KaoLu's Electronic Air Flow Control Valve

KaoLu's Electronic Air Flow Control Valve 

1. Overview

KaoLu's Electronic Air Flow Control Valve is actually the exact same control valve, only the OEM is different. As shown in Figure 1, this gas control valve is a needle valve driven by a stepper motor, which can convert an external control signal into a prescribed valve needle position, thereby adjusting the opening of the valve to reach gas flow control. The external control signal can be in the following three types :
(1) DC simulation voltage (0~10VDC)
(2) Interface module
(3) RS232 interface
For this gas control valve, INFICON and Pfeiffer provided matching controllers, as shown in Figure 2, the models are: INFICON: VCC500-Z; Pfeiffer: RVC 300.
This article will introduce the corresponding technical indicators for the above-mentioned control valves and controllers, and introduce the corresponding localized alternative products and their technical indicators, so as to provide cost-effective products for localized substitution.

2. Technical indicators of foreign products

2.1 Controller Technical Indicators

Operating Mode Pressure Control, Gas flow regulation
Analog Output 4 channels: vacuum pressure sensor signal, valve signal(0-10VDC), valve position, +10VDC reference voltage(10mA)
Number Output 8 channels: open valve, closed valve, valve position, valve error, sensor error, preparation, divergence, sensor condition
Analog Input 2 channels: vacuum pressure set point (standard value),flow set point (standard value)
Number Input 8 channels: flow reduction, flow addition, external closure, external open, flow mode, pressure mode, discharge open, exhausting open
Characteristic After power outage, turn on output "reach the standard value", then it can adjust tolerance
Display Unit mbar, Pa, Torr, mV
Language English, German
Communication Interface RS232C, RS485


Controller type PI automatic: it can choose control speed step 1-99
PID: Users can define parameters
Control Accuracy ±5% FS sensor
Display Accuracy ±0.2% FS sensor
Power Supply Voltage90 ~250VAC
Weight 1.65kg

From the above-mentioned controller technical indicators and practical application experience, it can be found that:
(1) Single-channel measurement and control: that is, only one vacuum gauge signal and one control valve can be collected. Although there are multiple analog and digital input and output channels, only one closed-loop control can be performed. This single channel controller will not be able to cover the wide range that requires two vacuum gauges to cover.
(2) No PID self-regulating function: Sometimes the optimal PID parameters cannot be obtained in the end, which seriously affects the control effect.
(3) Poor control accuracy: The control accuracy is ±5% of the full scale of sensor, which basically shows that acquisition and control circuit in the controller uses 12-bit A/D and D/A converters, which is the key to determining the control accuracy.

3. KaoLu’s electronic air flow control valve replaces INFICON and PFA control valves
The control valve of KaoLu's Electronic Air Flow Control Valve is a typical electronic air flow control valve driven by stepper motor. The performance indicator is very superior. The only disadvantage is that the opening of needle valve is small, thus it causes a small flow. Moreover, the price is too expensive.
In order to reach the replacement of gas flow control valve and improve the low cost high performance, KaoLu also used stepper motor in needle valve technology for localization, and developed a series of electronic air flow control valve with different flow rates.

As shown in Figure 3, fully realized it has been replaced, and the price is only one-third of foreign products. The detailed technical indicators are shown in Figure 4. Please visit https://www.genndih.com/proportional-flow-control-valve.htm

(Figure3 KaoLu’s FC electronic air flow control valve)

Model FC-20 FC-120 FC-300 FC-1000
Valve type Needle Valve
Spool Drift Diameter 0.9mm 2.25mm 2.75mm 4.10mm
Actuator Bipolar stepper motor control
Response time 0.8sec(Open to close)
Standard size G1/8” G3/8”
Fluid Inert gas and liquid
Contact Materials Stainless Steel
Pressure Range -1 ~ 7bar -1 ~ 5bar
Maximum Flow 50L/min @7bar 240L/min @7bar 290L/min @7bar 600L/min @7bar
Linearity ±2% ±0.1 ~ 1% ±0.2 ~ 5% ±11%
(Full scale)
Flow Resolution (Step length) 0.1L/min 0.1 ~ 0.2L/min 0.2 ~ 0.75L/min 1L/min
Shift Resolution (Step length) 12.7um 25.4um
Operating Temperature Range 0 ~ 84ºc
Seal Standard FKM or other choices of seals
Control Signal DC: 0 ~ 10V (or 4 ~ 20mA)
Power Supply DC: 24V (12W)
(Figure4 Technical indicators of KaoLu’s FC electronic air flow control valve)

3. Localized high-precision dual-channel PID controller replaces INFICON and PFA controllers
In order to use the measurement accuracy of vacuum gauges fully (such as capacitive film pressure gauges), at least 16-bit analog-to-digital and digital-to-analog converters are required for data acquisition and control of controller. In recent years, KaoLu have developed the FC series of high-precision 24-bit general-purpose PID controllers, as shown in Figure 5. This series of PID controllers is far more powerful than foreign products, but the price is only one-eighth of foreign products. Its main performance indicators are as follows:
(1) Precision: 24-bit A/D, 16-bit D/A.
(2) Multi-channel: independent 1-channel or 2-channel. 2 channels can realize the simultaneous measurement and control of temperature and pressure.
(3) A variety of output parameters: 47 kinds of input signals (thermocouple, thermal resistance, DC voltage) can reach simultaneous test, display and control of different parameters.
(4) Multi-function: forward, reverse, forward and reverse two-way control.
(5) PID control: The improved PID algorithm supports PV differential and differential advance control. There are 20 groups of PIDs.
(6) Dual sensor switching: Each channel can support dual sensor switching of high and low temperature and high and low vacuum. Two channels can form a control combination with a total of four sensors connected.
(7) Program control: You can create and store up to 20 condensation programs by yourself, and you only need to select and call to start condensation (program control mode).

In the vacuum degree control, downstream control mode is more suitable for vacuum degree close to atmospheric pressure, but upstream air intake control mode is required for vacuum degree control of less than 10mbar. Therefore, in order to satisfy the full control degree of vacuum, the dual sensor and two-way control mode as shown in Figure 6 can be used.
In the control mode shown in Figure 6, it is necessary to use the forward and reverse control and dual sensor automatic switching functions of the above FC-20 series dual-channel controller, that is, during different air pressure control processes; the controller automatically switches the corresponding range. Vacuum gauge, and select the corresponding electronic air flow control valve for control.