Filter Bag RFQ Checklist: 18 Data Points Suppliers Need

#	Data to provide	Preferred detail or unit	Why the supplier needs it
1	Industry and process	Plant, line, fuel/feedstock, process step	Establishes likely gas, dust and operating cycles
2	Dust-generation point	Kiln, boiler, dryer, mill, furnace, transfer point, etc.	Similar industries can have very different duty at different points
3	Collector identification	Manufacturer, model, baghouse type, compartment count	Defines cleaning and mechanical architecture
4	Gas flow	Normal and maximum actual m³/h; state actual or standard basis	Determines filtration load and bag quantity
5	Temperature profile	Minimum / normal / maximum °C; upset duration and frequency	Screens thermal range and cold-end condensation risk
6	Moisture and dew point	Vol% H₂O, water dew point, acid dew point, condensation history	Identifies blinding and corrosion risks
7	Oxygen and oxidizers	O₂ range plus relevant oxidizing species	Important to PPS and other oxidation-sensitive media
8	Gas chemistry	Species and min/normal/max concentration; measurement basis	Supports conditional chemical-compatibility review
9	Dust composition and loading	Components; g/Nm³ or grains/ft³; normal/max	Affects media, filtration load and chemical interaction
10	Dust behaviour	Particle size, abrasion, stickiness, hygroscopicity, combustibility	Affects surface, wear, cleaning and safety requirements
11	Emissions requirement	Target and current value; mg/Nm³ or relevant unit; test basis	Defines filtration objective and gap to close
12	Differential pressure	Clean/startup, normal range, alarm/trip; Pa or in. w.g.	Helps diagnose cake and cleaning behaviour
13	Cleaning system	Pulse-jet/reverse-air/shaker; pressure, duration, cycle/logic	Defines mechanical stress and dust-release demand
14	Air-to-cloth ratio	m/min or ft/min; or provide active area and actual flow	Measures superficial filtration velocity
15	Current media	Fibre, scrim, weight, thickness, membrane/finish, thread and seam	Establishes the technical baseline for comparison
16	Bag and cage construction	Drawings, dimensions, cuff/top, bottom, seam, cage wires and venturi	Prevents fit and installation errors
17	Service and failure history	Install/removal dates, failed locations, photos, lab results, trends	Directs root-cause review instead of blind substitution
18	Quantity and supply scope	Quantity, spares, destination, delivery date, documents, inspection	Makes the technical and commercial offer complete

1. Industry and process

State the plant, production line and fuel or feedstock. “Cement” is not enough: kiln inlet, kiln outlet, clinker cooler, raw mill and finish mill can impose different temperature, moisture and dust conditions. For a boiler, identify fuel mix, pollution-control equipment upstream and whether operation changes by season or load.

2. Dust-generation point

Describe exactly where the collector receives dust and any upstream conditioning, such as spray cooling, dry sorbent injection or pre-separation. Include process changes planned during the expected bag life.

3. Collector identification

Provide:

• Baghouse manufacturer and model;
• Pulse-jet, reverse-air or shaker cleaning;
• Number of compartments, rows and bags;
• Online or offline cleaning;
• Positive or negative pressure;
• Tubesheet orientation and access constraints.

A general arrangement drawing and collector nameplate photo are valuable.

4. Gas flow

Report normal and maximum flow, and state whether the value is actual cubic metres per hour (Am³/h) or normalized/standardized flow. Include reference temperature, pressure, oxygen and moisture basis where applicable. Air-to-cloth calculations require actual volume at the baghouse.

If one compartment is offline during cleaning or maintenance, state the active filtration area under that condition.

5. Temperature profile

Supply minimum, normal and maximum baghouse inlet temperatures. For every credible maximum, record how long it lasts and how often it occurs. Add startup, shutdown, bypass and control-system alarm values.

Do not select from a supplier’s “peak” temperature without defining the permitted duration and frequency. Short-term ratings are not continuous operating limits.

6. Moisture, dew point and condensation

Include measured or calculated moisture, water dew point and acid dew point when acid gases are present. Report cold-weather events, air ingress, wall temperatures, insulation condition, hopper heating and visible deposits. A high-temperature fibre does not prevent wet dust from blinding the bag.

For related troubleshooting, see how to prevent condensation in a baghouse.

7. Oxygen and oxidizing species

Give the normal and maximum oxygen range, measurement location and whether the value is wet or dry basis. List other relevant oxidizing species. This information is especially important when screening PPS filter bags. Do not substitute a generic oxygen threshold for an application review that includes temperature, moisture and exposure time.

8. Gas chemistry

List relevant gases and aerosols, not merely “corrosive gas.” Depending on the process, this may include SOx, NOx, HCl, HF, alkalis, solvents and process additives. Provide normal and maximum concentrations, units, test location, temperature and moisture basis.

