Liquid Filling Machine Selection｜Equipment Recommendations for Materials of Different Viscosities

In production lines for food, daily‑use chemicals, pharmaceuticals and chemical bottling, liquid filling machines are core equipment that determine filling accuracy and production efficiency. Many enterprises only consider filling volume and production speed when purchasing machines, while ignoring the viscosity characteristics of materials. This may result in large filling‑volume deviations, dripping and stringing, poor discharging, material foaming and other problems. Consequently, frequent on‑site commissioning is required, and in the worst case, the equipment cannot be put into normal production.

Material viscosity is the primary criterion for liquid filling machine selection. One filling machine that works stably and efficiently for low‑viscosity water‑based liquids may suffer various malfunctions when used for viscous pastes. This article classifies mainstream filling models by low‑, medium‑ and high‑viscosity materials, sorts out their advantages, disadvantages and applicable scenarios, and helps enterprises complete equipment selection quickly.

1. Low‑viscosity materials: good fluidity, flowing like water

Typical materials: Purified water, alcohol, disinfectant, liquor, beverages, dilute reagents, toner and other liquids with high fluidity and almost no wall‑sticking. Recommended models: Gravity filling machines, negative‑pressure vacuum filling machines, flow‑meter filling machines

1. Gravity filling machine Filling is completed relying on the self‑weight of materials. It features simple structure and low maintenance cost, and suits mass production of water‑based liquids. It applies to non‑foaming and non‑volatile materials. Its shortcoming is that filling accuracy is affected by liquid‑level height, and it is not suitable for viscous materials.
2. Negative‑pressure vacuum filling machine Negative pressure is formed inside bottles to suck materials into containers. It fits foaming and volatile materials and is widely adopted for small‑bottle disinfection and pharmaceutical production. It effectively reduces splashing and foaming for stable metering.
3. Flow‑meter filling machine Real‑time metering is realized via flow meters. Two‑stage fast‑and‑slow filling prevents splashing: high speed for main filling and low speed for volume trimming. It supports convenient adjustment for specification changes and is compatible with multiple low‑viscosity materials and various bottle types.

Selection tip: For low‑viscosity materials, prioritize anti‑foaming and anti‑dripping performance. Filling nozzles with suck‑back function are suggested to avoid liquid dripping contaminating bottle bodies and conveyor belts after filling.

2. Medium‑viscosity materials: moderate thickness with flow resistance

Typical materials: Edible oil, syrup, shampoo, body wash, lotion, oyster sauce, fermentation broth. These materials stick to surfaces when poured, flow slowly and some may delaminate slightly. Recommended models: Gear pump filling machines, cam rotor pump filling machines

1. Gear pump filling machine Volumetric metering delivers stable flow. It is widely used in daily‑care and oil industries for medium‑viscosity fluids without hard particles. It supports continuous high‑speed filling and is easy to disassemble and clean. It is not suitable for materials containing hard particles, as particles will abrade gear seals.
2. Cam rotor pump filling machine Low shear force minimizes damage to materials. It tolerates fine soft particles and fits syrup, sauces and emulsions with stable metering accuracy. It supports CIP cleaning and is preferred for food and pharmaceutical industries.

Selection tip: Temperature changes alter material viscosity. For workshops with large temperature fluctuations, take temperature variation into consideration. Falling temperatures thicken materials and may cause insufficient filling volume.

3. High‑viscosity materials: heavy consistency and poor fluidity

Typical materials: Honey, cream, sauces, gels, high‑concentration pharmaceuticals and certain chemical raw materials. They flow slowly, cling heavily to surfaces and some contain particles. Recommended model: Piston filling machine