What Does the Pressure Tank Do in an AB Adhesive Dispensing Filling Machine?

In an AB adhesive dispensing machine, the pressure tank is not just a container for glue. It is an integrated feeding unit that performs three critical functions: separate storage of the A and B components, pneumatic feeding, and pressure stabilization. These functions directly affect dispensing accuracy, production continuity, mixing ratio consistency, and the final quality of the cured product.

Without a stable pressure supply from the tank, even a high-precision metering pump cannot reliably maintain the correct A:B mixing ratio.

Why Does an AB Adhesive Dispensing Filling Machine Need Two Pressure Tanks?

AB adhesive consists of two reactive components: Part A and Part B. Once they are mixed, the curing reaction begins. The two components must therefore be kept completely separate until they reach the mixing valve.

This is why AB dispensing systems normally use two pressure tanks:

● One tank stores Part A.

● The other tank stores Part B.

● The components do not contact each other inside the tanks.

● The adhesive can remain in the tanks for longer periods without curing inside the equipment.

This dual-tank design is the basis for continuous production. If the two components were pre-mixed or stored together, the adhesive would begin to cure and the equipment would require frequent shutdowns for cleaning.

How Does the Pressure Tank Feed Adhesive?

The pressure tank does not generate flow by itself. It uses compressed air introduced into a sealed tank to pressurize the adhesive surface. This pressure pushes the adhesive out of the tank and fills the inlet of the downstream metering pump.

The required air pressure depends on adhesive viscosity and dispensing speed. Many systems operate in the range of 0.2–0.7 MPa, but the exact setting should be matched to the adhesive and process requirements.

The outlet position is also selected according to viscosity:

● Low-viscosity adhesives often use a top outlet.

● High-viscosity adhesives typically use a bottom outlet to ensure smooth and complete feeding.

How Does the Pressure Tank Affect AB Mixing Ratio Accuracy?

The mixing ratio of AB adhesive must be highly accurate. If the ratio shifts, the cured adhesive may become soft, brittle, under-cured, or inconsistent.

The pressure tank supports ratio accuracy in two main ways:

1. Stable pressure output

Each pressure tank is usually equipped with a precision pressure regulator. Its main job is to maintain stable fluid pressure from the tank to the dispensing valve. Stable pressure is the prerequisite for the metering pump—such as a screw pump or gear pump—to deliver a repeatable volume of adhesive.

2. Auxiliary ratio adjustment

In some systems, the output air pressure of the A and B tanks can be adjusted separately to help compensate for viscosity differences between the two components. The main ratio control is still performed by the downstream metering pumps, but pressure adjustment supports stable feeding.

With precision screw metering pumps and stable pressure tanks, feed control accuracy can reach the 0.01 mg level in high-precision systems, allowing the AB mixing ratio to be controlled within a narrow process window.

How Do Pressure Tanks Help Reduce Bubbles and Filler Settling?

Bubbles and filler settling are two common quality problems in AB adhesive dispensing. The pressure tank is an important front-end control point for both.

Bubble control

Air can enter the adhesive when the tank is refilled, pressurized, or operated at a low liquid level. By connecting the pressure tank to a vacuum system, the tank can also function as a vacuum degassing chamber.

In practice, a vacuum level of approximately −0.095 MPa or higher is often required for effective degassing. For high-viscosity adhesives, heating the adhesive to 30–40 °C can reduce viscosity and improve degassing efficiency.

Filler settling control

Adhesives containing fillers such as alumina or silica powder tend to settle during storage. If the filler settles, the upper layer becomes thinner and the lower layer becomes thicker, causing the mixing ratio and dispensed volume to drift.

Pressure tanks equipped with low-speed stirring keep the filler suspended and prevent separation. Stirring speed can typically be adjusted within a wide range, such as 30–4000 rpm, depending on adhesive viscosity and filler content. Some production lines also use timed circulation to help prevent settling.

What Functions Can Modern Pressure Tanks Integrate?

Modern pressure tanks have evolved into modular process platforms. Common integrated functions include:

Liquid-level monitoring is also important. If the adhesive level becomes too low, pressurized air may be drawn into the outlet line, causing intermittent dispensing and increased bubbles. A low-level alarm is therefore a basic requirement for stable feeding.

Selection and Operating Tips

Match the tank to the adhesive

● For filled or settling-prone adhesives, choose a tank with stirring.

● For high-viscosity or bubble-sensitive processes, consider vacuum degassing.

● For frequent adhesive changes, look for easy-clean designs or direct cartridge/inner-liner use.

Pay attention to air supply stability

Unstable compressed air is one of the most common causes of inconsistent dispensed volume. The air supply should generally be stable at 0.4–0.6 MPa, and a pressure regulator should be installed upstream of the pressure tank. Avoid setting the regulator in the very low range of the gauge, where adjustment sensitivity and stability may be poor.

FAQ

1.How do I choose the pressure tank capacity?

Common capacities range from 5 L to 30 L. The right size depends on adhesive change frequency and adhesive consumption per shift. A tank that is too large increases residence time, which can be unfavorable for settling-prone or pot-life-sensitive adhesives. A tank that is too small requires frequent refilling and may disturb continuous production.

2.Do the A and B tanks need the same pressure setting?

Not necessarily. When Part A and Part B have significantly different viscosities, separate pressure settings can help both components feed smoothly. However, the main mixing ratio control is still performed by the downstream metering pumps. Pressure adjustment is an auxiliary measure, not a replacement for metering control.

3.Can a pressure tank be used without stirring?

It depends on the adhesive. Low-viscosity adhesives without fillers may not require stirring in continuous production. However, if the adhesive contains powder fillers or pigments, settling is almost inevitable without stirring, and the mixing ratio and dispensed volume may gradually drift.

4.Why do bubbles appear when the tank is nearly empty?

When the adhesive level is too low, pressurized air may be entrained near the outlet and enter the adhesive line. Keeping the adhesive above the safe minimum level and using a low-level alarm to refill in time is an effective way to avoid end-of-batch bubbles.

5.What pressure tank parts should be checked regularly?

The four key items are the seals, pressure gauge, safety valve, and pressure regulator. Seal failure can cause pressure instability and adhesive leakage. A malfunctioning safety valve creates an overpressure risk. These items should be included in routine inspection rather than checked only after dispensing problems appear.

Key Takeaway

The pressure tank is the front-end stabilizer of an AB adhesive dispensing machine. It protects mixing ratio accuracy through separate storage, creates stable feeding through pneumatic pressure, and helps prevent defects through optional vacuum degassing, stirring, and heating. In short, it is essential for consistent AB adhesive dispensing quality.