Description of the M-68 hygrometer:

M-68 hygrometers (hair, in a round metal frame) have been used and are still used in domestic practice for a long time

M-68 hygrometers and their analogs with pointers are inertial devices that operate with a delay in the readings of the pointer, slowly reacting to sharp fluctuations in air humidity.

It should be emphasized that all hygrometers are relative devices and show any arbitrary numbers without preliminary adjustment. Therefore, hygrometers must be pre-adjusted according to the standard (aspiration psychrometer, etc.) and then periodically checked and adjusted. In the absence of a control device (standard), the hygrometer can be checked and adjusted using improvised means. You need a 3-4 liter container and a sealed transparent lid for it (made of a sheet of glass, plexiglass). A saturated solution of table salt with a small amount of solid phase is poured into the bottom of the container. The liquid depth is 2-3 cm. A high holder is placed in the container, on which the device can be placed. If there is a tight seal, the device should show 76% after a few hours. By periodically removing and adjusting the device, repeating acclimatization, you can set the hygrometer quite accurately. The salt solution should not get on the device.

Hygrometers M-68 and their analogues are stationary hanging devices. Any hygrometer must have an output for its adjustment - this is the most important condition for choosing a particular model.

By periodically checking and adjusting hygrometers, you can use them successfully for a long time in archival practice.

Characteristics of the hygrometer M-68:

Hygrometer M-68 is a laboratory device designed to measure relative air humidity.

Operating temperature - from +10?С to +35?С.

Measurement limits - 30% - 100%.

Operating principle of the M-68:

The M-68 hygrometers operate on the principle of a hair hygrometer. The operation of these devices is based on the property of defatted hair to change its length when the air humidity changes.

Structurally, the M-68 hygrometer is made in a round metal box, inside which is the mechanism of the device. The hair is stretched on a metal frame. The change in hair length is transmitted to the arrow, moving along the scale.