system comprises a hollow plastic housing comprising a top wall that defines an opening for receiving the fill material. The top wall forms a ridge surrounding the opening and the lid seals the opening in the top wall. The lid comprises a peripheral edge that forms a u-shaped rim. The u-shaped rim has a locking means to tightly fit over the ridge so that the rim interlocks with the ridge so as to seal the opening.

Abstract: An electrolytic cell includes at least a first and a second, generally planar, membrane-supporting frame each having a plurality of through-holes. Each is sealed to a plurality of annular coupling members located between the frames and generally aligned with a respective through-hole of each frame to thereby define a plurality of sealed conduits through the frames. Each coupling member is attached in a sealed relationship to the first frame by a number of bolts passing through oversized holes in the first frame so as to be capable of movement parallel to the plane of the first frame during assembly of the cell and is sealed to the second frame at a cylindrical interface which provides sealing at a range of distances between the first and second frames. This construction reduces the manufacturing tolerances required for the cell components.

Abstract: A filter media support system that reduces media clogging and head loss in granular filtration systems by providing a layered porous plate. The porous plate can have multiple layers of fine sized and coarse sized pores. The porous plate is positioned between the media and the filter bottom. The filter media support system is securely anchored to the infrastructure of the underdrain system thereby inhibiting media penetration of the filter bottom and avoiding seal failures. The infrastructure can be air lateral piping fitted beneath the underdrain blocks of the support system. The anchors can be secured to pipe clamps circumscribing the air laterals.

Abstract: An electrolyte cell includes a membrane (114) supporting frame (104) which having an aperture (180) having a stepped sidewall, including a peripheral sealing ledge (182) in which is set a seal (184), a membrane (114) whose periphery is urged against the seal (114) by a subframe (202) mounted in the aperture (180), the sub-frame (202) being provided with vertically extending stand-offs (218) at each corner so as to define a cavity partially bounded by the frame (104) and sub-frame (202) at the top of bottom of the aperture (180), the top and bottom edges of the sub-frame (202) being provided with a plurality of through-holes (216).

Abstract: A method for retrofitting a gravity filter with a porous plate filter media support that increase filter production by increasing the depth of the media, allows installation of an air backwash system in filters having a monolithic underdrain system, and reduces turbulence and head loss in granular filtration systems. The method comprising removal of existing media and gravel media-support bed and installation of a porous plate media support. The porous plate can have multiple layers of fine sized and coarse sized pores. The porous plate is positioned between the media and the filter bottom and is securely anchored to the monolithic underdrain system thereby allowing uniform distribution of backwash, inhibiting media penetration of the filter bottom and avoiding seal failures.

Abstract: A countertorque arm assembly mounts onto a pressure cylinder valve body for cradling an actuator that operates to rotate the valve stem in response to a sensed condition.

Abstract: In an amperimetric measurement apparatus comprising an amperimetric cell having a pair of electrodes arranged for contact with a solution, a potential difference is established between the electrodes, and a corresponding electric current is conducted in a forward direction through a current path which includes the electrodes and the solution. An output corresponding to the current indicates the concentration of a solute in the solution. The electrical charge passing through said cell in response to said potential difference is monitored by an integrator. The forward current is interrupted repeatedly and a reverse electric current is imposed on the cell during the interruptions of forward current. The magnitude and duration of the reverse current are regulated in response to the electrical charge flow corresponding to the forward current, so that the net flow of charge through the cell over a time period including an equal number of intervals of forward and reverse current intervals is substantially zero.

Abstract: A liquefied gas, such as liquefied chlorine, which is injected into a liquid stream such as an aqueous stream, in the liquid state, is prevented from causing the liquid stream to freeze by cooling the liquefied gas to a temperature below its boiling point at the pressure of the liquid stream.

Abstract: Apparatus particularly suited for use in mixing ammonia gas with hard water is disclosed. The apparatus includes an ejector assembly having a throat with a flexible tubular liner which is periodically flexed inwardly to loosen any solid matter which may have formed on the inside of the liner. The liner is flexed by a three-way valve connected to the water supply line and controlled by timers and a pressure switch. If desired, a similarly-lined tubular extension may be mounted downstream of the throat and flexed periodically to loosen any matter deposited therein. An orifice may be mounted in a diaphragm upstream of the throat to move in response to liner flexure for limiting solid matter accumulation adjacent the throat inlet.

Abstract: A gas sensing apparatus is adapted to detect the presence of a gas of interest in air in very small quantities and to provide a rapid alarm or other indication in response to the presence of such gas. The apparatus incorporates a gas sensing composition which changes its electrical resistance more dramatically than previously possible in response to the presence of the gas and electronic circuitry designed to sense and evaluate the patterns of resistance change during the first approximately 30 seconds after exposure to gas and to accurately estimate gas concentration based on such initial resistance variations. The system also looks at overall change in sensor resistance to detect gradually increasing gas levels. A preferred method of manufacturing the sensor and a sensor configuration particularly suited to the early detection of gas levels are disclosed.

Abstract: Apparatus for use in contacting a gas with a liquid comprises a pair of ported injector pipes onto which elastic sleeves having a series of slits therein are mounted by means of axially-spaced bands. The elastic sleeves expand as gas flows from the pipe to open the slits for discharging the gas into the liquid. The apparatus functions to maintain a desired gas flow rate irrespective of the accumulation of gas-liquid reaction products tending to block the slits.