液位傳感第2部分：光學(xué)、重力和聲波技術(shù)

　　在上一篇關(guān)于液位傳感的文章中，我們討論了可以通過機(jī)電開關(guān)、霍爾效應(yīng)開關(guān)、電阻分壓器傳感和基于電容定時(shí)的傳感技術(shù)和方法來檢測液位和限制的技術(shù)和產(chǎn)品。

　　本文探討通過光學(xué)，重力和聲波技術(shù)的液位檢測。

　　分離步驟檢測

　　雖然電阻和電容技術(shù)是有效的，易于實(shí)現(xiàn)，但它們不是檢測揮發(fā)性和有毒液體的最佳選擇。在這里，你想消除任何暴露在電，甚至潛在的電弧，可以爆炸點(diǎn)燃液體。

　　與第1部分中描述的離散步驟傳感器技術(shù)類似，隔離步驟檢測，而不是使用單獨(dú)安裝的機(jī)電開關(guān)，使用在所需光波長上為透明或半透明的單個(gè)垂直柱。

　　Several optical-slot-type sensors can be employed. For industrial designers， well- engineered off-the-shelf solutions such as the Omron EE-SPX613 should be considered. This is a sealed and self-contained optical slot sensor that can use 6 to 13-mm tube diameters with a wall thickness up to 1 mm.

　　These 12 to 24-V parts are more than just emitters and detectors. They contain a bit of intelligence. The sensitivity is adjustable， and there is a mode select option as well. There is also a built-in amplifier with an open collector 100-mA npn transistor output capable of driving a load relay directly （Figure 1）.