Choosing the right electroplating fume exhaust is more than picking a duct: the system carries every mist and vapor a plating line generates — chromic acid, hydrochloric and sulfuric acid, cyanide — and it has to contain them safely for the life of the line. The design follows a fixed order: classify the tank chemistry, estimate the airflow from the classification tables, segregate cyanide from acid, select the duct material and size, place the scrubber deliberately, and confirm makeup air. This guide walks that sequence for an electroplating fume exhaust: the hazard and classification system, the airflow calculation, the material matrix, duct sizing, scrubber placement, two worked examples, and the spec sheet to hand your engineer or supplier. One boundary up front: fan static pressure, duct pressure drop, and scrubber selection stay with the system engineer and the equipment vendors — this page gives the method and the screening numbers, not the final design.
Key Takeaways
- Start with hazard classification. Size plating exhaust from the tank chemistry and temperature using the open-surface-tank class system (hazard A–D × rate 1–4), then the control-velocity and exhaust-rate tables.
- Cyanide and acid exhaust must never share a duct. OSHA 29 CFR 1910.124(b)(6) requires independent exhaust systems, and mixing the two generates hydrogen cyanide gas (IDLH 50 ppm).
- PP is the default duct candidate. It handles chromic acid, HCl and H₂SO₄ mist, and cyanide alkali mist to about 90 °C; PVC, CPVC, FRP, and SS 316 cover the branches that outrun it.
- Place the scrubber on purpose. Upstream of the fan protects the fan; downstream makes the scrubber the final stage and calls for a PP or FRP fan. Either works — decide it, don’t inherit it.
- Send a spec sheet, not a guess. The checklist at the end (tank list, chemistry, temperature, airflow, segregation, duct size, makeup air, inspection plan) is what a supplier quotes from.
What Is an Electroplating Fume Exhaust System?
An electroplating fume exhaust system is the local exhaust ventilation setup that captures fumes and mists at the surface of plating, anodizing, pickling, and other open-surface process tanks and carries them out of the building. It has five parts: a hood at the tank edge, ductwork that transports the contaminated air, a fan that provides the airflow, a scrubber (in most installations) that cleans the air before discharge, and a stack that releases it above the roof line. Every part matters, but the hood and the duct are where most plating-line ventilation problems start.
Plating baths generate a small set of fume families, and each one changes what the system must do. Chromic acid tanks produce a fine hexavalent chromium mist with an OSHA permissible exposure limit (PEL) of 5 µg/m³ as an 8-hour TWA. Cyanide baths can release cyanide mist and, in the wrong conditions, hydrogen cyanide gas. Acid pickling and anodizing lines evolve hydrochloric or sulfuric acid mist that corrodes building steel and irritates airways. Degreasing stations add solvent vapor. A duct system that handles all of these is a corrosion-resistant, tightly sealed, physically segregated system — not a general-purpose HVAC duct (the PP air duct guide covers the duct family and its fitting system).
The design sequence in this guide follows the decisions you actually make on a plating line. You classify the tank by chemistry and temperature, estimate the exhaust airflow from the classification tables, split cyanide and acid into separate systems, choose a duct material and size, decide where the scrubber sits relative to the fan, and confirm makeup air. Two worked examples at the end walk a decorative chromium tank and a cyanide zinc line through the same sequence, and the final checklist turns the whole guide into a one-page spec sheet you can send to a ventilation engineer or a duct supplier.
Two boundaries keep this guide honest. First, it gives you the sizing method and order-of-magnitude numbers, not a finished design: fan static pressure, duct pressure drop, and scrubber efficiency belong to a professional engineer and the equipment vendors, and the duct material and size still need confirmation against your specific bath chemistry. Second, it does not select scrubbers. Scrubber chemistry, packing, and removal efficiency are the equipment supplier’s scope — this guide tells you where the scrubber sits and why, then hands the selection over. For the same reason, the focus keyword here is the system, not the device: you are designing an electroplating fume exhaust, not buying a fume scrubber — decide the system, and let the specialists own the device.
