Double bag filter

Product description

Double Bag Filter – High-Efficiency Liquid Purification for Continuous Production

In the food and beverage, pharmaceutical, and industrial processing industries, 

the removal of invisible solid impurities from liquids is essential to ensuring product quality, safety, 

and process consistency. The Double Bag Filter is a high-performance liquid filtration system designed to

 efficiently purify a wide range of liquids, including fresh milk, sugar solutions, beverages, oral liquids, 

and various industrial fluids. Featuring a dual-cylinder design that enables filter bag replacement without 

process interruption, this system is ideal for long-term continuous production environments.

This article provides a comprehensive overview of the Double Bag Filter, including its product features, 

technical specifications, working principle, application fields, and a detailed FAQ section to support your 

product selection and operational planning.

I. Product Overview

The Double Bag Filter consists of two cylindrical filter housings, with both internal and external surfaces

 meticulously polished to ensure smooth flow and easy cleaning. Each cylinder is equipped with a 

top-mounted pressure gauge and an exhaust valve for convenient monitoring and venting. 

The system is designed with flexibility and compactness in mind, offering simple operation and

 straightforward maintenance.

The two filter cylinders operate alternately, allowing one bag to be replaced while the other continues filtering, 

ensuring zero production downtime. This makes the Double Bag Filter particularly suitable for applications

 requiring uninterrupted, long-term continuous production.

II. Key Features and Advantages

1. Alternating Dual-Bag Design – Two filter cylinders operate in parallel, enabling seamless bag replacement

 without stopping the production process. This ensures continuous operation and maximizes productivity.

2. High-Quality Surface Finish – Both internal and external surfaces are precision-polished (mirror finish or 

matte finish available), minimizing product adhesion, facilitating thorough cleaning, and meeting hygiene standards 

for food and pharmaceutical applications.

3. Compact and Flexible Configuration – The system features a space-saving, compact design with flexible installation options,

 making it suitable for workshops with limited floor space.

4. Easy Operation and Maintenance – Simple bag change mechanism and accessible housing design reduce operator 

effort and maintenance time, improving overall operational efficiency.

5. Real-Time Monitoring – Equipped with top-mounted pressure gauges and exhaust valves on each cylinder, 

allowing operators to monitor filter condition and vent trapped air for optimal filtration performance.

6. Wide Range of Filtration Options – Available with filter mesh sizes from 60 to 400 meshes, accommodating 

diverse filtration precision requirements for different liquids.

7. Excellent Material Quality – Constructed from high-grade 304 or 316L stainless steel, offering excellent corrosion resistance, 

durability, and compliance with food-grade and sanitary standards.

8. Versatile Capacity Range – Available in multiple flow capacities (1t/h, 3t/h, 5t/h, 10t/h) to suit different production scales.

III. Technical Specifications

Parameter Specification

Product Name Double Bag Filter

Filtration Area 0.15㎡, 0.30㎡ (selectable)

Filtration Capacity 1t/h, 3t/h, 5t/h, 10t/h (selectable)

Applicable Temperature ≤120°C

Filter Mesh Size 60 ~ 400 meshes (selectable)

Working Pressure ≤0.2 MPa

Filter Material 304 stainless steel / 316L stainless steel

Surface Treatment Internal mirror polished; External mirror polished or matte finish

Seal Material Food-grade silicone / EPDM / FKM (optional)

Connection Type Flange / Quick-release clamp (optional)

IV. Working Principle

The Double Bag Filter operates on a simple yet effective pressure-filtration principle:

1. The liquid to be filtered enters the filter cylinder through the inlet port.

2. As the liquid passes through the filter bag (with a specified mesh size), solid impurities, particles, and invisible 

contaminants are trapped inside the bag.

3. The clean, purified liquid flows out through the outlet port, ready for downstream processing or packaging.

4. The two cylinders work alternately: while one cylinder is in operation, the other can be taken offline for bag replacement,

 cleaning, or maintenance, ensuring continuous production.

The pressure gauge monitors the differential pressure across the filter bag; when the pressure rises to a predetermined level, 

it indicates that the bag is clogged and requires replacement.

V. Application Fields

The Double Bag Filter is widely used across multiple industries for liquid purification and solid impurity removal:

1. Food and Beverage Industry – Filtration of fresh milk, sugar solutions, syrups, juices, beverages, edible oils, 

and other liquid food products, ensuring clarity and compliance with hygiene standards.

2. Pharmaceutical Industry – Purification of oral liquids, liquid medicines, injection water, and other pharmaceutical

 intermediates, meeting strict GMP requirements.

3. Water Treatment – System purification in cooling units, oilfield water injection, well-free filtration, 

power plant condensate water purification, and ion exchange resin recovery.

4. Automobile Manufacturing – Filtration of electrophoretic paint, hardeners, solvents, and pre-packaging filtration in

 automotive coating processes.

5. Aluminum Manufacturing – Sediment removal and filtration in phosphate tanks, precious metal recovery from process

 streams.

6. Electronics Industry – Removal of zinc deposits from zinc hydroxide solvents, impurity removal from copper electrolytic 

stabilization cells, and high-purity water pre-filtration.

7. Chemical Industry – Filtration of various chemical solutions, solvents, and intermediate products requiring solid-liquid 

separation.

VI. Frequently Asked Questions (FAQ)

Q1: How does the alternating dual-bag design work?