Chemical compatibility is conditional. No material should be specified as resistant to every chemical and concentration.

9. Dust composition and loading

Provide a composition or safety data sheet where possible, plus inlet mass loading under normal and maximum production. State whether dust chemistry changes with fuel, raw material, product grade or reagent use.

10. Particle behaviour and safety

Useful information includes:

• Particle-size distribution, especially fine fraction;
• Abrasive or sharp particles;
• Sticky, oily or hygroscopic behaviour;
• Bulk density and cohesiveness;
• Combustible-dust test data and hazard assessment, where applicable.

Antistatic filter media is one component, not a substitute for explosion protection, grounding and the facility’s hazard controls.

11. Outlet requirement

State the legal limit, customer target or internal target, plus the normal current result and test method. Include reference conditions: dry/wet basis, oxygen correction and normal/standard volume. Suppliers cannot compare a target expressed on a different basis from the measured value.

If particle-count or opacity monitoring is used, supply trends and event timestamps alongside gravimetric test results.

12. Differential pressure

Report the pressure drop after new-bag conditioning, the normal operating range, cleaning trigger and high alarm/trip. Include at least several weeks of trend data if investigating short life or high resistance. Mark production rate, temperature and cleaning changes on the same timeline where possible.

13. Cleaning system

For pulse-jet collectors, provide header pressure at the manifold, pulse duration, interval, on-demand or timer logic, valve and diaphragm condition, blowpipe alignment and compressed-air quality. For reverse-air or shaker systems, provide the cleaning sequence, isolation arrangement and mechanical settings.

“Pulse pressure 6 bar” is incomplete if the pressure at the baghouse collapses during a cleaning sequence or nozzles are misaligned.

14. Air-to-cloth ratio

Air-to-cloth ratio is actual gas flow divided by active filter area and has the dimensions of velocity. Provide the calculated value and inputs, or send gas flow, bag count and bag dimensions so it can be checked. A system average may hide overloaded compartments or local high-velocity zones.

The US EPA identifies air-to-cloth ratio as a central design parameter and pressure drop as a key operating parameter. A media change should therefore be reviewed with system load, not as an isolated purchase.

15. Current media and construction

Copy the current TDS or purchase specification. Include:

• Fibre and blend percentage;
• Scrim material;
• Nominal weight and thickness;
• Air permeability and test method;
• Singeing, calendering, impregnation or coating;
• ePTFE membrane and backing material;
• Sewing thread and seam design;
• Conductive structure and electrical test if antistatic performance is required.

Do not write only “PTFE.” Full PTFE felt, ePTFE membrane on PPS and PTFE impregnation are different products. Read PPS vs PTFE filter bags for the distinction.

16. Bag, cage and hardware construction

Send a dimensioned drawing rather than relying on a nominal length. Include:

• Bag outside diameter or lay-flat width;
• Overall and effective length;
• Snap-band groove/tubesheet thickness or other top design;
• Cuff material and venturi relationship;
• Bottom disc/reinforcement and wear strip;
• Seam type and orientation;
• Cage diameter, length, wire count, ring spacing and joint;
• Cage coating/material and condition;
• Venturi dimensions and grounding details where relevant.

Add close-up photos with a scale. Inspect filter cages for corrosion, burrs, broken wires and distortion before installing new bags.

17. Service and failure history

Record installation date, first symptom, removal date and affected location. Useful evidence includes:

• Photos of both clean- and dirty-side surfaces;
• Close-ups of holes, glaze, caking, discoloration, brittle areas and seams;
• Map of failures by row and compartment;
• Differential-pressure, temperature and emissions trends;
• Cleaning changes and process upsets;
• Used-bag laboratory results, if available.

Do not remove all evidence before the investigation. Label representative bags by position, seal them cleanly and agree on the samples required for analysis.

18. Quantity, delivery and documentation

State required quantity, commissioning spares, installation schedule, delivery location and packaging constraints. List the required documents, such as technical data sheet, drawing approval, material certificate, inspection plan, packing list, certificate of origin or specific compliance records.

Separate mandatory requirements from preferences so suppliers can identify deviations clearly.

