A wiped film system is a continuous thermal separation unit in which a rotor mechanically spreads feed into a thin, constantly renewed film on a heated, jacketed wall under deep vacuum, so volatile fractions evaporate in seconds rather than minutes. That short time on heat is the point: it lets you separate a heat-sensitive botanical oil at a jacket temperature that does not degrade the target compounds.
The problem for buyers is not the physics. It is that two quotes for “a wiped film system” can describe two very different packages at two very different prices. This piece walks the spec sheet the way an engineer reads it: what the terminology means, what number actually sizes the system, what the vacuum train buys you, and what you should require before the equipment ships.
How do you read a wiped film spec sheet, line by line?
Read each spec line as a scope statement and ask what it constrains. Six lines decide the purchase: heated surface area, wiper geometry, vacuum train depth, feed requirements, compliance marks, and factory acceptance testing. The table below is the short version; the sections after it explain each row.
| Spec line as vendors print it | What it actually constrains | What to require in writing |
|---|---|---|
| “Capacity: X liters per hour” | Nothing on its own. Throughput is an output of surface area against a specific feed, not an input you can buy to. | The feed composition, vacuum level and jacket temperature at which that rate was measured, plus a trial run on your own material. |
| “Heat transfer surface area: X m²” | The evaporation rate, set by heat transfer area and the temperature driving force across the film. This is the number that sizes the system. | The m² figure and the duty it was sized against: 0.15, 0.30 or 0.40 m² on the WFDS-1S; 0.30, 0.40 or 0.60 m² on the WFDS-2S. |
| “Body material” | Durability against the service and whether the process is visible. | 316L stainless steel for production bodies, Hastelloy for aggressive service, borosilicate glass only where lab-scale visibility outweighs durability. |
| “Wiper type: fixed / hinged / roller” | Film thickness, wear-part life, and how forgiving the system is when run below its rated feed rate. | The geometry selected against your feed viscosity and fouling tendency, and replacement intervals in hours of operation for wiper blades, mechanical seal and drive bearing. |
| “Vacuum pump: model / ultimate pressure” | The pump, not the process. Pressure drop between the evaporating film and the pump is what you actually operate against. | A design absolute pressure at the chamber in torr or mbar, the condenser arrangement (internal or external), and the entrainment separator’s design vapor flow and vacuum level. |
| “Cold trap included” | Vacuum depth and how much condensable load reaches the pump. | Trap staging. WFDS Series systems are available with dual cold trap protection using dry ice and automated LN2 staging. |
| “Vacuum gauge” | What you believe your process is doing. Pirani-type thermal-conductivity gauges drift under solvent and terpene vapor. | Gauge type and mounting point at the chamber, with a capacitance manometer where absolute pressure independent of gas composition is needed, plus a vacuum rise test and measured leak rate at commissioning. |
| “UL 508A” | The industrial control panel: general industrial use at 1000 volts or less, for installation in ordinary locations per the National Electrical Code. | Which components are hazardous (classified) location rated, and written confirmation of the room’s classification from your AHJ, fire and electrical engineers and insurer. |
| “ASME” | The pressure vessel it is applied to: design, fabrication, inspection, testing and certification under Section VIII, Division 1 above 15 psig. Nothing else in the package inherits that scope. | Which vessel or vessels in the system carry the stamp. |
| “GMP-ready” | Design and documentation, not a regulatory status. | The documentation package that supports your quality system. |
| “Tested before shipment” | Whatever the vendor chooses to test. | Vacuum rise and leak check, hydrostatic testing where applicable, and a documented operational run. |
| “System” or “complete package” | Scope, which is where two quotes diverge most. | A written scope of supply naming pump models, trap staging and utility requirements. If a quote does not name those, it is not yet a quote. |
What does “wiped film” mean on an equipment spec sheet?
“Wiped film” describes the mechanism, not a product category. A drive unit turns a rotor inside a heated cylindrical body; wipers on the rotor spread incoming feed into a film a fraction of a millimeter thick and continuously renew it, while a condenser recovers the vapor as distillate and the heavier residue discharges at the bottom. We design, fabricate, assemble and test these systems in our vertically integrated Michigan facility, so the vocabulary below is how our own engineers read a competing spec sheet.
What names do vendors use for the same architecture?
