How to Choose a Screw Valve? A Complete Analysis of Single-Liquid, Two-Liquid, and Dynamic Mixing Types | 2026 Industrial Dispensing Selection Guide
Table of Contents
- 01 What is a screw valve? Why is it being used in industrial dispensing?
- 02 Complete Disassembly of Three Types of Screw Valves
- 03 Screw Valve vs. General Dispensing Valve | Five Key Differences
- 04 Five Key Indicators for Screw Valve Selection (30-Second Decision Table)
- 05 Breakdown of Three Real-World Application Scenarios
- 06 Common Errors and Lightning Protection Guidelines for Screw Valves
- 07 Conclusion | How Should You Proceed?
- 08 FAQ｜5 Most Frequently Asked Questions about Screw Valves
Last week, a customer who makes automotive electronics called and his first words were: "My batch of PCBs has another problem with the potting compound. The mixing ratio is off, and the whole batch needs to be redone." This is the third time this month.
He wasn't using a screw valve .
If you've ever encountered similar situations—uneven amounts of glue, uneven mixing of AB glue, or having to stop the machine for half a day to clean—then reading this article will at least help you avoid making two similar mistakes.
You're evaluating dispensing equipment, but terms like "screw valve," "screw dispensing valve," and "progressive chamber pump" are all mixed up, making it unclear what the differences are and which one to choose. Specifications on the market are full of technical terms, but few tell you "what the consequences of choosing the wrong one are."
The document includes a comparison table of the core differences between three types of screw valves, five key selection criteria, three sets of real-world application scenarios (PCB potting, LED packaging, and automotive electronics), and a selection checklist that can be used directly for competitive bidding with suppliers.
01 | What is a screw valve? Why is it being used in industrial dispensing?
The operating principle of a screw valve (Progressive Cavity Pump, also known as a progressive cavity pump or screw dispensing valve) is completely different from that of a general pneumatic dispensing valve.
The pneumatic valve uses air pressure to extrude adhesive, and the amount of adhesive dispensed is affected by temperature, remaining material, and air pressure fluctuations. The screw valve uses a volumetric dispensing principle —the amount of adhesive dispensed is fixed for each revolution of the motor. Two revolutions double the amount, and it stops when stopped.
This difference may seem small, but it will manifest as several things on the production line:
- The stability of adhesive content was reduced from ±5% to within ±1%.
- Even high-viscosity adhesives (above 10,000 cps) can be dispensed smoothly.
- Filler-containing adhesives (silver paste, silicone, epoxy) are less likely to clog or wear nozzles.
- Clean start-stop, no trailing residue.
Simply put, when you need "precise, stable, and repeatable" dispensing , screw valves are almost an unavoidable choice. Automotive electronic packaging, PCB potting, LED packaging, and medical device dispensing—applications with extremely low tolerance for quality errors—mostly now rely on screw valves.
02 | Complete Disassembly of Three Major Types of Screw Valves
There isn't just one type of screw valve. Based on whether the adhesive is a "single-component" or "two-component" compound, and whether the two-component compound requires dynamic mixing, they are divided into three main categories:
F Series | Single-component screw dispensing valve : The simplest type. A single hose is connected, and the screw rotates to dispense a measured amount of adhesive. Suitable for single-component adhesives: UV adhesives, instant adhesives, silicone, and grease-based lubricants. Advantages include simple structure, easy maintenance, and extremely stable dispensing volume. Common applications: adhesive application to mobile phone camera modules, bearing lubrication, and UV adhesive positioning dispensing.
M Series | Two-component AB glue static screw valve : Two glue tubes (A agent + B agent) are fed simultaneously in a specific ratio, mixed through a static mixing tube (internal spiral blades) before being dispensed. The ratio can be customized from 1:1 to 10:1. Suitable for medium viscosity AB glues: epoxy resin encapsulants, PU potting compounds, and structural acrylic adhesives.
