{
    "schemaVersion": "ooitech-article.v1",
    "url": "https://www.ooitech.com/laminator-vacuum-pumps-types-and-eva-window.html",
    "language": "en",
    "title": "Laminator Vacuum Pumps: Types and the EVA Window | Ooitech",
    "description": "Why rotary vane, Roots and dry screw pumps are combined on a solar laminator, and how the EVA melt and crosslink window sets the pumping deadline.",
    "keywords": "laminator vacuum pump, vacuum pump for laminator, rotary vane vacuum pump, roots vacuum pump, dry screw vacuum pump, EVA degassing window, solar laminator vacuum system",
    "ogType": "website",
    "image": "https://cdn.ooitech.com/static/upload/image/20250723/1753270698863235.webp",
    "headings": [
        {
            "level": 1,
            "text": "Laminator Vacuum Pumps: Types and the EVA Window"
        },
        {
            "level": 2,
            "text": "Laminator Vacuum Pumps: Types and the EVA Window"
        },
        {
            "level": 2,
            "text": "1. The EVA Window That Sets Everything Else"
        },
        {
            "level": 2,
            "text": "2. Why Dual-Chamber Laminators Exist"
        },
        {
            "level": 2,
            "text": "3. The Three Pump Types You Will Find on a Laminator"
        },
        {
            "level": 3,
            "text": "Rotary vane pump"
        },
        {
            "level": 3,
            "text": "Roots pump"
        },
        {
            "level": 3,
            "text": "Dry screw pump"
        },
        {
            "level": 2,
            "text": "4. Comparing the Three"
        },
        {
            "level": 2,
            "text": "5. Why the Pump Set Belongs in the Laminator Specification"
        },
        {
            "level": 2,
            "text": "FAQ"
        },
        {
            "level": 3,
            "text": "Why does a dual-chamber laminator run its first chamber cooler?"
        },
        {
            "level": 3,
            "text": "Why do laminators pair a Roots pump with rotary vane pumps?"
        },
        {
            "level": 3,
            "text": "What does the oil do in a rotary vane pump?"
        },
        {
            "level": 3,
            "text": "Is a dry screw pump worth the extra cost?"
        },
        {
            "level": 3,
            "text": "Why does EVA temperature matter so much to the vacuum system?"
        },
        {
            "level": 3,
            "text": "What happens if the chamber is not pumped down fast enough?"
        },
        {
            "level": 2,
            "text": "Final Thoughts"
        },
        {
            "level": 5,
            "text": "Tags :"
        },
        {
            "level": 5,
            "text": "Table of Contents"
        },
        {
            "level": 5,
            "text": "Category"
        },
        {
            "level": 5,
            "text": "Related Posts"
        },
        {
            "level": 6,
            "text": "TOPCon Solar Cell Manufacturing Process:"
        },
        {
            "level": 6,
            "text": "How a Tabber & Stringer Works"
        },
        {
            "level": 6,
            "text": "Triple-Junction GaAs Solar Cells: A Detailed Look"
        },
        {
            "level": 6,
            "text": "33.25% Efficiency, 96% MPPT Retention After 1000 Hours:"
        },
        {
            "level": 6,
            "text": "26.2% Certified Efficiency Breakthrough"
        },
        {
            "level": 5,
            "text": "Recent Post"
        },
        {
            "level": 6,
            "text": "Laminator Vacuum Pumps: Types and the EVA Window"
        },
        {
            "level": 6,
            "text": "Why Solar Panel Glass Is Textured, Not Smooth"
        },
        {
            "level": 6,
            "text": "BC Cell Technology Roadmap: Structure to Process"
        },
        {
            "level": 5,
            "text": "Popular Tags"
        },
        {
            "level": 3,
            "text": "Request A Quote"
        },
        {
            "level": 2,
            "text": "We deliver expertise you can trust our service"
        },
        {
            "level": 3,
            "text": "Cost-Effective Advantages"
        },
        {
            "level": 3,
            "text": "Our Experience Team"
        },
        {
            "level": 3,
