负压输送

Via pressure blowing or vacuum suction, pneumatic conveying systems can be divided as pressure system and vacuum system.

Vacuum system is more common for lower conveying capacity and shorter conveying distance as the pressure drop has a limitation normally up to 0.5bar, and almost no way to go to 1 bar.

Vacuum systems normally employ simple and cheaper pick up nozzles / wands instead of expensive rotary valve. However a rotary valve may be need in case of poor flowing product or higher conveying capacity.

通过压缩空气吹送还是负压抽吸，气力输送系统可以区分为正压输送和负压输送。

负压输送系统更适合于小能力、短距离输送场合，因为可获取的负压压头一般不超过-0.5barg，很难接近绝对真空。

负压输送一般取料只需采用简单廉价的负压吸咀而无须气锁。但在较高输送能力或物料不易流动的场合，取料点旋转阀仍有可能必须。

Compass provides modular vaccum receivers via vacuum pump (series Loader P) or venturi vacuum generator (series Load V, client to provide compressed air) and vacuum sequencing system, either in dilute phase conveying technology or dense phase conveying technology denpending on the actual industrial application.

康柏斯提供模块化的负压上料器、通过真空泵输送（P系列真空上料器）、或自带文丘里真空发生器（V系列真空上料器、需要客户提供压缩空气通过真空发生器产生真空源），以及负压集中输送系统，可以采用稀相输送技术，也可以采用密相输送技术，取决于具体实际应用。

Advantages 负压输送的优势

• At the source: 在起点处

• Less cost (normally no Aerolock) 通常不需要旋转阀，投资低

• Lower head height 高度更低

• Easier for multiple sources (just need diverter valve or hose switch) 适合多个输送起点取料

• Avoids dust at the source 输送起点没有粉尘

• Prevents dust leakage 避免对外粉尘泄露（因为负压对系统内吸气）

• Uses cool, ambient conveying air 直接采用自然较冷的环境空气输送、不会加热物料

Disadvantages 负压输送的劣势

• At the destination: 在终点处

• More cost (the receiver must withstand high vacuum) 终点接收器需要承受较高负压，意味着成本更高

• A destination Aerolock is prone to wear 终点处如采用旋转阀连续输送，也会产生磨损

• Vacuum blower’s exhaust adds heat and noise to the room 负压风机排气可能会增加房间内的噪音和温度

• Vacuum is less efficient; line sizes are bigger 负压输送效率相对更低，需要更大的输送管径

• The blower is bigger (more cost) because it has a higher inlet air flow than a pressure blower 输送负压风机会更大，因而成本与能耗更高