Dry Pilot Actuator Spring-Biased Seal for Low Gas Pressure
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Solution Overview
Problem
Existing dry-pilot actuators for fire protection systems require high sealing gas pressures to maintain a sealed condition, which is undesirable and may not be suitable for residential applications, and there is a need for a mechanically operated alternative to diaphragm-type dry-pilot actuators.
Innovation Solution
A mechanically operated dry pilot actuator with a housing and internal chamber design that includes a sealing member biased by a spring member, allowing for a high liquid to sealing/trip gas operating ratio greater than six, and a configuration that is normally biased open, providing an alternate option to diaphragm-type actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diaphragm-type dry pilot actuators are used, then fluid control valve actuation is achieved, but high sealing gas pressures (above 20 psi) are required which are undesirable for residential applications
Solution Approach 1:
The actuator is divided into separate functional components: a pilot valve assembly with sealing member, a main valve assembly, and a diaphragm chamber. The pilot valve controls fluid pressure to the diaphragm chamber, creating a differential pressure system that amplifies the effect of low sealing gas pressure on the main valve diaphragm, enabling reliable sealing at residential gas pressures of 0-14 psi
Solution Approach 2:
A pilot valve acts as an intermediary device between the sealing gas source and the main fluid control valve. The pilot valve uses a small amount of sealing gas to control a larger fluid pressure through the diaphragm chamber, thereby reducing the required sealing gas pressure while maintaining reliable valve sealing through differential pressure amplification
2Adaptability or versatility
If mechanically operated actuators are used, then alternative to diaphragm-type actuators is provided, but complex internal chamber design with multiple ports and sealing members is required
Solution Approach 1:
The actuator design integrates multiple functions into a single compact unit: the pilot valve assembly handles both sealing and actuation functions, the diaphragm chamber serves as both a pressure control mechanism and a mechanical amplification device, and the main valve assembly provides both flow control and mechanical operation. This multi-functionality reduces the need for separate components while achieving versatile operation
Solution Approach 2:
The pilot valve assembly is nested within the main valve body, with the sealing member positioned inside the internal chamber. The diaphragm chamber is integrated into the valve structure, creating a compact nested arrangement where smaller components are housed within larger structures, reducing overall complexity while maintaining functional independence of each subsystem
3Stress or pressure
If high liquid to gas operating ratio greater than six is achieved, then lower gas pressures are sufficient, but precise port isolation and sealing member positioning are required
Solution Approach 1:
A flexible diaphragm is used as a sealing film that can deflect to isolate ports and control fluid flow. The diaphragm's flexibility allows it to maintain sealing under differential pressure while accommodating manufacturing tolerances, achieving port isolation without requiring extremely precise rigid component positioning. The diaphragm acts as a compliant sealing element that compensates for minor dimensional variations
Solution Approach 2:
The sealing function is extracted from rigid mechanical components and assigned to the flexible diaphragm and pilot valve sealing members. This separation allows the rigid structural components to focus on providing structural support and flow paths, while the sealing function is handled by compliant elements that are less sensitive to manufacturing precision requirements, enabling higher pressure ratios with standard manufacturing tolerances
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables the dry pilot actuator to maintain a sealed state at lower gas pressures while allowing fluid flow at higher liquid pressures, suitable for residential fire protection systems with PVC piping and gas pressures up to 14 psi, enhancing the reliability and efficiency of dry pipe fire protection systems.
Implementation Method 1
at least one spring member disposed between the interior surface of the housing and the seal member to bias the seal member toward the open position
Implementation Method 2
gas pressure is used to regulate the position of the internal diaphragm of the pilot actuator to regulate the flow of fluid out of the diaphragm chamber of the fluid control valve
Implementation Method 3
maintain a sealed state at lower gas pressures while allowing fluid flow at higher liquid pressures
Data Source
AI summary
A dry pilot actuator provides for a high liquid to gas trip ratio. The actuator includes a housing having an interior surface defining an internal chamber with a central axis. The valve further includes a first inlet port; a second pilot port and a third drain port, each in communication with the internal chamber. A first actuator seat is disposed along the interior surface of the housing circumscribed about the central axis and a second actuator seat is circumscribed about the first actuator seat. A seal member having a sealed position and an open position is substantially aligned with the central axis of the housing in each of the sealed and open positions. The third port is isolated from the first and second port when the sealing member is in the sealed position, and in fluid communication with the first port when the sealing member is in the open position. The second port is isolated from the first and third ports when the sealing member is in the actuated position. A spring member biases the seal member toward the open position.