Abstract: A dual air vent assembly for wet pipe fire protection sprinkler systems allows air or gas to vent from system pipes as they fill, without spilling any water into the fire-protected environment, even if an air vent valve, operative to discharge air or gas but not fluid, fails. A shut-off valve is upstream of the first air vent valve, and a reservoir is downstream of it. Small amounts of water that escape the first air vent valve are collected in the downstream reservoir, and evaporate. The reservoir also collects fluid if the first air vent valve fails. In response to fluid in the reservoir at or above a predetermined level, the shut-off valve is actuated to arrest the flow of fluid into the first air vent valve. No water escapes the assembly, even if the first air vent valve fails. The shut-off valve may be electronically or mechanically actuated.

Abstract: A dual air vent assembly for wet pipe fire protection sprinkler systems allows air or gas to vent from system pipes as they fill, without spilling any water into the fire-protected environment, even if an air vent valve, operative to discharge air or gas but not fluid, fails. A shut-off valve is upstream of the first air vent valve, and a reservoir is downstream of it. Small amounts of water that escape the first air vent valve are collected in the downstream reservoir, and evaporate. The reservoir also collects fluid if the first air vent valve fails. In response to fluid in the reservoir at or above a predetermined level, the shut-off valve is actuated to arrest the flow of fluid into the first air vent valve. No water escapes the assembly, even if the first air vent valve fails. The shut-off valve may be electronically or mechanically actuated.

Abstract: Techniques are disclosed for canceling an offset component (e.g., dc component or dc offset) in an amplifier circuit. For example, an apparatus comprises an amplifier circuit with an amplifier element and a feedback resistor network coupled between an output of the amplifier element and an input of the amplifier element. The apparatus also comprises a current source coupled to the feedback resistor network, the current source generating a current signal that generates a voltage in a first portion of the feedback resistor network that cancels an offset component present in an input signal received by the amplifier circuit. A second portion of the feedback resistor network may be adjustable so that a gain applied to the input signal is adjustable while the offset component is canceled from the input signal. One or more resistors in the feedback resistor network may be composed of the same or substantially similar material as one or more resistors associated with the current source.

Abstract: Techniques are disclosed for canceling an offset component (e.g., dc component or dc offset) in an amplifier circuit. For example, an apparatus comprises an amplifier circuit with an amplifier element and a feedback resistor network coupled between an output of the amplifier element and an input of the amplifier element. The apparatus also comprises a current source coupled to the feedback resistor network, the current source generating a current signal that generates a voltage in a first portion of the feedback resistor network that cancels an offset component present in an input signal received by the amplifier circuit. A second portion of the feedback resistor network may be adjustable so that a gain applied to the input signal is adjustable while the offset component is canceled from the input signal. One or more resistors in the feedback resistor network may be composed of the same or substantially similar material as one or more resistors associated with the current source.