What a Plating Line Exhaust Must Handle
The design starts with what comes off the tank. Each bath chemistry produces a different contaminant with a different toxicity, and the classification system that sizes the exhaust is built directly on that. Take the four fume families in order, then the OSHA classification method, because the airflow tables in the next section only make sense once you know your tank class.
The four fume families on a plating line
Cyanide plating (zinc, copper, brass, and silver cyanide baths) releases alkaline cyanide mist from gassing at the cathode, plus the standing hazard that acid can convert cyanide into hydrogen cyanide (HCN) gas. Chromic acid baths — decorative and hard chrome plating, plus chromic acid anodizing — emit a hexavalent chromium mist that is both a strong oxidizer and a regulated carcinogen. Acid and alkali processes (hydrochloric acid pickling, sulfuric acid anodizing, caustic cleaners, alkaline electrocleaners) generate acid or caustic mist that attacks workers, equipment, and the building itself. Solvent degreasing adds organic vapor that is often flammable at concentration and frequently incompatible with plastics. You can identify most of these by reading the bath composition sheet; the classification tables below then tell you how hazardous each one is and how fast it evolves.
Why Cr(VI) gets special treatment
Hexavalent chromium is the contaminant that most plating shops design around, and the numbers explain why. OSHA’s Chromium (VI) standard (29 CFR 1910.1026) sets a PEL of 5 µg/m³ as an 8-hour time-weighted average and an action level of 2.5 µg/m³; employers above the action level must monitor, and above the PEL must use engineering and work-practice controls before respirators. In the hazard-classification table used for open-surface tanks, a mist with a threshold limit value around 0.0002 mg/m³ (the current ACGIH TLV-TWA for water-soluble chromium(VI) compounds, as Cr(VI)) falls in the most severe hazard band.
That is why chrome tanks sit at the top of the exhaust priority list, why decorative chrome gets a higher design capture velocity than plain acid mist, and why the hood, the duct, and the scrubber train are all treated as compliance equipment, not housekeeping.
The OSHA tank-class system
Open-surface tank ventilation design classifies every tank into one of 16 classes, A-1 through D-4, from two factors. Hazard potential (A through D) reflects the toxicity or flammability of the vapor, gas, or mist, judged against its exposure limit: band A covers gas or vapor at 0–10 ppm or mist at 0–0.1 mg/m³, band B covers 11–100 ppm or 0.11–1.0 mg/m³, band C covers 101–500 ppm or 1.1–10 mg/m³, and band D covers everything above that.
Evolution rate (1 through 4) reflects how fast the contaminant leaves the bath, from liquid temperature and how far below the boiling point it runs: rate 1 is a hot bath above 93 °C (200 °F) close to its boiling point with fast evaporation and high gassing, rate 2 runs 65–93 °C (150–200 °F), rate 3 runs 34–65 °C (94–149 °F), and rate 4 is a cool bath below 34 °C (94 °F).
A heated chromic acid tank at roughly 55 °C (131 °F) lands in hazard band A (the Cr(VI) mist exposure band) and rate 3 (the 34–65 °C band), which makes it an A-3 class example. A cyanide zinc bath running near 30 °C with a cyanide mist exposure limit around 5 mg/m³ lands in a lower hazard band and a slower rate. Your bath will not always map cleanly, and the tables are deliberately conservative — where evaporation and gassing disagree, the lower rate governs, and the more hazardous band wins. Before you size anything, decide which class your tank falls into, because the control velocity and the exhaust rate both come straight from that letter and number. If the bath chemistry sheet does not tell you the exposure band, flag the tank for the ventilation engineer instead of guessing.
How Much Exhaust Air Does a Plating Tank Need?
Once the tank class is known, airflow follows from two numbers: the control velocity you need at the tank surface and the exhaust rate per square foot of tank area that produces it. The method is the same for every open-surface tank — electroplating, anodizing, pickling, alkaline cleaning, rinsing — and it is the part of plating ventilation that most published articles skip.