            "text": "15+ Years Industry Experience"
        },
        {
            "level": 2,
            "text": "What Our Client Say's about us"
        },
        {
            "level": 3,
            "text": "KTECH"
        },
        {
            "level": 3,
            "text": "Mark"
        },
        {
            "level": 3,
            "text": "Diarra From Africa"
        },
        {
            "level": 3,
            "text": "Amjad"
        },
        {
            "level": 3,
            "text": "Jizzakh Polytechnic Institute"
        },
        {
            "level": 2,
            "text": "Our Latest Products"
        },
        {
            "level": 3,
            "text": "HDX200-P Half Cell Auto Bussing Machine"
        },
        {
            "level": 3,
            "text": "Interconnection Busbar – Solar Cell String Current"
        },
        {
            "level": 3,
            "text": "Wire Drawing Machine for Solar Ribbon Production Line"
        },
        {
            "level": 3,
            "text": "AM050FH MBB PV Cell Soldering Stringer"
        },
        {
            "level": 3,
            "text": "Solar Glass for PV Modules"
        },
        {
            "level": 3,
            "text": "Automatic Layup & Bussing Integrated Machine"
        }
    ],
    "wordCount": 2891,
    "markdown": "# Laminator Vacuum Pumps: Types and the EVA Window | Ooitech\n\n> Why rotary vane, Roots and dry screw pumps are combined on a solar laminator, and how the EVA melt and crosslink window sets the pumping deadline.\n\n![Laminator Vacuum Pumps: Types and the EVA Window](https://cdn.ooitech.com/static/upload/image/20260325/2026032517892939.webp)\n\n- ** 2026-09-20\n- ** 3 Views\n- ** [Blog](/Blog.html)\n\n## Laminator Vacuum Pumps: Types and the EVA Window\n\nA laminator is judged on yield, and yield is decided largely by one component that buyers rarely look at during a factory visit: the vacuum pump set. Getting it wrong produces micro-bubbles that no amount of downstream inspection can remove.\n\nPV Module Manufacturing · Lamination Process · by Jerry, Ooitech\n\n## 1. The EVA Window That Sets Everything Else\n\nEthylene vinyl acetate does not simply melt and stay put. It passes through two distinct stages, and the gap between them is the time the vacuum system has to work in.\n\n| Stage | Temperature | What it means for vacuum |\n| --- | --- | --- |\n| Melting | About 70–80 °C | The film enters its molten phase. This is the ideal moment to evacuate, because the encapsulant is soft enough to release trapped air but has not yet begun to set. |\n| Crosslinking | About 130 °C | Crosslinking begins and accelerates. Below this temperature the reaction is very slow, which is precisely why the first chamber of a dual-chamber laminator is normally held at or below 125 °C. |\n\nEverything that follows is a consequence of the interval between those two temperatures. If the chamber is already hot when the film melts, the melt-to-crosslink interval is short. In a single-chamber process the chamber typically sits above 140 °C, leaving only about **60 to 90 seconds** to reach the required vacuum. Miss that window and air remains trapped in the encapsulant, forming micro-bubbles and defects that show up later in the finished module.\n\n![Solar panel laminator with its vacuum pump station and receiver tank on a module factory floor](https://cdn.ooitech.com/static/upload/image/20260325/2026032517892939.webp)\n\nFig. 1: A laminator with its vacuum pump set installed alongside on the factory floor. The pumps are a separate installation with their own piping, receiver vessel and service access, which is why they are easy to overlook during layout planning and expensive to relocate afterwards.\n\n## 2. Why Dual-Chamber Laminators Exist\n\nThe dual-chamber design is essentially a way of buying time. By holding the first chamber in the 100 to 120 °C range, the encapsulant melts more slowly and crosslinking starts later, which extends the degassing window well beyond what a single hot chamber allows. The module is then transferred to a second, hotter chamber to complete crosslinking.