Bag Filter Manufacturer in India | Industrial Dust Collection Systems
AS Engineers designs and manufactures bag filter systems for industrial dust collection and air pollution control. Our systems are built to meet CPCB outlet emission norms, sized to your actual gas volume and dust load, and supplied with filter media matched to the temperature, moisture, and chemical conditions of your specific process.
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A bag filter is not optional for most industrial processes in India today. Under the Environment Protection Act 1986 and CPCB stack emission standards, industrial units across cement, chemical, pharma, and power sectors are required to maintain particulate matter (SPM) levels at the stack outlet – typically below 150 mg/Nm³ for large boilers and below 50 mg/Nm³ for many process industries. NGT directions have tightened enforcement further since 2015.
If your plant generates dusty exhaust – from a kiln, dryer, grinder, classifier, conveying system, or any combustion process – we can design a bag filter system to bring it into compliance and keep it there.
Talk to our engineers about your application
How a Bag Filter Works
Dust-laden gas enters the bag filter housing through an inlet duct. Inside the housing, fabric filter bags are suspended vertically from a tube sheet. As gas passes through the fabric, particulate matter is captured on the outer surface of the bags. Cleaned gas passes through the inner bore of the bags and exits through the clean air plenum at the outlet.
Over time, the dust cake that accumulates on the bag surface increases the pressure drop across the filter. A cleaning mechanism dislodges the cake at controlled intervals, dropping the collected dust into a hopper below for discharge through a rotary airlock valve or screw conveyor.
A centrifugal blower or ID fan positioned upstream or downstream of the housing provides the required draft. For gas streams with very high dust concentrations, a cyclone separator is installed upstream as a pre-separator, reducing the load on the filter bags and extending their service life.
Cleaning Mechanisms: Pulse-Jet, Reverse Air, and Shaker
The cleaning mechanism determines maintenance frequency, compressed air consumption, and suitability for different dust types. AS Engineers manufactures all three types:
Pulse-Jet Bag Filter (most common) Compressed air pulses are fired sequentially through venturi nozzles into each row of bags. The pressure wave inflates and flexes the bag, breaking the dust cake loose. Cleaning happens online – the unit does not need to be taken offline. Suitable for fine, free-flowing dusts. Air-to-cloth ratio typically 1.5 to 3.0 m/min depending on dust characteristics.
Reverse Air Bag Filter The dirty air chamber is isolated compartment by compartment. A fan blows clean air backward through the bags, gently collapsing them and releasing the dust cake. No compressed air needed. Preferred for fragile filter media (woven fiberglass) and for dusts that are difficult to dislodge without bag damage.
Mechanical Shaker Bag Filter A mechanical shaker vibrates the bag tops in a sinusoidal motion. Offline cleaning: the compartment is taken out of service during cleaning. Lower capital cost. Suitable for coarser, free-flowing dust where online cleaning is not required.
| Cleaning Type | Online/Offline | Compressed Air | Best For |
|---|---|---|---|
| Pulse-Jet | Online | Yes | Fine dust, cement, chemical, pharma |
| Reverse Air | Offline | No | Fragile media, high temp, fragile dust cake |
| Mechanical Shaker | Offline | No | Coarse dust, lower-cost applications |
Filter Media Selection
The wrong filter media is the most common cause of premature bag failure. Selection depends on gas temperature, moisture content, chemical composition, and the abrasiveness of the dust. AS Engineers specifies media based on your process data, not convenience.
| Media | Max Temp (°C) | Key Properties | Typical Applications |
|---|---|---|---|
| Polyester (felt) | 135 | Good chemical resistance, economical | Cement, general dust, food |
| Polypropylene (felt) | 90 | Excellent acid resistance | Chemical, fertilizer, wet applications |
| Fiberglass (woven) | 250 | High temp, low elongation | Cement kiln, boiler fly ash |
| Nomex (Aramid) | 200 | High temp, good mechanical strength | Asphalt, carbon black, hot gas |
| PTFE membrane laminate | 260 | Sub-micron filtration, non-stick surface | Pharma, specialty chemical, pigments |
| Ryton (PPS) | 190 | Acid and alkali resistant, high temp | Boilers with high SOx, chemical |
PTFE membrane laminate bags can achieve outlet emissions below 10 mg/Nm³ in applications where standard felt media cannot sustain that level.
Technical Specifications
AS Engineers bag filter systems are designed and fabricated to the following general parameters. Every system is custom-engineered to your process data.