D Series | Dual-Liquid Dynamic Mixing Screw Valve : Advanced Version. In addition to the static mixing tube, a dynamic motor mixing mechanism is added to actively stir the two components. Specifically designed for handling difficult adhesives: AB adhesives with high viscosity differences (A component is thick, B component is thin), adhesives containing large amounts of filler, and formulations with extreme mixing ratios (above 20:1). Common applications: High-frequency transformer potting, motor coil encapsulation, and high-filler silicone potting.
| model | Applicable adhesives | Viscosity range | Mixing ratio | Typical applications |
|---|---|---|---|---|
| F single liquid | single component | 1 ~ 100,000 cps | — | UV adhesive, super glue, grease |
| M Two-Liquid Static | AB two-component | 100 ~ 50,000 cps | 1:1 ~ 10:1 | Epoxy encapsulant, PU potting compound |
| D Two-liquid dynamics | AB two-component (high viscosity difference) | 100 ~ 200,000 cps | 1:1 ~ 50:1 | High-filler silicone, motor potting |
03 | Screw Valve vs. General Dispensing Valve | Five Key Differences
Many people ask, "Why not just use a cheaper pneumatic valve?" Here are five differences you'll notice on-site:
| Comparison items | pneumatic dispensing valve | Screw valve |
|---|---|---|
| Quantitative accuracy | ±5% (affected by air pressure) | ±1% (volume-based quantification) |
| High viscosity capability | <10,000 cps is preferred | Up to 200,000 cps |
| Filler-containing adhesives | Easy to wear and clog | Large flow channel, wear-resistant |
| Start-stop residue | Easy to drag and drip | Reverse suction function for clean cutting |
| Single cost | Low (inexpensive consumables) | High (but with a good long-term ROI) |
The key isn't which one is better, but which one suits your application best . If you're doing low-viscosity water-based adhesives, high-volume coatings with low precision requirements, a pneumatic valve is actually more cost-effective. However, if any of the following situations apply—precision requirements within ±2%, adhesives containing fillers, 24-hour continuous production lines, or high-priced products (electronic packaging, medical components)—a screw valve is almost always the best choice.
Looking for a more comprehensive comparison of screw valves versus pneumatic valves? We've compiled a complete 12-page comparison guide.
Request the complete comparison table04 | Five Key Indicators for Screw Valve Selection (30-Second Decision Sheet)
Choosing a product isn't about price; it's about these five things:
Adhesive components: Single-component → F; Two-component → M or D
Adhesive viscosity <50,000 cps → M is sufficient; >50,000 cps or contains a large amount of filler → go directly to D.
Mixing ratio 1:1 ~ 10:1 → M; 10:1 and above → D
Production line cycle time: multiple points per second / 24 hours continuous operation → Screw valve (regardless of model)
High-cost adhesive materials (silver adhesive, UV adhesive) → Screw valves prevent waste.
30-Second Selection Decision Form :
Save this table; you can refer to it next time you talk to the business team.
05 | Breakdown of Three Real-World Application Scenarios
Scenario A | PCB potting (automotive electronics)
The adhesive material is epoxy resin AB glue, with a ratio of 2:1 and a viscosity of 8,000 cps. It gels within 30 minutes after mixing.
The pain point is that the mixing ratio drifts when using a pneumatic valve, and some boards are found to be incompletely gelled after filling.
Scenario B | Transformer Coil Encapsulation
High-filler silicone adhesive, component A viscosity 80,000 cps, component B viscosity 5,000 cps, ratio 10:1
The problem is that the viscosity difference between the two agents is too large, and the mixture often separates into layers when coming out of the static mixing tube.
Scenario C | UV Adhesive Positioning of Mobile Phone Camera Module
UV adhesive , single component, viscosity 3,000 cps
The amount of adhesive applied to the pain point must be precise to 0.01g, and there should be no stringy residue.