\n\nThat is the process reason behind a decision that otherwise looks like a purely mechanical choice. It also explains why the vacuum system is not a peripheral accessory: it is the part of the machine that has to perform within the window the thermal design creates. The wider context of the lamination step is covered in [the lamination stage of the production process](https://www.ooitech.com/solar-panel-production-process-lamination.html), and the machine itself in our [guide to the solar panel laminator](https://www.ooitech.com/solar-panel-laminator-the-heart-of-pv-module-encapsulation.html).\n\n![Semi automatic solar panel laminator with the chamber lid open showing the vacuum chamber and control panel](https://cdn.ooitech.com/static/upload/image/20260417/2026041717573839.webp)\n\nFig. 2: A laminator chamber with the lid open. The chamber volume, the seal condition and the pumping speed together determine how quickly the required vacuum is reached, and therefore whether the degassing window is met or missed.\n\n## 3. The Three Pump Types You Will Find on a Laminator\n\n### Rotary vane pump\n\nThe oil-lubricated rotary vane pump is the workhorse of lamination vacuum systems. A single unit typically pumps at **60 to 100 litres per second**. Inside the pump body a rotor is mounted off-centre, carrying vanes that are pushed outward by springs and centrifugal force to stay against the bore. The crescent-shaped space between rotor and bore is divided into several chambers of changing volume.\n\nEach chamber runs a continuous three-part cycle. It opens to the inlet while expanding, drawing gas in. It then closes off and shrinks, compressing the trapped gas. Finally the pressure exceeds atmospheric and the gas lifts the exhaust valve, passing through the oil layer and out. This is a positive displacement pump: it moves fixed volumes of gas rather than relying on any other mechanism.\n\nThe oil does more than lubricate. It seals the clearances between the vanes and the bore so gas cannot leak back, it lubricates the moving parts, and because the exhaust valve sits under oil, it prevents atmosphere from flowing back into the chamber when the pump stops. All three functions matter in a lamination system, where backstreaming would contaminate the module.\n\n### Roots pump\n\nA Roots pump is almost never used alone. On a laminator it serves as a booster stage, and a common configuration for the first chamber is **two rotary vane pumps with one Roots pump**. Pumping speeds above **1,200 litres per second** are typical, which is why it is used where volume has to be moved quickly.\n\nThe mechanism is two figure-eight rotors, gear-driven to rotate in opposite directions in synchronisation. The rotors never touch each other or the bore; clearances are in the order of **0.1 to 0.3 mm**, so no oil is needed for sealing or lubrication inside the pumping chamber.\n\nThe consequence of that design is the key to understanding where it belongs. A Roots pump has **no internal compression**: gas is captured in a fixed space and carried round to the outlet without being squeezed. When that space opens to the exhaust, gas at higher pressure flows back, so the pump cannot on its own reach a high compression ratio or discharge to atmosphere. It needs a backing pump to bring the system down to a pressure where the Roots stage works efficiently. That is the real reason a Roots pump is paired with rotary vane pumps rather than replacing them.\n\n![Roots vacuum pump with drive motor on a mounting frame](https://cdn.ooitech.com/static/upload/image/20260920/2026092017898897968.webp)\n\nFig. 3: A Roots pump with its drive motor. Large pumping speed, no contact between rotors, and no ability to work against atmospheric pressure on its own. It is a booster by design, not by convention.\n\n### Dry screw pump\n\nThe dry screw pump is a fully oil-free positive displacement design, and in higher-end applications it is the replacement for oil-sealed pumps rather than an addition to them. Nothing in the pumping chamber uses oil or water as a sealing or lubricating medium, and the result is a clean vacuum with no oil carry-over into the process.\n\nInside, a pair of parallel helical rotors with opposite hand are driven by precision timing gears and rotate at speed in opposite directions. As with the Roots design, the rotors do not touch each other or the housing, so no lubricant is needed in the gas path. Gas is captured between the screw and the housing and carried towards the outlet, and the volume steadily decreases along the way, so the gas is compressed before discharge.