The height of the valve slit during homogenizer operation does not exceed 0.1 mm. In the non-operating position the valve is tightly pressed against the seat by a spring, which is compressed by a screw, and in the operating position the valve is raised by the liquid pressure and is in a «floating» state. When the screw is tightened, the spring pressure on the valve increases, resulting in a lower valve slot height. This leads to an increase in hydraulic resistance as the ointment moves through the valve.

The homogenizer is provided with a safety spring valve through which the ointment escapes when the pressure in the apparatus is higher than the set pressure. Moving at high speed, the ointment has a strong mechanical impact on the seat and valve, which causes them to wear out quickly. The valve and seat are made of high hardness steel. They are usually symmetrically shaped and have working surfaces on both sides. This makes it possible, after noticeable wear of the working surfaces, to turn the seat and valve the other way around to use the second pair of working surfaces and extend the life of the homogenizing valve by a factor of 2. In such valves homogenization occurs in two stages, ie, the ointment passes sequentially «through two homogenizing valves.

The essence of the process is as follows: the product with a plunger pump is pumped into the side of the homogenizing valve, pressed against the seat spring and adjusting screw. The product is then directed towards the homogenizing valve of the second stage. In each valve, the spring pressure on the valve is adjusted by its own screw. The operating pressure in the discharge chamber is equal to the sum of both differential pressures. An example of a valve-type homogenizer is the high-pressure homogenizer produced by the German IKA group of companies.

The operating principle of the apparatus is as follows: the product enters the homogenizing valve at low speed and high pressure, which is caused by the small gap between the plug and the outlet head. In the homogenizer, the product is subjected to various kinds of influences that result in particle size reduction: intense acceleration followed by a sharp deceleration leads to cavitation and then to the explosion of globules.

Homogenization can be carried out by means of a single (for uniform dispersion of immiscible substances) or double (for emulsion production and viscosity control) homogenizing valve. All homogenizing valves are equipped with an oil-pneumatic device to regulate the homogenization pressure and to absorb any possible hydro-impact. The maximum capacity of this unit is 3 l/h. The valve type high pressure homogenizer is manufactured by GEA Niro Soavi (Germany-Denmark-Italy). It is used in the pharmaceutical cosmetic industry for the production of ointments and creams. This homogenizer combines high performance and very high pressure for product processing.

The GEA Niro Soavi homogenizer produces a more stable product with effective dispersion of active ingredients than conventional agitators, mashers or colloid mills. The result is a product with high stability and long shelf life. The radical reduction in particle size also contributes to the fact that the skin absorbs these products much better.