06 | Common Screw Valve Errors and Lightning Protection Guide
Having worked with hundreds of factories, these are the four most common pitfalls I've encountered:
Lei 1 | Only looking at price, not the cost of consumables
The screw valve body is purchased once, but the static mixing tube is a consumable and needs to be replaced with a new one for each production batch. Before purchasing, clarify the unit price of the mixing tube, its compatibility with specifications, and the stability of delivery time.
Ray 2 | Wrong Mixing Ratio
Some customers bought the 1:1 M series adhesive, but when they switched to a 4:1 formulation, the entire batch needed to be modified. Before buying, confirm the list of adhesives you might use within the next two years and allow for adjustments to the ratio.
Lei 3 | Ignoring the Cost of Adhesive Cleaning
After the dual-liquid screw valve is shut down, the adhesive inside the mixing tube will harden. For extended shutdowns, the mixing tube must be removed for cleaning or discarded. This should be taken into account when scheduling production lines.
Lei 4 | No automated platform
The screw valve is just the dispensing end. What truly increases production capacity is the complete solution of "screw valve + three-axis dispensing platform". Buying only the valve without planning the platform is like buying an engine but not a car.
07 | Conclusion | How should you proceed?
By now, you should have a basic understanding of the model logic for screw valves. Next steps:
- First, confirm the adhesive list —list all the adhesives currently in use and those that may be used in the future, including their viscosity, composition, and proportions.
- Referring to the selection decision table in this article , we can initially identify possible models (F, M, or D).
- Obtain the specifications from the supplier —compare the accuracy, warranty, and consumable costs of different brands.
- Require an on-site demo – test it with your own adhesive material; don't trust the ideal values on the specification sheet.
If you want to skip steps 1-3 and proceed directly to step 4, Huasheng Technology offers free screw valve selection consultation and on-site demo services. With 30 years of experience in dispensing machine manufacturing, an 85% market share, and sales in 20 countries worldwide, tell us your application scenario, and our engineering team will provide you with specific advice.
Tell Huasheng about your application scenario, and our engineering team will give you specific selection advice.
Whether you're evaluating a screw valve for the first time or looking to upgrade your existing dispensing equipment, our 30-year experienced engineering team offers free selection consultations and on-site demos. Bring your current adhesive materials for testing; don't rely on the ideal values on the specifications sheet.
Schedule a free screw valve selection consultation now →08 | FAQ | 5 Most Common Screw Valve Questions
Are Q screw valve and screw dispensing valve the same thing?
Yes. The Chinese terminology is inconsistent; "screw valve," "screw dispensing valve," "progressive cavity pump," and "PCP pump" all refer to the same type of equipment. The standard English name is Progressive Cavity Pump Dispenser.
Can a screw valve be used for small-volume dispensing? What is the minimum dispensing volume?
Yes. Currently, the minimum dispensing volume of mainstream screw valves can reach 0.001 ml (1 microliter), which is used in mobile phone camera modules, semiconductor packaging, and medical micro-dispensing. The minimum value may vary depending on the model; please ask directly when requesting the datasheet.
How often should a Q screw valve be serviced? How much do the consumables cost?
Routine maintenance (replacing seals and checking screw wear) should be performed every 6 months under normal use. Consumables are mainly mixing tubes, which are replaced with each production batch; the cost per tube varies from tens to hundreds of yuan depending on the specifications. It is recommended to inquire about the estimated annual usage of consumables when purchasing.
Can Q screw valves handle adhesives containing metal fillers, such as silver adhesive?
Yes, but you should choose a screw valve model with a wear-resistant rating . Generally, stainless steel screws are used. For screws containing packing material, it's recommended to choose hardened or ceramic-coated screws to prevent proportional drift after wear.
How long is the warranty for Q screw valves? Is there original manufacturer technical support in Taiwan?
Huasheng Technology's screw valves come with a standard 1-year warranty, with extended warranties available for purchase. The original manufacturer's technical team at its Taoyuan, Taiwan headquarters is available 24/7 and can provide on-site service on the same day (depending on distance).