Capture and control velocity
A hood pulls air across the tank surface, and the velocity of that air at the point where the contaminant is generated is the control velocity. The design tables for undisturbed locations list control velocities of 50 to 150 fpm by class: high-hazard classes need about 100 fpm for lateral exhaust, lower classes drop to 75 or 50 fpm, and an enclosing hood that wraps the tank on several sides needs less because the openings are smaller. Two practical rules from OSHA’s Technical Manual keep the numbers honest: the minimum capture velocity worth designing for is about 50 fpm, and a simple capture hood should sit within 1.5 duct diameters of the source — a 6 in hood opening, for example, should not be more than 9 in from the fume source. Cross-drafts, open doors, and moving equipment all erode control velocity, so the tables assume an undisturbed location and a real shop should add margin.
Lateral exhaust rates
For the standard plating-tank layout — a slot hood along one side of the tank pulling air across the surface — the required airflow is read from the lateral-exhaust table, which gives cubic feet per minute per square foot of tank area for each control velocity and for the ratio of tank width to tank length (W/L). At a 100 fpm control velocity, a hood along one side with the opposite side against a wall or baffle needs about 100 cfm/ft² for a long narrow tank (W/L 0.0–0.09) rising to 200 cfm/ft² for a square tank (W/L 1.0–2.0); the same tank standing free needs 150 to 250 cfm/ft².
At 75 fpm, the numbers drop to roughly 90–170 cfm/ft² (wall) or 110–190 cfm/ft² (free-standing). The total airflow is simply the rate times the tank surface area: a 2 m × 1 m tank (21.5 ft²) at 175 cfm/ft² needs about 3,800 CFM. Tanks wider than about 2 times their length cannot be ventilated across the long dimension, which is why wide tanks get hoods on two sides or a center manifold.
Push-pull and hood variants
When a tank is too wide for one lateral hood to pull across, push-pull ventilation adds a low-velocity air supply on the far side that pushes contaminants toward the exhaust slot. The design rules are specific: the supply air volume plus entrained air must not exceed 50% of the exhaust volume, and the receiving hood, including any baffle, must be at least one-quarter of the tank width tall. Push-pull is the standard answer for wide decorative and hard chrome tanks, and a properly tuned system needs noticeably less exhaust airflow than a single hood would.
Canopy hoods suspended above the tank are a poor fit for hazard band A processes because the plume has already dispersed before it reaches the hood, and they need two to three times the airflow of a slot hood; reserve them for harmless heated rinse vapor. A slot velocity around 2,000 fpm at the hood opening is the common design starting point cited by exhaust-system engineers, with the exact value set by the hood geometry.
To estimate airflow for your own tank, run the sequence in order: class the tank (hazard band and rate), read the control velocity, pick the hood arrangement (lateral, two-sided, or push-pull), look up the cfm/ft² from the W/L ratio and wall condition, and multiply by the surface area. The result is a design airflow, not a final specification — the fan and duct still need a pressure-drop calculation, which the duct sizing guide covers separately. But the number you get is the right order of magnitude to start the conversation, and it is the number a duct supplier will ask for first.
Never Mix Cyanide and Acid Exhaust
This is the one rule that cannot be bent on a plating line: cyanide-bearing exhaust and acid-bearing exhaust must be physically separate from the hood to the stack. The regulatory anchor is direct. OSHA 29 CFR 1910.124, the standard for dipping and coating operations, requires that each tank have an independent exhaust system unless the combination of substances being removed will not cause a fire, an explosion, or a chemical reaction.
Acid plus cyanide is the chemical-reaction case: if hydrochloric or sulfuric acid mist — even a trace drawn in through a shared manifold — contacts cyanide salts that have settled on duct walls, it generates hydrogen cyanide gas inside the ductwork. HCN has a NIOSH IDLH of 50 ppm, meaning a leak into an occupied area can be lethal within a short exposure. No downstream scrubber or filter recovers a contaminant that was allowed to react inside the duct.
