Vacuum Precooler & Freeze Dryer – Frequently Asked Questions (FAQ)

Question 1

How does a vacuum precooler work?

Accepted Answer

A vacuum precooler uses the principle of evaporative cooling under low pressure to rapidly chill food products. Food is loaded into a sealed chamber, the vacuum pump evacuates the chamber to 100–600 Pa, moisture on the food surface evaporates rapidly at that low pressure absorbing roughly 2,500 J per gram, and the food temperature drops from 25–30°C to 0–5°C within 30 minutes. A refrigeration system condenses the evaporated moisture to prevent over-dehydration, keeping moisture loss below 2%.

Question 2

How does vacuum precooling compare to traditional methods such as forced-air cooling, hydro-cooling, and ice cooling?

Accepted Answer

Vacuum precooling cools food in just 5–30 minutes vs. 4–8 hours for forced-air cold rooms. Moisture loss is under 2% vs. 5–15% for forced-air cooling. Cooling is uniform from core to surface. The footprint is small (1.5–12 m²). Comprehensive operating costs are 30–50% lower. The sealed chamber eliminates cross-contamination risk. Vacuum precooling is the preferred choice for modern food cold chains.

Question 3

Are a vacuum precooler and a food vacuum rapid cooler the same machine?

Accepted Answer

They are related but serve different purposes. A vacuum precooler is primarily for pre-cooling fresh produce after harvest, targeting 0–5°C, used by vegetable farms and fresh produce distributors (representative models: CVF-100, CVF-500, CVF-800). A food vacuum rapid cooler is for chilling cooked and processed food, targeting 0–10°C, used by central kitchens and food factories (representative models: CVF-30, CVF-150). Contact us for a free application assessment if you are unsure.

Question 4

What types of food can be processed in a vacuum precooler?

Accepted Answer

Vacuum precoolers handle: leafy vegetables (5–10 min), cauliflower and broccoli (10–15 min), root vegetables (15–25 min), berries (8–15 min), cooked food and ready meals (10–20 min), braised and roasted meats (15–25 min), meat carcasses (20–30 min), shrimp and fish (10–20 min), and bakery products such as bread and cakes (8–12 min). All Vacuum-Fresh machines ship with pre-programmed recipes for common food categories.

Question 5

How do I choose the right vacuum precooler model?

Accepted Answer

Use 4 criteria: Batch capacity — under 500 kg/day choose CVF-30, 500–2000 kg/day choose CVF-100, 2000–8000 kg/day choose CVF-500, over 8000 kg/day choose CVF-800 or custom. Food type — fresh produce use CVF series, cooked food use CVF-30 or CVF-150, freeze-drying needs use VFD series. Floor space — CVF-30 needs as little as 2 m². Power budget — CVF-30 uses 3–5 kWh per cycle, CVF-800 uses 15–20 kWh per cycle. Share your product type and daily volume for a free selection report.

Question 6

Is the VFD-H040 small freeze dryer suitable for home use or small workshops?

Accepted Answer

Absolutely. The VFD-H040 processes 40 kg fresh weight per batch yielding approximately 8–10 kg dry product. Its footprint is only 1.5 m² and it weighs 280 kg. It requires 380V three-phase power at about 5 kW. Cycle time is 16–24 hours with PLC automatic one-button operation. Ideal for home food processing, e-commerce startups, small food workshops producing 8–20 kg dry output daily, and research labs. Note: 380V three-phase power is required; standard residential buildings cannot support this.

Question 7

How fast does a vacuum precooler cool food?

Accepted Answer

Reference cooling times from 25°C to 2–5°C: leafy vegetables 5–10 min, cauliflower and broccoli 10–15 min, root vegetables 15–25 min, cooked food 10–20 min, meat carcasses 20–30 min, berries 8–15 min, bread and cakes 8–12 min. A traditional forced-air cold room takes 4–8 hours for the same result — vacuum precooling is 15–50 times faster.

Question 8

How do I set vacuum precooling process parameters for different foods?

Accepted Answer

Leafy vegetables: 400–600 Pa, target 1–3°C, 5–10 min; avoid too deep a vacuum to prevent over-dehydration. Root vegetables: 300–500 Pa, 2–5°C, 15–25 min. Berries: 500–700 Pa, 2–4°C, 8–15 min; too low a vacuum may crack thin skins. Cooked food: 300–500 Pa, 3–8°C, 10–20 min. Meat and poultry: 100–300 Pa, 0–4°C, 20–30 min. Bread and baked goods: 500–800 Pa, 5–10°C, 8–12 min. All Vacuum-Fresh machines ship with pre-programmed recipes ready to use.

Question 9

Is the energy consumption high? What are the operating costs?

