> News > Company News > How Does a Two-Stage Valve Work? Uncovering the Core Technology Behind the DC-1’s ±1g High Accuracy

How Does a Two-Stage Valve Work? Uncovering the Core Technology Behind the DC-1’s ±1g High Accuracy

Ben Cai | Published on March 17, 2026

In the world of automatic dosing, there is a well-known challenge: How do you maintain high final accuracy while adding material quickly?

Add too slowly, and efficiency suffers. Add too quickly, and you risk overshooting the target. This causes material waste or even complete batch scrapping. This conflict is especially acute in small batch, multiple product production scenarios like paints, inks, and adhesives.

Sightec’s DC-1 Mobile Dosing Station provides a clear answer: the two-stage multi-flow valve. This core technology allows the DC-1 to achieve ±1g dosing accuracy over a 30kg range, while maintaining a production efficiency of just 1-2 minutes per 20L.

This article will dive deep into how the two-stage valve works. We will explain the control logic behind this technology and show how it solves the “impossible triangle” of dosing accuracy versus efficiency.

Part 1: Why Can’t Traditional Single Valves Achieve ±1g?

Before we understand the advantages of a two-stage valve, let’s look at why traditional single-valve systems struggle to balance efficiency and accuracy.

The Inherent Flaw of Single Valves: Overshoot

Traditional dosing systems usually use just one valve to control material flow. Open the valve, material flows. Close the valve, material stops. It sounds simple. But in actual control, there is a critical problem: response delay.

When the control system sends the “close valve” command, the valve takes a certain amount of time to fully shut. During this millisecond-level delay, material continues to flow out. This portion of material, which cannot be precisely controlled, is called the “overshoot amount.”

The size of the overshoot depends on:

Valve Response Speed: Pneumatic valves are usually faster than electric valves, but delay still exists

Material Flow Rate: The faster the flow, the more material flows during the same delay time

Material Characteristics: High-viscosity materials cut off more cleanly. Low-viscosity materials tend to “dribble” out

To reduce errors caused by overshoot, operators often have to slow down early. When the weight is still some distance from the target, they manually or automatically reduce the flow rate. But this creates a new problem: dosing time increases significantly.

This creates a difficult choice:

Pursue Efficiency: Keep high-speed dosing, overshoot is large, accuracy suffers

Pursue Accuracy: Slow down early, efficiency drops, production cycles lengthen

Traditional single-valve systems simply cannot break through this contradiction.

Part 2: The Two-Stage Valve – Achieving Both “Efficiency” and “Accuracy”

The two-stage multi-flow valve used in the DC-1 was designed specifically to solve this conflict.

What is a Two-Stage Valve?

A two-stage valve, as the name suggests, divides the dosing process into two phases, completed by two independent control units working together:

1.High-Speed Valve (Coarse Adjustment Phase): Responsible for quickly adding material, completing 90%-95% of the total target weight.

2.Fine-Tuning Valve (Precise Adjustment Phase): Responsible for precisely adding the remaining 5%-10%, ensuring final accuracy.

These two valves are not simply stacked together. They work in coordination through a precise control system to achieve “fast without overshoot, accurate without slowing down.”

The Two-Stage Valve Workflow

Let’s use a specific dosing task as an example. Assume the target weight is 10,000g:

Step 1: Coarse Adjustment Phase (High-Speed Dosing)

The control system sends a command. The high-speed valve opens completely.

Material flows in rapidly at maximum flow rate, potentially hundreds of grams per second.

The system continuously monitors real-time data from the load cell.

When the accumulated weight reaches a preset switch point (for example, 9,500g, or 95% of the target), the system commands the high-speed valve to close.

Step 2: Fine-Tuning Phase (Precise Dosing)

As the high-speed valve closes, the fine-tuning valve opens.

The flow rate of the fine-tuning valve is precisely designed. It is usually only 1/10th of the high-speed valve’s rate, or even smaller.

Material flows in slowly as a thin stream, avoiding overshoot.

The system monitors weight changes in real-time, dynamically calculating the remaining amount needed.

As the weight approaches the target, the control system, using a lead compensation algorithm, sends the close command at the precise moment.

Step 3: Dosing Complete

The fine-tuning valve closes. The final weight stops within the range of 10,000g ±1g.

The entire process is typically completed within 1-2 minutes.

The Critical Control Point: Choosing the Switch Point

The most sophisticated part of the two-stage valve is deciding when to switch from the coarse phase to the fine phase.

Switch too early: A lot of time is wasted on slow dosing. Efficiency drops.
Switch too late: Too much material is added during the coarse phase. Even after switching to the fine-tuning valve, there might not be enough time to “brake,” causing overshoot.

The DC-1’s control system uses a dynamic learning algorithm. It automatically optimizes the switch point for each channel based on factors like:

Flow characteristics of different materials

Pipeline pressure

Environmental temperature

With every dosing operation, the system is “learning” and “evolving.” This makes the next dose more accurate and efficient.

Part 3: Core Technical Advantages of the Two-Stage Valve

1. Eliminates Overshoot, Achieves ±1g High Accuracy

The two-stage valve design fundamentally solves the overshoot problem of single valves.