Segregation therefore runs through the whole system, not just the duct. Cyanide tanks get their own hoods, their own duct runs, their own scrubber (typically alkaline, run at a pH well above 10 to absorb cyanide and prevent HCN release), and their own stack. Acid tanks — pickling, anodizing, acid chrome — get a parallel, independent set with a separate scrubber. The two systems never join at a manifold, never share a fan, and never discharge into the same stack. On a mixed line this means two complete trains, and the cost of the second train is simply the price of the chemistry: combining them creates a hydrogen cyanide generator, not a cost saving.
The layout consequences are concrete. Duct runs for cyanide and acid zones should be routed so that a maintenance error cannot join them: separate physical paths, clear labeling at every access point, and different hood and tank assignments recorded on the line drawing. When a line is extended or a new tank is added, the segregation check comes before the airflow check — confirm which zone the new tank belongs to, then size its branch into that zone’s system. If a process owner proposes venting a cyanide tank into an acid duct “just for the moment,” that is the moment to stop and correct the drawing, because the failure mode is gas generation, not merely corrosion. State the rule plainly in the project spec: cyanide exhaust and acid exhaust are separate systems, no exceptions, and verify it on the final as-built before the line starts.
Choosing Duct Material for Plating Fumes
Duct material for plating exhaust is chosen against the same chemistry list the hoods capture: chromic acid mist, hydrochloric and sulfuric acid mist, cyanide alkali mist, and the occasional solvent vapor. The matrix below maps the fume families to the duct candidates you will actually compare — polypropylene (PP), PVC, CPVC, FRP with a vinyl ester resin, and stainless steel 316 — using the temperature and chemical boundaries verified in the material comparison and corrosive-fume guides already published on this site.
| Fume / contaminant | PP (to ~90 °C) | PVC (to ~60 °C) | CPVC (to ~93 °C) | FRP, vinyl ester (resin-dependent, ~121 °C) | SS 316 (passive oxide layer) |
|---|---|---|---|---|---|
| Chromic acid mist (CrO₃) | Resistant — standard choice | Resistant, lower temperature limit | Resistant | Resistant | Resistant at low chloride; confirm |
| Hydrochloric acid mist (HCl) | Resistant | Resistant | Resistant | Resistant | Limited — chloride pitting risk |
| Sulfuric acid mist (H₂SO₄) | Resistant | Resistant | Resistant | Resistant | Resistant at low concentration |
| Cyanide alkali mist | Resistant | Resistant | Resistant | Resistant | Resistant |
| Solvent vapor (degreasing) | Limited — verify per solvent | Limited — verify per solvent | Limited — verify per solvent | Limited — verify per solvent | Resistant — common choice |
PP as the workhorse
Polypropylene is the default duct material for plating exhaust for three reasons. It resists the acids, alkalis, and salt solutions that dominate plating — chromic acid mist, HCl, H₂SO₄, and cyanide alkali mist all fall inside its compatibility envelope — and its continuous-service temperature of roughly 90 °C (grade- and load-dependent) covers every plating bath temperature you will meet short of hot processes above 90 °C. It is also the lightest of the candidates at about 0.91 g/cm³, roughly one-eighth the density of steel, which keeps roof loads and support structures modest.
PP is fabricated by extrusion and hot-air welding into continuous, sealed duct runs, which matters twice on a plating line: a welded seam has no gasket to leak corrosive mist, and a smooth welded interior gives condensation nowhere to hide. The trade-offs are the same ones documented in the material guides: PP expands with heat at roughly 0.10–0.15 mm/m·°C (about ten times steel), so long straight runs need expansion compensation and sliding supports, and PP is a plastic — it softens above its rated temperature and is attacked by strong oxidizers and many organic solvents, which is why the solvent row in the matrix says verify.