Accepted Answer

Energy consumption is significantly lower than traditional pre-cooling. CVF-30 uses 3–5 kWh per cycle for 30–50 kg; CVF-100 uses 6–10 kWh for 100–150 kg; CVF-500 uses 20–30 kWh for 500–600 kg; CVF-800 uses 30–40 kWh for 800 kg plus. Forced-air cold rooms use 2–3 times more electricity for the same cooling load. Comprehensive operating cost savings are 30–50%.

Question 10

Is maintenance expensive?

Accepted Answer

Day-to-day maintenance is simple and low-cost. Component lifespans: vacuum pump 5–8 years (replace oil every 500 hours), refrigeration compressor 8–10 years (annual refrigerant check), PLC control system 10 or more years, stainless-steel chamber 10–15 years. Annual maintenance cost estimate: consumables approximately 500–1500 CNY per year, scheduled servicing approximately 800–2000 CNY per year, totalling about 1.5–3% of purchase price per year. Vacuum-Fresh includes one free annual on-site service visit for the first 3 years after purchase.

Question 11

What is the price range for vacuum precoolers?

Accepted Answer

Reference prices in CNY: CVF-30 small single-phase machine 30,000–50,000; CVF-100 mid-size standard 80,000–120,000; CVF-500 large machine 120,000–180,000; CVF-800 heavy-duty 200,000–300,000; VFD-H040 small freeze dryer 60,000–100,000; VFD-H060 standard freeze dryer 100,000–150,000. Pricing factors include capacity specification, custom configurations, installation location, and whether a maintenance package is included. Contact us with your product type and daily throughput for a tailored proposal.

Question 12

What is Vacuum-Fresh's warranty and after-sales policy?

Accepted Answer

Warranty: full machine warranty 1 year, core components (compressor and vacuum pump) 3 years, lifetime technical support. After-sales services include: nationwide on-site installation and commissioning, operator training with video manual, 24-hour fault response with remote diagnosis, on-site repair within 48 hours in South China or 72 hours elsewhere, spare parts shipped within 48 hours, and one free on-site annual maintenance visit per year for the first 3 years after purchase.

Question 13

What vacuum level is required for effective precooling?

Accepted Answer

Required vacuum levels vary by food type: fruits and vegetables 100–600 Pa, meat and poultry 50–300 Pa, cooked food and ready meals 80–500 Pa. Insufficient vacuum (pressure not low enough) results in slow cooling and poor results. Excessive vacuum (pressure too low) causes over-dehydration and quality degradation. All Vacuum-Fresh models achieve a stable vacuum of 100 Pa or lower, meeting every food-processing application.

Question 14

What are the key components and their expected lifespans?

Accepted Answer

Four key components: vacuum pump (evacuates chamber, 5–8 year lifespan, reputable domestic or optional imported brand); refrigeration compressor (condenses moisture, 8–10 year lifespan, Copeland, Bitzer, or FUSHENG); PLC control system (automation and alarms, 10 or more year lifespan, Siemens or Mitsubishi); stainless-steel chamber (sealed food container, 10–15 year lifespan, 304 or 316 food-grade stainless steel).

Question 15

How much floor space is needed for installation?

Accepted Answer

CVF-30 dimensions approximately 1200×900×1500 mm, minimum floor area 2–3 m², doorway height at least 1800 mm. CVF-100 approximately 2200×1100×1800 mm, 5–8 m², doorway at least 2000 mm. CVF-500 approximately 4500×1400×2000 mm, 12–18 m², doorway at least 2200 mm. CVF-800 approximately 6000×1600×2200 mm, 20–30 m², doorway at least 2400 mm. Site requirements: good ventilation with 1 m clearance on all sides, 380V three-phase power, floor drain nearby, floor load capacity at least 1000 kg per m² for large models.

Question 16

What are the installation prerequisites?

Accepted Answer

Power supply: 380V three-phase four-wire with circuit rated at 1.2 times machine rated power; CVF-30 single-phase version needs 220V only. Drainage: floor drain near the machine for cleaning water. Floor level: flatness deviation no more than 5 mm; large models need floor load capacity of at least 1000 kg per m². Ambient temperature: 5–40°C; outdoor installation not recommended. Ventilation: 1 m minimum clearance around machine. Operator: no special certification required; free training provided. Our engineers conduct a pre-installation site survey before commencing work.

Question 17

How noisy is a vacuum precooler during operation?

Accepted Answer

Operating noise levels: CVF-30 is 68 dB or less (similar to normal conversation), CVF-100 is 72 dB or less (similar to a busy street), CVF-500 and CVF-800 are 75 dB or less (meets industrial site environmental standards). Options to reduce noise include an optional soundproof enclosure for an additional 5–10 dB reduction, installing in a dedicated equipment room separated from the production floor, and custom acoustic solutions available on request.

