红油压差表是一种用于测量正负压差的仪表，广泛应用于药厂、电子厂洁净厂房和暖通空调过滤网等场所。其工作原理基于液体内部压强公式P=ρgh，通过两个不同压力产生的液柱高度来显示压差。该仪表具有超低量程、廉价、结构牢固的特点，并且可以固定安装在任何垂直表面上。

       Red oil pressure difference meter is a kind of instrument for measuring positive and negative pressure difference, widely used in pharmaceutical factory, electronic factory clean workshop and HVAC filter screen and other places. The principle is based on the internal pressure formula p = ρ g h, which shows the pressure difference by the height of the liquid column produced by two different pressures. The instrument has the characteristics of ultra-low range, low cost, strong structure, and can be fixed on any vertical surface.