\n\nMany designs use a **variable pitch** along the rotor. This spreads the compression more evenly and gives the gas more opportunity to be cooled as it is transported, which keeps the pump body temperature under control. On a laminator, where the gas stream carries EVA volatiles at elevated temperature, that thermal management is part of the pump's fitness for the duty rather than an optional refinement.\n\n## 4. Comparing the Three\n\n|   | Rotary vane | Roots | Dry screw |\n| --- | --- | --- | --- |\n| Role on a laminator | Primary pump | Booster, paired with rotary vane | Primary pump, oil-free alternative |\n| Typical pumping speed | 60–100 L/s per unit | Above 1,200 L/s | Application dependent |\n| Sealing medium | Oil | None, close clearance only | None, close clearance only |\n| Internal compression | Yes | No | Yes, along the screw |\n| Can discharge to atmosphere alone | Yes | No, requires a backing pump | Yes |\n| Process cleanliness | Oil present; backstreaming must be managed | Clean pumping chamber | Fully oil-free gas path |\n| Consumables | Oil and filters | Minimal | Minimal |\n\nRead as a purchasing decision rather than a technical ranking, the trade is straightforward. A rotary vane set costs less and is well understood, at the price of oil changes, filter changes and managing backstreaming. A Roots booster is not optional on larger chambers, because the vane pumps alone cannot move the volume fast enough inside the window. A dry screw pump removes oil from the gas path altogether and is usually chosen where contamination risk or maintenance burden is the deciding factor.\n\n## 5. Why the Pump Set Belongs in the Laminator Specification\n\nBecause the pump configuration is sized against the chamber volume and the degassing window, it is a laminator specification item, not a separate purchase. Three questions settle most of it.\n\n- **What is the chamber volume and target pressure?** Together with the window length, this sets the required pumping speed and therefore whether a single vane pump is adequate or a Roots booster is needed.\n- **Single or dual chamber?** A dual-chamber machine runs a cooler first chamber, which lengthens the window and relaxes the instantaneous speed requirement, but adds a second chamber to evacuate. This is covered further in [how to choose the right solar module laminator](https://www.ooitech.com/how-to-choose-the-right-solar-module-laminator.html).\n- **What is the maintenance plan?** Oil and filter intervals on a vane set, versus the higher capital cost and lower consumable burden of a dry screw. Over a ten-year life the two totals are closer than the purchase prices suggest.\n\nA vacuum system that is undersized for the chamber does not fail immediately. It produces modules that pass final inspection and fail later, and the defect signature — micro-bubbles and voids in the encapsulant — is the subject of [not every laminate bubble is the encapsulant's fault](https://www.ooitech.com/not-every-laminate-bubble-is-the-encapsulants-fault-the-real-causes-behind-solar-module-bubbles.html). Encapsulant selection interacts with the same window, as set out in our guide to [EVA, POE and EPE encapsulant films](https://www.ooitech.com/EVA-POE-EPE-Encapsulant-Film-for-Solar-Panel-Manufacturing-Complete-Technical-Guide.html).\n\n## FAQ\n\n### Why does a dual-chamber laminator run its first chamber cooler?\n\nTo lengthen the degassing window. EVA melts around 70 to 80 °C and begins crosslinking around 130 °C. Holding the first chamber at roughly 100 to 120 °C slows both stages, giving the vacuum system more time to remove trapped air before the encapsulant starts to set.\n\n### Why do laminators pair a Roots pump with rotary vane pumps?\n\nBecause a Roots pump cannot discharge to atmosphere by itself. Its rotors trap gas in a fixed volume without compressing it, so gas flows back at the outlet and it cannot achieve a high compression ratio alone. It provides high pumping speed for its size, and the rotary vane pumps provide the compression that gets the gas out. Two vane pumps plus one Roots pump is a common first-chamber arrangement.\n\n### What does the oil do in a rotary vane pump?\n\nThree things. It seals the clearances between the vanes and the pump bore so gas cannot leak back, it lubricates the moving parts, and because the exhaust valve is immersed in oil it prevents atmosphere from flowing back into the chamber when the pump is not running.\n\n### Is a dry screw pump worth the extra cost?