Bidirectional Pressure Relief Valve for Medical Fluid Reservoirs
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Solution Overview
Problem
Medical fluid reservoirs often experience pressure differentials between ambient air and the interior that exceed intended levels, leading to undesirable consequences such as damage to the system and potential harm to patients, as existing technologies fail to effectively manage both positive and negative pressure differentials.
Innovation Solution
A pressure differential relief valve comprising a valve body, a resilient member, and a movable element, which allows fluid communication between exterior and interior spaces through gas passageways, moving to relieve pressure differentials by adjusting its position in response to atmospheric pressure differences, thereby preventing damage and ensuring safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a pressure relief valve is designed to relieve only positive pressure differentials, then it can maintain simple structure, but it cannot protect the system from negative pressure differentials
Solution Approach 1:
The relief valve is designed with a movable element that can respond to both positive and negative pressure differentials, enabling a single device to perform multiple protective functions. The valve body includes first and second gas passageways that allow the movable element to be actuated by pressure changes in either direction, providing universal pressure relief capability without requiring separate valves for positive and negative pressure scenarios.
Solution Approach 2:
The valve design incorporates bidirectional pressure sensing capability by positioning the movable element to respond to pressure differentials from both directions. The first gas passageway allows atmospheric pressure to act on one side of the movable element while the second gas passageway allows atmospheric pressure to act on the other side, creating a dimensionally symmetric response to both positive and negative pressure differentials.
2Reliability
If the relief valve activates at low pressure differential levels, then it provides early protection, but it may activate unnecessarily due to normal system pressure variations
Solution Approach 1:
The activation threshold of the relief valve can be adjusted by changing the weight of the movable element or the spring constant of the resilient member. This allows the pressure differential threshold to be optimized based on system requirements, ensuring activation only when truly necessary while providing early warning before dangerous pressure levels are reached. The design enables parameter tuning to distinguish between normal variations and hazardous conditions.
3Reliability
If the valve body is designed with long gas passageways, then it provides adequate pressure equalization, but it increases the overall valve length and complexity
Solution Approach 1:
The gas passageway is divided into two separate passageways (first and second gas passageways) that can be positioned adjacently or in parallel within the valve body. This segmentation allows for efficient pressure equalization through multiple simultaneous flow paths while maintaining a compact overall valve length. The segmented design provides adequate pressure equalization without requiring excessively long single passageways.
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 effectively relieves both positive and negative pressure differentials, preventing system damage and patient harm, is cost-effective for one-time-use medical applications, and allows for adjustable activation levels, ensuring safe and reliable operation of medical fluid systems.
Implementation Method 1
a resilient member (230)... When the movable element is in the second end position, the first exterior region and the second exterior region are in fluid flow communication through at least the second gas passageway, and the movable element has deflected the resilient member
Data Source
AI summary
Devices and methods for enhancing the operations of fluid systems are provided. For example, this document provides pressure differential relief valves that are well suited for use with medical fluid reservoirs. The pressure differential relief valves provided herein are described in the context of a medical fluid system, such as an extracorporeal blood flow circuit, but the devices and methods provided herein can be implemented in other types of fluid systems including, but not limited to, pneumatic systems, hydraulic systems, fluid power systems, petroleum systems, and various other types of gaseous or liquid-based fluid systems.