PROPORTION-AIR: Control Technology of Electric Proportional Valve in Flow System of Flow Cytometer

Flow cytometry is a kind of automatic medical instrument based on the principle of flow cytometry for quantitative and qualitative analysis and separation of single cells and particles. Flow system as the basic system of flow cytometer,The sample fluid containing the fluorescently stained cells or microparticles is injected into the flow cell at a certain pressure ratio with the sheath fluid as a buffer.,The flow focusing principle is used to make cells or micro-particles pass through the detection area of the flow chamber in sequence in a laminar flow state.Controlling the stable ratio of the inlet pressure of the sample liquid and the sheath liquid is the prerequisite for the formation of laminar flow in the micro-flow chamber and the guarantee of subsequent signal detection.,It is also one of the core technologies of the whole instrument.

Single Loop Control Schematic of Fluid Flow System

The flow system of the flow cytometer mainly controls the power source such as air pressure and vacuum pressure supply through the control valve body.,Functional implementation is based on a valid and relatively accurate system model.,The problem of safety and speed of pressure supply is solved. But the flow system is a time-varying, time-lag, nonlinear system.,Moreover, the high-speed pressure supply of the air source has random interference on the liquid flow system.,Feedback adjustment parameter acquisition lag,It takes a long time to reach stability,It is difficult to establish an accurate and dynamic mathematical model.

Current solutions focus on the research and development of high-performance electrical proportional valves,Introducing Feedback in Control Systems,Establish pressure closed loop,Laminar flow control system and control method for real-time adjustment and stable pressure output.

United StatesPROPORTION-AIRThe company is a world-famous and professional high-precision electric-Gas proportional control comprehensive solution provider.

PROPORTION-AIR Ultra-high resolution closed-loop voltage controlQpv & MPVSeries of products, including2A built-in solenoid valve,1 Pressure sensors, electronic control circuits, etc..The improved electronic circuit inside the air inlet has1A precise proportional valve that eliminates electronic steps, noise, and wear between the valve and the device. At the same time, it also overcomes the problems left over in the traditional technology of liquid flow system, such as being affected by external shock and vibration, no closed loop ability, output pressure changing with input pressure, no feedback, etc.

In a nutshellQpv & MPVThe series of products provide the most convenient operation function for users, solve the problems inherent in the traditional technology of the liquid flow system, and meet the needs of the application to the greatest extent.




















Qpv & MPVWorking principle                      Qpv & MPVTechnical parameters

Electronic parameters

Power supply voltage

15 - 24VDC

Input command




0 - 10V

4 - 20mA

Analog monitoring input




0 - 10V

4 - 20mA

Pneumatic parameters

Intake pressure


Output pressure



0 - 28.2L/min

This seriesQPV1andMPV1Products, a complete closed-loop control

Valves, incl.2 solenoid valves, 1 base, 1 integral pressure transmission

sensor and1 electronic control circuit. Two valves respectively control the intake,

To take it out. Control of intake valve and pressure signal supplied by electronic circuit


Built-in pressure sensor measures output pressure and provides feedback

to the control circuit. The feedback signal is compared with the input command when two

At the same time, one of the valves is opened. If you want to reach

The pressure required by the system will cause the intake valve to act and eliminate proportionally.

differences in the signal.

Ultra-high resolution dual sensorQPV2/MPV2 also has fine

Pneumatic control, which can be obtained from the second pressure sensor downstream.

signal and compared with the input signal. If the downstream sensor output is low

At the input command, the intake valve opens proportionally to eliminate the signal and the required pressure.

The force difference. enables the user to not only monitor the main control from the downstream

The signal can also enable the pressure to reach the value.

Qpv & MPVTraditional with flow cytometryI/P Converter Comparison

TraditionI/P Converter

Qpv & MPV

Traditional I/P Converter

Qpv & MPV

1. Open-loop products, diaphragm, spring, coil structure, low linearity;

1. Closed-loop control, built-in PID circuit, pressure sensor, solenoid valve, high precision/linearity;

2. The output pressure range is limited and the resolution is low;

2, the output pressure range can be arbitrarily calibrated, high resolution;

3. The air source needs to be regulated in advance, otherwise the output pressure will be affected by the pressure fluctuation of the air source;

3. The air source does not need to be regulated in advance, and the output pressure is not affected by the fluctuation of the air source;

4. Affected by shock and vibration;

4. Not affected by shock and vibration;

5, no built-in pressure sensor analog pressure signal output, can not effectively monitor and control processing.

5. Built-in pressure sensor, can output analog pressure signal, real-time monitoring and control processing.





Tianjin Liankesi Technology Development Co., Ltd.It's the United StatesPROPORTION-AIR's authorized agent in China is responsible for the sales, technical support and pre-sales and after-sales services of PROPORTION-AIR products in China. PROPORTION-AIR's electrical proportional valves, electrical servo valves, electrical converters, electrical proportional flow valves, electrical flow control systems, flow sensors, pressure sensors and other professional high-precision electrical proportional control products have been widely used in flow cytometry, Tire rubber, low-pressure casting, plastics and pipes, semiconductor equipment, spraying equipment, textile machinery and other industries.

Our company is a high-tech enterprise recognized by Tianjin municipal governmentIt has a professional R & D team and has obtained several national intellectual property certificates, and can provide integrated services of design, R & D, production and sales according to customer requirements. Over the years, adhering to the "quality-oriented, technology first, service leading" business philosophy, and has been determined to continue to innovate, improve the management system, and constantly enhance the competitiveness of products. Welcome friends from all walks of life to contact and cooperate to discuss!

Sales Hotline:15822721002 (Manager Zhang)

18698032466 (Manager Li)

Electronic E-mail:rosezhang@linkstrong-tech.com




Electrical, pressure, control, output, system, signal, flow, qpv & mpv, pressure sensor