When to step up or confirm
The matrix has three escape routes, and knowing when to take them is the material decision. First, temperature: any exhaust that runs above roughly 90 °C pushes past PP — consider CPVC (to ~93 °C) at the margin or FRP with a vinyl ester resin (commonly cited to ~121 °C, resin-dependent) for sustained heat. Second, oxidizers and solvents: strong oxidizing acids at concentration and organic solvent vapor are where PP and the other plastics start needing a compatibility check against the specific chemical and concentration; if the degreasing vapor is a solvent the plastic does not tolerate, stainless steel or a confirmed FRP resin becomes the candidate. Third, chlorides: SS 316 resists corrosion through a self-healing chromium oxide passive layer, but high-chloride service (hot HCl) attacks that layer and causes pitting — in that service a plastic or FRP is usually the safer duct, not stainless.
Whenever the chemistry sheet shows a contaminant at the edge of a compatibility band, request the manufacturer’s chemical-resistance data for the exact concentration and temperature before you select. For the full nine-material comparison and the concentration-temperature method behind these boundaries, the material selection and corrosive-fume guides cover it in depth; here the working conclusion is that on a typical plating line you choose PP first, and you step to FRP, CPVC, or stainless only when a specific contaminant or temperature demands it.
Round or Square, and What Size
Plating exhaust ductwork is round duct, and the reason is condensation. Plating air is humid — mist-laden air from a warm bath carries water vapor that condenses as the duct cools — and a round duct drains that condensate along its bottom curve toward a low-point drain, while a square or rectangular duct collects it in the bottom corners where it pools, corrodes the seam, and hides from inspection. Round duct also has lower pressure drop per foot than a rectangular duct of the same area.
For the same reasons, plating exhaust runs are welded where possible and flanged only at equipment interfaces (fan, scrubber, dampers), and horizontal runs are sloped toward drain points so acid condensate never sits in a low section. The product family and fitting range for PP duct — elbows, tees, reducers, flanges, dampers, rain caps — are all available for a round-system build-out, with square duct reserved for tight wall-hugging layouts where the space constraint justifies the condensate trade-off.
Duct diameter follows airflow and transport velocity. The duct must move the contaminated air fast enough that mist and particulate stay suspended — exhaust-system engineers describe the failure mode plainly: if transport velocity is too low, the duct narrows with fallout until it reaches the velocity it needs, which is how plating ducts clog. The practical band for corrosive mist service is roughly 1,500–2,500 fpm (about 8–12 m/s), the same industrial duct-velocity range the sizing guides on this site use, with mist service at the higher end to keep the duct self-cleaning. Diameter is then a geometry calculation: airflow in CFM divided by velocity in fpm gives the duct area in square feet, and the diameter follows. The table below runs the calculation for four airflow points at the two ends of the band, with the PP family sizes (about φ20–600 mm) as the nearest practical match; above 600 mm, duct is fabricated from sheet and welded.
| Exhaust airflow (CFM) | Duct diameter @ 1,500 fpm | Duct diameter @ 2,000 fpm | Nearest PP family size |
|---|---|---|---|
| 1,000 | 11 in (280 mm) | 10 in (250 mm) | 250–315 mm |
| 2,000 | 16 in (400 mm) | 14 in (350 mm) | 350–400 mm |
| 3,800 | 22 in (550 mm) | 19 in (500 mm) | 500–560 mm |
| 6,000 | 27 in (690 mm) | 24 in (600 mm) | 600 mm or sheet-welded |
To select a size for your own branch, take the airflow you estimated in the exhaust-air section, pick the transport velocity your system can afford (2,000 fpm is a defensible default for mist service), read the diameter, and move to the nearest family size that does not drop below your design velocity. Then check the pressure-drop consequences against the duct sizing guide, because a longer run with more elbows may push you up a size or force a larger fan — and confirm the final diameter with the duct supplier against your exact airflow and run length.
Scrubber Placement and Makeup Air
The scrubber is where the exhaust air is cleaned before it leaves the building, and on a plating line its position in the system is a decision you make deliberately, not a detail the vendor drops in. Two configurations dominate, and each has a clear trade-off.