Wiped film evaporator (WFE), thin film evaporator, agitated thin film evaporator, wiped film still, molecular still, and rolled or roller film unit all describe the same mechanically renewed film architecture. Naming varies by vendor, industry sector and geography. “Wiped film” and “thin film” are used interchangeably, and a “molecular still” is generally a wiped film body operating at very low pressure with an internal condenser close to the evaporating surface.
What is a wiped film system not?
It is not a rotary evaporator, not a falling film evaporator, and not a batch glass short path rig. A rotary evaporator has no mechanical wiper and belongs to bulk solvent duty, not refinement. In a falling film evaporator, gravity forms the film and nothing renews it mechanically. A batch glass short path rig holds material on heat for the length of a run and needs an operator standing over it — note that “short path” is used both for those batch glass rigs and, loosely, for continuous wiped film bodies, so confirm which one a vendor means.
Why does the naming confusion cost buyers money?
Because the word covers two different packages. One vendor quotes an evaporator body. Another quotes a train: evaporator, condenser, cold traps, vacuum pumps, feed pump, heating and cooling loops, controls and skid. Ask for a written scope of supply before you compare price. If a quote does not name the pump models, the trap staging and the utility requirements, it is not yet a quote.
How is a wiped film system sized — by surface area or by liters per hour?
Wiped film systems are sized by heated surface area in square meters, because evaporation rate is set by the heat transfer area and the temperature driving force across the film, not by a vessel volume. Liters per hour is an output of that sizing against a specific feed, not an input you can buy to.
What does m² of heat transfer surface actually buy you?
More surface area means more volatile mass removed per pass at the same jacket temperature, or the same removal at a gentler temperature. Our WFDS Series is offered in single-stage and dual-stage configurations with heat transfer surface area from 0.15 to 0.60 square meters, with the WFDS-1S available at 0.15, 0.30 and 0.40 m² and the WFDS-2S at 0.30, 0.40 and 0.60 m². The lower end of that range is sized for pilot work and single-line first-pass refinement; the upper end is sized for a production line expected to run a full shift without becoming the chokepoint. Materials matter alongside area: production bodies are typically 316L stainless steel, with Hastelloy specified for aggressive service and borosilicate glass reserved for small lab units where process visibility outweighs durability.
How do you size a WFDS, step by step?
Size from the duty backwards to the surface area, in this order, and state every input in engineering units.
- Name the separation duty. Which fraction has to come off, and to what target purity — first-pass refinement, a light-fraction strip, or a main-body cut.
- Fix the process window. The maximum jacket temperature in °C that the feed tolerates without degradation, and the design absolute pressure at the chamber in torr or mbar needed to hit the cut at that temperature.
- Characterize the feed. Viscosity at feed-line temperature, the volatile mass fraction that must be removed per pass, and residual extraction solvent content, because light volatiles load the traps and push achievable pressure the wrong direction.
- Convert production targets to a feed rate in liters per hour. Take your required output per shift, divide by the hours you actually run, and subtract cleaning and changeover hours per year before you treat any rated throughput as annual capacity.
- Match that duty to heated surface area in m². 0.15, 0.30 or 0.40 m² on the WFDS-1S; 0.30, 0.40 or 0.60 m² on the WFDS-2S; pilot and single-line first-pass work at the lower end, full-shift production at the upper end.
- Choose stage count. Single stage for one separation duty and a tighter footprint; dual stage when a light-fraction strip and a main-body cut need to happen on one integrated platform instead of two passes through one body.
- Validate against your own material. Run a trial. Modelling alone carries meaningful spread against experiment.
- Close the utilities. Total connected electrical load and voltage/phase, heating fluid loop temperature and flow, chilled fluid supply temperature and heat rejection duty, and vertical headroom in the room for rotor removal.
Why is a single throughput figure always conditional?
Because throughput at a given surface area moves with feed viscosity, how much volatile mass has to come off, target purity, vacuum depth and jacket temperature. A vendor quoting one flat liters-per-hour number without naming the feed condition is quoting a best case. Ask the question that separates an engineering quote from a marketing quote: at what feed composition, vacuum level and jacket temperature was that throughput measured?
Validate the answer against your own material. Published modelling work on wiped film evaporators shows meaningful spread between prediction and experiment, on the order of ±25% for simulated heat flow and ±40% for mean residence time, according to a 2025 Separation and Purification Technology modelling study. Expect a trial run.
Which WFDS configuration should you specify?
