Model NK33EX-90 Explosion-Proof Thermal Mass Flow Switch Instruction for Use

Product use 

Model NK33EX-90 explosion-proof flow switch can be widely used for flow measurement and control of flammable and combustible places for petroleum,chemical industry, electric power, metallurgy industries etc.

Characteristics

• No movable mechanical part, corrosion-resistant, stable & reliable, long life, no special maintenance for long-term operation;

• Integrated design of detection probe and signal processing circuit, to make the installation & use be convenient;

• Built-in temperature compensation circuit, to minimize the deviation of fluid flow caused by the medium and ambient temperature;

• Optimized new type of circuit, to make DC 24V±15% current ≤100 mA, with little circuit heating, components surface mounting, to improve the reliability;

• Exd II BT6 explosion-proof shell, used in dangerous places in zone 1 or 2 containing Grade IIA & IIB explosive gas or steam.

Parameters:

• Power source: DC24V±15%/100 mA.
• Medium temperature: -45~ 80 ℃
• Relative humidity: 5%~ 95%
• Nominal pressure: 0~ 10 Mpa
• Gas flow rate: DN150: 0.2~ 3.0 m/S (3.53 L-53 L/s)

• Protection grade: IP65
• Explosion proof grade: ExdⅡCT6
• Explosion proof certificate no.: CNEx19.1466X

电压 Voltage

流速 Flow rate

图四：流量开关水中流速与对应电压曲线图

Fig. 4: Flow Rate of Flow Switch in Water ~ Voltage Curve

1. Instrument debugging

Switch on 24V power source and carry out the instrument debugging after 3 minutes. “Com” refers to the common test point, “TP” the test point corresponding to the fluid (flow) and circuit voltage;

“W” potentiometer for threshold voltage regulation; “HZ” test point for voltage regulation of W potentiometer; “VC” power supply indication, and; “VH” relay action indication.

Fig. 4 shows the curve of measuring flow rate of this flow switch in tap water under 20℃ temperature VS TP1 voltage and can be used for reference when setting potentiometer is regulated by the flow switch.

Determine the set value for flow switch action (digital multimeter is required): divide the sum of voltage corresponding to com and TP at low speed of fluid and voltage corresponding to com and TP at high

图 四：流量开关水 中 流速与对应 电压 曲 线 图 流速 cm/s

V ：压电speed by 2, i.e. threshold voltage of TP relay (through regulating W).

Set value of flow switch action: after determining the set value of flow switch action, regulate potentiometer (W) to make the voltage between com and ZH be equal to such value.

图一、流量开关安装示意图

Fig. 1: Installation Instruction for Flow Switch

上盖锁丝 Lock screw of upper cover

电缆锁紧螺丝 Lock screw of cable

上盖 Upper cover

防爆壳体 Explosion-proof shell

六棱锁丝 Hexagonal lock screw

焊接短接 Welded shorting

橡胶圈 Rubber ring

压紧螺帽 Gland nut传感器 Sensor

焊接 Weld

DN10-25 流体管线 DN10-25 fluid pipeline