Rotational viscometer

Japanese: 回転粘度計 - かいてんねんどけい（英語表記）rotational viscometer

A viscometer that uses the rotational method to measure the viscosity of a liquid. When a liquid is placed between two concentric cylinders, the inner cylinder is suspended by a spring, and the outer cylinder is rotated at a constant angular velocity, a couple is generated by the viscosity of the liquid, which causes the inner cylinder to rotate, but the spring balances it out with a constant torsion. The viscometer developed by Searle and Stoma measures the viscosity from the torsion angle. The Eimer-Ammend viscometer measures the viscosity by hanging a disk on a wire in a cylindrical container filled with liquid, rotating the cylinder, and measuring the couple (the twist of the wire) acting on the disk. There is also the Vogel viscometer, which applies rotational vibration to a disk suspended in the liquid and measures the viscosity from the damping rate. The viscosity of a gas can also be measured by rotating the lower disk of two horizontally spaced disks, which are also a type of rotational viscometer. There are many other viscometers that utilize the state of liquid flow in a thin tube.

Source: Encyclopaedia Britannica Concise Encyclopedia About Encyclopaedia Britannica Concise Encyclopedia Information

Japanese:

液体の粘性率を回転法で求める計器。2個の同心円筒の間に液体を入れ，内円筒をばねでつるし，外円筒を一定角速度で回転すると，液の粘性により内円筒もついて回る偶力を生じるが，ばねのため一定のねじれで釣合う。そのねじれ角から粘性率を求めるのがサール，ストーマらの粘度計。液を入れた円筒容器に円板を針金でつるし，円筒を回転させて円板にかかる偶力 (針金のねじれ) 測定によるのがアイマー・アメンド粘度計。また液中につるした円板に回転振動を与え，その減衰率から粘性率を求めるフォーゲル粘度計などがある。気体の粘性率も，水平に一定間隔にある2枚の円板の，下方を回転して上方円板にかかる偶力から測定する方法があり，これも一種の回転粘度計である。なお粘度計には，このほかに細管内の液流の状態を利用する非常に多くの計器が考案されている。

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