| Parameter | Range |
|---|---|
| Inlet gas volume | 500 to 2,00,000 m³/hr |
| Inlet dust concentration | Up to 200 g/Nm³ (with cyclone pre-separator) |
| Inlet gas temperature | Ambient to 260°C (higher with PTFE/ceramic media on request) |
| Outlet SPM emission | As per CPCB norms (typically less than 50 mg/Nm³) |
| Filtration efficiency | 99 to 99.9% depending on media and dust |
| Housing material | MS (IS 2062), SS 304, SS 316 depending on application |
| Filter bag diameter | 120 mm to 200 mm |
| Number of compartments | 1 to 12+ (multi-compartment for high-volume or online-cleaning systems) |
| Cleaning mechanism | Pulse-jet, reverse air, or mechanical shaker |
| Hopper discharge | Rotary airlock valve, screw conveyor, or manual discharge |
Applications by Industry
Bag filters serve any process that generates dust or fine particulate at the stack or vent. Common applications across the industries AS Engineers serves:
- Cement: Kiln inlet and outlet, raw mill, cement mill, clinker cooler, packing plant
- Chemical and Fertilizer: Dryer vent, reactor exhaust, granulator, spray dryer outlet
- Pharmaceutical: Fluid bed dryer vent, blender exhaust, spray dryer, containment applications
- Food Processing: Spray dryer vent, flour mill, sugar handling, spice grinding
- Steel and Metals: Electric arc furnace, induction furnace, shot blasting
- Power Plants: Boiler fly ash collection, coal handling, ash conveying
- Pulp and Paper: Dryer section exhaust, lime kiln, recovery boiler
- Automotive: Paint booth exhaust, welding fume extraction, foundry
For pharma and food-grade applications, we supply SS 304 or SS 316 housing with PTFE membrane filter bags, compliant with GMP requirements.
For dust-intensive applications such as cement kilns and chemical dryers, we recommend pairing the bag filter with an upstream cyclone separator to reduce inlet dust loading and extend bag life.
Bag Filter and Blower – Designing the Complete Air Circuit
A bag filter is one component in a system. It requires a draft fan or industrial blower sized to overcome the combined resistance of the ductwork, bag filter housing, and filter cake at end-of-cycle conditions.
Under-sized blowers cause insufficient gas capture at the source hood or duct pickup points. Over-sized blowers cause excess air ingress and can compromise filtration by exceeding the design air-to-cloth ratio.
AS Engineers designs both bag filter systems and the centrifugal blowers or ID fans that drive them. When we supply both, the air circuit is optimised together – airflow, static pressure, and system resistance are matched from the source capture point to the stack outlet.
See our centrifugal blower range
Why AS Engineers
We have been manufacturing industrial equipment since 1997 – first in centrifugal blowers and fans, expanded into paddle dryers, and now pollution control systems including bag filters, cyclone separators, and scrubbers. Clients across cement, chemical, pharma, food, and water treatment have qualified us to their approved vendor lists.
What that means for a purchase manager or plant head evaluating vendors:
- Engineering from process data, not catalog selection. We ask for your gas volume, temperature, dust load, and outlet requirement before proposing a system. Bag filters sized to wrong parameters fail within months.
- Material traceability. Housing plates, filter cage wire, and bag media are sourced with material test certificates. GMP applications include PMI verification on request.
- ISO 9001:2015 certified manufacturing with in-house fabrication and quality inspection at Ahmedabad.
- Integration with upstream and downstream equipment. If your application needs a cyclone pre-separator and a blower alongside the bag filter, we design and supply the complete system – a single point of responsibility for the air circuit.
- After-sales support. Replacement filter bags, cages, rotary airlock valves, and solenoid valves are available as spare parts. We also provide performance inspection and bag life assessment for existing bag filter installations.
Send us your process data for a system proposal
Frequently Asked Questions
What is the difference between a pulse-jet bag filter and a reverse air bag filter?
Pulse-jet systems clean bags online using compressed air pulses – the unit continues operating during cleaning. Reverse air systems clean offline by directing clean air backward through the bags, isolating one compartment at a time. Pulse-jet suits most fine-dust applications and is the most common choice. Reverse air is preferred where filter media is fragile (fiberglass) or where compressed air supply is limited.
What outlet emission level can a bag filter achieve?
A well-designed pulse-jet bag filter with felt media typically achieves SPM below 50 mg/Nm³. With PTFE membrane laminate bags, outlet emissions below 10 mg/Nm³ are achievable. The actual outlet level depends on inlet dust concentration, filter media, air-to-cloth ratio, and cleaning frequency – all of which are set at the design stage.
Do I need a cyclone separator before my bag filter?
If your inlet dust concentration exceeds 20 to 30 g/Nm³, a cyclone pre-separator significantly reduces the load on the filter bags, extends their service life, and allows the bag filter to be sized for a lower effective dust loading. For cement kiln, coal handling, and grinding applications, a cyclone upstream is standard practice.
What filter media should I use for a cement plant bag filter?
Cement kiln exhaust typically runs at 150 to 220°C. Fiberglass woven bags are the standard choice for this range – they handle the temperature and resist the slightly alkaline dust chemistry. For cooler sections (raw mill, cement mill), polyester felt bags are economical and sufficient.
What information do you need to quote a bag filter system?
To size and quote a system accurately: gas flow rate (m³/hr or Nm³/hr), inlet gas temperature (°C), inlet dust concentration (g/Nm³), dust characteristics (type, particle size, abrasiveness), outlet emission requirement (mg/Nm³ or as per CPCB norm), and available footprint. Where some parameters are unknown, we can assist with estimation from process type and capacity.
Request a Bag Filter System Proposal
Share your process details with our engineers – gas volume, temperature, dust type, and outlet requirement. We will return with a preliminary system design, filter media recommendation, and commercial proposal within 3 to 5 working days.
Call: +91 99090 33851 | +91 82386 77554 Email: info@theasengineers.com