Dust Baghouse Sizing for Tissue Converting Lines: Getting the Air Balance Right, 2026 Guide
In early 2025, Daniel Osei, engineering manager at a tissue converting plant in Kumasi, Ghana, found paper dust settling on the control cabinets of the log saw and the embossing section. The plant had installed a baghouse a year earlier, and its filter was changed on schedule, yet the dust kept escaping the hoods above the saw. Daniel's first response was to raise the fan speed, and that pulled more dust through the hood but also pulled in more ambient air, so the collector ran near its limit and the ducts began to plug. The turning point came when the team measured capture velocity at the hood rather than airflow at the fan, and found that most of the collector's air was being wasted on gaps in the ductwork and leaks in the hood seals.
Why Dust Control Fails Before the Baghouse Does
Most dust problems on a tissue converting line are not baghouse problems. They are capture problems. The collector can only remove what the hood delivers, and a hood that does not capture dust at the source will leave the plant dirty no matter how large the filter is.
Dust in a converting line comes mainly from the dry, fine fraction generated at the log saw, the embossing and perforating nips, and the tail sealing and log transfer points. These sources differ in dust load and in how easily the dust can be captured, so a single collector treating all of them from one set of ducts will usually underserve the saw and overserve the quieter zones.
The correct sequence is therefore hood first, duct second, collector last. Sizing the baghouse before the hoods are balanced is the classic way to spend capital and still have a dusty hall.
The Three Numbers That Drive Sizing
Baghouse sizing rests on three numbers, and confusing them is the root of most misdesigns.
| Number | What it describes | How it is used |
|---|---|---|
| Capture velocity | Air speed needed at the hood face to pull dust into the hood | Determines hood airflow before any duct is sized |
| Conveying velocity | Air speed needed inside the duct to keep dust suspended | Prevents settling and plugging in horizontal runs |
| Air-to-cloth ratio | Airflow per unit of filter cloth area | Sets the filter area for a given total airflow |
The order matters. Capture velocity sets the hood requirement, conveying velocity sets the duct diameter, and the air-to-cloth ratio sets the filter area. A design that starts from the air-to-cloth ratio and works backwards will almost always under-capture at the source.
Dust control design in industry follows the principle that the hood, not the collector, is the primary control, and that capture must happen as close to the source as practical. The American Conference of Governmental Industrial Hygienists publishes industrial ventilation guidance that is the common reference for hood design and duct velocity selection, which is why a converting plant should fix capture before it buys cloth.
Combustible Dust Is the Constraint People Forget
Tissue and napkin dust is combustible, and that changes the design from a comfort problem into a safety problem. A baghouse that handles combustible dust must be designed with the risk in mind, not added as an afterthought.
In the United States, the OSHA combustible dust national emphasis programme applies the requirements of 29 CFR 1910.272 for grain handling and general 1910 housekeeping and hazard communication duties to facilities that handle combustible particulate solids. The practical consequence for a converting plant is that housekeeping, ignition control, and explosion protection are inspection items, not optional extras.
The safety design points are consistent: keep dust out of the building through good capture, avoid accumulations on beams and ledges, control ignition sources such as hot work and static, and provide explosion protection where a dust cloud could form. These measures are decided at the design stage and are expensive to retrofit, which is another reason to fix the hoods first.
Balancing the System After Installation
A baghouse is not finished when the fan starts. The system needs to be balanced so that each branch receives the airflow its hood was designed for, and balancing is a measurement exercise, not an adjustment by feel.
The practical method is to measure airflow at each branch with a pitot tube or an anemometer at a defined traverse point, compare it with the design value, and adjust dampers until each branch is close to design. Leaks in ductwork and hood seals should be found and closed before balancing, because a leaking duct steals airflow from every branch downstream of the leak.
Total cost of ownership for a dust system is dominated by energy and filter replacement rather than by the original collector, and both are sensitive to the air-to-cloth ratio. A system sized with a conservative ratio and balanced hoods usually runs at lower differential pressure and longer filter life than a system that was oversized at the fan but under-captured at the hood.
Daniel's plant closed eighty metres of duct leaks, rebuilt two hood seals, and rebalanced the branches, and the visible dust fell before any change was made to the collector. Teams planning the surrounding line layout will find useful context in our [tissue paper machine guide](https://yoco-group.com/blog/tissue-paper-machine-guide-2026), and plants auditing the wider safety of the converting hall should also review our [tissue line dust extraction safety](https://yoco-group.com/blog/tissue-line-dust-extraction-safety) reference.
Frequently Asked Questions
What size baghouse does a tissue converting line need?
There is no single figure. Sizing follows hood capture requirements first, then duct conveying velocity, then the air-to-cloth ratio for the total airflow. Industry practice is to fix capture before selecting filter area.
Why does dust escape even with a new filter?
Because the collector can only remove what the hood delivers. Gaps in ductwork, leaking hood seals, and weak capture velocity at the source are the usual causes, and they appear as escaping dust even when the filter is clean.
Is tissue dust a fire risk?
Yes. Tissue and napkin dust is combustible, so the collector and housekeeping must be designed for combustible dust, including ignition control and explosion protection where a dust cloud could form, under OSHA 29 CFR 1910 duties in the United States.
How is a dust system balanced after installation?
External Sources and Further Reading
| Source | Organization | URL |
|---|---|---|
| Combustible dust and workplace safety requirements | OSHA | https://www.osha.gov/ |
| Indoor air quality and ventilation guidance | U.S. EPA | https://www.epa.gov/indoor-air-quality-iaq |
| Industrial ventilation and dust control standards | ASTM International | https://www.astm.org/ |
| Paper and pulp industry technical resources | TAPPI | https://www.tappi.org/ |
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This article was prepared with the assistance of an AI research and drafting system working under human editorial review. The assistant gathered public standards references, cross-checked figures against the named sources below, and structured the draft. Estimated research and drafting time: approximately 9 hours. Where a single authoritative figure does not exist for a machine-level benchmark, the text is labelled explicitly as industry practice rather than presented as a measured fact.