\n\nIt depends on what you are optimising. A dry screw pump has no oil or water in the pumping chamber, so the vacuum is clean and there is no oil carry-over towards the module, and the consumable burden is lower. Against that, capital cost is higher. Where contamination risk or maintenance headcount is the constraint, the calculation usually favours it; where capital is tight and the process is well controlled, a vane set remains viable.\n\n### Why does EVA temperature matter so much to the vacuum system?\n\nBecause the two thermal stages define the deadline. The film only releases trapped air effectively once molten, and it stops doing so freely once crosslinking begins. The vacuum system has to reach the required pressure within that interval, which in a single-chamber process above 140 °C may be as little as 60 to 90 seconds.\n\n### What happens if the chamber is not pumped down fast enough?\n\nAir remains trapped in the encapsulant as it cures, producing micro-bubbles and voids. These are not always visible at the laminator exit, which makes the problem easy to miss until yield data or field returns reveal it. The defect is a pump performance issue as often as an encapsulant issue.\n\n## Final Thoughts\n\nThe vacuum pump set is where the thermal design of a laminator becomes a mechanical requirement. EVA melts at 70 to 80 °C and crosslinks from around 130 °C, and the vacuum system has to evacuate the chamber inside the interval between them. That is why dual-chamber machines run a cooler first chamber, why Roots boosters appear on larger chambers, and why oil-free pumping is worth considering where contamination or maintenance is the constraint. When you specify a laminator, ask for the chamber volume, the pump configuration, the pumping speeds and the achievable pump-down time as a set — a machine quoted without them is a machine whose yield you cannot predict. If you are evaluating laminators for a new line, send us the module format and target throughput and we will work through the chamber and pump sizing with you. To see the machine in context, the [OTCY-2754DD single-layer double-chamber laminator](https://www.ooitech.com/single-layer-double-chamber-automatic-bipv-laminator-otcy-2754dd-ooitech-solar-panel-lamination-equipment.html) page covers the chamber arrangement in detail.\n\n---\n\n##### Tags :\n\n\n![](/template/ooitech/assets/img/shape/06.png)\n\n![](https://cdn.ooitech.com/runtime/image/w800_h700_fitblur_v2_w800_h700_fitblur_v2_1757399770541443.webp)\n\n### Request A Quote\n\nAll uploads are secure and confidential.\n\n## We deliver expertise you can trust our service\n\nDirect-from-Factory Equipment.\n\n![](/template/ooitech/assets/img/icon/money-2.svg)\n\n### Cost-Effective Advantages\n\nWe deliver exceptional value, maximizing results while optimizing budgets for clients.\n\n![](/template/ooitech/assets/img/icon/staff.svg)\n\n### Our Experience Team\n\nOur skilled professionals specialize in innovative solutions and tailored strategies.\n\n![](/template/ooitech/assets/img/icon/certified.svg)\n\n### 15+ Years Industry Experience\n\nDeep expertise ensures reliable, trend-aware, and proven outcomes for success.\n\n![](https://cdn.ooitech.com/static/upload/image/20250910/1757477357667605.webp )\n\n![](https://cdn.ooitech.com/static/upload/image/20250910/1757477724911512.webp)\n\n![](/template/ooitech/assets/img/shape/06.png)\n\n## What Our Client Say's about us\n\nClient testimonials praise our deep understanding of their challenges, which leads to innovative solutions and strong ROI. Long-term collaborations—some over a decade—demonstrate their trust and satisfaction. Their success stories drive us to continually exceed expectations. [Know More **](#quote-form)\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThanks to Ooitech for providing highly suitable BC solar cell experimental equipment.\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1776426122864564.webp)\n\n### KTECH\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThank you again so much again for the very big big help for improving and fixing the factory and also teaching the workers how to use the machines\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1757479675272137.webp)\n\n### Mark\n\nBIPV Philippines\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nthank you for ooitech's professional support and on time after service.