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In chemical plants, electroplating shops, battery factories, and metal finishing lines, acid mist is simply part of the job. Hydrochloric acid (HCl), sulfuric acid (H₂SO₄), hydrofluoric acid (HF), nitric acid (HNO₃), and the rest of that corrosive family slip out of plating baths, pickling lines, and chemical reactors, and the mix they form is genuinely dangerous—it puts workers at risk, eats away at equipment, and pushes a plant past its environmental permit.
Two problems come together here. The first is corrosion: these gases are aggressively corrosive, and standard metal ductwork and steel scrubbers start rusting, pitting, and leaking within months of continuous exposure. The second is regulation. Emission standards keep tightening around the world, from China's GB standards to EU directives and EPA rules, and facilities are under real pressure to hit outlet concentrations that meet or beat the limits.
A medium-sized electroplating plant in southern China was living through all of this. Its steel scrubber had corroded to the point of constant leaks, and every patch and repair meant expensive downtime. Outlet emissions sometimes crept past the 30 mg/Nm³ regulatory limit, which put the operating permit on the line. What they needed was a corrosion-resistant, high-efficiency scrubber that could take continuous acid mist without wearing out—from a manufacturer who actually understood the chemistry of their process.
In the end, they went with Senotay.
Senotay (senotay.com), a Chinese manufacturer of industrial dust collectors and air filtration equipment since 2005, proposed a full PP Spray Tower solution. The idea is simple: instead of a metal scrubber that will eventually corrode, the company builds its industrial acid mist spray tower from premium polypropylene (PP), a material that shrugs off the acids, alkalis, and salts that wreck steel systems over time.
In plain terms, a PP Spray Tower is a vertical gas–liquid contact column that strips corrosive fumes, acid mists, and soluble gases out of industrial exhaust. Contaminated gas flows upward through polypropylene packing while a scrubbing liquid—usually water or an alkaline solution such as sodium hydroxide—sprays downward through nozzles. The counter-current contact is what guarantees thorough absorption, neutralization, or dissolution of the pollutants.
The process works as follows:
Gas Introduction: Acid mist exhaust gas is drawn into the purification tower through the air duct by a corrosion-resistant induced draft fan.
Packed-Bed Contact: The gas passes through a packing layer (PP Pall rings or structured packing) where it contacts a thin liquid film. The packing dramatically increases the gas-liquid contact surface area, promoting absorption and neutralization.
Spray Scrubbing: An acid-resistant pump delivers scrubbing liquid to spray nozzles at the top of the tower, creating a fine mist that rains downward through the packing. The liquid absorbs acid gases through chemical reaction—for example, sodium hydroxide neutralizes HCl to form salt and water.
Mist Elimination: A demister (mist eliminator) at the tower top strips out remaining liquid droplets, ensuring only clean, dry gas exits to the atmosphere.
Liquid Recirculation: The scrubbing liquid collects at the bottom of the tower and is recirculated by pump—significantly reducing fresh water consumption compared to single-pass systems.
Senotay's PPS Series PP Spray Towers are built in Hebei, China, by Hebei OuTai Environmental Protection Equipment Co., Ltd. Each unit is sized for its application—tower diameter, packing type, and liquid-to-gas ratio are all chosen according to the gas concentration and chemical composition the tower will actually see.
Typical Removal Efficiencies by Pollutant:
The electroplating facility got its Senotay PP Spray Tower on schedule. Commissioning and performance testing confirmed what the design promised:
The tower has run continuously ever since, with the polypropylene body holding up against the same HCl atmosphere that destroyed the old steel unit. The plant reached full regulatory compliance, unplanned downtime is a thing of the past, and the recirculation system trimmed operating costs.
The design leans on two things at once: thorough gas–liquid contact and proper mist elimination, which together support removal levels that meet or beat the strictest standards. Across Senotay's whole line of air pollution control equipment, the company's technical standard delivers up to 99.9% filtration efficiency.
Senotay, operating as Hebei OuTai Environmental Protection Equipment Co., Ltd., has been manufacturing industrial dust collectors and air purification equipment for over 15 years. Its 15,000+ m² facility in Botou, Hebei Province, turns out the full range of air pollution control equipment:
Pulse Jet Bag Filters (standard, high-temperature, anti-static)
Electrostatic Precipitators (ESP)
PP Spray Towers (Acid-Base Scrubbers)
Cyclone Dust Collectors
Wet Dust Collectors
Filter Cartridge Collectors
VOC Purifiers
ISO 9001:2015 — Quality Management System
ISO 14001 — Environmental Management
ISO 45001 — Occupational Health & Safety
CE Certified — European market compliance
Factory-direct pricing means no middleman markups and no hidden costs. Every PP Spray Tower is built in-house, which keeps quality control in the company's own hands from raw material to final shipment.
Senotay works with 30+ industries across several continents, including:
Electroplating & Metal Finishing: Acid mist from plating baths
Chemical Processing: HCl, HF, SO₂, and corrosive fume treatment
Battery Manufacturing: Acid fumes from production lines
Semiconductor & Electronics: Chemical exhaust scrubbing
Pharmaceutical: Fume and VOC removal
Laboratory & Research: Pilot and small-scale fume scrubbing
Q: What is a PP Spray Tower?
A PP Spray Tower is a vertical gas–liquid contact column that pulls corrosive fumes, acid mists, and soluble gases out of industrial exhaust. Polluted air rises through polypropylene packing while scrubbing liquid rains down from above, dissolving the pollutants on contact.
Q: What pollutants can a PP Spray Tower remove?
Hydrochloric acid (HCl), hydrofluoric acid (HF), sulfuric acid (H₂SO₄), sulfur dioxide (SO₂), ammonia (NH₃), chlorine (Cl₂), hydrogen sulfide (H₂S), nitric acid (HNO₃), and other acid and base fumes.
Q: What efficiency can Senotay PP Spray Towers achieve?
Removal efficiency runs from 85% to 99%, depending on tower size, packing type, and the pollutant in question.
Q: Why choose polypropylene (PP) over metal scrubbers?
Polypropylene stands up to the acids, alkalis, and salts that slowly corrode steel scrubbers. In practice that means a 10–15 year service life for a PP unit versus 3–5 years for steel.
Q: What certifications does Senotay hold?
Senotay is certified to ISO 9001:2015, ISO 14001, and ISO 45001, and holds CE certification.
Q: Can Senotay customize PP Spray Towers for specific applications?
Yes. Tower diameter, packing type, liquid-to-gas ratio, and scrubbing chemistry are all tailored to the gas concentration and chemical composition of the actual application.
Acid mist is a quiet adversary, working against your equipment, your people, and your environmental compliance all at once. The PP Spray Tower, built from corrosion-resistant polypropylene with efficient gas–liquid contact and recirculating scrubbing, is the dependable answer for capturing the acid gases that chew through metal scrubbers and threaten your permits.
Senotay brings two decades of manufacturing experience to this work. From its ISO-certified facility in Botou, China, the company supplies industrial acid mist spray towers that pair corrosion-resistant PP construction with 85–99% removal efficiency, recirculating liquid systems that cut water use, and factory-direct pricing. Every Senotay PP Spray Tower is sized for the gas volume, temperature, and chemical composition it will actually face—in industrial air pollution control, one size genuinely does not fit all.
Ready to talk about your acid mist control requirements?
Head to senotay.com or contact Senotay's engineering team for a customized PP Spray Tower solution built around your process conditions and emission targets.