Scrubber before or after the fan
In the upstream configuration, the scrubber sits between the duct and the fan: the fan pulls the exhaust air through the scrubber, so the air the fan handles has already been washed of acid mist and chromium aerosol. The fan sees cleaner air, which is a real longevity gain when the alternative is a coated steel wheel corroding in chrome mist. The cost is that the scrubber’s pressure drop (typically on the order of 500–1,500 Pa for a packed-bed unit, plus a mist eliminator) sits entirely on the fan’s suction side, and the scrubber itself handles saturated, corrosive air.
In the downstream configuration, the fan pushes the air through the scrubber as the final stage before the stack: the fan is upstream, the scrubber is the last component, and the fan must be built for the corrosive airstream it pushes — a PP or FRP fan instead of a coated steel one, since coated steel in HCl or chrome service typically fails at coating defects within a few years. The trade-off is therefore a fan-life-versus-fan-material decision: upstream-of-fan protects a standard fan but adds suction-side load; downstream-of-fan keeps the scrubber as a clean final stage but demands a corrosion-resistant fan.
Both configurations are used in the field, and the right answer depends on your fan, your scrubber’s pressure drop, and your maintenance access. What you should not do is decide the position by accident — select it, state it in the spec, and hand the scrubber itself (packing, chemistry, efficiency, blowdown) to the equipment supplier, whose scope this guide deliberately does not enter.
Makeup air and stack discharge
Every cubic foot the system exhausts has to be replaced, and the regulation is specific: a room with exhaust hoods must receive outside air of at least 90% of the exhaust volume. Skimp on makeup air and the building runs negative, pulling unfiltered air through door gaps and dock seals, dragging contaminants across the shop, and starving the hoods of the air they need to capture at the tank. The supply side deserves the same design attention as the exhaust side — a well-located makeup air system introduces clean air behind the operators so it flows across the tanks and into the hoods, instead of fighting the capture pattern.
Discharge matters equally: the stack should rise well above the roof line and away from any air intake, with 10 ft of clearance over nearby intakes as the practical rule of thumb from OSHA’s ventilation guidance, so the treated exhaust never re-enters the building. A mist eliminator at the hood or before the fan is a small investment that keeps droplets out of the ductwork in the first place, which reduces both corrosion and maintenance. When you assemble the system specification, list the makeup air rate (≥90% of exhaust), the stack height, and the eliminator as line items, and confirm them with the engineer — they are the difference between a system that performs on paper and one that performs in the shop.
Worked Examples
Two worked examples run the full sequence end to end so you can copy the method for your own line. Both are arithmetic exercises with stated assumptions — your bath chemistry and temperature will place your tanks in their own classes, and the final design belongs to the engineer and suppliers.
Decorative chromium tank
A decorative chromium plating tank measures 2 m × 1 m (6.6 ft × 3.3 ft), runs at about 55 °C, and produces a chromic acid mist. The surface area is 2 m², which is 21.5 ft². The bath chemistry and temperature place it in the A-3 class example: hazard band A because the Cr(VI) mist exposure band is the most severe, and rate 3 because 55 °C sits in the 34–65 °C band. From the control-velocity table, the lateral-exhaust control velocity for this class is about 100 fpm.
The tank’s width-to-length ratio is 1 m / 2 m = 0.5, so with a slot hood along one side and the opposite side against a wall or baffle, the lateral-exhaust table gives about 175 cfm/ft² at the 100 fpm control velocity. Airflow = 21.5 ft² × 175 cfm/ft² ≈ 3,800 CFM. At a 2,000 fpm transport velocity, that airflow needs a duct area of 3,800 / 2,000 = 1.9 ft², or a diameter of about 19 in (roughly 480 mm) — nearest family size 500 mm; at 1,500 fpm the diameter is about 22 in, nearest 550 mm.