Specify a single stage when you have one separation duty and a tighter footprint; the single-stage WFDS-1S configurations cover most first-pass refinement lines. Specify the dual-stage WFDS-2S when a light-fraction strip and a main-body cut need to happen on one integrated platform instead of two passes through one body.
Wiped film vs short path vs falling film: which duty is each one built for?
Wiped film is the continuous refinement option, with residence time in the range of seconds to a couple of minutes. A batch glass short path rig holds material on heat far longer and is attended by an operator for the entire run. Falling film is continuous but gravity-formed, and belongs to bulk volatile removal at low viscosity. That difference in residence time and film renewal drives most of the throughput and consistency gap between them.
| Decision axis | Wiped film | Batch glass short path | Falling film |
|---|---|---|---|
| Mode | Continuous | Batch | Continuous |
| Residence time | Seconds to a couple of minutes | Full run, hours on heat | Short, but gravity-set |
| Viscosity and fouling tolerance | High — film is mechanically renewed | Low to moderate | Low — no mechanical renewal |
| Wear parts | Wiper blades, mechanical seal, drive bearing | Glassware, gaskets | Few moving parts |
| Operator attention per liter | Low once the recipe is set | High, attended throughout | Low |
| Footprint | Compact vertical body plus vacuum train | Bench scale | Tall column |
| Position in the train | Refinement and fractional separation | Small-batch refinement | Bulk volatile removal at low viscosity |
Falling film relies on gravity to form the film, so it loses ground as viscosity and fouling tendency climb. That regime is exactly where a mechanically wiped film holds up, because the wiper renews the surface instead of waiting for the liquid to flow.
Sequencing matters as much as selection. A wiped film system is a refinement stage, not a solvent-removal stage, and bulk solvent should be off the feed upstream. Handle that with solvent recovery upstream of distillation and size the rest of the line against your real production rate using our guide to measuring extraction system throughput.
One honest limitation: a wiped film system costs more up front than a glass batch rig and has rotating wear parts that a glass rig does not. You buy that back in continuous output and fewer operator hours per liter.
How does rotor and wiper geometry affect film stability and wear life?
Wiper geometry is selected against feed viscosity and fouling tendency. It sets film thickness, wear-part life, and how forgiving the system is when you run below its rated feed rate.
What is the difference between fixed-clearance, hinged and roller wipers?
Rigid fixed-clearance blades are durable and easy to clean, and they dominate general vertical service. Hinged or spring blades are pressed toward the wall by centrifugal force and handle fouling-prone feeds and high evaporation ratios better. Roller wipers reduce sliding contact, which extends wiper life on abrasive duty.
Why is film stability a heat transfer problem?
Because film thickness is the key factor governing heat and mass transfer and liquid residence time distribution in a wiped film apparatus, and it depends on wall geometry, agitation and the physical properties of the fluid, per modelling work published in Chemical Engineering Science. Starve the wall and the film breaks up: insufficient wetting produces partial dewetting of the heated surface, which creates localized overheating and reduces heat transfer, as shown in recent Chemical Engineering Research and Design work. Running a system far below its rated feed rate can degrade separation rather than improve it.
How do rotor speed, seal life and maintenance access interact?
Lower rotor speed extends the service life of wiper blades, mechanical seals and drive bearings. Require the replacement interval in writing, stated in hours of operation for the wiper blades, the mechanical seal and the drive bearing, and price a change-out in downtime hours as well as parts — our operator training and commissioning walk your team through those intervals and the spares that cover them. Cleaning access belongs in the same calculation: our Quick Lift Evaporator design exists to cut cleaning and maintenance access time between product changes, and clean-in-place provisions on the feed and discharge side reduce what has to come apart at all. Ask for the changeover time, in hours, that a vendor expects from a trained operator, and multiply it by your planned changeovers per year before you treat a rated throughput as annual capacity.
Why does the vacuum train set your operating temperature?
Because vacuum depth, not jacket temperature, opens the separation window. Deep vacuum is what lets a heat-sensitive feed separate at a jacket temperature that does not damage it, so the vacuum train — not the evaporator body alone — sets your achievable process window.
The depth you need is set by the boiling point curve of the compounds you are separating and by the pressure drop between the evaporating film and the pump, which is why you should require a design absolute pressure at the chamber, in torr or mbar, on the quote rather than a pump specification alone.
Internal or external condenser: which should you specify?