\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1784509010217979.webp)\n\n### Diarra From Africa\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nThanks to Ooitech for providing the fully automated production equipment—your installation and after-sales service have been excellent.\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026041720921238.webp)\n\n### Amjad\n\n![](/template/ooitech/assets/img/icon/quote.svg)\n\nA man with a big soul. Thank you very much for your visit Mr Wu. Thank you very much for the services provided in installing equipment and training my students. The kindest person and professional in his field\n\n![](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026041716444445.webp)\n\n### Jizzakh Polytechnic Institute\n\n## Our Latest Products\n\n![HDX200-P Half Cell Auto Bussing Machine](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774341533138807.webp)\n\n- [** Rachael](/hdx200-p-half-cell-auto-bussing-machine-automatic-busbar-welding-machine-for-solar-panel-production.html)\n- [** 84644](/hdx200-p-half-cell-auto-bussing-machine-automatic-busbar-welding-machine-for-solar-panel-production.html)\n\n### HDX200-P Half Cell Auto Bussing Machine\n\nHDX200-P Half Cell Auto Bussing Machine features electromagnetic induction welding with 18 welding heads, cycle time under 18 seconds\n\n![Interconnection Busbar – Solar Cell String Current](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026032713037538.jpg.webp)\n\n- [** Rachael](/Interconnection-Busbar-for-Solar-Module-Assembly-High-Performance-Current-Collection-Solution.html)\n- [** 96674](/Interconnection-Busbar-for-Solar-Module-Assembly-High-Performance-Current-Collection-Solution.html)\n\n### Interconnection Busbar – Solar Cell String Current\n\nPremium interconnection busbar solutions for solar module assembly, featuring high-purity tinned copper construction\n\n![Wire Drawing Machine for Solar Ribbon Production Line](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_2026051187922761.webp)\n\n- [** ooitech](/wire-drawing-machine-for-solar-ribbon-production-line.html)\n- [** 466](/wire-drawing-machine-for-solar-ribbon-production-line.html)\n\n### Wire Drawing Machine for Solar Ribbon Production Line\n\nProfessional intermediate wire drawing machine for solar ribbon production line, featuring four-axis horizontal design\n\n![AM050FH MBB PV Cell Soldering Stringer](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774262936967131.webp)\n\n- [** ooitech](/am050fh-mbb-pv-cell-soldering-stringer-fully-automatic-solar-cell-tabber-stringer-machine-ooitech.html)\n- [** 56720](/am050fh-mbb-pv-cell-soldering-stringer-fully-automatic-solar-cell-tabber-stringer-machine-ooitech.html)\n\n### AM050FH MBB PV Cell Soldering Stringer\n\nAM050FH MBB PV Cell Soldering Stringer by Ooitech is a fully automatic tabber stringer machine featuring laser half-cut and 1/3-cut capability\n\n![Solar Glass for PV Modules](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774514074283403.webp)\n\n- [** ooitech](/Solar-Glass-Ultra-Clear-Low-Iron-Tempered-Glass-for-Photovoltaic-Modules.html)\n- [** 46929](/Solar-Glass-Ultra-Clear-Low-Iron-Tempered-Glass-for-Photovoltaic-Modules.html)\n\n### Solar Glass for PV Modules\n\nLow-iron tempered solar glass with AR coating – 91.5%+ light transmittance for maximum panel efficiency. Available in standard & textured versions.\n\n![Automatic Layup & Bussing Integrated Machine](https://cdn.ooitech.com/runtime/image/w800_h600_fitblur_v2_1774349342486074.webp)\n\n- [** Rachael](/automatic-layup-and-bussing-integrated-machine-saw-100a-solar-panel-production-equipment-ooitech.html)\n- [** 19507](/automatic-layup-and-bussing-integrated-machine-saw-100a-solar-panel-production-equipment-ooitech.html)\n\n### Automatic Layup & Bussing Integrated Machine\n\nOoitech SAW-100A Automatic Layup & Bussing Integrated Machine delivers high-efficiency cell string layup and terminal busbar welding with high\n",
    "endpoints": {
        "html": "https://www.ooitech.com/laminator-vacuum-pumps-types-and-eva-window.html",
        "markdown": "https://www.ooitech.com/laminator-vacuum-pumps-types-and-eva-window.md",
        "agentManifest": "https://www.ooitech.com/.well-known/agent.json",
        "llmsTxt": "https://www.ooitech.com/llms.txt",
        "sitemap": "https://www.ooitech.com/sitemap.xml",
        "quote": "https://m.ooitech.com/api/quote.php"
    }
}