进口先导式电磁阀（Pilot solenoid valve）适用范围于以蒸汽为加热介质，进行温度自动控制的执行机构。可对蒸汽加热器、散热器、干燥器等蒸汽设备及各类温度自控仪、蒸汽定型机、蒸染机、蒸汽回潮机等成套设备的锅炉蒸汽管道进行二位式自动控制和远程控制区。广泛应用于染化、纺织、印染、食品、医药、卷烟、水泥制品、石油化工、冶金等部门的自控系统。
进口先导式电磁阀主要特点
耐热：电磁部分、密封件部分用特种耐调温电工材料和密封材料，并应用了各种隔热措施。
耐磨：选材合理，阀杯和导向套间巧妙地利用流体的润滑作用，减少磨损
耐冷凝：蒸汽管道的冷凝水是影响蒸汽电磁阀动作的重要因素，本阀则不受冷凝水影响。
，Pilot solenoid valve，通电时，依靠电磁力提起阀杆，导阀口打开，此时电磁阀上腔通过先导孔卸压，在主阀芯周围形成上低下高的压差，在压力差的作用下，流体压力推动主阀芯向上移动将主阀口打开；断电时，在弹簧力和主阀芯重力的作用下，阀杆复位，电磁阀上腔压力升高，流体压力推动主阀芯向下移动，主阀口关闭。
德国托克（TOK）品牌：应用范围：
它广泛应用于航天、船舶重工、化工、锅炉、采暖设备、干燥设备、食品医疗设备、清洗设备、等加温管道系统中。
产品特点：
阀芯均为不锈钢材料、活塞式结构，活塞环用特殊耐温、耐磨材料制作；活塞与金属阀腔不产生直接摩擦，阀体安装方向无限制；特制线圈，不易烧毁；长时间停止动作重新启动，动作同样灵敏。
主要技术参数：

工作原理：
常闭：当线圈通电时，先导阀芯吸合，先导孔打开，阀上腔卸压，活塞靠下腔介质压力推动，电磁阀打开；当线圈断电时，先导阀芯靠弹簧复位，先导孔关闭，阀上腔由活塞节流孔增压和复位弹簧的推力，电磁阀关闭。
常开：当线圈通电时，先导孔关闭，阀上腔由活塞节流孔增压和复位弹簧的推力，电磁阀关闭。当线圈断电时，先导阀芯靠弹簧复位，先导孔打开，阀上腔卸压，活塞靠下腔介质压力推动，电磁阀打开。
规格尺寸：

注：出口端压力大于进口端压力，介质会反向导通。可安装止回阀或订制自带止回功能的阀。
Applications: 
It is widely used in aerospace, shipbuilding Heavy Industry, chemical industry, boiler, heating equipment, drying equipment, food and medical equipment, cleaning equipment, such as heating pipe system.
Features: 
Are all stainless steel valve, piston structure, piston ring with a special temperature, wear-resistant material; piston valve chamber with the metal does not have a direct friction, the valve mounting direction unlimited; special coil, not easy to burn; a long time to stop action Restart the action as sensitive.
Main technical parameters:

How it works: 
NC: When the coil is energized, the pilot spool pull the pilot hole to open, pressure relief valve on the chamber, the piston on the lower chamber medium pressure to promote, the electromagnetic valve is opened; When the coil power, the pilot valve by the spring return, pilot hole closed, the valve chamber and pressurized by the piston return spring throttle thrust, the electromagnetic valve is closed. 
Normally Open: When the coil is energized, the pilot hole closed, the valve chamber and pressurized by the piston return spring throttle thrust, the electromagnetic valve is closed. When the coil power, the pilot valve by the spring return, pilot hole open, pressure relief valve on the chamber, medium pressure piston push the lower chamber, the electromagnetic valve is opened.
Size:

Note: The outlet pressure is greater than the inlet pressure, the media will pass anti-wizard.Can be installed or custom built non-return valve function of the valve