While the Pomon wasn't a perfect filter (it only cleaned the air to 80% purity at 1 gram per cubic centimeter), the Soviets already had a better filter in 1940: the "Vortex", planned for installation on the T-50. The Vortex, developed at factory # 174, could filter the air to 98% purity without being cleaned for 10 hours. However, the T-50 fate was rather unfortunate, and it was not made in large numbers. The filter was then successfully used on KV tanks, until it was replaced by the Cyclone filter. It was also used on early KV-1S tanks, SU-152 SPGs, and the KV-13.
The air is cleared by entering the filter at an angle, and forming a vortex, dropping the dust into the oil pan underneath. The Cyclone filter, Vortex's replacement, reverses the flow of air, dropping the dust out of it more effectively, like so:
I have previously mentioned the Multicyclone filter. Let's take a closer look.
The air filter was installed in all Soviet medium and heavy tanks from 1943 onward.