A Pressure reservoir could be set to contain overpressure or vacuum. A valve would then be the required precise tool letting the vacuum or overpressure gain access to the test tubing. Two 2/2 valves or one 3/2 valve would be used to apply vacuum or overpressure to the test tubing.
The general work process of such a device would consist of:
1) The pump(s) building up pressure/vacuum. A pressure sensor would be used for loop control.
2) Once pressure is at desired level the valve(s) can be activated.
3) Valve(s) would be activated and would release the pressure/vacuum to push/suck liquid in/out of the test tubing.
Benfits of this approach:
- The pump(s) would only work sporadically, resulting in:
- lower energy consumption,
- no constant noise,
- no „on-demand-high-precision“ pump action,
- higher overall pump life expectation.
- Pressure/vacuum reservoir: The size of the reservoir can handle multiple „analysis runs“ with high repeatability
- More technical effort is required (pressure reservoir, sensors, valve for closed loop operation)