An internal condenser sits inches from the evaporating film and minimizes pressure drop, which lowers the achievable operating pressure and therefore the operating temperature. An external condenser adds large-diameter vacuum piping, supports and insulation to the installed scope, and every meter of that piping is pressure drop you pay for in jacket temperature. Ask also whether the system includes an entrainment separator, and at what vapor flow and vacuum level it was designed to work, because liquid carried into the vapor phase lands in your distillate.
What do cold traps do for vacuum depth and pump protection?
Cold traps preserve vacuum depth and protect the pump. WFDS Series systems are available with dual cold trap protection using dry ice and automated LN2 staging, designed to reduce thermal exposure downstream and protect the vacuum pump from condensable load.
Which vacuum gauge and leak test should you require?
Gauge type changes what you believe your process is doing. Thermal-conductivity gauges such as a Pirani drift under solvent and terpene vapor, while a capacitance manometer reads absolute pressure independent of gas composition. Specify the gauge type and its mounting point at the chamber, then trend it. At commissioning, a vacuum rise test and a measured leak rate tell you whether the system holds the vacuum it was sold on.
Which utility numbers do you need before layout?
Lock the utility side early, and get the numbers from the vendor in engineering units, not categories: total connected electrical load and voltage/phase for the drive, heaters and controls; heating fluid loop temperature and flow; chilled fluid supply temperature and heat rejection duty for the condenser and traps; and vertical headroom for rotor removal above the body. Facility and project engineers who leave these to the end redesign the room twice.
Why does feed preparation decide whether the system hits its rating?
Because a wiped film system separates what you give it. Inconsistent feed produces inconsistent distillate, and most reports of an underperforming evaporator trace back to feed condition rather than the evaporator.
- Remove and filter waxes and lipids upstream — see winterization hold time and filter capacity.
- Decarboxylate where the process requires it; our notes on designing a decarboxylation system cover sizing and control.
- Devolatilize residual extraction solvent before the feed reaches the still.
- Control feed viscosity and feed-line temperature so the gear pump delivers a steady rate.
- Plan residue handling: where bottoms discharge, how they are collected hot, and whether they get reprocessed.
Residual solvent in the feed is a vacuum problem before it is a purity problem. Light volatiles load the traps and push achievable pressure the wrong direction, which forces jacket temperature up and puts thermal stress back on the material you were trying to protect — which is why feed condition can cap throughput no matter how much surface area you bought.
Feed rate control is a quality variable, which is why the WFDS platform uses precision gear pumps with touchscreen control of temperature, vacuum, pump speeds and motor settings, so a recipe repeats across operators and shifts. If terpene fractions are part of your product plan, capture them on dedicated equipment such as the TES Series terpene distillation equipment rather than asking one body to do both duties.
Which compliance marks, controls and acceptance tests should you specify?
Compliance marks describe how a system was built and evaluated. Read them as scope statements rather than blanket approvals, and confirm which mark applies to which part of the package.
What do the marks on a spec sheet actually cover?
An ASME stamp covers a pressure vessel and a UL 508A mark covers a control panel; neither covers the room. ASME Boiler and Pressure Vessel Code Section VIII, Division 1 covers the design, fabrication, inspection, testing and certification of pressure vessels operating at internal or external pressures exceeding 15 psig, per ASME’s own scope statement. UL 508A covers industrial control panels for general industrial use operating at 1000 volts or less, intended for installation in ordinary locations in accordance with the National Electrical Code (ANSI/NFPA 70), according to the published UL 508A scope. The buyer’s takeaway: a UL 508A panel is scoped to ordinary locations, and equipment intended for hazardous (classified) locations is evaluated under separate standards. MACH equipment carries CE, IECEx, UL 508A, PSI and ASME marks, and we do not claim anything beyond that list.
Who decides area classification?
Area classification is a project decision, not a product feature. Which equipment is acceptable in your room is settled with your local authority having jurisdiction, your project’s fire and electrical engineers, and your insurer. It is not settled by a spec sheet. Bring those parties in during layout, before equipment is released for fabrication, and specify hazardous-location rated components where the assigned classification calls for them.
What should factory acceptance testing include?
Acceptance testing is your real leverage, and it should be named in the purchase order: vacuum rise and leak check, hydrostatic testing where applicable, and a documented operational run before the system ships. We test systems in our own facility before shipment, and the WFDS platform is built GMP-ready in design and documentation terms, with the records that support your quality system rather than a regulatory status asserted on your behalf. If a quality system is in scope for your build, read our approach to GMP documentation and controls that scale.