Copyable filter bag RFQ form

PROJECT / PLANT:
CONTACT / ROLE:

1. Industry and process:
2. Dust-generation point and upstream equipment:
3. Baghouse manufacturer / model / cleaning type:
4. Gas flow — normal / maximum and actual or standard basis:
5. Temperature — minimum / normal / maximum; upset duration and frequency:
6. Moisture / water dew point / acid dew point / condensation history:
7. O2 range and other oxidizing species:
8. Gas chemistry — species, min/normal/max concentrations and basis:
9. Dust composition and inlet loading:
10. Particle size / abrasion / stickiness / hygroscopicity / combustibility:
11. Outlet target, current result and measurement basis:
12. Differential pressure — startup / normal / alarm:
13. Cleaning — method, pressure, duration, cycle and logic:
14. Air-to-cloth ratio or actual flow plus active filtration area:
15. Current fibre / scrim / weight / membrane or finish / thread / seam:
16. Bag and cage drawings, dimensions, top, bottom and cage condition:
17. Current service life, failure locations, photos and trend files:
18. Quantity / spares / destination / delivery / required documents:

ATTACHMENTS:
[ ] Process or gas analysis
[ ] Baghouse general arrangement
[ ] Bag drawing
[ ] Cage drawing
[ ] Current TDS / purchase specification
[ ] Failure photos and location map
[ ] Temperature, differential-pressure and emissions trends
[ ] Dust SDS / particle data / combustible-dust assessment where applicable

How to compare supplier quotations

The lowest unit price is not automatically the lowest-cost option. Compare quotations in a fixed sequence so a cheaper but technically different bag is not mistaken for a better offer.

1. Lock the technical baseline

Before opening prices, create one approved baseline from the RFQ: fibre and scrim, weight, permeability, temperature profile, chemistry, dimensions, cage fit, cleaning conditions and acceptance target. If a supplier changes one of these items, record it as a deviation rather than silently treating it as equivalent.

2. Separate compliance from preference

Mark every line as Complies, Deviation, Clarification required or Not offered. A preferred finish may be negotiable; an incorrect bag diameter, missing chemistry limit or unverified temperature rating is a technical hold point.

3. Check construction equivalence

Confirm that “PTFE,” “membrane,” “aramid,” “antistatic” and similar labels describe the same complete construction. Ask for the backing/scrim, membrane or finish, thread, seam, cuff, bottom and test method. Two products with the same fibre name can have different pressure drop, cleaning behaviour and service risk.

4. Check operating assumptions

Make suppliers state whether temperature is continuous or short-term, the allowed duration of an excursion, the gas-flow basis, the chemistry range and any exclusions. An offer that is silent on these points is not a confirmed match.

5. Score technical risk before lifecycle cost

Resolve non-compliant items first. Then compare expected replacement interval, installation labour, disposal, energy impact, spares, delivery risk and outage consequence. Only use service-life estimates when the supplier states the operating assumptions and provides comparable evidence.

6. Record approvals and change control

Keep the approved drawing, TDS, deviation list and sample approval together. Any later change to fibre, scrim, finish, seam, dimensions or source should require written approval before production.

Use this comparison matrix during technical review. The supplier columns are deliberately blank because they must contain values from the actual quotations; the grey prompts show exactly what to enter and are not sample supplier claims:

Ask each supplier to mark assumptions, missing inputs and deviations. Quotations are comparable only when they describe substantially the same technical scope.

## Common RFQ mistakes

– Sending only a material name and bag quantity;
– Reporting average temperature but no minimum, maximum or excursion duration;
– Mixing actual and normalized flow or emission units;
– Omitting moisture and dew point;
– Describing chemistry without concentration;
– Confusing membrane, coating and full-fibre construction;
– Providing bag dimensions but no top, bottom or cage drawing;
– Replacing bags without sharing failure locations and trend data;
– Asking for guaranteed life while process conditions remain undefined;
– Selecting the lowest unit price before resolving technical deviations.

## Submit the completed RFQ for review

Send the completed form with drawings and operating data through the [YuanChen contact page](https://www.yc-group.com/contact/). YuanChen can then identify missing information, screen the media and construction, and prepare a technically clearer quotation. If critical conditions remain unknown, measurement or a controlled trial may be recommended before a firm commitment.

## Frequently asked questions

### What if I do not know all 18 data points?

Mark each missing field “unknown.” Send the available trends, drawings and photos. The supplier should explain which missing values are critical and how to obtain them.

### Is a used bag sample helpful?

Yes, especially when the problem is premature failure or high differential pressure. Keep location records and include a representative failed bag plus a less-affected comparison sample when practical.

### Can a photo replace a dimensioned drawing?

No. Photos help identify construction and damage, but perspective can distort dimensions. A drawing or carefully recorded measurement sheet is needed for production approval.

### Why is the cleaning system part of a filter bag RFQ?

Cleaning determines mechanical stress and cake release. Incorrect pressure, timing or alignment can shorten life or cause high resistance even when the material is chemically compatible.

### Should price be compared per bag?

Unit price is only one component. Compare technically equivalent constructions and include expected replacement interval, labour, energy, disposal and outage consequences where evidence supports the assumptions.