Machines that create fine, stable emulsions by driving a liquid through a narrow gap or valve under very high pressure, shattering fat globules and other particles to a uniform small size. They are standard equipment in dairies for milk and cream, and in plants making dressings, sauces, and beverages. Proper pressure control determines the final particle size and therefore the stability and mouthfeel of the product, while sanitation of the equipment keeps the product safe — any residue left in the valves can harbour microbes. Regular maintenance of seals and valves is essential for consistent performance.