Question 18

Can vacuum precoolers be customized? How long does it take?

Accepted Answer

Full customization is available including: non-standard capacity specifications, custom chamber dimensions, automated loading and unloading systems such as push carts or conveyors, ERP or MES integration and cloud remote monitoring, FDA, CE, and ISO certified models for export, and 316L stainless steel for seafood or high-salinity environments. Lead times: minor customization 7–15 days, moderate customization 15–25 days, deep customization 30–45 days.

Question 19

What advantages does Vacuum-Fresh offer over competitors?

Accepted Answer

Four core advantages: compact design with 30–50% smaller footprint than comparable competitors for equivalent capacity; energy efficiency with 10–20% lower energy consumption than industry average; fast delivery with standard models shipped in 7–15 days versus an industry average of 30–45 days; and free sample testing and factory trials that most competitors do not offer. Pricing is 15–25% lower than comparable premium brands. Core positioning: purpose-built for small-to-medium food processors and vegetable farms with full service support.

Question 20

Can I try the machine before purchasing?

Accepted Answer

Yes, three trial options are available. First, send a sample for testing: ship 1–5 kg of your product to our factory, we run the actual cooling cycle and provide a detailed test report with cooling time, moisture loss, and temperature curve, completely free with the report delivered within 7 business days. Second, factory visit and live demonstration: schedule a visit to our Dongguan factory to watch the machine run live with full technical briefings. Third, performance guarantee: if the machine does not meet contracted cooling targets after installation and commissioning, we provide free rectification until targets are achieved, with return or exchange possible in exceptional cases.

Criterion	Vacuum Precooler	Forced-Air Cold Room	Hydro-Cooling	Ice Cooling
Cooling time	10–40 min	4–8 hours	1–2 hours	2–4 hours
Moisture loss	<3%	5%–15%	~3%	~5%
Cooling uniformity	Core & surface simultaneously	Surface first, core lags	Surface only	Uneven
Footprint	Small (1.5–12 m²)	Requires large cold room	Needs large water tank	Requires bulk ice
Operating cost	30%–50% savings	Medium	Medium	High (ice cost)
Hygiene	Sealed chamber, no cross-contamination	Risk of cross-contamination	Water quality dependent	Contamination risk
Suitable products	vegetablw, cooked food, ,	Universal	Poultry, pork	Seafood

Dimension	Vacuum Precooler	Food Vacuum Rapid Cooler
Primary use	Pre-cooling fresh produce after harvest	Rapid chilling of cooked/processed food
Target temperature	0–5°C (just above freezing)	0–10°C (food-safety compliant)
Typical users	Vegetable farms, fresh produce distributors	Central kitchens, food factories, catering chains
Chamber design	Large-capacity with tray/cart loading	Food-grade certified, hygiene-focused interior
Representative models	CVF-1000, CVF-500, CVF-2000,CVF-3000	CVF-30 (single-phase), CVF-100,CVF-200,CVF-300

Daily throughput	Recommended model	Batch capacity
<500 kg/day	CVF-30	30–50 kg/batch
500–2,000 kg/day	CVF-100	100–150 kg/batch
2,000–8,000 kg/day	CVF-500	500–600 kg/batch
>8,000 kg/day	CVF-800 or custom	800 kg+/batch

Specification	VFD/CVD-H040
Fresh-weight batch capacity	40 kg/batch
Dry-weight yield	~8–10 kg/batch (75%–80% moisture removed)
Footprint	~1.5 m²
Machine weight	~100 kg
Power supply	380V 3-phase / ~5 kW
Cycle time	16–24 hours (varies by moisture content)
Operation	One-button start, PLC automatic control

Food type	Cooling time	Notes
Leafy vegetables (spinach, lettuce)	30–40 min	High moisture content, fast evaporation
Cooked food (rice, braised meats)	10–20 min	Varies with density and moisture
Berries (strawberry, grape)	8–15 min	Thin skin, high moisture
Bread / cakes	8–12 min	Porous structure aids fast heat removal

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Food category	Vacuum level	Target end temperature	Reference cycle time	Notes
Leafy vegetables	400–600 Pa	1–3°C	5–10 min	Avoid too deep a vacuum to prevent over-dehydration
Cooked food / ready meals	300–500 Pa	3–8°C	10–20 min	Must meet food-safety core-temperature requirements
Bread / baked goods	500–800 Pa	5–10°C	8–12 min	Avoid excessive vacuum to prevent surface collapse

