Safety workbench with controlled circulating air flow and method for its operation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing safety workbenches face challenges in accurately measuring and controlling the volume flow of circulating air blowers, leading to inconsistencies in personal and product protection due to factors like filter loading and external exhaust system changes, resulting in potential reductions in safety and increased energy consumption.
Innovation Solution
A safety workbench design with a differential pressure sensor and two pressure transducers, one positioned near the fan blades of the circulating air blower and another in a low-flow region, allows for more accurate measurement and control of the volume flow, minimizing interference from other factors and ensuring consistent air flow within predetermined limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard differential pressure measurement is used to control circulating air blower, then the control system is simple, but the measurement precision deteriorates due to interference from static pressure changes and flow conditions
Solution Approach 1:
The pressure measurement system is segmented into two independent measurement locations: one near the fan blades and another in a low-flow region. This segmentation allows the system to capture different pressure characteristics, with the near-blade measurement providing flow-proportional data and the low-flow region providing stable reference data, thereby improving measurement precision without excessive complexity
Solution Approach 2:
The low-flow region acts as an intermediary reference point that provides a stable pressure baseline unaffected by direct fan blade interference. By using this intermediary location for comparison, the system can accurately determine volume flow proportional to differential pressure while filtering out noise from static pressure changes and flow turbulence
2Reliability
If the circulating air blower speed is increased to maintain volume flow against increasing flow resistance, then the volume flow is maintained, but the energy consumption increases
Solution Approach 1:
The control system continuously monitors the differential pressure between the two measurement locations and adjusts the circulating air blower speed accordingly. This feedback mechanism ensures that the blower operates at the minimum necessary speed to maintain the desired volume flow, preventing excessive energy consumption while maintaining reliable flow consistency
Solution Approach 2:
The system dynamically changes the blower operating parameters (speed) based on actual flow conditions detected by the pressure sensors. By adjusting the speed parameter in response to differential pressure changes, the system maintains consistent volume flow while optimizing energy consumption to match actual operational needs
3Adaptability or versatility
If separate blowers are used for air circulation and exhaust air to allow independent setting, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The air movement function is segmented into two separate blowers: one dedicated to air circulation and another to exhaust air removal. This segmentation enables independent control and optimization of each flow path, providing adaptability for different operational requirements while maintaining manageable system complexity through functional separation
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
This approach enables precise regulation of the circulating air blower, maintaining constant volume flow and enhancing personal and product protection while reducing energy consumption and extending the safe operating time of the workbench.
Implementation Method 1
a differential pressure sensor and two pressure transducers associated with this, which are designed to measure a pressure at two different positions within the safety workbench
Implementation Method 2
a circulating air blower, which conveys a partial air flow of the total air flow drawn in by the exhaust blower through a recirculation filter as downwardly directed circulating air flow into the work space
Data Source
AI summary
The present invention relates to a safety workbench having a work space surrounded by a housing having a work opening located in the housing front side and adjustable with an adjustable front panel for admitting into the work space an air inlet flow, an exhaust blower and a circulating air blower for conveying an air flow in the safety workbench, which are designed such that a partial air flow drawn in by the exhaust blower is filtered through an exhaust air filter as exhaust air flow from the safety workbench and a partial air flow drawn in by the circulating air blower through a circulating air filter as downwardly directed circulating air flow into the work space, and a control device, a differential pressure sensor (16) and two pressure transducers connected thereto which are designed to measure a pressure at two different positions within the safety workbench d, wherein a first of the pressure transducers is arranged in the immediate vicinity of the fan blades on the low pressure side of the circulating air blower and a second of the pressure transducers is arranged in a low-flow area, on the low pressure side of the circulating air blower. The present invention further relates to a method of operating a safety workbench according to any of the preceding claims, comprising the steps of: a) determining a pressure difference between the first pressure transducer and the second pressure transducer by means of the differential pressure sensor, b1) comparing the pressure difference determined in a) with a nominal pressure difference stored in the control device, which corresponds to a nominal volume flow, or b2) converting the pressure difference measured in a) into an associated volume flow and comparing the calculated volume flow with one nominal volume flow stored in the control device, and c) regulating the circulating air blower such that the nominal volume flow is conveyed.