The material decision is PP: chromic acid mist at 55 °C sits inside the PP envelope, and the condensate argument favors round welded PP. The system spec then adds the separate chrome scrubber train with a mist eliminator, the Cr(VI) compliance position (the 5 µg/m³ PEL is the reason the chrome zone gets the high control velocity), and makeup air at 90% of the 3,800 CFM total.
Cyanide zinc line
A cyanide zinc line adds the segregation lesson. The cyanide zinc tank measures 1.5 m × 0.8 m (4.9 ft × 2.6 ft) and runs near 30 °C; the surface area is 1.2 m², or 12.9 ft². Its chemistry places it in a lower hazard band than chrome and a slow evolution rate, and the control velocity for its class is around 75 fpm. The width-to-length ratio is 0.8 / 1.5 = 0.53, so with the hood against a wall the lateral-exhaust table at 75 fpm gives about 150 cfm/ft². Airflow = 12.9 ft² × 150 cfm/ft² ≈ 1,900 CFM. At 2,000 fpm that needs a duct area of 0.97 ft² and a diameter of about 13–14 in (roughly 340 mm), nearest family size 350 mm.
The cyanide tank exhausts into the cyanide zone only: its own duct run, its own alkaline scrubber, and its own stack, never connected to the acid zone. The line’s acid tanks — a hydrochloric acid pickle, for example — would be sized the same way into the separate acid zone, and the two zones would be drawn, labeled, and verified as physically independent before startup. Makeup air covers 90% of the combined exhaust of both zones, and the quarterly inspection schedule applies to both trains. Run the same sequence with your own tank dimensions and bath chemistry, and you can decide which zone each tank belongs to before you size anything.
Electroplating Fume Exhaust: Selection Checklist and Next Steps
The checklist below condenses this guide into the one-page spec sheet you send to a ventilation engineer or a duct supplier. Fill it in for every tank on the line, and the conversation starts at the design point instead of at zero.
| Item | What to include |
|---|---|
| Tank list | Number, type (plating, anodizing, pickling, alkaline clean, rinse), inside dimensions, and whether one side sits against a wall or baffle |
| Chemistry | Bath composition and concentration for each tank, from the additive sheet |
| Temperature | Operating bath temperature and whether the bath gases heavily |
| Classification | The A-1 to D-4 class and the control velocity read from the tables |
| Airflow | Estimated CFM per tank and per zone (acid, chrome, cyanide — kept separate) |
| Segregation | Cyanide and acid zones physically separate from hood to stack, with their own scrubbers and stacks, plus the line drawing |
| Duct | Material (PP default), round vs square, diameter per branch, run length and elbow count |
| Scrubber position | Upstream or downstream of the fan, with the fan material the choice implies |
| Makeup air | 90% or more of the total exhaust volume, with supply location noted |
| Inspection plan | Quarterly corrosion and airflow checks (regulatory baseline) plus the maintenance calendar |
Two final points close the loop. First, the numbers in this guide are design starting points: the classification tables give you the right order of magnitude, and the final airflow, fan static pressure, and duct confirmation belong to the engineer and the suppliers working from your spec sheet. Second, every hard figure here traces to a published source — the OSHA ventilation and chromium standards, the open-surface-tank design tables, the NIOSH IDLH value, and the ACGIH exposure-limit system — so the sheet you send can carry the same citations when the project engineer asks where the numbers came from.
If you have read this far, you now hold the full method for sizing an electroplating fume exhaust: classify the tanks, separate the cyanide, choose PP first and step up only on evidence, size the round duct from airflow and velocity, place the scrubber deliberately, and send the checklist. The round PP duct product page is the place to confirm the duct family dimensions and fitting options against the diameters this guide produced; the broader application overview and the lab-scale cousin of this system (laboratory fume hood exhaust) sit alongside it in the same series, with the corrosive-fume material method and the duct sizing guide one click away for the details this page deliberately leaves to the specialists. Run the checklist once, decide each line, and you have the input the specialists need.