During the coarse dosing phase, even if there is a small amount of overshoot when the high-speed valve closes, this amount is far below the target value. It will not cause the batch to exceed specifications. Once the system enters the fine-tuning phase, the low flow rate of the fine-tuning valve gives the control system a sufficient time window for precise control. Paired with a high-resolution load cell (resolution can reach 0.1g or even higher), the system can calmly complete the final addition when only a few grams remain from the target.

2. Maintains High Efficiency, Does Not Sacrifice Productivity

You might ask: Since dosing is split into two phases, is it slower than full high-speed dosing with a single valve?

The answer is: It has almost no impact.

Why? Because the coarse dosing phase already completes 90%-95% of the total target. Only the final 5%-10% uses slow-speed dosing. Take a 10kg dose as an example:

Single valve full high-speed: 10kg added at full speed, but may need rework due to final overshoot.

Two-stage valve: 9.5kg added at full speed + 0.5kg added slowly for precise adjustment.

Actual test data shows that the DC-1 completes dosing for a 20L container in just 1-2 minutes. This efficiency is nearly identical to single-valve high-speed dosing. But the accuracy is something a single valve can never achieve.

3. Adaptive Learning – Gets More Accurate with Use

The DC-1’s control system features dynamic error compensation.

After each dosing operation, the system automatically records the deviation between the actual weight and the target. It analyzes the cause. Was it valve response delay? Was it a change in material viscosity? Was it pipeline pressure fluctuation? It then automatically adjusts the control parameters for the next dose.

This means:

For the same channel and same material, repeat dosing accuracy continuously improves.

When switching between different materials, the system quickly adapts to the new material’s flow characteristics.

The impact of environmental changes (temperature, humidity) is minimized.

4. Perfectly Integrated with the No-Clean Design

The DC-1’s two-stage valve has another hidden advantage: it is naturally compatible with the no-clean design.

Traditional single-valve systems often need complex structures to achieve a no-clean function. The DC-1’s two-stage valve uses a modular channel design. Each channel is controlled independently. The material path is simple and direct. When changing materials, you simply switch channels. No internal valve cleaning is required.

This not only prevents cross-contamination but also completely eliminates solvent consumption for cleaning and the cost of waste liquid disposal. This is one of the core advantages we discussed in our previous article, Small Batch, Multiple Product Paint Production Challenges.

Part 4: Data Speaks – Two-Stage Valve vs. Single Valve

Comparison Dimension	Traditional Single Valve	DC-1 Two-Stage Valve
Coarse Dosing Phase	Single flow rate throughout	High-speed valve fully open, completes 90%-95%
Fine-Tuning Phase	Requires manual intervention or early slowing down	Fine-tuning valve automatically controls, completes remaining 5%-10%
Overshoot Control	Difficult to avoid, especially with low-viscosity materials	Fine-tuning phase completely eliminates overshoot
Typical Accuracy	±5g to ±20g (depends on operator skill)	±1g (automatically guaranteed by system)
Dosing Efficiency (20L)	Fluctuates greatly, depends on operator skill level	Stable at 1-2 minutes
Batch Consistency	High variability, depends on human factors	Highly consistent, system-controlled
Learning Capability	None	Dynamic error compensation, gets more accurate with use

Part 5: Which Scenarios Benefit Most from the Two-Stage Valve?

✅ Small Batch Production with High Accuracy Requirements

For scenarios where each dose is only tens of kilograms, but formula accuracy is critical (such as industrial paints, automotive paints, electronic chemicals), the ±1g accuracy of the two-stage valve is an irreplaceable advantage. It ensures that every small batch meets the same high-quality standards as large-scale production, or even exceeds them.

✅ Frequent Switching Between Multiple Product Varieties

When you need to switch between different materials frequently, the fast response and adaptive capability of the two-stage valve allow the first dose after each switch to achieve high accuracy immediately. No repeated debugging is needed.

✅ Low-Viscosity Materials

Low-viscosity materials (like solvents, thinners) are highly fluid and the most difficult to control for overshoot. The two-stage valve solves this problem perfectly through the precise control of the fine-tuning phase.

✅ Cost-Sensitive Production

By eliminating waste from overshoot and increasing the first-pass yield, the two-stage valve directly reduces raw material losses and rework costs. Combined with ROI analysis, the payback period for this type of equipment is typically within 8-12 months.

Part 6: Conclusion – Accuracy Lies in the Details

The core value of automatic dosing equipment is not about how much capacity it has. It is about whether it can maintain stable, high accuracy for every single dose. The DC-1’s two-stage valve technology is the perfect embodiment of this philosophy.

It does not try to solve every problem with a single valve. Instead, it uses the wisdom of “division of labor” – letting the high-speed valve handle efficiency, and the fine-tuning valve handle accuracy – achieving both goals simultaneously. Combined with dynamic learning algorithms and a no-clean design, it is redefining the standard for dosing in small batch, multiple product production.

For professionals in the paint, ink, and adhesive industries, understanding the principle of the two-stage valve is not just about understanding one piece of equipment. It is about understanding the direction of future flexible manufacturing: using smarter control instead of cruder flow; using accumulated data instead of exploration based on experience.