A: The system features two independent filter cylinders connected in parallel. Under normal operation, 

both cylinders can run simultaneously, or one can run while the other is on standby. When the filter bag in the active 

cylinder becomes clogged (indicated by pressure gauge reading), you can switch flow to the standby cylinder and

 replace the bag in the first unit without stopping the production process, ensuring continuous operation.

Q2: How do I know when to replace the filter bag?

A: Monitor the pressure gauge on each cylinder. When the differential pressure rises to 0.1–0.15 MPa above the initial 

clean bag pressure, it indicates that the bag is clogged and requires replacement. The specific replacement threshold 

should be determined based on your process requirements and liquid characteristics.

Q3: Can the filter bag be cleaned and reused?

A: It depends on the bag type and application. Some filter bags (particularly woven mesh types) can be cleaned and

 reused multiple times, while others (especially depth-type felt bags) are designed for single-use. For food and 

pharmaceutical applications, we generally recommend single-use bags to ensure product purity and avoid 

cross-contamination. Please consult our technical team for specific recommendations.

Q4: What is the difference between 304 and 316L stainless steel?

A:

· 304 Stainless Steel: Standard food-grade material, suitable for most general-purpose applications with good corrosion 

resistance.

· 316L Stainless Steel: Contains molybdenum, offering superior corrosion resistance, particularly against chlorides and

 acidic media. Recommended for pharmaceutical, saltwater, and highly corrosive environments.

  Both materials meet food-grade and sanitary standards.

Q5: What mesh size should I choose for my application?

A: Mesh size selection depends on the particle size you need to remove:

· 60–100 meshes: Coarse filtration, removing larger visible particles.

· 150–200 meshes: Medium filtration for general liquid clarification.

· 250–400 meshes: Fine filtration for removing invisible solid impurities.

  For food and beverage applications, typical mesh sizes range from 100 to 300 meshes. Please contact our technical 

team for customized recommendations.

Q6: Can this filter handle high-temperature liquids?

A: Yes. The Double Bag Filter is designed to handle temperatures up to 120°C. For higher temperature applications,

 please consult our engineering team to select appropriate seal materials and housing designs.

Q7: What is the maximum working pressure of this filter?

A: The standard design working pressure is ≤0.2 MPa (approximately 2 bar). For higher pressure applications, 

we offer reinforced designs upon request.

Q8: Is this filter suitable for CIP (Clean-in-Place) cleaning?

A: Yes. The Double Bag Filter is designed with polished internal surfaces and sanitary connections, making it compatible 

with CIP cleaning systems. The smooth finish prevents product buildup and facilitates thorough cleaning.

Q9: How do I vent air from the filter system?

A: Each cylinder is equipped with a top-mounted exhaust valve. During initial filling or after bag replacement, 

open the exhaust valve to release trapped air until liquid flows out, then close the valve. This ensures optimal filtration 

performance and prevents air locks.

Q10: What seal material options are available?

A: We offer multiple seal material options to suit different applications:

· Silicone: Food-grade, suitable for general food and beverage applications.

· EPDM: Good chemical resistance, suitable for water treatment and some chemicals.

· FKM (Viton): Excellent high-temperature and chemical resistance, suitable for aggressive media.

  Please specify your working medium and temperature when ordering.

Q11: Can I use this filter for viscous liquids?

A: Yes. However, high-viscosity liquids may require larger filtration area or lower flow rates to maintain reasonable 

pressure drops. We recommend selecting a coarser mesh size and ensuring adequate inlet pressure. 

Our technical team can help optimize the configuration for your specific fluid properties.

Q12: How often should I perform maintenance on the filter housing?

A: We recommend inspecting the housing, seals, and pressure gauges during each bag change. Perform a thorough 

inspection and cleaning of the housing interior at least once a month. Replace seals annually or sooner if signs of 

wear or damage appear.

Q13: What is the recommended storage condition for unused filter bags?

A: Store filter bags in their original packaging in a dry, cool, and dust-free environment. Avoid direct sunlight, moisture,

 and exposure to chemicals. Recommended storage temperature is below 40°C with relative humidity under 70%.

Q14: How do I properly dispose of used filter bags?

A: Used filter bags may contain product residues or captured contaminants. Follow local environmental regulations

 for disposal. For food and beverage applications, bags should be drained and disposed of as general industrial waste;

 for pharmaceutical or chemical applications, they may require hazardous waste handling.

Q15: Can I customize the filter capacity for my production line?

A: Absolutely. We offer standard models at 1t/h, 3t/h, 5t/h, and 10t/h capacities. For other capacity requirements, 

we can provide customized solutions based on your flow rate, liquid properties, and space constraints. 

Please contact our sales team for detailed consultation.

Conclusion

The Double Bag Filter is a versatile, high-performance liquid purification system designed for industries requiring continuous,

uninterrupted filtration. Its innovative alternating dual-cylinder design allows filter bag replacement without production 

downtime, making it ideal for long-term continuous production in food, beverage, pharmaceutical, water treatment,

 automotive, aluminum manufacturing, electronics, and chemical industries.

With its compact construction, easy operation, low maintenance requirements, high-quality stainless steel materials, 

and a wide range of capacity and mesh size options, the Double Bag Filter delivers reliable, consistent filtration performance. 

Whether you are purifying fresh milk, sugar solutions, beverages, oral liquids, or industrial process fluids, 

this system provides the efficiency and reliability you need.

For more technical information, customized solutions, or selection support, please contact our sales and technical 

support team today.

Product Details