Model	Energy per cycle	Batch capacity	Energy per kg
CVF-30	3–5 kWh	30–50 kg	~0.06–0.10 kWh/kg
CVF-100	6–10 kWh	100–150 kg	~0.05–0.08 kWh/kg
CVF-500	20–30 kWh	500–600 kg	~0.04–0.06 kWh/kg
CVF-800	30–40 kWh	800 kg+	~0.04–0.05 kWh/kg

Component	Expected lifespan	Maintenance tips
Vacuum pump	5–8 years	Replace pump oil every 500 operating hours; inspect seals annually
Refrigeration compressor	8–10 years	Check refrigerant level and filters annually; ensure good airflow
PLC control system	10+ years	Keep control cabinet clean and dry
Steel spray painting/ Stainless-steel chamber	10–15 years	Wash after each use; prevent food residue corrosion

Model	Price range (CNY)	Best for
CVF-30 (small, single-phase)		Small restaurants, small-batch produce
CVF-100 (mid-size standard)		Vegetable farms, central kitchens, supermarket distribution
CVF-500 (Mid)		Large central kitchen, small and medium-sized farm vegetable base
CVF-1000 (heavy-duty)		Large food factories, export produce processing bases
CVF-2000 (standard machine)		Medium-sized fruit and vegetable farm, processing base
CVF-3000 (standard machine)		Medium-sized fruit and vegetable farm, processing base
CVF-3000 above		Large fruit and vegetable farm, processing base, export fruit and vegetable processing base
VFD-H040 (small freeze dryer)		Home / small workshop freeze drying
VFD-H060 (standard freeze dryer)		Small-to-mid-size freeze-dried food enterprises

Scope	Period
Full machine warranty	1 year
Core components (compressor, vacuum pump)	2 years
Lifetime technical support	Unlimited

Food category	Required vacuum level	Notes
Fruits & vegetables	500–600 Pa	Lower pressure = faster cooling, but higher moisture loss
Flower	800—1000 Pa	Temperatures that are too low will freeze flowers;
Cooked food / ready meals	500—600 Pa	Balances food safety and quality

Component	Function	Brand specification	Lifespan
Vacuum pump	Evacuates chamber to create low-pressure environment	Reputable domestic brand / optional imported	5–8 years
Refrigeration compressor	Condenses evaporated moisture; prevents over-dehydration	Copeland / Bitzer / Hanbell	8–10 years
PLC control system	Automates operation, displays parameters, triggers alarms	LS/Siemens / Mitsubishi PLC	10+ years
Chamber	Sealed food container, withstands vacuum pressure	Steel spray painting 304 / 316 food-grade stainless steel	10–15 years

Model	Machine dimensions	Minimum floor area	Doorway height
CVF-30	~1,200×900×1,500 mm	2–3 m²	≥1,800 mm
CVF-100	~1,600×1,100×1,800 mm	5–8 m²	≥2,000 mm
CVF-500	~2,800×1,400×2,000 mm	12–18 m²	≥2,200 mm
CVF-1000	约 4,500×1,600×2,200 mm	20—30 ㎡	≥2,400 mm

Category	Requirement
Power supply	380V three-phase four-wire; circuit rated at ≥1.2× machine rated power. CVF-30 single-phase: 220V only
Drainage	Floor drain near the machine for cleaning water
Floor level	Flatness deviation ≤5 mm; large models: ≥1,000 kg/m² load rating
Ambient temperature	5–40°C; outdoor / exposed installation not recommended
Ventilation	Minimum 1 m clearance around machine
Operator	No special certification required; free training provided by Vacuum-Fresh

Model	Operating noise	Comparison
CVF-30	≤68 dB	Similar to normal conversation
CVF-100	≤72 dB	Similar to a busy street
CVF-500 / CVF-800	≤75 dB	Meets industrial site environmental standards

Customization area	Details
Capacity specification	Non-standard volumes (e.g., 2500 kg per batch)
Chamber dimensions	Custom sizes to fit special products (e.g., large hay bales, full crates)
Loading/unloading	Automatic push carts, chain conveyors, robotic arm integration
Control system	ERP/MES integration, cloud remote monitoring, multi-machine management
Certifications	FDA / CE / ISO certified models for export markets
Special materials	316L stainless steel for seafood or high-salinity environments

Advantage	Vacuum-Fresh	Industry average
Compact design	30%–50% smaller footprint for equivalent capacity	Larger machines
Energy efficiency	10%–20% lower energy consumption	Industry average
Delivery speed	Standard models: 15–20 days	30–45 days typical
Trial service	Free sample testing / factory trial available	Mostly unavailable
Price point	15%–25% lower than comparable premium brands	Higher pricing
Technical support	In-house engineers; fast response	Some brands outsource after-sales