What does a wiped film system cost to own after the purchase order?
Capital price is the smaller half of the decision. Wiper blades, mechanical seals, bearings, trap consumables, cleaning labor and downtime per changeover set your cost per liter of distillate, and the lowest installed cost is rarely the lowest five-year cost.
Which costs recur after the purchase order?
Populate five lines before you sign: annual wear-part spend; cleaning hours per changeover multiplied by changeovers per year; operator hours per shift; utility load for heating fluid, chilled fluid and electrical; and expected downtime hours against the value of a spares kit sitting on your shelf. The mistake we correct most often is a buyer sizing surface area precisely and then ignoring changeover hours that quietly remove weeks of annual capacity.
How do you get repeatable results across shifts?
Touchscreen recipe control and automated vacuum protection are what let a second-shift operator reproduce a first-shift result without a specialist standing over the system. Put the support model in the comparison as well: MACH provides installation, operator training and on-demand technical support, and when the still is the chokepoint of a refinement line, how fast a problem gets diagnosed shows up directly in output.
Should you buy new or used?
Treat it as a lead-time-versus-known-condition tradeoff and price the unknowns. A used unit can compress lead time, and that is a real advantage when a license or a supply agreement is driving your schedule. It usually arrives without factory acceptance testing, without a known wiper and seal wear history, and without a support relationship.
The specification questions in this piece are the ones we work through with processors and project engineers: surface area against duty, wiper geometry against feed, vacuum train against target temperature, feed prep against rating, and acceptance testing against documentation. Review the WFDS Series wiped film distillation systems and the wider post-processing and refinement systems line, then talk through a wiped film specification with our engineering team before you release a purchase order.
Wiped film system FAQs
Is a wiped film evaporator the same as a thin film evaporator?
Yes. A wiped film evaporator and a thin film evaporator describe the same mechanically renewed film architecture, in which a rotor spreads feed on a heated wall under vacuum. Naming varies by vendor, industry sector and geography, and “agitated thin film evaporator” refers to the same equipment class.
What is the difference between wiped film and short path distillation?
A wiped film system runs continuously with residence time in the range of seconds to a couple of minutes. Batch glass short path distillation holds material on heat for the full run and requires operator attention throughout. The continuous mode is what gives wiped film its higher throughput ceiling and better run-to-run consistency.
How is a wiped film system sized?
A wiped film system is sized by heated surface area in square meters against the separation duty, then validated against your actual feed. A single quoted liters-per-hour figure is conditional, because throughput moves with feed viscosity, volatile load, target purity, vacuum depth and jacket temperature.
What surface areas are available on the MACH WFDS Series?
The WFDS Series is offered from 0.15 to 0.60 square meters of heat transfer surface area: the single-stage WFDS-1S at 0.15, 0.30 and 0.40 m², and the dual-stage WFDS-2S at 0.30, 0.40 and 0.60 m².
What has to happen to the feed before it enters a wiped film system?
Feed should be filtered and winterized to remove waxes and lipids, decarboxylated where the process requires it, and devolatilized of residual extraction solvent. It should reach the still at a controlled temperature and a steady pump rate. Residual solvent loads the cold traps and pushes achievable vacuum the wrong direction.
What compliance marks should a wiped film system carry?
MACH Technologies equipment carries CE, IECEx, UL 508A, PSI and ASME marks, and each mark covers a defined scope rather than the whole installation. Area classification for the room itself is settled with your local authority having jurisdiction and your project’s fire and electrical engineers, not by an equipment spec sheet.
What should a factory acceptance test include before shipment?
Ask for a vacuum rise and leak check, hydrostatic testing where applicable, and a documented operational run. MACH tests systems in its own facility before shipment.
MACH Technologies manufactures and sells processing equipment. It does not cultivate, produce, sell, or distribute botanical material or any botanical end product.
Extraction equipment must be installed, permitted, and operated in accordance with all applicable federal, state, and local fire, building, and electrical codes, including Class I Division 1 requirements where applicable. Consult your Authority Having Jurisdiction (AHJ) before installation.
Throughput, yield, purity, and solvent recovery figures vary with input material, system configuration, and process parameters. Published figures are not a guarantee of results.
Nothing on this site is medical advice, and no MACH Technologies equipment or the products made with it are represented as diagnosing, treating, curing, or preventing any disease.
Operators are responsible for verifying that their intended use is lawful in their jurisdiction.