Membrane level indicator SUM-1, Zhytomyr region.

SUM-1 U2 membrane type level indicator (SUM-1a) is intended for level controlgrains and other similar bulk products in production containers and gravity flows in the absence of direct exposure to solar radiation and atmospheric precipitation.
СУМ-1 U2 level detectors (СУМ-1а) are intended for operation under acanopy or in a room where fluctuations in temperature and air humidity do not significantly differ from fluctuations in the open air and there is relatively free access to outside air (in the absence of direct exposure to solar radiation and atmospheric precipitation).
Technical characteristics
Output switching current at ~220V 2 A
Guaranteed due to activation of 0.5 N
The guaranteed amount of activation is 30000
The average service life is 12 years.
The internal size of the mounting flange is 88 mm.
Weight, not more than 0.4 kg(//tractor-service.com)
Ambient temperature from -20 C to +50 C
Degree of protection IP65
Overall dimensions 130x115x77 mm
The SUM-1 body consists of impact-resistant technical thermoplastic resin (ABS plastic) and a metal flange.

The SUM-1 sensor consists of two cavities. In the front cavity of the sensor there is a working membrane, a weighing mechanism and a microswitch. In the rear cavity, there is a terminal block and a silicone diaphragm that compensates for excess air pressure inside the sensor during the impact on the working membrane.

On the outer side of the back cover there is a hole for atmospheric air to enter the back side of the diaphragm.

The mechanical impact of the bulk substance on the working membrane is further transmitted to the metal membrane and through the lever; on a microswitch.